diff options
| author | Tom Sepez <tsepez@chromium.org> | 2015-10-12 15:43:01 -0700 |
|---|---|---|
| committer | Tom Sepez <tsepez@chromium.org> | 2015-10-12 15:43:01 -0700 |
| commit | 5ef9faa8e8f5593556d78f775d86f1e52e4c341a (patch) | |
| tree | 6690eee12e5ab604337fe30db7c5a725aaac3e2c /third_party/lpng_v163/png.c | |
| parent | 0dfd03060be722485f44446f18e2e4eaf9344595 (diff) | |
| download | pdfium-5ef9faa8e8f5593556d78f775d86f1e52e4c341a.tar.xz | |
XFA: Move fx_codec's lpng and tiff to third_party/
We did this with the other codecs in master, but these two are
XFA-only, and did not get the same treatment.
Remove some fx_ prefixes in the third-party file names.
R=thestig@chromium.org
Review URL: https://codereview.chromium.org/1392373004 .
Diffstat (limited to 'third_party/lpng_v163/png.c')
| -rw-r--r-- | third_party/lpng_v163/png.c | 4297 |
1 files changed, 4297 insertions, 0 deletions
diff --git a/third_party/lpng_v163/png.c b/third_party/lpng_v163/png.c new file mode 100644 index 0000000000..93c675b085 --- /dev/null +++ b/third_party/lpng_v163/png.c @@ -0,0 +1,4297 @@ +/* png.c - location for general purpose libpng functions
+ *
+ * Last changed in libpng 1.6.2 [April 25, 2013]
+ * Copyright (c) 1998-2013 Glenn Randers-Pehrson
+ * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+ * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ */
+
+#include "pngpriv.h"
+
+/* Generate a compiler error if there is an old png.h in the search path. */
+typedef png_libpng_version_1_6_3 Your_png_h_is_not_version_1_6_3;
+
+/* Tells libpng that we have already handled the first "num_bytes" bytes
+ * of the PNG file signature. If the PNG data is embedded into another
+ * stream we can set num_bytes = 8 so that libpng will not attempt to read
+ * or write any of the magic bytes before it starts on the IHDR.
+ */
+
+#ifdef PNG_READ_SUPPORTED
+void PNGAPI
+png_set_sig_bytes(png_structrp png_ptr, int num_bytes)
+{
+ png_debug(1, "in png_set_sig_bytes");
+
+ if (png_ptr == NULL)
+ return;
+
+ if (num_bytes > 8)
+ png_error(png_ptr, "Too many bytes for PNG signature");
+
+ png_ptr->sig_bytes = (png_byte)(num_bytes < 0 ? 0 : num_bytes);
+}
+
+/* Checks whether the supplied bytes match the PNG signature. We allow
+ * checking less than the full 8-byte signature so that those apps that
+ * already read the first few bytes of a file to determine the file type
+ * can simply check the remaining bytes for extra assurance. Returns
+ * an integer less than, equal to, or greater than zero if sig is found,
+ * respectively, to be less than, to match, or be greater than the correct
+ * PNG signature (this is the same behavior as strcmp, memcmp, etc).
+ */
+int PNGAPI
+png_sig_cmp(png_const_bytep sig, png_size_t start, png_size_t num_to_check)
+{
+ png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10};
+
+ if (num_to_check > 8)
+ num_to_check = 8;
+
+ else if (num_to_check < 1)
+ return (-1);
+
+ if (start > 7)
+ return (-1);
+
+ if (start + num_to_check > 8)
+ num_to_check = 8 - start;
+
+ return ((int)(memcmp(&sig[start], &png_signature[start], num_to_check)));
+}
+
+#endif /* PNG_READ_SUPPORTED */
+
+#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
+/* Function to allocate memory for zlib */
+PNG_FUNCTION(voidpf /* PRIVATE */,
+png_zalloc,(voidpf png_ptr, uInt items, uInt size),PNG_ALLOCATED)
+{
+ png_alloc_size_t num_bytes = size;
+
+ if (png_ptr == NULL)
+ return NULL;
+
+ if (items >= (~(png_alloc_size_t)0)/size)
+ {
+ png_warning (png_voidcast(png_structrp, png_ptr),
+ "Potential overflow in png_zalloc()");
+ return NULL;
+ }
+
+ num_bytes *= items;
+ return png_malloc_warn(png_voidcast(png_structrp, png_ptr), num_bytes);
+}
+
+/* Function to free memory for zlib */
+void /* PRIVATE */
+png_zfree(voidpf png_ptr, voidpf ptr)
+{
+ png_free(png_voidcast(png_const_structrp,png_ptr), ptr);
+}
+
+/* Reset the CRC variable to 32 bits of 1's. Care must be taken
+ * in case CRC is > 32 bits to leave the top bits 0.
+ */
+void /* PRIVATE */
+png_reset_crc(png_structrp png_ptr)
+{
+ /* The cast is safe because the crc is a 32 bit value. */
+ png_ptr->crc = (png_uint_32)crc32(0, Z_NULL, 0);
+}
+
+/* Calculate the CRC over a section of data. We can only pass as
+ * much data to this routine as the largest single buffer size. We
+ * also check that this data will actually be used before going to the
+ * trouble of calculating it.
+ */
+void /* PRIVATE */
+png_calculate_crc(png_structrp png_ptr, png_const_bytep ptr, png_size_t length)
+{
+ int need_crc = 1;
+
+ if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name))
+ {
+ if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) ==
+ (PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN))
+ need_crc = 0;
+ }
+
+ else /* critical */
+ {
+ if (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE)
+ need_crc = 0;
+ }
+
+ /* 'uLong' is defined in zlib.h as unsigned long; this means that on some
+ * systems it is a 64 bit value. crc32, however, returns 32 bits so the
+ * following cast is safe. 'uInt' may be no more than 16 bits, so it is
+ * necessary to perform a loop here.
+ */
+ if (need_crc && length > 0)
+ {
+ uLong crc = png_ptr->crc; /* Should never issue a warning */
+
+ do
+ {
+ uInt safe_length = (uInt)length;
+ if (safe_length == 0)
+ safe_length = (uInt)-1; /* evil, but safe */
+
+ crc = crc32(crc, ptr, safe_length);
+
+ /* The following should never issue compiler warnings; if they do the
+ * target system has characteristics that will probably violate other
+ * assumptions within the libpng code.
+ */
+ ptr += safe_length;
+ length -= safe_length;
+ }
+ while (length > 0);
+
+ /* And the following is always safe because the crc is only 32 bits. */
+ png_ptr->crc = (png_uint_32)crc;
+ }
+}
+
+/* Check a user supplied version number, called from both read and write
+ * functions that create a png_struct.
+ */
+int
+png_user_version_check(png_structrp png_ptr, png_const_charp user_png_ver)
+{
+ if (user_png_ver)
+ {
+ int i = 0;
+
+ do
+ {
+ if (user_png_ver[i] != png_libpng_ver[i])
+ png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;
+ } while (png_libpng_ver[i++]);
+ }
+
+ else
+ png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;
+
+ if (png_ptr->flags & PNG_FLAG_LIBRARY_MISMATCH)
+ {
+ /* Libpng 0.90 and later are binary incompatible with libpng 0.89, so
+ * we must recompile any applications that use any older library version.
+ * For versions after libpng 1.0, we will be compatible, so we need
+ * only check the first and third digits (note that when we reach version
+ * 1.10 we will need to check the fourth symbol, namely user_png_ver[3]).
+ */
+ if (user_png_ver == NULL || user_png_ver[0] != png_libpng_ver[0] ||
+ (user_png_ver[0] == '1' && (user_png_ver[2] != png_libpng_ver[2] ||
+ user_png_ver[3] != png_libpng_ver[3])) ||
+ (user_png_ver[0] == '0' && user_png_ver[2] < '9'))
+ {
+#ifdef PNG_WARNINGS_SUPPORTED
+ size_t pos = 0;
+ char m[128];
+
+ pos = png_safecat(m, (sizeof m), pos,
+ "Application built with libpng-");
+ pos = png_safecat(m, (sizeof m), pos, user_png_ver);
+ pos = png_safecat(m, (sizeof m), pos, " but running with ");
+ pos = png_safecat(m, (sizeof m), pos, png_libpng_ver);
+
+ png_warning(png_ptr, m);
+#endif
+
+#ifdef PNG_ERROR_NUMBERS_SUPPORTED
+ png_ptr->flags = 0;
+#endif
+
+ return 0;
+ }
+ }
+
+ /* Success return. */
+ return 1;
+}
+
+/* Generic function to create a png_struct for either read or write - this
+ * contains the common initialization.
+ */
+PNG_FUNCTION(png_structp /* PRIVATE */,
+png_create_png_struct,(png_const_charp user_png_ver, png_voidp error_ptr,
+ png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
+ png_malloc_ptr malloc_fn, png_free_ptr free_fn),PNG_ALLOCATED)
+{
+ png_struct create_struct;
+# ifdef PNG_SETJMP_SUPPORTED
+ jmp_buf create_jmp_buf;
+# endif
+
+ /* This temporary stack-allocated structure is used to provide a place to
+ * build enough context to allow the user provided memory allocator (if any)
+ * to be called.
+ */
+ memset(&create_struct, 0, (sizeof create_struct));
+
+ /* Added at libpng-1.2.6 */
+# ifdef PNG_USER_LIMITS_SUPPORTED
+ create_struct.user_width_max = PNG_USER_WIDTH_MAX;
+ create_struct.user_height_max = PNG_USER_HEIGHT_MAX;
+
+# ifdef PNG_USER_CHUNK_CACHE_MAX
+ /* Added at libpng-1.2.43 and 1.4.0 */
+ create_struct.user_chunk_cache_max = PNG_USER_CHUNK_CACHE_MAX;
+# endif
+
+# ifdef PNG_USER_CHUNK_MALLOC_MAX
+ /* Added at libpng-1.2.43 and 1.4.1, required only for read but exists
+ * in png_struct regardless.
+ */
+ create_struct.user_chunk_malloc_max = PNG_USER_CHUNK_MALLOC_MAX;
+# endif
+# endif
+
+ /* The following two API calls simply set fields in png_struct, so it is safe
+ * to do them now even though error handling is not yet set up.
+ */
+# ifdef PNG_USER_MEM_SUPPORTED
+ png_set_mem_fn(&create_struct, mem_ptr, malloc_fn, free_fn);
+# endif
+
+ /* (*error_fn) can return control to the caller after the error_ptr is set,
+ * this will result in a memory leak unless the error_fn does something
+ * extremely sophisticated. The design lacks merit but is implicit in the
+ * API.
+ */
+ png_set_error_fn(&create_struct, error_ptr, error_fn, warn_fn);
+
+# ifdef PNG_SETJMP_SUPPORTED
+ if (!setjmp(create_jmp_buf))
+ {
+ /* Temporarily fake out the longjmp information until we have
+ * successfully completed this function. This only works if we have
+ * setjmp() support compiled in, but it is safe - this stuff should
+ * never happen.
+ */
+ create_struct.jmp_buf_ptr = &create_jmp_buf;
+ create_struct.jmp_buf_size = 0; /*stack allocation*/
+ create_struct.longjmp_fn = longjmp;
+# else
+ {
+# endif
+ /* Call the general version checker (shared with read and write code):
+ */
+ if (png_user_version_check(&create_struct, user_png_ver))
+ {
+ png_structrp png_ptr = png_voidcast(png_structrp,
+ png_malloc_warn(&create_struct, (sizeof *png_ptr)));
+
+ if (png_ptr != NULL)
+ {
+ /* png_ptr->zstream holds a back-pointer to the png_struct, so
+ * this can only be done now:
+ */
+ create_struct.zstream.zalloc = png_zalloc;
+ create_struct.zstream.zfree = png_zfree;
+ create_struct.zstream.opaque = png_ptr;
+
+# ifdef PNG_SETJMP_SUPPORTED
+ /* Eliminate the local error handling: */
+ create_struct.jmp_buf_ptr = NULL;
+ create_struct.jmp_buf_size = 0;
+ create_struct.longjmp_fn = 0;
+# endif
+
+ *png_ptr = create_struct;
+
+ /* This is the successful return point */
+ return png_ptr;
+ }
+ }
+ }
+
+ /* A longjmp because of a bug in the application storage allocator or a
+ * simple failure to allocate the png_struct.
+ */
+ return NULL;
+}
+
+/* Allocate the memory for an info_struct for the application. */
+PNG_FUNCTION(png_infop,PNGAPI
+png_create_info_struct,(png_const_structrp png_ptr),PNG_ALLOCATED)
+{
+ png_inforp info_ptr;
+
+ png_debug(1, "in png_create_info_struct");
+
+ if (png_ptr == NULL)
+ return NULL;
+
+ /* Use the internal API that does not (or at least should not) error out, so
+ * that this call always returns ok. The application typically sets up the
+ * error handling *after* creating the info_struct because this is the way it
+ * has always been done in 'example.c'.
+ */
+ info_ptr = png_voidcast(png_inforp, png_malloc_base(png_ptr,
+ (sizeof *info_ptr)));
+
+ if (info_ptr != NULL)
+ memset(info_ptr, 0, (sizeof *info_ptr));
+
+ return info_ptr;
+}
+
+/* This function frees the memory associated with a single info struct.
+ * Normally, one would use either png_destroy_read_struct() or
+ * png_destroy_write_struct() to free an info struct, but this may be
+ * useful for some applications. From libpng 1.6.0 this function is also used
+ * internally to implement the png_info release part of the 'struct' destroy
+ * APIs. This ensures that all possible approaches free the same data (all of
+ * it).
+ */
+void PNGAPI
+png_destroy_info_struct(png_const_structrp png_ptr, png_infopp info_ptr_ptr)
+{
+ png_inforp info_ptr = NULL;
+
+ png_debug(1, "in png_destroy_info_struct");
+
+ if (png_ptr == NULL)
+ return;
+
+ if (info_ptr_ptr != NULL)
+ info_ptr = *info_ptr_ptr;
+
+ if (info_ptr != NULL)
+ {
+ /* Do this first in case of an error below; if the app implements its own
+ * memory management this can lead to png_free calling png_error, which
+ * will abort this routine and return control to the app error handler.
+ * An infinite loop may result if it then tries to free the same info
+ * ptr.
+ */
+ *info_ptr_ptr = NULL;
+
+ png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1);
+ memset(info_ptr, 0, (sizeof *info_ptr));
+ png_free(png_ptr, info_ptr);
+ }
+}
+
+/* Initialize the info structure. This is now an internal function (0.89)
+ * and applications using it are urged to use png_create_info_struct()
+ * instead. Use deprecated in 1.6.0, internal use removed (used internally it
+ * is just a memset).
+ *
+ * NOTE: it is almost inconceivable that this API is used because it bypasses
+ * the user-memory mechanism and the user error handling/warning mechanisms in
+ * those cases where it does anything other than a memset.
+ */
+PNG_FUNCTION(void,PNGAPI
+png_info_init_3,(png_infopp ptr_ptr, png_size_t png_info_struct_size),
+ PNG_DEPRECATED)
+{
+ png_inforp info_ptr = *ptr_ptr;
+
+ png_debug(1, "in png_info_init_3");
+
+ if (info_ptr == NULL)
+ return;
+
+ if ((sizeof (png_info)) > png_info_struct_size)
+ {
+ *ptr_ptr = NULL;
+ /* The following line is why this API should not be used: */
+ free(info_ptr);
+ info_ptr = png_voidcast(png_inforp, png_malloc_base(NULL,
+ (sizeof *info_ptr)));
+ *ptr_ptr = info_ptr;
+ }
+
+ /* Set everything to 0 */
+ memset(info_ptr, 0, (sizeof *info_ptr));
+}
+
+/* The following API is not called internally */
+void PNGAPI
+png_data_freer(png_const_structrp png_ptr, png_inforp info_ptr,
+ int freer, png_uint_32 mask)
+{
+ png_debug(1, "in png_data_freer");
+
+ if (png_ptr == NULL || info_ptr == NULL)
+ return;
+
+ if (freer == PNG_DESTROY_WILL_FREE_DATA)
+ info_ptr->free_me |= mask;
+
+ else if (freer == PNG_USER_WILL_FREE_DATA)
+ info_ptr->free_me &= ~mask;
+
+ else
+ png_error(png_ptr, "Unknown freer parameter in png_data_freer");
+}
+
+void PNGAPI
+png_free_data(png_const_structrp png_ptr, png_inforp info_ptr, png_uint_32 mask,
+ int num)
+{
+ png_debug(1, "in png_free_data");
+
+ if (png_ptr == NULL || info_ptr == NULL)
+ return;
+
+#ifdef PNG_TEXT_SUPPORTED
+ /* Free text item num or (if num == -1) all text items */
+ if ((mask & PNG_FREE_TEXT) & info_ptr->free_me)
+ {
+ if (num != -1)
+ {
+ if (info_ptr->text && info_ptr->text[num].key)
+ {
+ png_free(png_ptr, info_ptr->text[num].key);
+ info_ptr->text[num].key = NULL;
+ }
+ }
+
+ else
+ {
+ int i;
+ for (i = 0; i < info_ptr->num_text; i++)
+ png_free_data(png_ptr, info_ptr, PNG_FREE_TEXT, i);
+ png_free(png_ptr, info_ptr->text);
+ info_ptr->text = NULL;
+ info_ptr->num_text=0;
+ }
+ }
+#endif
+
+#ifdef PNG_tRNS_SUPPORTED
+ /* Free any tRNS entry */
+ if ((mask & PNG_FREE_TRNS) & info_ptr->free_me)
+ {
+ png_free(png_ptr, info_ptr->trans_alpha);
+ info_ptr->trans_alpha = NULL;
+ info_ptr->valid &= ~PNG_INFO_tRNS;
+ }
+#endif
+
+#ifdef PNG_sCAL_SUPPORTED
+ /* Free any sCAL entry */
+ if ((mask & PNG_FREE_SCAL) & info_ptr->free_me)
+ {
+ png_free(png_ptr, info_ptr->scal_s_width);
+ png_free(png_ptr, info_ptr->scal_s_height);
+ info_ptr->scal_s_width = NULL;
+ info_ptr->scal_s_height = NULL;
+ info_ptr->valid &= ~PNG_INFO_sCAL;
+ }
+#endif
+
+#ifdef PNG_pCAL_SUPPORTED
+ /* Free any pCAL entry */
+ if ((mask & PNG_FREE_PCAL) & info_ptr->free_me)
+ {
+ png_free(png_ptr, info_ptr->pcal_purpose);
+ png_free(png_ptr, info_ptr->pcal_units);
+ info_ptr->pcal_purpose = NULL;
+ info_ptr->pcal_units = NULL;
+ if (info_ptr->pcal_params != NULL)
+ {
+ unsigned int i;
+ for (i = 0; i < info_ptr->pcal_nparams; i++)
+ {
+ png_free(png_ptr, info_ptr->pcal_params[i]);
+ info_ptr->pcal_params[i] = NULL;
+ }
+ png_free(png_ptr, info_ptr->pcal_params);
+ info_ptr->pcal_params = NULL;
+ }
+ info_ptr->valid &= ~PNG_INFO_pCAL;
+ }
+#endif
+
+#ifdef PNG_iCCP_SUPPORTED
+ /* Free any profile entry */
+ if ((mask & PNG_FREE_ICCP) & info_ptr->free_me)
+ {
+ png_free(png_ptr, info_ptr->iccp_name);
+ png_free(png_ptr, info_ptr->iccp_profile);
+ info_ptr->iccp_name = NULL;
+ info_ptr->iccp_profile = NULL;
+ info_ptr->valid &= ~PNG_INFO_iCCP;
+ }
+#endif
+
+#ifdef PNG_sPLT_SUPPORTED
+ /* Free a given sPLT entry, or (if num == -1) all sPLT entries */
+ if ((mask & PNG_FREE_SPLT) & info_ptr->free_me)
+ {
+ if (num != -1)
+ {
+ if (info_ptr->splt_palettes)
+ {
+ png_free(png_ptr, info_ptr->splt_palettes[num].name);
+ png_free(png_ptr, info_ptr->splt_palettes[num].entries);
+ info_ptr->splt_palettes[num].name = NULL;
+ info_ptr->splt_palettes[num].entries = NULL;
+ }
+ }
+
+ else
+ {
+ if (info_ptr->splt_palettes_num)
+ {
+ int i;
+ for (i = 0; i < info_ptr->splt_palettes_num; i++)
+ png_free_data(png_ptr, info_ptr, PNG_FREE_SPLT, (int)i);
+
+ png_free(png_ptr, info_ptr->splt_palettes);
+ info_ptr->splt_palettes = NULL;
+ info_ptr->splt_palettes_num = 0;
+ }
+ info_ptr->valid &= ~PNG_INFO_sPLT;
+ }
+ }
+#endif
+
+#ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
+ if ((mask & PNG_FREE_UNKN) & info_ptr->free_me)
+ {
+ if (num != -1)
+ {
+ if (info_ptr->unknown_chunks)
+ {
+ png_free(png_ptr, info_ptr->unknown_chunks[num].data);
+ info_ptr->unknown_chunks[num].data = NULL;
+ }
+ }
+
+ else
+ {
+ int i;
+
+ if (info_ptr->unknown_chunks_num)
+ {
+ for (i = 0; i < info_ptr->unknown_chunks_num; i++)
+ png_free_data(png_ptr, info_ptr, PNG_FREE_UNKN, (int)i);
+
+ png_free(png_ptr, info_ptr->unknown_chunks);
+ info_ptr->unknown_chunks = NULL;
+ info_ptr->unknown_chunks_num = 0;
+ }
+ }
+ }
+#endif
+
+#ifdef PNG_hIST_SUPPORTED
+ /* Free any hIST entry */
+ if ((mask & PNG_FREE_HIST) & info_ptr->free_me)
+ {
+ png_free(png_ptr, info_ptr->hist);
+ info_ptr->hist = NULL;
+ info_ptr->valid &= ~PNG_INFO_hIST;
+ }
+#endif
+
+ /* Free any PLTE entry that was internally allocated */
+ if ((mask & PNG_FREE_PLTE) & info_ptr->free_me)
+ {
+ png_free(png_ptr, info_ptr->palette);
+ info_ptr->palette = NULL;
+ info_ptr->valid &= ~PNG_INFO_PLTE;
+ info_ptr->num_palette = 0;
+ }
+
+#ifdef PNG_INFO_IMAGE_SUPPORTED
+ /* Free any image bits attached to the info structure */
+ if ((mask & PNG_FREE_ROWS) & info_ptr->free_me)
+ {
+ if (info_ptr->row_pointers)
+ {
+ png_uint_32 row;
+ for (row = 0; row < info_ptr->height; row++)
+ {
+ png_free(png_ptr, info_ptr->row_pointers[row]);
+ info_ptr->row_pointers[row] = NULL;
+ }
+ png_free(png_ptr, info_ptr->row_pointers);
+ info_ptr->row_pointers = NULL;
+ }
+ info_ptr->valid &= ~PNG_INFO_IDAT;
+ }
+#endif
+
+ if (num != -1)
+ mask &= ~PNG_FREE_MUL;
+
+ info_ptr->free_me &= ~mask;
+}
+#endif /* defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) */
+
+/* This function returns a pointer to the io_ptr associated with the user
+ * functions. The application should free any memory associated with this
+ * pointer before png_write_destroy() or png_read_destroy() are called.
+ */
+png_voidp PNGAPI
+png_get_io_ptr(png_const_structrp png_ptr)
+{
+ if (png_ptr == NULL)
+ return (NULL);
+
+ return (png_ptr->io_ptr);
+}
+
+#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
+# ifdef PNG_STDIO_SUPPORTED
+/* Initialize the default input/output functions for the PNG file. If you
+ * use your own read or write routines, you can call either png_set_read_fn()
+ * or png_set_write_fn() instead of png_init_io(). If you have defined
+ * PNG_NO_STDIO or otherwise disabled PNG_STDIO_SUPPORTED, you must use a
+ * function of your own because "FILE *" isn't necessarily available.
+ */
+void PNGAPI
+png_init_io(png_structrp png_ptr, png_FILE_p fp)
+{
+ png_debug(1, "in png_init_io");
+
+ if (png_ptr == NULL)
+ return;
+
+ png_ptr->io_ptr = (png_voidp)fp;
+}
+# endif
+
+#ifdef PNG_SAVE_INT_32_SUPPORTED
+/* The png_save_int_32 function assumes integers are stored in two's
+ * complement format. If this isn't the case, then this routine needs to
+ * be modified to write data in two's complement format. Note that,
+ * the following works correctly even if png_int_32 has more than 32 bits
+ * (compare the more complex code required on read for sign extension.)
+ */
+void PNGAPI
+png_save_int_32(png_bytep buf, png_int_32 i)
+{
+ buf[0] = (png_byte)((i >> 24) & 0xff);
+ buf[1] = (png_byte)((i >> 16) & 0xff);
+ buf[2] = (png_byte)((i >> 8) & 0xff);
+ buf[3] = (png_byte)(i & 0xff);
+}
+#endif
+
+# ifdef PNG_TIME_RFC1123_SUPPORTED
+/* Convert the supplied time into an RFC 1123 string suitable for use in
+ * a "Creation Time" or other text-based time string.
+ */
+int PNGAPI
+png_convert_to_rfc1123_buffer(char out[29], png_const_timep ptime)
+{
+ static PNG_CONST char short_months[12][4] =
+ {"Jan", "Feb", "Mar", "Apr", "May", "Jun",
+ "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};
+
+ if (out == NULL)
+ return 0;
+
+ if (ptime->year > 9999 /* RFC1123 limitation */ ||
+ ptime->month == 0 || ptime->month > 12 ||
+ ptime->day == 0 || ptime->day > 31 ||
+ ptime->hour > 23 || ptime->minute > 59 ||
+ ptime->second > 60)
+ return 0;
+
+ {
+ size_t pos = 0;
+ char number_buf[5]; /* enough for a four-digit year */
+
+# define APPEND_STRING(string) pos = png_safecat(out, 29, pos, (string))
+# define APPEND_NUMBER(format, value)\
+ APPEND_STRING(PNG_FORMAT_NUMBER(number_buf, format, (value)))
+# define APPEND(ch) if (pos < 28) out[pos++] = (ch)
+
+ APPEND_NUMBER(PNG_NUMBER_FORMAT_u, (unsigned)ptime->day);
+ APPEND(' ');
+ APPEND_STRING(short_months[(ptime->month - 1)]);
+ APPEND(' ');
+ APPEND_NUMBER(PNG_NUMBER_FORMAT_u, ptime->year);
+ APPEND(' ');
+ APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->hour);
+ APPEND(':');
+ APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->minute);
+ APPEND(':');
+ APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->second);
+ APPEND_STRING(" +0000"); /* This reliably terminates the buffer */
+
+# undef APPEND
+# undef APPEND_NUMBER
+# undef APPEND_STRING
+ }
+
+ return 1;
+}
+
+# if PNG_LIBPNG_VER < 10700
+/* To do: remove the following from libpng-1.7 */
+/* Original API that uses a private buffer in png_struct.
+ * Deprecated because it causes png_struct to carry a spurious temporary
+ * buffer (png_struct::time_buffer), better to have the caller pass this in.
+ */
+png_const_charp PNGAPI
+png_convert_to_rfc1123(png_structrp png_ptr, png_const_timep ptime)
+{
+ if (png_ptr != NULL)
+ {
+ /* The only failure above if png_ptr != NULL is from an invalid ptime */
+ if (!png_convert_to_rfc1123_buffer(png_ptr->time_buffer, ptime))
+ png_warning(png_ptr, "Ignoring invalid time value");
+
+ else
+ return png_ptr->time_buffer;
+ }
+
+ return NULL;
+}
+# endif
+# endif /* PNG_TIME_RFC1123_SUPPORTED */
+
+#endif /* defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) */
+
+png_const_charp PNGAPI
+png_get_copyright(png_const_structrp png_ptr)
+{
+ PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */
+#ifdef PNG_STRING_COPYRIGHT
+ return PNG_STRING_COPYRIGHT
+#else
+# ifdef __STDC__
+ return PNG_STRING_NEWLINE \
+ "libpng version 1.6.3 - July 18, 2013" PNG_STRING_NEWLINE \
+ "Copyright (c) 1998-2013 Glenn Randers-Pehrson" PNG_STRING_NEWLINE \
+ "Copyright (c) 1996-1997 Andreas Dilger" PNG_STRING_NEWLINE \
+ "Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc." \
+ PNG_STRING_NEWLINE;
+# else
+ return "libpng version 1.6.3 - July 18, 2013\
+ Copyright (c) 1998-2013 Glenn Randers-Pehrson\
+ Copyright (c) 1996-1997 Andreas Dilger\
+ Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.";
+# endif
+#endif
+}
+
+/* The following return the library version as a short string in the
+ * format 1.0.0 through 99.99.99zz. To get the version of *.h files
+ * used with your application, print out PNG_LIBPNG_VER_STRING, which
+ * is defined in png.h.
+ * Note: now there is no difference between png_get_libpng_ver() and
+ * png_get_header_ver(). Due to the version_nn_nn_nn typedef guard,
+ * it is guaranteed that png.c uses the correct version of png.h.
+ */
+png_const_charp PNGAPI
+png_get_libpng_ver(png_const_structrp png_ptr)
+{
+ /* Version of *.c files used when building libpng */
+ return png_get_header_ver(png_ptr);
+}
+
+png_const_charp PNGAPI
+png_get_header_ver(png_const_structrp png_ptr)
+{
+ /* Version of *.h files used when building libpng */
+ PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */
+ return PNG_LIBPNG_VER_STRING;
+}
+
+png_const_charp PNGAPI
+png_get_header_version(png_const_structrp png_ptr)
+{
+ /* Returns longer string containing both version and date */
+ PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */
+#ifdef __STDC__
+ return PNG_HEADER_VERSION_STRING
+# ifndef PNG_READ_SUPPORTED
+ " (NO READ SUPPORT)"
+# endif
+ PNG_STRING_NEWLINE;
+#else
+ return PNG_HEADER_VERSION_STRING;
+#endif
+}
+
+#ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
+int PNGAPI
+png_handle_as_unknown(png_const_structrp png_ptr, png_const_bytep chunk_name)
+{
+ /* Check chunk_name and return "keep" value if it's on the list, else 0 */
+ png_const_bytep p, p_end;
+
+ if (png_ptr == NULL || chunk_name == NULL || png_ptr->num_chunk_list == 0)
+ return PNG_HANDLE_CHUNK_AS_DEFAULT;
+
+ p_end = png_ptr->chunk_list;
+ p = p_end + png_ptr->num_chunk_list*5; /* beyond end */
+
+ /* The code is the fifth byte after each four byte string. Historically this
+ * code was always searched from the end of the list, this is no longer
+ * necessary because the 'set' routine handles duplicate entries correcty.
+ */
+ do /* num_chunk_list > 0, so at least one */
+ {
+ p -= 5;
+
+ if (!memcmp(chunk_name, p, 4))
+ return p[4];
+ }
+ while (p > p_end);
+
+ /* This means that known chunks should be processed and unknown chunks should
+ * be handled according to the value of png_ptr->unknown_default; this can be
+ * confusing because, as a result, there are two levels of defaulting for
+ * unknown chunks.
+ */
+ return PNG_HANDLE_CHUNK_AS_DEFAULT;
+}
+
+#ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
+int /* PRIVATE */
+png_chunk_unknown_handling(png_const_structrp png_ptr, png_uint_32 chunk_name)
+{
+ png_byte chunk_string[5];
+
+ PNG_CSTRING_FROM_CHUNK(chunk_string, chunk_name);
+ return png_handle_as_unknown(png_ptr, chunk_string);
+}
+#endif /* READ_UNKNOWN_CHUNKS */
+#endif /* SET_UNKNOWN_CHUNKS */
+
+#ifdef PNG_READ_SUPPORTED
+/* This function, added to libpng-1.0.6g, is untested. */
+int PNGAPI
+png_reset_zstream(png_structrp png_ptr)
+{
+ if (png_ptr == NULL)
+ return Z_STREAM_ERROR;
+
+ /* WARNING: this resets the window bits to the maximum! */
+ return (inflateReset(&png_ptr->zstream));
+}
+#endif /* PNG_READ_SUPPORTED */
+
+/* This function was added to libpng-1.0.7 */
+png_uint_32 PNGAPI
+png_access_version_number(void)
+{
+ /* Version of *.c files used when building libpng */
+ return((png_uint_32)PNG_LIBPNG_VER);
+}
+
+
+
+#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
+/* Ensure that png_ptr->zstream.msg holds some appropriate error message string.
+ * If it doesn't 'ret' is used to set it to something appropriate, even in cases
+ * like Z_OK or Z_STREAM_END where the error code is apparently a success code.
+ */
+void /* PRIVATE */
+png_zstream_error(png_structrp png_ptr, int ret)
+{
+ /* Translate 'ret' into an appropriate error string, priority is given to the
+ * one in zstream if set. This always returns a string, even in cases like
+ * Z_OK or Z_STREAM_END where the error code is a success code.
+ */
+ if (png_ptr->zstream.msg == NULL) switch (ret)
+ {
+ default:
+ case Z_OK:
+ png_ptr->zstream.msg = PNGZ_MSG_CAST("unexpected zlib return code");
+ break;
+
+ case Z_STREAM_END:
+ /* Normal exit */
+ png_ptr->zstream.msg = PNGZ_MSG_CAST("unexpected end of LZ stream");
+ break;
+
+ case Z_NEED_DICT:
+ /* This means the deflate stream did not have a dictionary; this
+ * indicates a bogus PNG.
+ */
+ png_ptr->zstream.msg = PNGZ_MSG_CAST("missing LZ dictionary");
+ break;
+
+ case Z_ERRNO:
+ /* gz APIs only: should not happen */
+ png_ptr->zstream.msg = PNGZ_MSG_CAST("zlib IO error");
+ break;
+
+ case Z_STREAM_ERROR:
+ /* internal libpng error */
+ png_ptr->zstream.msg = PNGZ_MSG_CAST("bad parameters to zlib");
+ break;
+
+ case Z_DATA_ERROR:
+ png_ptr->zstream.msg = PNGZ_MSG_CAST("damaged LZ stream");
+ break;
+
+ case Z_MEM_ERROR:
+ png_ptr->zstream.msg = PNGZ_MSG_CAST("insufficient memory");
+ break;
+
+ case Z_BUF_ERROR:
+ /* End of input or output; not a problem if the caller is doing
+ * incremental read or write.
+ */
+ png_ptr->zstream.msg = PNGZ_MSG_CAST("truncated");
+ break;
+
+ case Z_VERSION_ERROR:
+ png_ptr->zstream.msg = PNGZ_MSG_CAST("unsupported zlib version");
+ break;
+
+ case PNG_UNEXPECTED_ZLIB_RETURN:
+ /* Compile errors here mean that zlib now uses the value co-opted in
+ * pngpriv.h for PNG_UNEXPECTED_ZLIB_RETURN; update the switch above
+ * and change pngpriv.h. Note that this message is "... return",
+ * whereas the default/Z_OK one is "... return code".
+ */
+ png_ptr->zstream.msg = PNGZ_MSG_CAST("unexpected zlib return");
+ break;
+ }
+}
+
+/* png_convert_size: a PNGAPI but no longer in png.h, so deleted
+ * at libpng 1.5.5!
+ */
+
+/* Added at libpng version 1.2.34 and 1.4.0 (moved from pngset.c) */
+#ifdef PNG_GAMMA_SUPPORTED /* always set if COLORSPACE */
+static int
+png_colorspace_check_gamma(png_const_structrp png_ptr,
+ png_colorspacerp colorspace, png_fixed_point gAMA, int from)
+ /* This is called to check a new gamma value against an existing one. The
+ * routine returns false if the new gamma value should not be written.
+ *
+ * 'from' says where the new gamma value comes from:
+ *
+ * 0: the new gamma value is the libpng estimate for an ICC profile
+ * 1: the new gamma value comes from a gAMA chunk
+ * 2: the new gamma value comes from an sRGB chunk
+ */
+{
+ png_fixed_point gtest;
+
+ if ((colorspace->flags & PNG_COLORSPACE_HAVE_GAMMA) != 0 &&
+ (!png_muldiv(>est, colorspace->gamma, PNG_FP_1, gAMA) ||
+ png_gamma_significant(gtest)))
+ {
+ /* Either this is an sRGB image, in which case the calculated gamma
+ * approximation should match, or this is an image with a profile and the
+ * value libpng calculates for the gamma of the profile does not match the
+ * value recorded in the file. The former, sRGB, case is an error, the
+ * latter is just a warning.
+ */
+ if ((colorspace->flags & PNG_COLORSPACE_FROM_sRGB) != 0 || from == 2)
+ {
+ png_chunk_report(png_ptr, "gamma value does not match sRGB",
+ PNG_CHUNK_ERROR);
+ /* Do not overwrite an sRGB value */
+ return from == 2;
+ }
+
+ else /* sRGB tag not involved */
+ {
+ png_chunk_report(png_ptr, "gamma value does not match libpng estimate",
+ PNG_CHUNK_WARNING);
+ return from == 1;
+ }
+ }
+
+ return 1;
+}
+
+void /* PRIVATE */
+png_colorspace_set_gamma(png_const_structrp png_ptr,
+ png_colorspacerp colorspace, png_fixed_point gAMA)
+{
+ /* Changed in libpng-1.5.4 to limit the values to ensure overflow can't
+ * occur. Since the fixed point representation is assymetrical it is
+ * possible for 1/gamma to overflow the limit of 21474 and this means the
+ * gamma value must be at least 5/100000 and hence at most 20000.0. For
+ * safety the limits here are a little narrower. The values are 0.00016 to
+ * 6250.0, which are truly ridiculous gamma values (and will produce
+ * displays that are all black or all white.)
+ *
+ * In 1.6.0 this test replaces the ones in pngrutil.c, in the gAMA chunk
+ * handling code, which only required the value to be >0.
+ */
+ png_const_charp errmsg;
+
+ if (gAMA < 16 || gAMA > 625000000)
+ errmsg = "gamma value out of range";
+
+# ifdef PNG_READ_gAMA_SUPPORTED
+ /* Allow the application to set the gamma value more than once */
+ else if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0 &&
+ (colorspace->flags & PNG_COLORSPACE_FROM_gAMA) != 0)
+ errmsg = "duplicate";
+# endif
+
+ /* Do nothing if the colorspace is already invalid */
+ else if (colorspace->flags & PNG_COLORSPACE_INVALID)
+ return;
+
+ else
+ {
+ if (png_colorspace_check_gamma(png_ptr, colorspace, gAMA, 1/*from gAMA*/))
+ {
+ /* Store this gamma value. */
+ colorspace->gamma = gAMA;
+ colorspace->flags |=
+ (PNG_COLORSPACE_HAVE_GAMMA | PNG_COLORSPACE_FROM_gAMA);
+ }
+
+ /* At present if the check_gamma test fails the gamma of the colorspace is
+ * not updated however the colorspace is not invalidated. This
+ * corresponds to the case where the existing gamma comes from an sRGB
+ * chunk or profile. An error message has already been output.
+ */
+ return;
+ }
+
+ /* Error exit - errmsg has been set. */
+ colorspace->flags |= PNG_COLORSPACE_INVALID;
+ png_chunk_report(png_ptr, errmsg, PNG_CHUNK_WRITE_ERROR);
+}
+
+void /* PRIVATE */
+png_colorspace_sync_info(png_const_structrp png_ptr, png_inforp info_ptr)
+{
+ if (info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID)
+ {
+ /* Everything is invalid */
+ info_ptr->valid &= ~(PNG_INFO_gAMA|PNG_INFO_cHRM|PNG_INFO_sRGB|
+ PNG_INFO_iCCP);
+
+# ifdef PNG_COLORSPACE_SUPPORTED
+ /* Clean up the iCCP profile now if it won't be used. */
+ png_free_data(png_ptr, info_ptr, PNG_FREE_ICCP, -1/*not used*/);
+# else
+ PNG_UNUSED(png_ptr)
+# endif
+ }
+
+ else
+ {
+# ifdef PNG_COLORSPACE_SUPPORTED
+ /* Leave the INFO_iCCP flag set if the pngset.c code has already set
+ * it; this allows a PNG to contain a profile which matches sRGB and
+ * yet still have that profile retrievable by the application.
+ */
+ if (info_ptr->colorspace.flags & PNG_COLORSPACE_MATCHES_sRGB)
+ info_ptr->valid |= PNG_INFO_sRGB;
+
+ else
+ info_ptr->valid &= ~PNG_INFO_sRGB;
+
+ if (info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS)
+ info_ptr->valid |= PNG_INFO_cHRM;
+
+ else
+ info_ptr->valid &= ~PNG_INFO_cHRM;
+# endif
+
+ if (info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA)
+ info_ptr->valid |= PNG_INFO_gAMA;
+
+ else
+ info_ptr->valid &= ~PNG_INFO_gAMA;
+ }
+}
+
+#ifdef PNG_READ_SUPPORTED
+void /* PRIVATE */
+png_colorspace_sync(png_const_structrp png_ptr, png_inforp info_ptr)
+{
+ if (info_ptr == NULL) /* reduce code size; check here not in the caller */
+ return;
+
+ info_ptr->colorspace = png_ptr->colorspace;
+ png_colorspace_sync_info(png_ptr, info_ptr);
+}
+#endif
+#endif
+
+#ifdef PNG_COLORSPACE_SUPPORTED
+/* Added at libpng-1.5.5 to support read and write of true CIEXYZ values for
+ * cHRM, as opposed to using chromaticities. These internal APIs return
+ * non-zero on a parameter error. The X, Y and Z values are required to be
+ * positive and less than 1.0.
+ */
+static int
+png_xy_from_XYZ(png_xy *xy, const png_XYZ *XYZ)
+{
+ png_int_32 d, dwhite, whiteX, whiteY;
+
+ d = XYZ->red_X + XYZ->red_Y + XYZ->red_Z;
+ if (!png_muldiv(&xy->redx, XYZ->red_X, PNG_FP_1, d)) return 1;
+ if (!png_muldiv(&xy->redy, XYZ->red_Y, PNG_FP_1, d)) return 1;
+ dwhite = d;
+ whiteX = XYZ->red_X;
+ whiteY = XYZ->red_Y;
+
+ d = XYZ->green_X + XYZ->green_Y + XYZ->green_Z;
+ if (!png_muldiv(&xy->greenx, XYZ->green_X, PNG_FP_1, d)) return 1;
+ if (!png_muldiv(&xy->greeny, XYZ->green_Y, PNG_FP_1, d)) return 1;
+ dwhite += d;
+ whiteX += XYZ->green_X;
+ whiteY += XYZ->green_Y;
+
+ d = XYZ->blue_X + XYZ->blue_Y + XYZ->blue_Z;
+ if (!png_muldiv(&xy->bluex, XYZ->blue_X, PNG_FP_1, d)) return 1;
+ if (!png_muldiv(&xy->bluey, XYZ->blue_Y, PNG_FP_1, d)) return 1;
+ dwhite += d;
+ whiteX += XYZ->blue_X;
+ whiteY += XYZ->blue_Y;
+
+ /* The reference white is simply the sum of the end-point (X,Y,Z) vectors,
+ * thus:
+ */
+ if (!png_muldiv(&xy->whitex, whiteX, PNG_FP_1, dwhite)) return 1;
+ if (!png_muldiv(&xy->whitey, whiteY, PNG_FP_1, dwhite)) return 1;
+
+ return 0;
+}
+
+static int
+png_XYZ_from_xy(png_XYZ *XYZ, const png_xy *xy)
+{
+ png_fixed_point red_inverse, green_inverse, blue_scale;
+ png_fixed_point left, right, denominator;
+
+ /* Check xy and, implicitly, z. Note that wide gamut color spaces typically
+ * have end points with 0 tristimulus values (these are impossible end
+ * points, but they are used to cover the possible colors.)
+ */
+ if (xy->redx < 0 || xy->redx > PNG_FP_1) return 1;
+ if (xy->redy < 0 || xy->redy > PNG_FP_1-xy->redx) return 1;
+ if (xy->greenx < 0 || xy->greenx > PNG_FP_1) return 1;
+ if (xy->greeny < 0 || xy->greeny > PNG_FP_1-xy->greenx) return 1;
+ if (xy->bluex < 0 || xy->bluex > PNG_FP_1) return 1;
+ if (xy->bluey < 0 || xy->bluey > PNG_FP_1-xy->bluex) return 1;
+ if (xy->whitex < 0 || xy->whitex > PNG_FP_1) return 1;
+ if (xy->whitey < 0 || xy->whitey > PNG_FP_1-xy->whitex) return 1;
+
+ /* The reverse calculation is more difficult because the original tristimulus
+ * value had 9 independent values (red,green,blue)x(X,Y,Z) however only 8
+ * derived values were recorded in the cHRM chunk;
+ * (red,green,blue,white)x(x,y). This loses one degree of freedom and
+ * therefore an arbitrary ninth value has to be introduced to undo the
+ * original transformations.
+ *
+ * Think of the original end-points as points in (X,Y,Z) space. The
+ * chromaticity values (c) have the property:
+ *
+ * C
+ * c = ---------
+ * X + Y + Z
+ *
+ * For each c (x,y,z) from the corresponding original C (X,Y,Z). Thus the
+ * three chromaticity values (x,y,z) for each end-point obey the
+ * relationship:
+ *
+ * x + y + z = 1
+ *
+ * This describes the plane in (X,Y,Z) space that intersects each axis at the
+ * value 1.0; call this the chromaticity plane. Thus the chromaticity
+ * calculation has scaled each end-point so that it is on the x+y+z=1 plane
+ * and chromaticity is the intersection of the vector from the origin to the
+ * (X,Y,Z) value with the chromaticity plane.
+ *
+ * To fully invert the chromaticity calculation we would need the three
+ * end-point scale factors, (red-scale, green-scale, blue-scale), but these
+ * were not recorded. Instead we calculated the reference white (X,Y,Z) and
+ * recorded the chromaticity of this. The reference white (X,Y,Z) would have
+ * given all three of the scale factors since:
+ *
+ * color-C = color-c * color-scale
+ * white-C = red-C + green-C + blue-C
+ * = red-c*red-scale + green-c*green-scale + blue-c*blue-scale
+ *
+ * But cHRM records only white-x and white-y, so we have lost the white scale
+ * factor:
+ *
+ * white-C = white-c*white-scale
+ *
+ * To handle this the inverse transformation makes an arbitrary assumption
+ * about white-scale:
+ *
+ * Assume: white-Y = 1.0
+ * Hence: white-scale = 1/white-y
+ * Or: red-Y + green-Y + blue-Y = 1.0
+ *
+ * Notice the last statement of the assumption gives an equation in three of
+ * the nine values we want to calculate. 8 more equations come from the
+ * above routine as summarised at the top above (the chromaticity
+ * calculation):
+ *
+ * Given: color-x = color-X / (color-X + color-Y + color-Z)
+ * Hence: (color-x - 1)*color-X + color.x*color-Y + color.x*color-Z = 0
+ *
+ * This is 9 simultaneous equations in the 9 variables "color-C" and can be
+ * solved by Cramer's rule. Cramer's rule requires calculating 10 9x9 matrix
+ * determinants, however this is not as bad as it seems because only 28 of
+ * the total of 90 terms in the various matrices are non-zero. Nevertheless
+ * Cramer's rule is notoriously numerically unstable because the determinant
+ * calculation involves the difference of large, but similar, numbers. It is
+ * difficult to be sure that the calculation is stable for real world values
+ * and it is certain that it becomes unstable where the end points are close
+ * together.
+ *
+ * So this code uses the perhaps slightly less optimal but more
+ * understandable and totally obvious approach of calculating color-scale.
+ *
+ * This algorithm depends on the precision in white-scale and that is
+ * (1/white-y), so we can immediately see that as white-y approaches 0 the
+ * accuracy inherent in the cHRM chunk drops off substantially.
+ *
+ * libpng arithmetic: a simple invertion of the above equations
+ * ------------------------------------------------------------
+ *
+ * white_scale = 1/white-y
+ * white-X = white-x * white-scale
+ * white-Y = 1.0
+ * white-Z = (1 - white-x - white-y) * white_scale
+ *
+ * white-C = red-C + green-C + blue-C
+ * = red-c*red-scale + green-c*green-scale + blue-c*blue-scale
+ *
+ * This gives us three equations in (red-scale,green-scale,blue-scale) where
+ * all the coefficients are now known:
+ *
+ * red-x*red-scale + green-x*green-scale + blue-x*blue-scale
+ * = white-x/white-y
+ * red-y*red-scale + green-y*green-scale + blue-y*blue-scale = 1
+ * red-z*red-scale + green-z*green-scale + blue-z*blue-scale
+ * = (1 - white-x - white-y)/white-y
+ *
+ * In the last equation color-z is (1 - color-x - color-y) so we can add all
+ * three equations together to get an alternative third:
+ *
+ * red-scale + green-scale + blue-scale = 1/white-y = white-scale
+ *
+ * So now we have a Cramer's rule solution where the determinants are just
+ * 3x3 - far more tractible. Unfortunately 3x3 determinants still involve
+ * multiplication of three coefficients so we can't guarantee to avoid
+ * overflow in the libpng fixed point representation. Using Cramer's rule in
+ * floating point is probably a good choice here, but it's not an option for
+ * fixed point. Instead proceed to simplify the first two equations by
+ * eliminating what is likely to be the largest value, blue-scale:
+ *
+ * blue-scale = white-scale - red-scale - green-scale
+ *
+ * Hence:
+ *
+ * (red-x - blue-x)*red-scale + (green-x - blue-x)*green-scale =
+ * (white-x - blue-x)*white-scale
+ *
+ * (red-y - blue-y)*red-scale + (green-y - blue-y)*green-scale =
+ * 1 - blue-y*white-scale
+ *
+ * And now we can trivially solve for (red-scale,green-scale):
+ *
+ * green-scale =
+ * (white-x - blue-x)*white-scale - (red-x - blue-x)*red-scale
+ * -----------------------------------------------------------
+ * green-x - blue-x
+ *
+ * red-scale =
+ * 1 - blue-y*white-scale - (green-y - blue-y) * green-scale
+ * ---------------------------------------------------------
+ * red-y - blue-y
+ *
+ * Hence:
+ *
+ * red-scale =
+ * ( (green-x - blue-x) * (white-y - blue-y) -
+ * (green-y - blue-y) * (white-x - blue-x) ) / white-y
+ * -------------------------------------------------------------------------
+ * (green-x - blue-x)*(red-y - blue-y)-(green-y - blue-y)*(red-x - blue-x)
+ *
+ * green-scale =
+ * ( (red-y - blue-y) * (white-x - blue-x) -
+ * (red-x - blue-x) * (white-y - blue-y) ) / white-y
+ * -------------------------------------------------------------------------
+ * (green-x - blue-x)*(red-y - blue-y)-(green-y - blue-y)*(red-x - blue-x)
+ *
+ * Accuracy:
+ * The input values have 5 decimal digits of accuracy. The values are all in
+ * the range 0 < value < 1, so simple products are in the same range but may
+ * need up to 10 decimal digits to preserve the original precision and avoid
+ * underflow. Because we are using a 32-bit signed representation we cannot
+ * match this; the best is a little over 9 decimal digits, less than 10.
+ *
+ * The approach used here is to preserve the maximum precision within the
+ * signed representation. Because the red-scale calculation above uses the
+ * difference between two products of values that must be in the range -1..+1
+ * it is sufficient to divide the product by 7; ceil(100,000/32767*2). The
+ * factor is irrelevant in the calculation because it is applied to both
+ * numerator and denominator.
+ *
+ * Note that the values of the differences of the products of the
+ * chromaticities in the above equations tend to be small, for example for
+ * the sRGB chromaticities they are:
+ *
+ * red numerator: -0.04751
+ * green numerator: -0.08788
+ * denominator: -0.2241 (without white-y multiplication)
+ *
+ * The resultant Y coefficients from the chromaticities of some widely used
+ * color space definitions are (to 15 decimal places):
+ *
+ * sRGB
+ * 0.212639005871510 0.715168678767756 0.072192315360734
+ * Kodak ProPhoto
+ * 0.288071128229293 0.711843217810102 0.000085653960605
+ * Adobe RGB
+ * 0.297344975250536 0.627363566255466 0.075291458493998
+ * Adobe Wide Gamut RGB
+ * 0.258728243040113 0.724682314948566 0.016589442011321
+ */
+ /* By the argument, above overflow should be impossible here. The return
+ * value of 2 indicates an internal error to the caller.
+ */
+ if (!png_muldiv(&left, xy->greenx-xy->bluex, xy->redy - xy->bluey, 7))
+ return 2;
+ if (!png_muldiv(&right, xy->greeny-xy->bluey, xy->redx - xy->bluex, 7))
+ return 2;
+ denominator = left - right;
+
+ /* Now find the red numerator. */
+ if (!png_muldiv(&left, xy->greenx-xy->bluex, xy->whitey-xy->bluey, 7))
+ return 2;
+ if (!png_muldiv(&right, xy->greeny-xy->bluey, xy->whitex-xy->bluex, 7))
+ return 2;
+
+ /* Overflow is possible here and it indicates an extreme set of PNG cHRM
+ * chunk values. This calculation actually returns the reciprocal of the
+ * scale value because this allows us to delay the multiplication of white-y
+ * into the denominator, which tends to produce a small number.
+ */
+ if (!png_muldiv(&red_inverse, xy->whitey, denominator, left-right) ||
+ red_inverse <= xy->whitey /* r+g+b scales = white scale */)
+ return 1;
+
+ /* Similarly for green_inverse: */
+ if (!png_muldiv(&left, xy->redy-xy->bluey, xy->whitex-xy->bluex, 7))
+ return 2;
+ if (!png_muldiv(&right, xy->redx-xy->bluex, xy->whitey-xy->bluey, 7))
+ return 2;
+ if (!png_muldiv(&green_inverse, xy->whitey, denominator, left-right) ||
+ green_inverse <= xy->whitey)
+ return 1;
+
+ /* And the blue scale, the checks above guarantee this can't overflow but it
+ * can still produce 0 for extreme cHRM values.
+ */
+ blue_scale = png_reciprocal(xy->whitey) - png_reciprocal(red_inverse) -
+ png_reciprocal(green_inverse);
+ if (blue_scale <= 0) return 1;
+
+
+ /* And fill in the png_XYZ: */
+ if (!png_muldiv(&XYZ->red_X, xy->redx, PNG_FP_1, red_inverse)) return 1;
+ if (!png_muldiv(&XYZ->red_Y, xy->redy, PNG_FP_1, red_inverse)) return 1;
+ if (!png_muldiv(&XYZ->red_Z, PNG_FP_1 - xy->redx - xy->redy, PNG_FP_1,
+ red_inverse))
+ return 1;
+
+ if (!png_muldiv(&XYZ->green_X, xy->greenx, PNG_FP_1, green_inverse))
+ return 1;
+ if (!png_muldiv(&XYZ->green_Y, xy->greeny, PNG_FP_1, green_inverse))
+ return 1;
+ if (!png_muldiv(&XYZ->green_Z, PNG_FP_1 - xy->greenx - xy->greeny, PNG_FP_1,
+ green_inverse))
+ return 1;
+
+ if (!png_muldiv(&XYZ->blue_X, xy->bluex, blue_scale, PNG_FP_1)) return 1;
+ if (!png_muldiv(&XYZ->blue_Y, xy->bluey, blue_scale, PNG_FP_1)) return 1;
+ if (!png_muldiv(&XYZ->blue_Z, PNG_FP_1 - xy->bluex - xy->bluey, blue_scale,
+ PNG_FP_1))
+ return 1;
+
+ return 0; /*success*/
+}
+
+static int
+png_XYZ_normalize(png_XYZ *XYZ)
+{
+ png_int_32 Y;
+
+ if (XYZ->red_Y < 0 || XYZ->green_Y < 0 || XYZ->blue_Y < 0 ||
+ XYZ->red_X < 0 || XYZ->green_X < 0 || XYZ->blue_X < 0 ||
+ XYZ->red_Z < 0 || XYZ->green_Z < 0 || XYZ->blue_Z < 0)
+ return 1;
+
+ /* Normalize by scaling so the sum of the end-point Y values is PNG_FP_1.
+ * IMPLEMENTATION NOTE: ANSI requires signed overflow not to occur, therefore
+ * relying on addition of two positive values producing a negative one is not
+ * safe.
+ */
+ Y = XYZ->red_Y;
+ if (0x7fffffff - Y < XYZ->green_X) return 1;
+ Y += XYZ->green_Y;
+ if (0x7fffffff - Y < XYZ->blue_X) return 1;
+ Y += XYZ->blue_Y;
+
+ if (Y != PNG_FP_1)
+ {
+ if (!png_muldiv(&XYZ->red_X, XYZ->red_X, PNG_FP_1, Y)) return 1;
+ if (!png_muldiv(&XYZ->red_Y, XYZ->red_Y, PNG_FP_1, Y)) return 1;
+ if (!png_muldiv(&XYZ->red_Z, XYZ->red_Z, PNG_FP_1, Y)) return 1;
+
+ if (!png_muldiv(&XYZ->green_X, XYZ->green_X, PNG_FP_1, Y)) return 1;
+ if (!png_muldiv(&XYZ->green_Y, XYZ->green_Y, PNG_FP_1, Y)) return 1;
+ if (!png_muldiv(&XYZ->green_Z, XYZ->green_Z, PNG_FP_1, Y)) return 1;
+
+ if (!png_muldiv(&XYZ->blue_X, XYZ->blue_X, PNG_FP_1, Y)) return 1;
+ if (!png_muldiv(&XYZ->blue_Y, XYZ->blue_Y, PNG_FP_1, Y)) return 1;
+ if (!png_muldiv(&XYZ->blue_Z, XYZ->blue_Z, PNG_FP_1, Y)) return 1;
+ }
+
+ return 0;
+}
+
+static int
+png_colorspace_endpoints_match(const png_xy *xy1, const png_xy *xy2, int delta)
+{
+ /* Allow an error of +/-0.01 (absolute value) on each chromaticity */
+ return !(PNG_OUT_OF_RANGE(xy1->whitex, xy2->whitex,delta) ||
+ PNG_OUT_OF_RANGE(xy1->whitey, xy2->whitey,delta) ||
+ PNG_OUT_OF_RANGE(xy1->redx, xy2->redx, delta) ||
+ PNG_OUT_OF_RANGE(xy1->redy, xy2->redy, delta) ||
+ PNG_OUT_OF_RANGE(xy1->greenx, xy2->greenx,delta) ||
+ PNG_OUT_OF_RANGE(xy1->greeny, xy2->greeny,delta) ||
+ PNG_OUT_OF_RANGE(xy1->bluex, xy2->bluex, delta) ||
+ PNG_OUT_OF_RANGE(xy1->bluey, xy2->bluey, delta));
+}
+
+/* Added in libpng-1.6.0, a different check for the validity of a set of cHRM
+ * chunk chromaticities. Earlier checks used to simply look for the overflow
+ * condition (where the determinant of the matrix to solve for XYZ ends up zero
+ * because the chromaticity values are not all distinct.) Despite this it is
+ * theoretically possible to produce chromaticities that are apparently valid
+ * but that rapidly degrade to invalid, potentially crashing, sets because of
+ * arithmetic inaccuracies when calculations are performed on them. The new
+ * check is to round-trip xy -> XYZ -> xy and then check that the result is
+ * within a small percentage of the original.
+ */
+static int
+png_colorspace_check_xy(png_XYZ *XYZ, const png_xy *xy)
+{
+ int result;
+ png_xy xy_test;
+
+ /* As a side-effect this routine also returns the XYZ endpoints. */
+ result = png_XYZ_from_xy(XYZ, xy);
+ if (result) return result;
+
+ result = png_xy_from_XYZ(&xy_test, XYZ);
+ if (result) return result;
+
+ if (png_colorspace_endpoints_match(xy, &xy_test,
+ 5/*actually, the math is pretty accurate*/))
+ return 0;
+
+ /* Too much slip */
+ return 1;
+}
+
+/* This is the check going the other way. The XYZ is modified to normalize it
+ * (another side-effect) and the xy chromaticities are returned.
+ */
+static int
+png_colorspace_check_XYZ(png_xy *xy, png_XYZ *XYZ)
+{
+ int result;
+ png_XYZ XYZtemp;
+
+ result = png_XYZ_normalize(XYZ);
+ if (result) return result;
+
+ result = png_xy_from_XYZ(xy, XYZ);
+ if (result) return result;
+
+ XYZtemp = *XYZ;
+ return png_colorspace_check_xy(&XYZtemp, xy);
+}
+
+/* Used to check for an endpoint match against sRGB */
+static const png_xy sRGB_xy = /* From ITU-R BT.709-3 */
+{
+ /* color x y */
+ /* red */ 64000, 33000,
+ /* green */ 30000, 60000,
+ /* blue */ 15000, 6000,
+ /* white */ 31270, 32900
+};
+
+static int
+png_colorspace_set_xy_and_XYZ(png_const_structrp png_ptr,
+ png_colorspacerp colorspace, const png_xy *xy, const png_XYZ *XYZ,
+ int preferred)
+{
+ if (colorspace->flags & PNG_COLORSPACE_INVALID)
+ return 0;
+
+ /* The consistency check is performed on the chromaticities; this factors out
+ * variations because of the normalization (or not) of the end point Y
+ * values.
+ */
+ if (preferred < 2 && (colorspace->flags & PNG_COLORSPACE_HAVE_ENDPOINTS))
+ {
+ /* The end points must be reasonably close to any we already have. The
+ * following allows an error of up to +/-.001
+ */
+ if (!png_colorspace_endpoints_match(xy, &colorspace->end_points_xy, 100))
+ {
+ colorspace->flags |= PNG_COLORSPACE_INVALID;
+ png_benign_error(png_ptr, "inconsistent chromaticities");
+ return 0; /* failed */
+ }
+
+ /* Only overwrite with preferred values */
+ if (!preferred)
+ return 1; /* ok, but no change */
+ }
+
+ colorspace->end_points_xy = *xy;
+ colorspace->end_points_XYZ = *XYZ;
+ colorspace->flags |= PNG_COLORSPACE_HAVE_ENDPOINTS;
+
+ /* The end points are normally quoted to two decimal digits, so allow +/-0.01
+ * on this test.
+ */
+ if (png_colorspace_endpoints_match(xy, &sRGB_xy, 1000))
+ colorspace->flags |= PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB;
+
+ else
+ colorspace->flags &= PNG_COLORSPACE_CANCEL(
+ PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB);
+
+ return 2; /* ok and changed */
+}
+
+int /* PRIVATE */
+png_colorspace_set_chromaticities(png_const_structrp png_ptr,
+ png_colorspacerp colorspace, const png_xy *xy, int preferred)
+{
+ /* We must check the end points to ensure they are reasonable - in the past
+ * color management systems have crashed as a result of getting bogus
+ * colorant values, while this isn't the fault of libpng it is the
+ * responsibility of libpng because PNG carries the bomb and libpng is in a
+ * position to protect against it.
+ */
+ png_XYZ XYZ;
+
+ switch (png_colorspace_check_xy(&XYZ, xy))
+ {
+ case 0: /* success */
+ return png_colorspace_set_xy_and_XYZ(png_ptr, colorspace, xy, &XYZ,
+ preferred);
+
+ case 1:
+ /* We can't invert the chromaticities so we can't produce value XYZ
+ * values. Likely as not a color management system will fail too.
+ */
+ colorspace->flags |= PNG_COLORSPACE_INVALID;
+ png_benign_error(png_ptr, "invalid chromaticities");
+ break;
+
+ default:
+ /* libpng is broken; this should be a warning but if it happens we
+ * want error reports so for the moment it is an error.
+ */
+ colorspace->flags |= PNG_COLORSPACE_INVALID;
+ png_error(png_ptr, "internal error checking chromaticities");
+ break;
+ }
+
+ return 0; /* failed */
+}
+
+int /* PRIVATE */
+png_colorspace_set_endpoints(png_const_structrp png_ptr,
+ png_colorspacerp colorspace, const png_XYZ *XYZ_in, int preferred)
+{
+ png_XYZ XYZ = *XYZ_in;
+ png_xy xy;
+
+ switch (png_colorspace_check_XYZ(&xy, &XYZ))
+ {
+ case 0:
+ return png_colorspace_set_xy_and_XYZ(png_ptr, colorspace, &xy, &XYZ,
+ preferred);
+
+ case 1:
+ /* End points are invalid. */
+ colorspace->flags |= PNG_COLORSPACE_INVALID;
+ png_benign_error(png_ptr, "invalid end points");
+ break;
+
+ default:
+ colorspace->flags |= PNG_COLORSPACE_INVALID;
+ png_error(png_ptr, "internal error checking chromaticities");
+ break;
+ }
+
+ return 0; /* failed */
+}
+
+#if defined(PNG_sRGB_SUPPORTED) || defined(PNG_iCCP_SUPPORTED)
+/* Error message generation */
+static char
+png_icc_tag_char(png_uint_32 byte)
+{
+ byte &= 0xff;
+ if (byte >= 32 && byte <= 126)
+ return (char)byte;
+ else
+ return '?';
+}
+
+static void
+png_icc_tag_name(char *name, png_uint_32 tag)
+{
+ name[0] = '\'';
+ name[1] = png_icc_tag_char(tag >> 24);
+ name[2] = png_icc_tag_char(tag >> 16);
+ name[3] = png_icc_tag_char(tag >> 8);
+ name[4] = png_icc_tag_char(tag );
+ name[5] = '\'';
+}
+
+static int
+is_ICC_signature_char(png_alloc_size_t it)
+{
+ return it == 32 || (it >= 48 && it <= 57) || (it >= 65 && it <= 90) ||
+ (it >= 97 && it <= 122);
+}
+
+static int is_ICC_signature(png_alloc_size_t it)
+{
+ return is_ICC_signature_char(it >> 24) /* checks all the top bits */ &&
+ is_ICC_signature_char((it >> 16) & 0xff) &&
+ is_ICC_signature_char((it >> 8) & 0xff) &&
+ is_ICC_signature_char(it & 0xff);
+}
+
+static int
+png_icc_profile_error(png_const_structrp png_ptr, png_colorspacerp colorspace,
+ png_const_charp name, png_alloc_size_t value, png_const_charp reason)
+{
+ size_t pos;
+ char message[196]; /* see below for calculation */
+
+ if (colorspace != NULL)
+ colorspace->flags |= PNG_COLORSPACE_INVALID;
+
+ pos = png_safecat(message, (sizeof message), 0, "profile '"); /* 9 chars */
+ pos = png_safecat(message, pos+79, pos, name); /* Truncate to 79 chars */
+ pos = png_safecat(message, (sizeof message), pos, "': "); /* +2 = 90 */
+ if (is_ICC_signature(value))
+ {
+ /* So 'value' is at most 4 bytes and the following cast is safe */
+ png_icc_tag_name(message+pos, (png_uint_32)value);
+ pos += 6; /* total +8; less than the else clause */
+ message[pos++] = ':';
+ message[pos++] = ' ';
+ }
+# ifdef PNG_WARNINGS_SUPPORTED
+ else
+ {
+ char number[PNG_NUMBER_BUFFER_SIZE]; /* +24 = 114*/
+
+ pos = png_safecat(message, (sizeof message), pos,
+ png_format_number(number, number+(sizeof number),
+ PNG_NUMBER_FORMAT_x, value));
+ pos = png_safecat(message, (sizeof message), pos, "h: "); /*+2 = 116*/
+ }
+# endif
+ /* The 'reason' is an arbitrary message, allow +79 maximum 195 */
+ pos = png_safecat(message, (sizeof message), pos, reason);
+
+ /* This is recoverable, but make it unconditionally an app_error on write to
+ * avoid writing invalid ICC profiles into PNG files. (I.e. we handle them
+ * on read, with a warning, but on write unless the app turns off
+ * application errors the PNG won't be written.)
+ */
+ png_chunk_report(png_ptr, message,
+ (colorspace != NULL) ? PNG_CHUNK_ERROR : PNG_CHUNK_WRITE_ERROR);
+
+ return 0;
+}
+#endif /* sRGB || iCCP */
+
+#ifdef PNG_sRGB_SUPPORTED
+int /* PRIVATE */
+png_colorspace_set_sRGB(png_const_structrp png_ptr, png_colorspacerp colorspace,
+ int intent)
+{
+ /* sRGB sets known gamma, end points and (from the chunk) intent. */
+ /* IMPORTANT: these are not necessarily the values found in an ICC profile
+ * because ICC profiles store values adapted to a D50 environment; it is
+ * expected that the ICC profile mediaWhitePointTag will be D50, see the
+ * checks and code elsewhere to understand this better.
+ *
+ * These XYZ values, which are accurate to 5dp, produce rgb to gray
+ * coefficients of (6968,23435,2366), which are reduced (because they add up
+ * to 32769 not 32768) to (6968,23434,2366). These are the values that
+ * libpng has traditionally used (and are the best values given the 15bit
+ * algorithm used by the rgb to gray code.)
+ */
+ static const png_XYZ sRGB_XYZ = /* D65 XYZ (*not* the D50 adapted values!) */
+ {
+ /* color X Y Z */
+ /* red */ 41239, 21264, 1933,
+ /* green */ 35758, 71517, 11919,
+ /* blue */ 18048, 7219, 95053
+ };
+
+ /* Do nothing if the colorspace is already invalidated. */
+ if (colorspace->flags & PNG_COLORSPACE_INVALID)
+ return 0;
+
+ /* Check the intent, then check for existing settings. It is valid for the
+ * PNG file to have cHRM or gAMA chunks along with sRGB, but the values must
+ * be consistent with the correct values. If, however, this function is
+ * called below because an iCCP chunk matches sRGB then it is quite
+ * conceivable that an older app recorded incorrect gAMA and cHRM because of
+ * an incorrect calculation based on the values in the profile - this does
+ * *not* invalidate the profile (though it still produces an error, which can
+ * be ignored.)
+ */
+ if (intent < 0 || intent >= PNG_sRGB_INTENT_LAST)
+ return png_icc_profile_error(png_ptr, colorspace, "sRGB",
+ (unsigned)intent, "invalid sRGB rendering intent");
+
+ if ((colorspace->flags & PNG_COLORSPACE_HAVE_INTENT) != 0 &&
+ colorspace->rendering_intent != intent)
+ return png_icc_profile_error(png_ptr, colorspace, "sRGB",
+ (unsigned)intent, "inconsistent rendering intents");
+
+ if ((colorspace->flags & PNG_COLORSPACE_FROM_sRGB) != 0)
+ {
+ png_benign_error(png_ptr, "duplicate sRGB information ignored");
+ return 0;
+ }
+
+ /* If the standard sRGB cHRM chunk does not match the one from the PNG file
+ * warn but overwrite the value with the correct one.
+ */
+ if ((colorspace->flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0 &&
+ !png_colorspace_endpoints_match(&sRGB_xy, &colorspace->end_points_xy,
+ 100))
+ png_chunk_report(png_ptr, "cHRM chunk does not match sRGB",
+ PNG_CHUNK_ERROR);
+
+ /* This check is just done for the error reporting - the routine always
+ * returns true when the 'from' argument corresponds to sRGB (2).
+ */
+ (void)png_colorspace_check_gamma(png_ptr, colorspace, PNG_GAMMA_sRGB_INVERSE,
+ 2/*from sRGB*/);
+
+ /* intent: bugs in GCC force 'int' to be used as the parameter type. */
+ colorspace->rendering_intent = (png_uint_16)intent;
+ colorspace->flags |= PNG_COLORSPACE_HAVE_INTENT;
+
+ /* endpoints */
+ colorspace->end_points_xy = sRGB_xy;
+ colorspace->end_points_XYZ = sRGB_XYZ;
+ colorspace->flags |=
+ (PNG_COLORSPACE_HAVE_ENDPOINTS|PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB);
+
+ /* gamma */
+ colorspace->gamma = PNG_GAMMA_sRGB_INVERSE;
+ colorspace->flags |= PNG_COLORSPACE_HAVE_GAMMA;
+
+ /* Finally record that we have an sRGB profile */
+ colorspace->flags |=
+ (PNG_COLORSPACE_MATCHES_sRGB|PNG_COLORSPACE_FROM_sRGB);
+
+ return 1; /* set */
+}
+#endif /* sRGB */
+
+#ifdef PNG_iCCP_SUPPORTED
+/* Encoded value of D50 as an ICC XYZNumber. From the ICC 2010 spec the value
+ * is XYZ(0.9642,1.0,0.8249), which scales to:
+ *
+ * (63189.8112, 65536, 54060.6464)
+ */
+static const png_byte D50_nCIEXYZ[12] =
+ { 0x00, 0x00, 0xf6, 0xd6, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0xd3, 0x2d };
+
+int /* PRIVATE */
+png_icc_check_length(png_const_structrp png_ptr, png_colorspacerp colorspace,
+ png_const_charp name, png_uint_32 profile_length)
+{
+ if (profile_length < 132)
+ return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
+ "too short");
+
+ if (profile_length & 3)
+ return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
+ "invalid length");
+
+ return 1;
+}
+
+int /* PRIVATE */
+png_icc_check_header(png_const_structrp png_ptr, png_colorspacerp colorspace,
+ png_const_charp name, png_uint_32 profile_length,
+ png_const_bytep profile/* first 132 bytes only */, int color_type)
+{
+ png_uint_32 temp;
+
+ /* Length check; this cannot be ignored in this code because profile_length
+ * is used later to check the tag table, so even if the profile seems over
+ * long profile_length from the caller must be correct. The caller can fix
+ * this up on read or write by just passing in the profile header length.
+ */
+ temp = png_get_uint_32(profile);
+ if (temp != profile_length)
+ return png_icc_profile_error(png_ptr, colorspace, name, temp,
+ "length does not match profile");
+
+ temp = png_get_uint_32(profile+128); /* tag count: 12 bytes/tag */
+ if (temp > 357913930 || /* (2^32-4-132)/12: maximum possible tag count */
+ profile_length < 132+12*temp) /* truncated tag table */
+ return png_icc_profile_error(png_ptr, colorspace, name, temp,
+ "tag count too large");
+
+ /* The 'intent' must be valid or we can't store it, ICC limits the intent to
+ * 16 bits.
+ */
+ temp = png_get_uint_32(profile+64);
+ if (temp >= 0xffff) /* The ICC limit */
+ return png_icc_profile_error(png_ptr, colorspace, name, temp,
+ "invalid rendering intent");
+
+ /* This is just a warning because the profile may be valid in future
+ * versions.
+ */
+ if (temp >= PNG_sRGB_INTENT_LAST)
+ (void)png_icc_profile_error(png_ptr, NULL, name, temp,
+ "intent outside defined range");
+
+ /* At this point the tag table can't be checked because it hasn't necessarily
+ * been loaded; however, various header fields can be checked. These checks
+ * are for values permitted by the PNG spec in an ICC profile; the PNG spec
+ * restricts the profiles that can be passed in an iCCP chunk (they must be
+ * appropriate to processing PNG data!)
+ */
+
+ /* Data checks (could be skipped). These checks must be independent of the
+ * version number; however, the version number doesn't accomodate changes in
+ * the header fields (just the known tags and the interpretation of the
+ * data.)
+ */
+ temp = png_get_uint_32(profile+36); /* signature 'ascp' */
+ if (temp != 0x61637370)
+ return png_icc_profile_error(png_ptr, colorspace, name, temp,
+ "invalid signature");
+
+ /* Currently the PCS illuminant/adopted white point (the computational
+ * white point) are required to be D50,
+ * however the profile contains a record of the illuminant so perhaps ICC
+ * expects to be able to change this in the future (despite the rationale in
+ * the introduction for using a fixed PCS adopted white.) Consequently the
+ * following is just a warning.
+ */
+ if (memcmp(profile+68, D50_nCIEXYZ, 12) != 0)
+ (void)png_icc_profile_error(png_ptr, NULL, name, 0/*no tag value*/,
+ "PCS illuminant is not D50");
+
+ /* The PNG spec requires this:
+ * "If the iCCP chunk is present, the image samples conform to the colour
+ * space represented by the embedded ICC profile as defined by the
+ * International Color Consortium [ICC]. The colour space of the ICC profile
+ * shall be an RGB colour space for colour images (PNG colour types 2, 3, and
+ * 6), or a greyscale colour space for greyscale images (PNG colour types 0
+ * and 4)."
+ *
+ * This checking code ensures the embedded profile (on either read or write)
+ * conforms to the specification requirements. Notice that an ICC 'gray'
+ * color-space profile contains the information to transform the monochrome
+ * data to XYZ or L*a*b (according to which PCS the profile uses) and this
+ * should be used in preference to the standard libpng K channel replication
+ * into R, G and B channels.
+ *
+ * Previously it was suggested that an RGB profile on grayscale data could be
+ * handled. However it it is clear that using an RGB profile in this context
+ * must be an error - there is no specification of what it means. Thus it is
+ * almost certainly more correct to ignore the profile.
+ */
+ temp = png_get_uint_32(profile+16); /* data colour space field */
+ switch (temp)
+ {
+ case 0x52474220: /* 'RGB ' */
+ if (!(color_type & PNG_COLOR_MASK_COLOR))
+ return png_icc_profile_error(png_ptr, colorspace, name, temp,
+ "RGB color space not permitted on grayscale PNG");
+ break;
+
+ case 0x47524159: /* 'GRAY' */
+ if (color_type & PNG_COLOR_MASK_COLOR)
+ return png_icc_profile_error(png_ptr, colorspace, name, temp,
+ "Gray color space not permitted on RGB PNG");
+ break;
+
+ default:
+ return png_icc_profile_error(png_ptr, colorspace, name, temp,
+ "invalid ICC profile color space");
+ }
+
+ /* It is up to the application to check that the profile class matches the
+ * application requirements; the spec provides no guidance, but it's pretty
+ * weird if the profile is not scanner ('scnr'), monitor ('mntr'), printer
+ * ('prtr') or 'spac' (for generic color spaces). Issue a warning in these
+ * cases. Issue an error for device link or abstract profiles - these don't
+ * contain the records necessary to transform the color-space to anything
+ * other than the target device (and not even that for an abstract profile).
+ * Profiles of these classes may not be embedded in images.
+ */
+ temp = png_get_uint_32(profile+12); /* profile/device class */
+ switch (temp)
+ {
+ case 0x73636E72: /* 'scnr' */
+ case 0x6D6E7472: /* 'mntr' */
+ case 0x70727472: /* 'prtr' */
+ case 0x73706163: /* 'spac' */
+ /* All supported */
+ break;
+
+ case 0x61627374: /* 'abst' */
+ /* May not be embedded in an image */
+ return png_icc_profile_error(png_ptr, colorspace, name, temp,
+ "invalid embedded Abstract ICC profile");
+
+ case 0x6C696E6B: /* 'link' */
+ /* DeviceLink profiles cannnot be interpreted in a non-device specific
+ * fashion, if an app uses the AToB0Tag in the profile the results are
+ * undefined unless the result is sent to the intended device,
+ * therefore a DeviceLink profile should not be found embedded in a
+ * PNG.
+ */
+ return png_icc_profile_error(png_ptr, colorspace, name, temp,
+ "unexpected DeviceLink ICC profile class");
+
+ case 0x6E6D636C: /* 'nmcl' */
+ /* A NamedColor profile is also device specific, however it doesn't
+ * contain an AToB0 tag that is open to misintrepretation. Almost
+ * certainly it will fail the tests below.
+ */
+ (void)png_icc_profile_error(png_ptr, NULL, name, temp,
+ "unexpected NamedColor ICC profile class");
+ break;
+
+ default:
+ /* To allow for future enhancements to the profile accept unrecognized
+ * profile classes with a warning, these then hit the test below on the
+ * tag content to ensure they are backward compatible with one of the
+ * understood profiles.
+ */
+ (void)png_icc_profile_error(png_ptr, NULL, name, temp,
+ "unrecognized ICC profile class");
+ break;
+ }
+
+ /* For any profile other than a device link one the PCS must be encoded
+ * either in XYZ or Lab.
+ */
+ temp = png_get_uint_32(profile+20);
+ switch (temp)
+ {
+ case 0x58595A20: /* 'XYZ ' */
+ case 0x4C616220: /* 'Lab ' */
+ break;
+
+ default:
+ return png_icc_profile_error(png_ptr, colorspace, name, temp,
+ "unexpected ICC PCS encoding");
+ }
+
+ return 1;
+}
+
+int /* PRIVATE */
+png_icc_check_tag_table(png_const_structrp png_ptr, png_colorspacerp colorspace,
+ png_const_charp name, png_uint_32 profile_length,
+ png_const_bytep profile /* header plus whole tag table */)
+{
+ png_uint_32 tag_count = png_get_uint_32(profile+128);
+ png_uint_32 itag;
+ png_const_bytep tag = profile+132; /* The first tag */
+
+ /* First scan all the tags in the table and add bits to the icc_info value
+ * (temporarily in 'tags').
+ */
+ for (itag=0; itag < tag_count; ++itag, tag += 12)
+ {
+ png_uint_32 tag_id = png_get_uint_32(tag+0);
+ png_uint_32 tag_start = png_get_uint_32(tag+4); /* must be aligned */
+ png_uint_32 tag_length = png_get_uint_32(tag+8);/* not padded */
+
+ /* The ICC specification does not exclude zero length tags, therefore the
+ * start might actually be anywhere if there is no data, but this would be
+ * a clear abuse of the intent of the standard so the start is checked for
+ * being in range. All defined tag types have an 8 byte header - a 4 byte
+ * type signature then 0.
+ */
+ if ((tag_start & 3) != 0)
+ {
+ /* CNHP730S.icc shipped with Microsoft Windows 64 violates this, it is
+ * only a warning here because libpng does not care about the
+ * alignment.
+ */
+ (void)png_icc_profile_error(png_ptr, NULL, name, tag_id,
+ "ICC profile tag start not a multiple of 4");
+ }
+
+ /* This is a hard error; potentially it can cause read outside the
+ * profile.
+ */
+ if (tag_start > profile_length || tag_length > profile_length - tag_start)
+ return png_icc_profile_error(png_ptr, colorspace, name, tag_id,
+ "ICC profile tag outside profile");
+ }
+
+ return 1; /* success, maybe with warnings */
+}
+
+#ifdef PNG_sRGB_SUPPORTED
+/* Information about the known ICC sRGB profiles */
+static const struct
+{
+ png_uint_32 adler, crc, length;
+ png_uint_32 md5[4];
+ png_byte have_md5;
+ png_byte is_broken;
+ png_uint_16 intent;
+
+# define PNG_MD5(a,b,c,d) { a, b, c, d }, (a!=0)||(b!=0)||(c!=0)||(d!=0)
+# define PNG_ICC_CHECKSUM(adler, crc, md5, intent, broke, date, length, fname)\
+ { adler, crc, length, md5, broke, intent },
+
+} png_sRGB_checks[] =
+{
+ /* This data comes from contrib/tools/checksum-icc run on downloads of
+ * all four ICC sRGB profiles from www.color.org.
+ */
+ /* adler32, crc32, MD5[4], intent, date, length, file-name */
+ PNG_ICC_CHECKSUM(0x0a3fd9f6, 0x3b8772b9,
+ PNG_MD5(0x29f83dde, 0xaff255ae, 0x7842fae4, 0xca83390d), 0, 0,
+ "2009/03/27 21:36:31", 3048, "sRGB_IEC61966-2-1_black_scaled.icc")
+
+ /* ICC sRGB v2 perceptual no black-compensation: */
+ PNG_ICC_CHECKSUM(0x4909e5e1, 0x427ebb21,
+ PNG_MD5(0xc95bd637, 0xe95d8a3b, 0x0df38f99, 0xc1320389), 1, 0,
+ "2009/03/27 21:37:45", 3052, "sRGB_IEC61966-2-1_no_black_scaling.icc")
+
+ PNG_ICC_CHECKSUM(0xfd2144a1, 0x306fd8ae,
+ PNG_MD5(0xfc663378, 0x37e2886b, 0xfd72e983, 0x8228f1b8), 0, 0,
+ "2009/08/10 17:28:01", 60988, "sRGB_v4_ICC_preference_displayclass.icc")
+
+ /* ICC sRGB v4 perceptual */
+ PNG_ICC_CHECKSUM(0x209c35d2, 0xbbef7812,
+ PNG_MD5(0x34562abf, 0x994ccd06, 0x6d2c5721, 0xd0d68c5d), 0, 0,
+ "2007/07/25 00:05:37", 60960, "sRGB_v4_ICC_preference.icc")
+
+ /* The following profiles have no known MD5 checksum. If there is a match
+ * on the (empty) MD5 the other fields are used to attempt a match and
+ * a warning is produced. The first two of these profiles have a 'cprt' tag
+ * which suggests that they were also made by Hewlett Packard.
+ */
+ PNG_ICC_CHECKSUM(0xa054d762, 0x5d5129ce,
+ PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 1, 0,
+ "2004/07/21 18:57:42", 3024, "sRGB_IEC61966-2-1_noBPC.icc")
+
+ /* This is a 'mntr' (display) profile with a mediaWhitePointTag that does not
+ * match the D50 PCS illuminant in the header (it is in fact the D65 values,
+ * so the white point is recorded as the un-adapted value.) The profiles
+ * below only differ in one byte - the intent - and are basically the same as
+ * the previous profile except for the mediaWhitePointTag error and a missing
+ * chromaticAdaptationTag.
+ */
+ PNG_ICC_CHECKSUM(0xf784f3fb, 0x182ea552,
+ PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 0, 1/*broken*/,
+ "1998/02/09 06:49:00", 3144, "HP-Microsoft sRGB v2 perceptual")
+
+ PNG_ICC_CHECKSUM(0x0398f3fc, 0xf29e526d,
+ PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 1, 1/*broken*/,
+ "1998/02/09 06:49:00", 3144, "HP-Microsoft sRGB v2 media-relative")
+};
+
+static int
+png_compare_ICC_profile_with_sRGB(png_const_structrp png_ptr,
+ png_const_bytep profile, uLong adler)
+{
+ /* The quick check is to verify just the MD5 signature and trust the
+ * rest of the data. Because the profile has already been verified for
+ * correctness this is safe. png_colorspace_set_sRGB will check the 'intent'
+ * field too, so if the profile has been edited with an intent not defined
+ * by sRGB (but maybe defined by a later ICC specification) the read of
+ * the profile will fail at that point.
+ */
+ png_uint_32 length = 0;
+ png_uint_32 intent = 0x10000; /* invalid */
+#if PNG_sRGB_PROFILE_CHECKS > 1
+ uLong crc = 0; /* the value for 0 length data */
+#endif
+ unsigned int i;
+
+ for (i=0; i < (sizeof png_sRGB_checks) / (sizeof png_sRGB_checks[0]); ++i)
+ {
+ if (png_get_uint_32(profile+84) == png_sRGB_checks[i].md5[0] &&
+ png_get_uint_32(profile+88) == png_sRGB_checks[i].md5[1] &&
+ png_get_uint_32(profile+92) == png_sRGB_checks[i].md5[2] &&
+ png_get_uint_32(profile+96) == png_sRGB_checks[i].md5[3])
+ {
+ /* This may be one of the old HP profiles without an MD5, in that
+ * case we can only use the length and Adler32 (note that these
+ * are not used by default if there is an MD5!)
+ */
+# if PNG_sRGB_PROFILE_CHECKS == 0
+ if (png_sRGB_checks[i].have_md5)
+ return 1+png_sRGB_checks[i].is_broken;
+# endif
+
+ /* Profile is unsigned or more checks have been configured in. */
+ if (length == 0)
+ {
+ length = png_get_uint_32(profile);
+ intent = png_get_uint_32(profile+64);
+ }
+
+ /* Length *and* intent must match */
+ if (length == png_sRGB_checks[i].length &&
+ intent == png_sRGB_checks[i].intent)
+ {
+ /* Now calculate the adler32 if not done already. */
+ if (adler == 0)
+ {
+ adler = adler32(0, NULL, 0);
+ adler = adler32(adler, profile, length);
+ }
+
+ if (adler == png_sRGB_checks[i].adler)
+ {
+ /* These basic checks suggest that the data has not been
+ * modified, but if the check level is more than 1 perform
+ * our own crc32 checksum on the data.
+ */
+# if PNG_sRGB_PROFILE_CHECKS > 1
+ if (crc == 0)
+ {
+ crc = crc32(0, NULL, 0);
+ crc = crc32(crc, profile, length);
+ }
+
+ /* So this check must pass for the 'return' below to happen.
+ */
+ if (crc == png_sRGB_checks[i].crc)
+# endif
+ {
+ if (png_sRGB_checks[i].is_broken)
+ {
+ /* These profiles are known to have bad data that may cause
+ * problems if they are used, therefore attempt to
+ * discourage their use, skip the 'have_md5' warning below,
+ * which is made irrelevant by this error.
+ */
+ png_chunk_report(png_ptr, "known incorrect sRGB profile",
+ PNG_CHUNK_ERROR);
+ }
+
+ /* Warn that this being done; this isn't even an error since
+ * the profile is perfectly valid, but it would be nice if
+ * people used the up-to-date ones.
+ */
+ else if (!png_sRGB_checks[i].have_md5)
+ {
+ png_chunk_report(png_ptr,
+ "out-of-date sRGB profile with no signature",
+ PNG_CHUNK_WARNING);
+ }
+
+ return 1+png_sRGB_checks[i].is_broken;
+ }
+ }
+ }
+
+# if PNG_sRGB_PROFILE_CHECKS > 0
+ /* The signature matched, but the profile had been changed in some
+ * way. This is an apparent violation of the ICC terms of use and,
+ * anyway, probably indicates a data error or uninformed hacking.
+ */
+ if (png_sRGB_checks[i].have_md5)
+ png_benign_error(png_ptr,
+ "copyright violation: edited ICC profile ignored");
+# endif
+ }
+ }
+
+ return 0; /* no match */
+}
+#endif
+
+#ifdef PNG_sRGB_SUPPORTED
+void /* PRIVATE */
+png_icc_set_sRGB(png_const_structrp png_ptr,
+ png_colorspacerp colorspace, png_const_bytep profile, uLong adler)
+{
+ /* Is this profile one of the known ICC sRGB profiles? If it is, just set
+ * the sRGB information.
+ */
+ if (png_compare_ICC_profile_with_sRGB(png_ptr, profile, adler))
+ (void)png_colorspace_set_sRGB(png_ptr, colorspace,
+ (int)/*already checked*/png_get_uint_32(profile+64));
+}
+#endif /* PNG_READ_sRGB_SUPPORTED */
+
+int /* PRIVATE */
+png_colorspace_set_ICC(png_const_structrp png_ptr, png_colorspacerp colorspace,
+ png_const_charp name, png_uint_32 profile_length, png_const_bytep profile,
+ int color_type)
+{
+ if (colorspace->flags & PNG_COLORSPACE_INVALID)
+ return 0;
+
+ if (png_icc_check_length(png_ptr, colorspace, name, profile_length) &&
+ png_icc_check_header(png_ptr, colorspace, name, profile_length, profile,
+ color_type) &&
+ png_icc_check_tag_table(png_ptr, colorspace, name, profile_length,
+ profile))
+ {
+# ifdef PNG_sRGB_SUPPORTED
+ /* If no sRGB support, don't try storing sRGB information */
+ png_icc_set_sRGB(png_ptr, colorspace, profile, 0);
+# endif
+ return 1;
+ }
+
+ /* Failure case */
+ return 0;
+}
+#endif /* iCCP */
+
+#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
+void /* PRIVATE */
+png_colorspace_set_rgb_coefficients(png_structrp png_ptr)
+{
+ /* Set the rgb_to_gray coefficients from the colorspace. */
+ if (!png_ptr->rgb_to_gray_coefficients_set &&
+ (png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
+ {
+ /* png_set_background has not been called, get the coefficients from the Y
+ * values of the colorspace colorants.
+ */
+ png_fixed_point r = png_ptr->colorspace.end_points_XYZ.red_Y;
+ png_fixed_point g = png_ptr->colorspace.end_points_XYZ.green_Y;
+ png_fixed_point b = png_ptr->colorspace.end_points_XYZ.blue_Y;
+ png_fixed_point total = r+g+b;
+
+ if (total > 0 &&
+ r >= 0 && png_muldiv(&r, r, 32768, total) && r >= 0 && r <= 32768 &&
+ g >= 0 && png_muldiv(&g, g, 32768, total) && g >= 0 && g <= 32768 &&
+ b >= 0 && png_muldiv(&b, b, 32768, total) && b >= 0 && b <= 32768 &&
+ r+g+b <= 32769)
+ {
+ /* We allow 0 coefficients here. r+g+b may be 32769 if two or
+ * all of the coefficients were rounded up. Handle this by
+ * reducing the *largest* coefficient by 1; this matches the
+ * approach used for the default coefficients in pngrtran.c
+ */
+ int add = 0;
+
+ if (r+g+b > 32768)
+ add = -1;
+ else if (r+g+b < 32768)
+ add = 1;
+
+ if (add != 0)
+ {
+ if (g >= r && g >= b)
+ g += add;
+ else if (r >= g && r >= b)
+ r += add;
+ else
+ b += add;
+ }
+
+ /* Check for an internal error. */
+ if (r+g+b != 32768)
+ png_error(png_ptr,
+ "internal error handling cHRM coefficients");
+
+ else
+ {
+ png_ptr->rgb_to_gray_red_coeff = (png_uint_16)r;
+ png_ptr->rgb_to_gray_green_coeff = (png_uint_16)g;
+ }
+ }
+
+ /* This is a png_error at present even though it could be ignored -
+ * it should never happen, but it is important that if it does, the
+ * bug is fixed.
+ */
+ else
+ png_error(png_ptr, "internal error handling cHRM->XYZ");
+ }
+}
+#endif
+
+#endif /* COLORSPACE */
+
+void /* PRIVATE */
+png_check_IHDR(png_const_structrp png_ptr,
+ png_uint_32 width, png_uint_32 height, int bit_depth,
+ int color_type, int interlace_type, int compression_type,
+ int filter_type)
+{
+ int error = 0;
+
+ /* Check for width and height valid values */
+ if (width == 0)
+ {
+ png_warning(png_ptr, "Image width is zero in IHDR");
+ error = 1;
+ }
+
+ if (height == 0)
+ {
+ png_warning(png_ptr, "Image height is zero in IHDR");
+ error = 1;
+ }
+
+# ifdef PNG_SET_USER_LIMITS_SUPPORTED
+ if (width > png_ptr->user_width_max)
+
+# else
+ if (width > PNG_USER_WIDTH_MAX)
+# endif
+ {
+ png_warning(png_ptr, "Image width exceeds user limit in IHDR");
+ error = 1;
+ }
+
+# ifdef PNG_SET_USER_LIMITS_SUPPORTED
+ if (height > png_ptr->user_height_max)
+# else
+ if (height > PNG_USER_HEIGHT_MAX)
+# endif
+ {
+ png_warning(png_ptr, "Image height exceeds user limit in IHDR");
+ error = 1;
+ }
+
+ if (width > PNG_UINT_31_MAX)
+ {
+ png_warning(png_ptr, "Invalid image width in IHDR");
+ error = 1;
+ }
+
+ if (height > PNG_UINT_31_MAX)
+ {
+ png_warning(png_ptr, "Invalid image height in IHDR");
+ error = 1;
+ }
+
+ if (width > (PNG_UINT_32_MAX
+ >> 3) /* 8-byte RGBA pixels */
+ - 48 /* bigrowbuf hack */
+ - 1 /* filter byte */
+ - 7*8 /* rounding of width to multiple of 8 pixels */
+ - 8) /* extra max_pixel_depth pad */
+ png_warning(png_ptr, "Width is too large for libpng to process pixels");
+
+ /* Check other values */
+ if (bit_depth != 1 && bit_depth != 2 && bit_depth != 4 &&
+ bit_depth != 8 && bit_depth != 16)
+ {
+ png_warning(png_ptr, "Invalid bit depth in IHDR");
+ error = 1;
+ }
+
+ if (color_type < 0 || color_type == 1 ||
+ color_type == 5 || color_type > 6)
+ {
+ png_warning(png_ptr, "Invalid color type in IHDR");
+ error = 1;
+ }
+
+ if (((color_type == PNG_COLOR_TYPE_PALETTE) && bit_depth > 8) ||
+ ((color_type == PNG_COLOR_TYPE_RGB ||
+ color_type == PNG_COLOR_TYPE_GRAY_ALPHA ||
+ color_type == PNG_COLOR_TYPE_RGB_ALPHA) && bit_depth < 8))
+ {
+ png_warning(png_ptr, "Invalid color type/bit depth combination in IHDR");
+ error = 1;
+ }
+
+ if (interlace_type >= PNG_INTERLACE_LAST)
+ {
+ png_warning(png_ptr, "Unknown interlace method in IHDR");
+ error = 1;
+ }
+
+ if (compression_type != PNG_COMPRESSION_TYPE_BASE)
+ {
+ png_warning(png_ptr, "Unknown compression method in IHDR");
+ error = 1;
+ }
+
+# ifdef PNG_MNG_FEATURES_SUPPORTED
+ /* Accept filter_method 64 (intrapixel differencing) only if
+ * 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
+ * 2. Libpng did not read a PNG signature (this filter_method is only
+ * used in PNG datastreams that are embedded in MNG datastreams) and
+ * 3. The application called png_permit_mng_features with a mask that
+ * included PNG_FLAG_MNG_FILTER_64 and
+ * 4. The filter_method is 64 and
+ * 5. The color_type is RGB or RGBA
+ */
+ if ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) &&
+ png_ptr->mng_features_permitted)
+ png_warning(png_ptr, "MNG features are not allowed in a PNG datastream");
+
+ if (filter_type != PNG_FILTER_TYPE_BASE)
+ {
+ if (!((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
+ (filter_type == PNG_INTRAPIXEL_DIFFERENCING) &&
+ ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) == 0) &&
+ (color_type == PNG_COLOR_TYPE_RGB ||
+ color_type == PNG_COLOR_TYPE_RGB_ALPHA)))
+ {
+ png_warning(png_ptr, "Unknown filter method in IHDR");
+ error = 1;
+ }
+
+ if (png_ptr->mode & PNG_HAVE_PNG_SIGNATURE)
+ {
+ png_warning(png_ptr, "Invalid filter method in IHDR");
+ error = 1;
+ }
+ }
+
+# else
+ if (filter_type != PNG_FILTER_TYPE_BASE)
+ {
+ png_warning(png_ptr, "Unknown filter method in IHDR");
+ error = 1;
+ }
+# endif
+
+ if (error == 1)
+ png_error(png_ptr, "Invalid IHDR data");
+}
+
+#if defined(PNG_sCAL_SUPPORTED) || defined(PNG_pCAL_SUPPORTED)
+/* ASCII to fp functions */
+/* Check an ASCII formated floating point value, see the more detailed
+ * comments in pngpriv.h
+ */
+/* The following is used internally to preserve the sticky flags */
+#define png_fp_add(state, flags) ((state) |= (flags))
+#define png_fp_set(state, value) ((state) = (value) | ((state) & PNG_FP_STICKY))
+
+int /* PRIVATE */
+png_check_fp_number(png_const_charp string, png_size_t size, int *statep,
+ png_size_tp whereami)
+{
+ int state = *statep;
+ png_size_t i = *whereami;
+
+ while (i < size)
+ {
+ int type;
+ /* First find the type of the next character */
+ switch (string[i])
+ {
+ case 43: type = PNG_FP_SAW_SIGN; break;
+ case 45: type = PNG_FP_SAW_SIGN + PNG_FP_NEGATIVE; break;
+ case 46: type = PNG_FP_SAW_DOT; break;
+ case 48: type = PNG_FP_SAW_DIGIT; break;
+ case 49: case 50: case 51: case 52:
+ case 53: case 54: case 55: case 56:
+ case 57: type = PNG_FP_SAW_DIGIT + PNG_FP_NONZERO; break;
+ case 69:
+ case 101: type = PNG_FP_SAW_E; break;
+ default: goto PNG_FP_End;
+ }
+
+ /* Now deal with this type according to the current
+ * state, the type is arranged to not overlap the
+ * bits of the PNG_FP_STATE.
+ */
+ switch ((state & PNG_FP_STATE) + (type & PNG_FP_SAW_ANY))
+ {
+ case PNG_FP_INTEGER + PNG_FP_SAW_SIGN:
+ if (state & PNG_FP_SAW_ANY)
+ goto PNG_FP_End; /* not a part of the number */
+
+ png_fp_add(state, type);
+ break;
+
+ case PNG_FP_INTEGER + PNG_FP_SAW_DOT:
+ /* Ok as trailer, ok as lead of fraction. */
+ if (state & PNG_FP_SAW_DOT) /* two dots */
+ goto PNG_FP_End;
+
+ else if (state & PNG_FP_SAW_DIGIT) /* trailing dot? */
+ png_fp_add(state, type);
+
+ else
+ png_fp_set(state, PNG_FP_FRACTION | type);
+
+ break;
+
+ case PNG_FP_INTEGER + PNG_FP_SAW_DIGIT:
+ if (state & PNG_FP_SAW_DOT) /* delayed fraction */
+ png_fp_set(state, PNG_FP_FRACTION | PNG_FP_SAW_DOT);
+
+ png_fp_add(state, type | PNG_FP_WAS_VALID);
+
+ break;
+
+ case PNG_FP_INTEGER + PNG_FP_SAW_E:
+ if ((state & PNG_FP_SAW_DIGIT) == 0)
+ goto PNG_FP_End;
+
+ png_fp_set(state, PNG_FP_EXPONENT);
+
+ break;
+
+ /* case PNG_FP_FRACTION + PNG_FP_SAW_SIGN:
+ goto PNG_FP_End; ** no sign in fraction */
+
+ /* case PNG_FP_FRACTION + PNG_FP_SAW_DOT:
+ goto PNG_FP_End; ** Because SAW_DOT is always set */
+
+ case PNG_FP_FRACTION + PNG_FP_SAW_DIGIT:
+ png_fp_add(state, type | PNG_FP_WAS_VALID);
+ break;
+
+ case PNG_FP_FRACTION + PNG_FP_SAW_E:
+ /* This is correct because the trailing '.' on an
+ * integer is handled above - so we can only get here
+ * with the sequence ".E" (with no preceding digits).
+ */
+ if ((state & PNG_FP_SAW_DIGIT) == 0)
+ goto PNG_FP_End;
+
+ png_fp_set(state, PNG_FP_EXPONENT);
+
+ break;
+
+ case PNG_FP_EXPONENT + PNG_FP_SAW_SIGN:
+ if (state & PNG_FP_SAW_ANY)
+ goto PNG_FP_End; /* not a part of the number */
+
+ png_fp_add(state, PNG_FP_SAW_SIGN);
+
+ break;
+
+ /* case PNG_FP_EXPONENT + PNG_FP_SAW_DOT:
+ goto PNG_FP_End; */
+
+ case PNG_FP_EXPONENT + PNG_FP_SAW_DIGIT:
+ png_fp_add(state, PNG_FP_SAW_DIGIT | PNG_FP_WAS_VALID);
+
+ break;
+
+ /* case PNG_FP_EXPONEXT + PNG_FP_SAW_E:
+ goto PNG_FP_End; */
+
+ default: goto PNG_FP_End; /* I.e. break 2 */
+ }
+
+ /* The character seems ok, continue. */
+ ++i;
+ }
+
+PNG_FP_End:
+ /* Here at the end, update the state and return the correct
+ * return code.
+ */
+ *statep = state;
+ *whereami = i;
+
+ return (state & PNG_FP_SAW_DIGIT) != 0;
+}
+
+
+/* The same but for a complete string. */
+int
+png_check_fp_string(png_const_charp string, png_size_t size)
+{
+ int state=0;
+ png_size_t char_index=0;
+
+ if (png_check_fp_number(string, size, &state, &char_index) &&
+ (char_index == size || string[char_index] == 0))
+ return state /* must be non-zero - see above */;
+
+ return 0; /* i.e. fail */
+}
+#endif /* pCAL or sCAL */
+
+#ifdef PNG_sCAL_SUPPORTED
+# ifdef PNG_FLOATING_POINT_SUPPORTED
+/* Utility used below - a simple accurate power of ten from an integral
+ * exponent.
+ */
+static double
+png_pow10(int power)
+{
+ int recip = 0;
+ double d = 1;
+
+ /* Handle negative exponent with a reciprocal at the end because
+ * 10 is exact whereas .1 is inexact in base 2
+ */
+ if (power < 0)
+ {
+ if (power < DBL_MIN_10_EXP) return 0;
+ recip = 1, power = -power;
+ }
+
+ if (power > 0)
+ {
+ /* Decompose power bitwise. */
+ double mult = 10;
+ do
+ {
+ if (power & 1) d *= mult;
+ mult *= mult;
+ power >>= 1;
+ }
+ while (power > 0);
+
+ if (recip) d = 1/d;
+ }
+ /* else power is 0 and d is 1 */
+
+ return d;
+}
+
+/* Function to format a floating point value in ASCII with a given
+ * precision.
+ */
+void /* PRIVATE */
+png_ascii_from_fp(png_const_structrp png_ptr, png_charp ascii, png_size_t size,
+ double fp, unsigned int precision)
+{
+ /* We use standard functions from math.h, but not printf because
+ * that would require stdio. The caller must supply a buffer of
+ * sufficient size or we will png_error. The tests on size and
+ * the space in ascii[] consumed are indicated below.
+ */
+ if (precision < 1)
+ precision = DBL_DIG;
+
+ /* Enforce the limit of the implementation precision too. */
+ if (precision > DBL_DIG+1)
+ precision = DBL_DIG+1;
+
+ /* Basic sanity checks */
+ if (size >= precision+5) /* See the requirements below. */
+ {
+ if (fp < 0)
+ {
+ fp = -fp;
+ *ascii++ = 45; /* '-' PLUS 1 TOTAL 1 */
+ --size;
+ }
+
+ if (fp >= DBL_MIN && fp <= DBL_MAX)
+ {
+ int exp_b10; /* A base 10 exponent */
+ double base; /* 10^exp_b10 */
+
+ /* First extract a base 10 exponent of the number,
+ * the calculation below rounds down when converting
+ * from base 2 to base 10 (multiply by log10(2) -
+ * 0.3010, but 77/256 is 0.3008, so exp_b10 needs to
+ * be increased. Note that the arithmetic shift
+ * performs a floor() unlike C arithmetic - using a
+ * C multiply would break the following for negative
+ * exponents.
+ */
+ (void)frexp(fp, &exp_b10); /* exponent to base 2 */
+
+ exp_b10 = (exp_b10 * 77) >> 8; /* <= exponent to base 10 */
+
+ /* Avoid underflow here. */
+ base = png_pow10(exp_b10); /* May underflow */
+
+ while (base < DBL_MIN || base < fp)
+ {
+ /* And this may overflow. */
+ double test = png_pow10(exp_b10+1);
+
+ if (test <= DBL_MAX)
+ ++exp_b10, base = test;
+
+ else
+ break;
+ }
+
+ /* Normalize fp and correct exp_b10, after this fp is in the
+ * range [.1,1) and exp_b10 is both the exponent and the digit
+ * *before* which the decimal point should be inserted
+ * (starting with 0 for the first digit). Note that this
+ * works even if 10^exp_b10 is out of range because of the
+ * test on DBL_MAX above.
+ */
+ fp /= base;
+ while (fp >= 1) fp /= 10, ++exp_b10;
+
+ /* Because of the code above fp may, at this point, be
+ * less than .1, this is ok because the code below can
+ * handle the leading zeros this generates, so no attempt
+ * is made to correct that here.
+ */
+
+ {
+ int czero, clead, cdigits;
+ char exponent[10];
+
+ /* Allow up to two leading zeros - this will not lengthen
+ * the number compared to using E-n.
+ */
+ if (exp_b10 < 0 && exp_b10 > -3) /* PLUS 3 TOTAL 4 */
+ {
+ czero = -exp_b10; /* PLUS 2 digits: TOTAL 3 */
+ exp_b10 = 0; /* Dot added below before first output. */
+ }
+ else
+ czero = 0; /* No zeros to add */
+
+ /* Generate the digit list, stripping trailing zeros and
+ * inserting a '.' before a digit if the exponent is 0.
+ */
+ clead = czero; /* Count of leading zeros */
+ cdigits = 0; /* Count of digits in list. */
+
+ do
+ {
+ double d;
+
+ fp *= 10;
+ /* Use modf here, not floor and subtract, so that
+ * the separation is done in one step. At the end
+ * of the loop don't break the number into parts so
+ * that the final digit is rounded.
+ */
+ if (cdigits+czero-clead+1 < (int)precision)
+ fp = modf(fp, &d);
+
+ else
+ {
+ d = floor(fp + .5);
+
+ if (d > 9)
+ {
+ /* Rounding up to 10, handle that here. */
+ if (czero > 0)
+ {
+ --czero, d = 1;
+ if (cdigits == 0) --clead;
+ }
+ else
+ {
+ while (cdigits > 0 && d > 9)
+ {
+ int ch = *--ascii;
+
+ if (exp_b10 != (-1))
+ ++exp_b10;
+
+ else if (ch == 46)
+ {
+ ch = *--ascii, ++size;
+ /* Advance exp_b10 to '1', so that the
+ * decimal point happens after the
+ * previous digit.
+ */
+ exp_b10 = 1;
+ }
+
+ --cdigits;
+ d = ch - 47; /* I.e. 1+(ch-48) */
+ }
+
+ /* Did we reach the beginning? If so adjust the
+ * exponent but take into account the leading
+ * decimal point.
+ */
+ if (d > 9) /* cdigits == 0 */
+ {
+ if (exp_b10 == (-1))
+ {
+ /* Leading decimal point (plus zeros?), if
+ * we lose the decimal point here it must
+ * be reentered below.
+ */
+ int ch = *--ascii;
+
+ if (ch == 46)
+ ++size, exp_b10 = 1;
+
+ /* Else lost a leading zero, so 'exp_b10' is
+ * still ok at (-1)
+ */
+ }
+ else
+ ++exp_b10;
+
+ /* In all cases we output a '1' */
+ d = 1;
+ }
+ }
+ }
+ fp = 0; /* Guarantees termination below. */
+ }
+
+ if (d == 0)
+ {
+ ++czero;
+ if (cdigits == 0) ++clead;
+ }
+ else
+ {
+ /* Included embedded zeros in the digit count. */
+ cdigits += czero - clead;
+ clead = 0;
+
+ while (czero > 0)
+ {
+ /* exp_b10 == (-1) means we just output the decimal
+ * place - after the DP don't adjust 'exp_b10' any
+ * more!
+ */
+ if (exp_b10 != (-1))
+ {
+ if (exp_b10 == 0) *ascii++ = 46, --size;
+ /* PLUS 1: TOTAL 4 */
+ --exp_b10;
+ }
+ *ascii++ = 48, --czero;
+ }
+
+ if (exp_b10 != (-1))
+ {
+ if (exp_b10 == 0) *ascii++ = 46, --size; /* counted
+ above */
+ --exp_b10;
+ }
+ *ascii++ = (char)(48 + (int)d), ++cdigits;
+ }
+ }
+ while (cdigits+czero-clead < (int)precision && fp > DBL_MIN);
+
+ /* The total output count (max) is now 4+precision */
+
+ /* Check for an exponent, if we don't need one we are
+ * done and just need to terminate the string. At
+ * this point exp_b10==(-1) is effectively if flag - it got
+ * to '-1' because of the decrement after outputing
+ * the decimal point above (the exponent required is
+ * *not* -1!)
+ */
+ if (exp_b10 >= (-1) && exp_b10 <= 2)
+ {
+ /* The following only happens if we didn't output the
+ * leading zeros above for negative exponent, so this
+ * doest add to the digit requirement. Note that the
+ * two zeros here can only be output if the two leading
+ * zeros were *not* output, so this doesn't increase
+ * the output count.
+ */
+ while (--exp_b10 >= 0) *ascii++ = 48;
+
+ *ascii = 0;
+
+ /* Total buffer requirement (including the '\0') is
+ * 5+precision - see check at the start.
+ */
+ return;
+ }
+
+ /* Here if an exponent is required, adjust size for
+ * the digits we output but did not count. The total
+ * digit output here so far is at most 1+precision - no
+ * decimal point and no leading or trailing zeros have
+ * been output.
+ */
+ size -= cdigits;
+
+ *ascii++ = 69, --size; /* 'E': PLUS 1 TOTAL 2+precision */
+
+ /* The following use of an unsigned temporary avoids ambiguities in
+ * the signed arithmetic on exp_b10 and permits GCC at least to do
+ * better optimization.
+ */
+ {
+ unsigned int uexp_b10;
+
+ if (exp_b10 < 0)
+ {
+ *ascii++ = 45, --size; /* '-': PLUS 1 TOTAL 3+precision */
+ uexp_b10 = -exp_b10;
+ }
+
+ else
+ uexp_b10 = exp_b10;
+
+ cdigits = 0;
+
+ while (uexp_b10 > 0)
+ {
+ exponent[cdigits++] = (char)(48 + uexp_b10 % 10);
+ uexp_b10 /= 10;
+ }
+ }
+
+ /* Need another size check here for the exponent digits, so
+ * this need not be considered above.
+ */
+ if ((int)size > cdigits)
+ {
+ while (cdigits > 0) *ascii++ = exponent[--cdigits];
+
+ *ascii = 0;
+
+ return;
+ }
+ }
+ }
+ else if (!(fp >= DBL_MIN))
+ {
+ *ascii++ = 48; /* '0' */
+ *ascii = 0;
+ return;
+ }
+ else
+ {
+ *ascii++ = 105; /* 'i' */
+ *ascii++ = 110; /* 'n' */
+ *ascii++ = 102; /* 'f' */
+ *ascii = 0;
+ return;
+ }
+ }
+
+ /* Here on buffer too small. */
+ png_error(png_ptr, "ASCII conversion buffer too small");
+}
+
+# endif /* FLOATING_POINT */
+
+# ifdef PNG_FIXED_POINT_SUPPORTED
+/* Function to format a fixed point value in ASCII.
+ */
+void /* PRIVATE */
+png_ascii_from_fixed(png_const_structrp png_ptr, png_charp ascii,
+ png_size_t size, png_fixed_point fp)
+{
+ /* Require space for 10 decimal digits, a decimal point, a minus sign and a
+ * trailing \0, 13 characters:
+ */
+ if (size > 12)
+ {
+ png_uint_32 num;
+
+ /* Avoid overflow here on the minimum integer. */
+ if (fp < 0)
+ *ascii++ = 45, --size, num = -fp;
+ else
+ num = fp;
+
+ if (num <= 0x80000000) /* else overflowed */
+ {
+ unsigned int ndigits = 0, first = 16 /* flag value */;
+ char digits[10];
+
+ while (num)
+ {
+ /* Split the low digit off num: */
+ unsigned int tmp = num/10;
+ num -= tmp*10;
+ digits[ndigits++] = (char)(48 + num);
+ /* Record the first non-zero digit, note that this is a number
+ * starting at 1, it's not actually the array index.
+ */
+ if (first == 16 && num > 0)
+ first = ndigits;
+ num = tmp;
+ }
+
+ if (ndigits > 0)
+ {
+ while (ndigits > 5) *ascii++ = digits[--ndigits];
+ /* The remaining digits are fractional digits, ndigits is '5' or
+ * smaller at this point. It is certainly not zero. Check for a
+ * non-zero fractional digit:
+ */
+ if (first <= 5)
+ {
+ unsigned int i;
+ *ascii++ = 46; /* decimal point */
+ /* ndigits may be <5 for small numbers, output leading zeros
+ * then ndigits digits to first:
+ */
+ i = 5;
+ while (ndigits < i) *ascii++ = 48, --i;
+ while (ndigits >= first) *ascii++ = digits[--ndigits];
+ /* Don't output the trailing zeros! */
+ }
+ }
+ else
+ *ascii++ = 48;
+
+ /* And null terminate the string: */
+ *ascii = 0;
+ return;
+ }
+ }
+
+ /* Here on buffer too small. */
+ png_error(png_ptr, "ASCII conversion buffer too small");
+}
+# endif /* FIXED_POINT */
+#endif /* READ_SCAL */
+
+#if defined(PNG_FLOATING_POINT_SUPPORTED) && \
+ !defined(PNG_FIXED_POINT_MACRO_SUPPORTED) && \
+ (defined(PNG_gAMA_SUPPORTED) || defined(PNG_cHRM_SUPPORTED) || \
+ defined(PNG_sCAL_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED) || \
+ defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)) || \
+ (defined(PNG_sCAL_SUPPORTED) && \
+ defined(PNG_FLOATING_ARITHMETIC_SUPPORTED))
+png_fixed_point
+png_fixed(png_const_structrp png_ptr, double fp, png_const_charp text)
+{
+ double r = floor(100000 * fp + .5);
+
+ if (r > 2147483647. || r < -2147483648.)
+ png_fixed_error(png_ptr, text);
+
+ return (png_fixed_point)r;
+}
+#endif
+
+#if defined(PNG_READ_GAMMA_SUPPORTED) || \
+ defined(PNG_INCH_CONVERSIONS_SUPPORTED) || defined(PNG_READ_pHYs_SUPPORTED)
+/* muldiv functions */
+/* This API takes signed arguments and rounds the result to the nearest
+ * integer (or, for a fixed point number - the standard argument - to
+ * the nearest .00001). Overflow and divide by zero are signalled in
+ * the result, a boolean - true on success, false on overflow.
+ */
+int
+png_muldiv(png_fixed_point_p res, png_fixed_point a, png_int_32 times,
+ png_int_32 divisor)
+{
+ /* Return a * times / divisor, rounded. */
+ if (divisor != 0)
+ {
+ if (a == 0 || times == 0)
+ {
+ *res = 0;
+ return 1;
+ }
+ else
+ {
+#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
+ double r = a;
+ r *= times;
+ r /= divisor;
+ r = floor(r+.5);
+
+ /* A png_fixed_point is a 32-bit integer. */
+ if (r <= 2147483647. && r >= -2147483648.)
+ {
+ *res = (png_fixed_point)r;
+ return 1;
+ }
+#else
+ int negative = 0;
+ png_uint_32 A, T, D;
+ png_uint_32 s16, s32, s00;
+
+ if (a < 0)
+ negative = 1, A = -a;
+ else
+ A = a;
+
+ if (times < 0)
+ negative = !negative, T = -times;
+ else
+ T = times;
+
+ if (divisor < 0)
+ negative = !negative, D = -divisor;
+ else
+ D = divisor;
+
+ /* Following can't overflow because the arguments only
+ * have 31 bits each, however the result may be 32 bits.
+ */
+ s16 = (A >> 16) * (T & 0xffff) +
+ (A & 0xffff) * (T >> 16);
+ /* Can't overflow because the a*times bit is only 30
+ * bits at most.
+ */
+ s32 = (A >> 16) * (T >> 16) + (s16 >> 16);
+ s00 = (A & 0xffff) * (T & 0xffff);
+
+ s16 = (s16 & 0xffff) << 16;
+ s00 += s16;
+
+ if (s00 < s16)
+ ++s32; /* carry */
+
+ if (s32 < D) /* else overflow */
+ {
+ /* s32.s00 is now the 64-bit product, do a standard
+ * division, we know that s32 < D, so the maximum
+ * required shift is 31.
+ */
+ int bitshift = 32;
+ png_fixed_point result = 0; /* NOTE: signed */
+
+ while (--bitshift >= 0)
+ {
+ png_uint_32 d32, d00;
+
+ if (bitshift > 0)
+ d32 = D >> (32-bitshift), d00 = D << bitshift;
+
+ else
+ d32 = 0, d00 = D;
+
+ if (s32 > d32)
+ {
+ if (s00 < d00) --s32; /* carry */
+ s32 -= d32, s00 -= d00, result += 1<<bitshift;
+ }
+
+ else
+ if (s32 == d32 && s00 >= d00)
+ s32 = 0, s00 -= d00, result += 1<<bitshift;
+ }
+
+ /* Handle the rounding. */
+ if (s00 >= (D >> 1))
+ ++result;
+
+ if (negative)
+ result = -result;
+
+ /* Check for overflow. */
+ if ((negative && result <= 0) || (!negative && result >= 0))
+ {
+ *res = result;
+ return 1;
+ }
+ }
+#endif
+ }
+ }
+
+ return 0;
+}
+#endif /* READ_GAMMA || INCH_CONVERSIONS */
+
+#if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_INCH_CONVERSIONS_SUPPORTED)
+/* The following is for when the caller doesn't much care about the
+ * result.
+ */
+png_fixed_point
+png_muldiv_warn(png_const_structrp png_ptr, png_fixed_point a, png_int_32 times,
+ png_int_32 divisor)
+{
+ png_fixed_point result;
+
+ if (png_muldiv(&result, a, times, divisor))
+ return result;
+
+ png_warning(png_ptr, "fixed point overflow ignored");
+ return 0;
+}
+#endif
+
+#ifdef PNG_GAMMA_SUPPORTED /* more fixed point functions for gamma */
+/* Calculate a reciprocal, return 0 on div-by-zero or overflow. */
+png_fixed_point
+png_reciprocal(png_fixed_point a)
+{
+#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
+ double r = floor(1E10/a+.5);
+
+ if (r <= 2147483647. && r >= -2147483648.)
+ return (png_fixed_point)r;
+#else
+ png_fixed_point res;
+
+ if (png_muldiv(&res, 100000, 100000, a))
+ return res;
+#endif
+
+ return 0; /* error/overflow */
+}
+
+/* This is the shared test on whether a gamma value is 'significant' - whether
+ * it is worth doing gamma correction.
+ */
+int /* PRIVATE */
+png_gamma_significant(png_fixed_point gamma_val)
+{
+ return gamma_val < PNG_FP_1 - PNG_GAMMA_THRESHOLD_FIXED ||
+ gamma_val > PNG_FP_1 + PNG_GAMMA_THRESHOLD_FIXED;
+}
+#endif
+
+#ifdef PNG_READ_GAMMA_SUPPORTED
+/* A local convenience routine. */
+static png_fixed_point
+png_product2(png_fixed_point a, png_fixed_point b)
+{
+ /* The required result is 1/a * 1/b; the following preserves accuracy. */
+#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
+ double r = a * 1E-5;
+ r *= b;
+ r = floor(r+.5);
+
+ if (r <= 2147483647. && r >= -2147483648.)
+ return (png_fixed_point)r;
+#else
+ png_fixed_point res;
+
+ if (png_muldiv(&res, a, b, 100000))
+ return res;
+#endif
+
+ return 0; /* overflow */
+}
+
+/* The inverse of the above. */
+png_fixed_point
+png_reciprocal2(png_fixed_point a, png_fixed_point b)
+{
+ /* The required result is 1/a * 1/b; the following preserves accuracy. */
+#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
+ double r = 1E15/a;
+ r /= b;
+ r = floor(r+.5);
+
+ if (r <= 2147483647. && r >= -2147483648.)
+ return (png_fixed_point)r;
+#else
+ /* This may overflow because the range of png_fixed_point isn't symmetric,
+ * but this API is only used for the product of file and screen gamma so it
+ * doesn't matter that the smallest number it can produce is 1/21474, not
+ * 1/100000
+ */
+ png_fixed_point res = png_product2(a, b);
+
+ if (res != 0)
+ return png_reciprocal(res);
+#endif
+
+ return 0; /* overflow */
+}
+#endif /* READ_GAMMA */
+
+#ifdef PNG_READ_GAMMA_SUPPORTED /* gamma table code */
+#ifndef PNG_FLOATING_ARITHMETIC_SUPPORTED
+/* Fixed point gamma.
+ *
+ * The code to calculate the tables used below can be found in the shell script
+ * contrib/tools/intgamma.sh
+ *
+ * To calculate gamma this code implements fast log() and exp() calls using only
+ * fixed point arithmetic. This code has sufficient precision for either 8-bit
+ * or 16-bit sample values.
+ *
+ * The tables used here were calculated using simple 'bc' programs, but C double
+ * precision floating point arithmetic would work fine.
+ *
+ * 8-bit log table
+ * This is a table of -log(value/255)/log(2) for 'value' in the range 128 to
+ * 255, so it's the base 2 logarithm of a normalized 8-bit floating point
+ * mantissa. The numbers are 32-bit fractions.
+ */
+static const png_uint_32
+png_8bit_l2[128] =
+{
+ 4270715492U, 4222494797U, 4174646467U, 4127164793U, 4080044201U, 4033279239U,
+ 3986864580U, 3940795015U, 3895065449U, 3849670902U, 3804606499U, 3759867474U,
+ 3715449162U, 3671346997U, 3627556511U, 3584073329U, 3540893168U, 3498011834U,
+ 3455425220U, 3413129301U, 3371120137U, 3329393864U, 3287946700U, 3246774933U,
+ 3205874930U, 3165243125U, 3124876025U, 3084770202U, 3044922296U, 3005329011U,
+ 2965987113U, 2926893432U, 2888044853U, 2849438323U, 2811070844U, 2772939474U,
+ 2735041326U, 2697373562U, 2659933400U, 2622718104U, 2585724991U, 2548951424U,
+ 2512394810U, 2476052606U, 2439922311U, 2404001468U, 2368287663U, 2332778523U,
+ 2297471715U, 2262364947U, 2227455964U, 2192742551U, 2158222529U, 2123893754U,
+ 2089754119U, 2055801552U, 2022034013U, 1988449497U, 1955046031U, 1921821672U,
+ 1888774511U, 1855902668U, 1823204291U, 1790677560U, 1758320682U, 1726131893U,
+ 1694109454U, 1662251657U, 1630556815U, 1599023271U, 1567649391U, 1536433567U,
+ 1505374214U, 1474469770U, 1443718700U, 1413119487U, 1382670639U, 1352370686U,
+ 1322218179U, 1292211689U, 1262349810U, 1232631153U, 1203054352U, 1173618059U,
+ 1144320946U, 1115161701U, 1086139034U, 1057251672U, 1028498358U, 999877854U,
+ 971388940U, 943030410U, 914801076U, 886699767U, 858725327U, 830876614U,
+ 803152505U, 775551890U, 748073672U, 720716771U, 693480120U, 666362667U,
+ 639363374U, 612481215U, 585715177U, 559064263U, 532527486U, 506103872U,
+ 479792461U, 453592303U, 427502463U, 401522014U, 375650043U, 349885648U,
+ 324227938U, 298676034U, 273229066U, 247886176U, 222646516U, 197509248U,
+ 172473545U, 147538590U, 122703574U, 97967701U, 73330182U, 48790236U,
+ 24347096U, 0U
+
+#if 0
+ /* The following are the values for 16-bit tables - these work fine for the
+ * 8-bit conversions but produce very slightly larger errors in the 16-bit
+ * log (about 1.2 as opposed to 0.7 absolute error in the final value). To
+ * use these all the shifts below must be adjusted appropriately.
+ */
+ 65166, 64430, 63700, 62976, 62257, 61543, 60835, 60132, 59434, 58741, 58054,
+ 57371, 56693, 56020, 55352, 54689, 54030, 53375, 52726, 52080, 51439, 50803,
+ 50170, 49542, 48918, 48298, 47682, 47070, 46462, 45858, 45257, 44661, 44068,
+ 43479, 42894, 42312, 41733, 41159, 40587, 40020, 39455, 38894, 38336, 37782,
+ 37230, 36682, 36137, 35595, 35057, 34521, 33988, 33459, 32932, 32408, 31887,
+ 31369, 30854, 30341, 29832, 29325, 28820, 28319, 27820, 27324, 26830, 26339,
+ 25850, 25364, 24880, 24399, 23920, 23444, 22970, 22499, 22029, 21562, 21098,
+ 20636, 20175, 19718, 19262, 18808, 18357, 17908, 17461, 17016, 16573, 16132,
+ 15694, 15257, 14822, 14390, 13959, 13530, 13103, 12678, 12255, 11834, 11415,
+ 10997, 10582, 10168, 9756, 9346, 8937, 8531, 8126, 7723, 7321, 6921, 6523,
+ 6127, 5732, 5339, 4947, 4557, 4169, 3782, 3397, 3014, 2632, 2251, 1872, 1495,
+ 1119, 744, 372
+#endif
+};
+
+static png_int_32
+png_log8bit(unsigned int x)
+{
+ unsigned int lg2 = 0;
+ /* Each time 'x' is multiplied by 2, 1 must be subtracted off the final log,
+ * because the log is actually negate that means adding 1. The final
+ * returned value thus has the range 0 (for 255 input) to 7.994 (for 1
+ * input), return -1 for the overflow (log 0) case, - so the result is
+ * always at most 19 bits.
+ */
+ if ((x &= 0xff) == 0)
+ return -1;
+
+ if ((x & 0xf0) == 0)
+ lg2 = 4, x <<= 4;
+
+ if ((x & 0xc0) == 0)
+ lg2 += 2, x <<= 2;
+
+ if ((x & 0x80) == 0)
+ lg2 += 1, x <<= 1;
+
+ /* result is at most 19 bits, so this cast is safe: */
+ return (png_int_32)((lg2 << 16) + ((png_8bit_l2[x-128]+32768)>>16));
+}
+
+/* The above gives exact (to 16 binary places) log2 values for 8-bit images,
+ * for 16-bit images we use the most significant 8 bits of the 16-bit value to
+ * get an approximation then multiply the approximation by a correction factor
+ * determined by the remaining up to 8 bits. This requires an additional step
+ * in the 16-bit case.
+ *
+ * We want log2(value/65535), we have log2(v'/255), where:
+ *
+ * value = v' * 256 + v''
+ * = v' * f
+ *
+ * So f is value/v', which is equal to (256+v''/v') since v' is in the range 128
+ * to 255 and v'' is in the range 0 to 255 f will be in the range 256 to less
+ * than 258. The final factor also needs to correct for the fact that our 8-bit
+ * value is scaled by 255, whereas the 16-bit values must be scaled by 65535.
+ *
+ * This gives a final formula using a calculated value 'x' which is value/v' and
+ * scaling by 65536 to match the above table:
+ *
+ * log2(x/257) * 65536
+ *
+ * Since these numbers are so close to '1' we can use simple linear
+ * interpolation between the two end values 256/257 (result -368.61) and 258/257
+ * (result 367.179). The values used below are scaled by a further 64 to give
+ * 16-bit precision in the interpolation:
+ *
+ * Start (256): -23591
+ * Zero (257): 0
+ * End (258): 23499
+ */
+static png_int_32
+png_log16bit(png_uint_32 x)
+{
+ unsigned int lg2 = 0;
+
+ /* As above, but now the input has 16 bits. */
+ if ((x &= 0xffff) == 0)
+ return -1;
+
+ if ((x & 0xff00) == 0)
+ lg2 = 8, x <<= 8;
+
+ if ((x & 0xf000) == 0)
+ lg2 += 4, x <<= 4;
+
+ if ((x & 0xc000) == 0)
+ lg2 += 2, x <<= 2;
+
+ if ((x & 0x8000) == 0)
+ lg2 += 1, x <<= 1;
+
+ /* Calculate the base logarithm from the top 8 bits as a 28-bit fractional
+ * value.
+ */
+ lg2 <<= 28;
+ lg2 += (png_8bit_l2[(x>>8)-128]+8) >> 4;
+
+ /* Now we need to interpolate the factor, this requires a division by the top
+ * 8 bits. Do this with maximum precision.
+ */
+ x = ((x << 16) + (x >> 9)) / (x >> 8);
+
+ /* Since we divided by the top 8 bits of 'x' there will be a '1' at 1<<24,
+ * the value at 1<<16 (ignoring this) will be 0 or 1; this gives us exactly
+ * 16 bits to interpolate to get the low bits of the result. Round the
+ * answer. Note that the end point values are scaled by 64 to retain overall
+ * precision and that 'lg2' is current scaled by an extra 12 bits, so adjust
+ * the overall scaling by 6-12. Round at every step.
+ */
+ x -= 1U << 24;
+
+ if (x <= 65536U) /* <= '257' */
+ lg2 += ((23591U * (65536U-x)) + (1U << (16+6-12-1))) >> (16+6-12);
+
+ else
+ lg2 -= ((23499U * (x-65536U)) + (1U << (16+6-12-1))) >> (16+6-12);
+
+ /* Safe, because the result can't have more than 20 bits: */
+ return (png_int_32)((lg2 + 2048) >> 12);
+}
+
+/* The 'exp()' case must invert the above, taking a 20-bit fixed point
+ * logarithmic value and returning a 16 or 8-bit number as appropriate. In
+ * each case only the low 16 bits are relevant - the fraction - since the
+ * integer bits (the top 4) simply determine a shift.
+ *
+ * The worst case is the 16-bit distinction between 65535 and 65534, this
+ * requires perhaps spurious accuracty in the decoding of the logarithm to
+ * distinguish log2(65535/65534.5) - 10^-5 or 17 bits. There is little chance
+ * of getting this accuracy in practice.
+ *
+ * To deal with this the following exp() function works out the exponent of the
+ * frational part of the logarithm by using an accurate 32-bit value from the
+ * top four fractional bits then multiplying in the remaining bits.
+ */
+static const png_uint_32
+png_32bit_exp[16] =
+{
+ /* NOTE: the first entry is deliberately set to the maximum 32-bit value. */
+ 4294967295U, 4112874773U, 3938502376U, 3771522796U, 3611622603U, 3458501653U,
+ 3311872529U, 3171459999U, 3037000500U, 2908241642U, 2784941738U, 2666869345U,
+ 2553802834U, 2445529972U, 2341847524U, 2242560872U
+};
+
+/* Adjustment table; provided to explain the numbers in the code below. */
+#if 0
+for (i=11;i>=0;--i){ print i, " ", (1 - e(-(2^i)/65536*l(2))) * 2^(32-i), "\n"}
+ 11 44937.64284865548751208448
+ 10 45180.98734845585101160448
+ 9 45303.31936980687359311872
+ 8 45364.65110595323018870784
+ 7 45395.35850361789624614912
+ 6 45410.72259715102037508096
+ 5 45418.40724413220722311168
+ 4 45422.25021786898173001728
+ 3 45424.17186732298419044352
+ 2 45425.13273269940811464704
+ 1 45425.61317555035558641664
+ 0 45425.85339951654943850496
+#endif
+
+static png_uint_32
+png_exp(png_fixed_point x)
+{
+ if (x > 0 && x <= 0xfffff) /* Else overflow or zero (underflow) */
+ {
+ /* Obtain a 4-bit approximation */
+ png_uint_32 e = png_32bit_exp[(x >> 12) & 0xf];
+
+ /* Incorporate the low 12 bits - these decrease the returned value by
+ * multiplying by a number less than 1 if the bit is set. The multiplier
+ * is determined by the above table and the shift. Notice that the values
+ * converge on 45426 and this is used to allow linear interpolation of the
+ * low bits.
+ */
+ if (x & 0x800)
+ e -= (((e >> 16) * 44938U) + 16U) >> 5;
+
+ if (x & 0x400)
+ e -= (((e >> 16) * 45181U) + 32U) >> 6;
+
+ if (x & 0x200)
+ e -= (((e >> 16) * 45303U) + 64U) >> 7;
+
+ if (x & 0x100)
+ e -= (((e >> 16) * 45365U) + 128U) >> 8;
+
+ if (x & 0x080)
+ e -= (((e >> 16) * 45395U) + 256U) >> 9;
+
+ if (x & 0x040)
+ e -= (((e >> 16) * 45410U) + 512U) >> 10;
+
+ /* And handle the low 6 bits in a single block. */
+ e -= (((e >> 16) * 355U * (x & 0x3fU)) + 256U) >> 9;
+
+ /* Handle the upper bits of x. */
+ e >>= x >> 16;
+ return e;
+ }
+
+ /* Check for overflow */
+ if (x <= 0)
+ return png_32bit_exp[0];
+
+ /* Else underflow */
+ return 0;
+}
+
+static png_byte
+png_exp8bit(png_fixed_point lg2)
+{
+ /* Get a 32-bit value: */
+ png_uint_32 x = png_exp(lg2);
+
+ /* Convert the 32-bit value to 0..255 by multiplying by 256-1, note that the
+ * second, rounding, step can't overflow because of the first, subtraction,
+ * step.
+ */
+ x -= x >> 8;
+ return (png_byte)((x + 0x7fffffU) >> 24);
+}
+
+static png_uint_16
+png_exp16bit(png_fixed_point lg2)
+{
+ /* Get a 32-bit value: */
+ png_uint_32 x = png_exp(lg2);
+
+ /* Convert the 32-bit value to 0..65535 by multiplying by 65536-1: */
+ x -= x >> 16;
+ return (png_uint_16)((x + 32767U) >> 16);
+}
+#endif /* FLOATING_ARITHMETIC */
+
+png_byte
+png_gamma_8bit_correct(unsigned int value, png_fixed_point gamma_val)
+{
+ if (value > 0 && value < 255)
+ {
+# ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
+ double r = floor(255*pow(value/255.,gamma_val*.00001)+.5);
+ return (png_byte)r;
+# else
+ png_int_32 lg2 = png_log8bit(value);
+ png_fixed_point res;
+
+ if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1))
+ return png_exp8bit(res);
+
+ /* Overflow. */
+ value = 0;
+# endif
+ }
+
+ return (png_byte)value;
+}
+
+png_uint_16
+png_gamma_16bit_correct(unsigned int value, png_fixed_point gamma_val)
+{
+ if (value > 0 && value < 65535)
+ {
+# ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
+ double r = floor(65535*pow(value/65535.,gamma_val*.00001)+.5);
+ return (png_uint_16)r;
+# else
+ png_int_32 lg2 = png_log16bit(value);
+ png_fixed_point res;
+
+ if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1))
+ return png_exp16bit(res);
+
+ /* Overflow. */
+ value = 0;
+# endif
+ }
+
+ return (png_uint_16)value;
+}
+
+/* This does the right thing based on the bit_depth field of the
+ * png_struct, interpreting values as 8-bit or 16-bit. While the result
+ * is nominally a 16-bit value if bit depth is 8 then the result is
+ * 8-bit (as are the arguments.)
+ */
+png_uint_16 /* PRIVATE */
+png_gamma_correct(png_structrp png_ptr, unsigned int value,
+ png_fixed_point gamma_val)
+{
+ if (png_ptr->bit_depth == 8)
+ return png_gamma_8bit_correct(value, gamma_val);
+
+ else
+ return png_gamma_16bit_correct(value, gamma_val);
+}
+
+/* Internal function to build a single 16-bit table - the table consists of
+ * 'num' 256 entry subtables, where 'num' is determined by 'shift' - the amount
+ * to shift the input values right (or 16-number_of_signifiant_bits).
+ *
+ * The caller is responsible for ensuring that the table gets cleaned up on
+ * png_error (i.e. if one of the mallocs below fails) - i.e. the *table argument
+ * should be somewhere that will be cleaned.
+ */
+static void
+png_build_16bit_table(png_structrp png_ptr, png_uint_16pp *ptable,
+ PNG_CONST unsigned int shift, PNG_CONST png_fixed_point gamma_val)
+{
+ /* Various values derived from 'shift': */
+ PNG_CONST unsigned int num = 1U << (8U - shift);
+ PNG_CONST unsigned int max = (1U << (16U - shift))-1U;
+ PNG_CONST unsigned int max_by_2 = 1U << (15U-shift);
+ unsigned int i;
+
+ png_uint_16pp table = *ptable =
+ (png_uint_16pp)png_calloc(png_ptr, num * (sizeof (png_uint_16p)));
+
+ for (i = 0; i < num; i++)
+ {
+ png_uint_16p sub_table = table[i] =
+ (png_uint_16p)png_malloc(png_ptr, 256 * (sizeof (png_uint_16)));
+
+ /* The 'threshold' test is repeated here because it can arise for one of
+ * the 16-bit tables even if the others don't hit it.
+ */
+ if (png_gamma_significant(gamma_val))
+ {
+ /* The old code would overflow at the end and this would cause the
+ * 'pow' function to return a result >1, resulting in an
+ * arithmetic error. This code follows the spec exactly; ig is
+ * the recovered input sample, it always has 8-16 bits.
+ *
+ * We want input * 65535/max, rounded, the arithmetic fits in 32
+ * bits (unsigned) so long as max <= 32767.
+ */
+ unsigned int j;
+ for (j = 0; j < 256; j++)
+ {
+ png_uint_32 ig = (j << (8-shift)) + i;
+# ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
+ /* Inline the 'max' scaling operation: */
+ double d = floor(65535*pow(ig/(double)max, gamma_val*.00001)+.5);
+ sub_table[j] = (png_uint_16)d;
+# else
+ if (shift)
+ ig = (ig * 65535U + max_by_2)/max;
+
+ sub_table[j] = png_gamma_16bit_correct(ig, gamma_val);
+# endif
+ }
+ }
+ else
+ {
+ /* We must still build a table, but do it the fast way. */
+ unsigned int j;
+
+ for (j = 0; j < 256; j++)
+ {
+ png_uint_32 ig = (j << (8-shift)) + i;
+
+ if (shift)
+ ig = (ig * 65535U + max_by_2)/max;
+
+ sub_table[j] = (png_uint_16)ig;
+ }
+ }
+ }
+}
+
+/* NOTE: this function expects the *inverse* of the overall gamma transformation
+ * required.
+ */
+static void
+png_build_16to8_table(png_structrp png_ptr, png_uint_16pp *ptable,
+ PNG_CONST unsigned int shift, PNG_CONST png_fixed_point gamma_val)
+{
+ PNG_CONST unsigned int num = 1U << (8U - shift);
+ PNG_CONST unsigned int max = (1U << (16U - shift))-1U;
+ unsigned int i;
+ png_uint_32 last;
+
+ png_uint_16pp table = *ptable =
+ (png_uint_16pp)png_calloc(png_ptr, num * (sizeof (png_uint_16p)));
+
+ /* 'num' is the number of tables and also the number of low bits of low
+ * bits of the input 16-bit value used to select a table. Each table is
+ * itself index by the high 8 bits of the value.
+ */
+ for (i = 0; i < num; i++)
+ table[i] = (png_uint_16p)png_malloc(png_ptr,
+ 256 * (sizeof (png_uint_16)));
+
+ /* 'gamma_val' is set to the reciprocal of the value calculated above, so
+ * pow(out,g) is an *input* value. 'last' is the last input value set.
+ *
+ * In the loop 'i' is used to find output values. Since the output is
+ * 8-bit there are only 256 possible values. The tables are set up to
+ * select the closest possible output value for each input by finding
+ * the input value at the boundary between each pair of output values
+ * and filling the table up to that boundary with the lower output
+ * value.
+ *
+ * The boundary values are 0.5,1.5..253.5,254.5. Since these are 9-bit
+ * values the code below uses a 16-bit value in i; the values start at
+ * 128.5 (for 0.5) and step by 257, for a total of 254 values (the last
+ * entries are filled with 255). Start i at 128 and fill all 'last'
+ * table entries <= 'max'
+ */
+ last = 0;
+ for (i = 0; i < 255; ++i) /* 8-bit output value */
+ {
+ /* Find the corresponding maximum input value */
+ png_uint_16 out = (png_uint_16)(i * 257U); /* 16-bit output value */
+
+ /* Find the boundary value in 16 bits: */
+ png_uint_32 bound = png_gamma_16bit_correct(out+128U, gamma_val);
+
+ /* Adjust (round) to (16-shift) bits: */
+ bound = (bound * max + 32768U)/65535U + 1U;
+
+ while (last < bound)
+ {
+ table[last & (0xffU >> shift)][last >> (8U - shift)] = out;
+ last++;
+ }
+ }
+
+ /* And fill in the final entries. */
+ while (last < (num << 8))
+ {
+ table[last & (0xff >> shift)][last >> (8U - shift)] = 65535U;
+ last++;
+ }
+}
+
+/* Build a single 8-bit table: same as the 16-bit case but much simpler (and
+ * typically much faster). Note that libpng currently does no sBIT processing
+ * (apparently contrary to the spec) so a 256 entry table is always generated.
+ */
+static void
+png_build_8bit_table(png_structrp png_ptr, png_bytepp ptable,
+ PNG_CONST png_fixed_point gamma_val)
+{
+ unsigned int i;
+ png_bytep table = *ptable = (png_bytep)png_malloc(png_ptr, 256);
+
+ if (png_gamma_significant(gamma_val)) for (i=0; i<256; i++)
+ table[i] = png_gamma_8bit_correct(i, gamma_val);
+
+ else for (i=0; i<256; ++i)
+ table[i] = (png_byte)i;
+}
+
+/* Used from png_read_destroy and below to release the memory used by the gamma
+ * tables.
+ */
+void /* PRIVATE */
+png_destroy_gamma_table(png_structrp png_ptr)
+{
+ png_free(png_ptr, png_ptr->gamma_table);
+ png_ptr->gamma_table = NULL;
+
+ if (png_ptr->gamma_16_table != NULL)
+ {
+ int i;
+ int istop = (1 << (8 - png_ptr->gamma_shift));
+ for (i = 0; i < istop; i++)
+ {
+ png_free(png_ptr, png_ptr->gamma_16_table[i]);
+ }
+ png_free(png_ptr, png_ptr->gamma_16_table);
+ png_ptr->gamma_16_table = NULL;
+ }
+
+#if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
+ defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
+ defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
+ png_free(png_ptr, png_ptr->gamma_from_1);
+ png_ptr->gamma_from_1 = NULL;
+ png_free(png_ptr, png_ptr->gamma_to_1);
+ png_ptr->gamma_to_1 = NULL;
+
+ if (png_ptr->gamma_16_from_1 != NULL)
+ {
+ int i;
+ int istop = (1 << (8 - png_ptr->gamma_shift));
+ for (i = 0; i < istop; i++)
+ {
+ png_free(png_ptr, png_ptr->gamma_16_from_1[i]);
+ }
+ png_free(png_ptr, png_ptr->gamma_16_from_1);
+ png_ptr->gamma_16_from_1 = NULL;
+ }
+ if (png_ptr->gamma_16_to_1 != NULL)
+ {
+ int i;
+ int istop = (1 << (8 - png_ptr->gamma_shift));
+ for (i = 0; i < istop; i++)
+ {
+ png_free(png_ptr, png_ptr->gamma_16_to_1[i]);
+ }
+ png_free(png_ptr, png_ptr->gamma_16_to_1);
+ png_ptr->gamma_16_to_1 = NULL;
+ }
+#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
+}
+
+/* We build the 8- or 16-bit gamma tables here. Note that for 16-bit
+ * tables, we don't make a full table if we are reducing to 8-bit in
+ * the future. Note also how the gamma_16 tables are segmented so that
+ * we don't need to allocate > 64K chunks for a full 16-bit table.
+ */
+void /* PRIVATE */
+png_build_gamma_table(png_structrp png_ptr, int bit_depth)
+{
+ png_debug(1, "in png_build_gamma_table");
+
+ /* Remove any existing table; this copes with multiple calls to
+ * png_read_update_info. The warning is because building the gamma tables
+ * multiple times is a performance hit - it's harmless but the ability to call
+ * png_read_update_info() multiple times is new in 1.5.6 so it seems sensible
+ * to warn if the app introduces such a hit.
+ */
+ if (png_ptr->gamma_table != NULL || png_ptr->gamma_16_table != NULL)
+ {
+ png_warning(png_ptr, "gamma table being rebuilt");
+ png_destroy_gamma_table(png_ptr);
+ }
+
+ if (bit_depth <= 8)
+ {
+ png_build_8bit_table(png_ptr, &png_ptr->gamma_table,
+ png_ptr->screen_gamma > 0 ? png_reciprocal2(png_ptr->colorspace.gamma,
+ png_ptr->screen_gamma) : PNG_FP_1);
+
+#if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
+ defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
+ defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
+ if (png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY))
+ {
+ png_build_8bit_table(png_ptr, &png_ptr->gamma_to_1,
+ png_reciprocal(png_ptr->colorspace.gamma));
+
+ png_build_8bit_table(png_ptr, &png_ptr->gamma_from_1,
+ png_ptr->screen_gamma > 0 ? png_reciprocal(png_ptr->screen_gamma) :
+ png_ptr->colorspace.gamma/* Probably doing rgb_to_gray */);
+ }
+#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
+ }
+ else
+ {
+ png_byte shift, sig_bit;
+
+ if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)
+ {
+ sig_bit = png_ptr->sig_bit.red;
+
+ if (png_ptr->sig_bit.green > sig_bit)
+ sig_bit = png_ptr->sig_bit.green;
+
+ if (png_ptr->sig_bit.blue > sig_bit)
+ sig_bit = png_ptr->sig_bit.blue;
+ }
+ else
+ sig_bit = png_ptr->sig_bit.gray;
+
+ /* 16-bit gamma code uses this equation:
+ *
+ * ov = table[(iv & 0xff) >> gamma_shift][iv >> 8]
+ *
+ * Where 'iv' is the input color value and 'ov' is the output value -
+ * pow(iv, gamma).
+ *
+ * Thus the gamma table consists of up to 256 256 entry tables. The table
+ * is selected by the (8-gamma_shift) most significant of the low 8 bits of
+ * the color value then indexed by the upper 8 bits:
+ *
+ * table[low bits][high 8 bits]
+ *
+ * So the table 'n' corresponds to all those 'iv' of:
+ *
+ * <all high 8-bit values><n << gamma_shift>..<(n+1 << gamma_shift)-1>
+ *
+ */
+ if (sig_bit > 0 && sig_bit < 16U)
+ shift = (png_byte)(16U - sig_bit); /* shift == insignificant bits */
+
+ else
+ shift = 0; /* keep all 16 bits */
+
+ if (png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8))
+ {
+ /* PNG_MAX_GAMMA_8 is the number of bits to keep - effectively
+ * the significant bits in the *input* when the output will
+ * eventually be 8 bits. By default it is 11.
+ */
+ if (shift < (16U - PNG_MAX_GAMMA_8))
+ shift = (16U - PNG_MAX_GAMMA_8);
+ }
+
+ if (shift > 8U)
+ shift = 8U; /* Guarantees at least one table! */
+
+ png_ptr->gamma_shift = shift;
+
+#ifdef PNG_16BIT_SUPPORTED
+ /* NOTE: prior to 1.5.4 this test used to include PNG_BACKGROUND (now
+ * PNG_COMPOSE). This effectively smashed the background calculation for
+ * 16-bit output because the 8-bit table assumes the result will be reduced
+ * to 8 bits.
+ */
+ if (png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8))
+#endif
+ png_build_16to8_table(png_ptr, &png_ptr->gamma_16_table, shift,
+ png_ptr->screen_gamma > 0 ? png_product2(png_ptr->colorspace.gamma,
+ png_ptr->screen_gamma) : PNG_FP_1);
+
+#ifdef PNG_16BIT_SUPPORTED
+ else
+ png_build_16bit_table(png_ptr, &png_ptr->gamma_16_table, shift,
+ png_ptr->screen_gamma > 0 ? png_reciprocal2(png_ptr->colorspace.gamma,
+ png_ptr->screen_gamma) : PNG_FP_1);
+#endif
+
+#if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
+ defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
+ defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
+ if (png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY))
+ {
+ png_build_16bit_table(png_ptr, &png_ptr->gamma_16_to_1, shift,
+ png_reciprocal(png_ptr->colorspace.gamma));
+
+ /* Notice that the '16 from 1' table should be full precision, however
+ * the lookup on this table still uses gamma_shift, so it can't be.
+ * TODO: fix this.
+ */
+ png_build_16bit_table(png_ptr, &png_ptr->gamma_16_from_1, shift,
+ png_ptr->screen_gamma > 0 ? png_reciprocal(png_ptr->screen_gamma) :
+ png_ptr->colorspace.gamma/* Probably doing rgb_to_gray */);
+ }
+#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
+ }
+}
+#endif /* READ_GAMMA */
+
+/* HARDWARE OPTION SUPPORT */
+#ifdef PNG_SET_OPTION_SUPPORTED
+int PNGAPI
+png_set_option(png_structrp png_ptr, int option, int onoff)
+{
+ if (png_ptr != NULL && option >= 0 && option < PNG_OPTION_NEXT &&
+ (option & 1) == 0)
+ {
+ int mask = 3 << option;
+ int setting = (2 + (onoff != 0)) << option;
+ int current = png_ptr->options;
+
+ png_ptr->options = (png_byte)((current & ~mask) | setting);
+
+ return (current & mask) >> option;
+ }
+
+ return PNG_OPTION_INVALID;
+}
+#endif
+
+/* sRGB support */
+#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\
+ defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
+/* sRGB conversion tables; these are machine generated with the code in
+ * contrib/tools/makesRGB.c. The actual sRGB transfer curve defined in the
+ * specification (see the article at http://en.wikipedia.org/wiki/SRGB)
+ * is used, not the gamma=1/2.2 approximation use elsewhere in libpng.
+ * The sRGB to linear table is exact (to the nearest 16 bit linear fraction).
+ * The inverse (linear to sRGB) table has accuracies as follows:
+ *
+ * For all possible (255*65535+1) input values:
+ *
+ * error: -0.515566 - 0.625971, 79441 (0.475369%) of readings inexact
+ *
+ * For the input values corresponding to the 65536 16-bit values:
+ *
+ * error: -0.513727 - 0.607759, 308 (0.469978%) of readings inexact
+ *
+ * In all cases the inexact readings are off by one.
+ */
+
+#ifdef PNG_SIMPLIFIED_READ_SUPPORTED
+/* The convert-to-sRGB table is only currently required for read. */
+const png_uint_16 png_sRGB_table[256] =
+{
+ 0,20,40,60,80,99,119,139,
+ 159,179,199,219,241,264,288,313,
+ 340,367,396,427,458,491,526,562,
+ 599,637,677,718,761,805,851,898,
+ 947,997,1048,1101,1156,1212,1270,1330,
+ 1391,1453,1517,1583,1651,1720,1790,1863,
+ 1937,2013,2090,2170,2250,2333,2418,2504,
+ 2592,2681,2773,2866,2961,3058,3157,3258,
+ 3360,3464,3570,3678,3788,3900,4014,4129,
+ 4247,4366,4488,4611,4736,4864,4993,5124,
+ 5257,5392,5530,5669,5810,5953,6099,6246,
+ 6395,6547,6700,6856,7014,7174,7335,7500,
+ 7666,7834,8004,8177,8352,8528,8708,8889,
+ 9072,9258,9445,9635,9828,10022,10219,10417,
+ 10619,10822,11028,11235,11446,11658,11873,12090,
+ 12309,12530,12754,12980,13209,13440,13673,13909,
+ 14146,14387,14629,14874,15122,15371,15623,15878,
+ 16135,16394,16656,16920,17187,17456,17727,18001,
+ 18277,18556,18837,19121,19407,19696,19987,20281,
+ 20577,20876,21177,21481,21787,22096,22407,22721,
+ 23038,23357,23678,24002,24329,24658,24990,25325,
+ 25662,26001,26344,26688,27036,27386,27739,28094,
+ 28452,28813,29176,29542,29911,30282,30656,31033,
+ 31412,31794,32179,32567,32957,33350,33745,34143,
+ 34544,34948,35355,35764,36176,36591,37008,37429,
+ 37852,38278,38706,39138,39572,40009,40449,40891,
+ 41337,41785,42236,42690,43147,43606,44069,44534,
+ 45002,45473,45947,46423,46903,47385,47871,48359,
+ 48850,49344,49841,50341,50844,51349,51858,52369,
+ 52884,53401,53921,54445,54971,55500,56032,56567,
+ 57105,57646,58190,58737,59287,59840,60396,60955,
+ 61517,62082,62650,63221,63795,64372,64952,65535
+};
+
+#endif /* simplified read only */
+
+/* The base/delta tables are required for both read and write (but currently
+ * only the simplified versions.)
+ */
+const png_uint_16 png_sRGB_base[512] =
+{
+ 128,1782,3383,4644,5675,6564,7357,8074,
+ 8732,9346,9921,10463,10977,11466,11935,12384,
+ 12816,13233,13634,14024,14402,14769,15125,15473,
+ 15812,16142,16466,16781,17090,17393,17690,17981,
+ 18266,18546,18822,19093,19359,19621,19879,20133,
+ 20383,20630,20873,21113,21349,21583,21813,22041,
+ 22265,22487,22707,22923,23138,23350,23559,23767,
+ 23972,24175,24376,24575,24772,24967,25160,25352,
+ 25542,25730,25916,26101,26284,26465,26645,26823,
+ 27000,27176,27350,27523,27695,27865,28034,28201,
+ 28368,28533,28697,28860,29021,29182,29341,29500,
+ 29657,29813,29969,30123,30276,30429,30580,30730,
+ 30880,31028,31176,31323,31469,31614,31758,31902,
+ 32045,32186,32327,32468,32607,32746,32884,33021,
+ 33158,33294,33429,33564,33697,33831,33963,34095,
+ 34226,34357,34486,34616,34744,34873,35000,35127,
+ 35253,35379,35504,35629,35753,35876,35999,36122,
+ 36244,36365,36486,36606,36726,36845,36964,37083,
+ 37201,37318,37435,37551,37668,37783,37898,38013,
+ 38127,38241,38354,38467,38580,38692,38803,38915,
+ 39026,39136,39246,39356,39465,39574,39682,39790,
+ 39898,40005,40112,40219,40325,40431,40537,40642,
+ 40747,40851,40955,41059,41163,41266,41369,41471,
+ 41573,41675,41777,41878,41979,42079,42179,42279,
+ 42379,42478,42577,42676,42775,42873,42971,43068,
+ 43165,43262,43359,43456,43552,43648,43743,43839,
+ 43934,44028,44123,44217,44311,44405,44499,44592,
+ 44685,44778,44870,44962,45054,45146,45238,45329,
+ 45420,45511,45601,45692,45782,45872,45961,46051,
+ 46140,46229,46318,46406,46494,46583,46670,46758,
+ 46846,46933,47020,47107,47193,47280,47366,47452,
+ 47538,47623,47709,47794,47879,47964,48048,48133,
+ 48217,48301,48385,48468,48552,48635,48718,48801,
+ 48884,48966,49048,49131,49213,49294,49376,49458,
+ 49539,49620,49701,49782,49862,49943,50023,50103,
+ 50183,50263,50342,50422,50501,50580,50659,50738,
+ 50816,50895,50973,51051,51129,51207,51285,51362,
+ 51439,51517,51594,51671,51747,51824,51900,51977,
+ 52053,52129,52205,52280,52356,52432,52507,52582,
+ 52657,52732,52807,52881,52956,53030,53104,53178,
+ 53252,53326,53400,53473,53546,53620,53693,53766,
+ 53839,53911,53984,54056,54129,54201,54273,54345,
+ 54417,54489,54560,54632,54703,54774,54845,54916,
+ 54987,55058,55129,55199,55269,55340,55410,55480,
+ 55550,55620,55689,55759,55828,55898,55967,56036,
+ 56105,56174,56243,56311,56380,56448,56517,56585,
+ 56653,56721,56789,56857,56924,56992,57059,57127,
+ 57194,57261,57328,57395,57462,57529,57595,57662,
+ 57728,57795,57861,57927,57993,58059,58125,58191,
+ 58256,58322,58387,58453,58518,58583,58648,58713,
+ 58778,58843,58908,58972,59037,59101,59165,59230,
+ 59294,59358,59422,59486,59549,59613,59677,59740,
+ 59804,59867,59930,59993,60056,60119,60182,60245,
+ 60308,60370,60433,60495,60558,60620,60682,60744,
+ 60806,60868,60930,60992,61054,61115,61177,61238,
+ 61300,61361,61422,61483,61544,61605,61666,61727,
+ 61788,61848,61909,61969,62030,62090,62150,62211,
+ 62271,62331,62391,62450,62510,62570,62630,62689,
+ 62749,62808,62867,62927,62986,63045,63104,63163,
+ 63222,63281,63340,63398,63457,63515,63574,63632,
+ 63691,63749,63807,63865,63923,63981,64039,64097,
+ 64155,64212,64270,64328,64385,64443,64500,64557,
+ 64614,64672,64729,64786,64843,64900,64956,65013,
+ 65070,65126,65183,65239,65296,65352,65409,65465
+};
+
+const png_byte png_sRGB_delta[512] =
+{
+ 207,201,158,129,113,100,90,82,77,72,68,64,61,59,56,54,
+ 52,50,49,47,46,45,43,42,41,40,39,39,38,37,36,36,
+ 35,34,34,33,33,32,32,31,31,30,30,30,29,29,28,28,
+ 28,27,27,27,27,26,26,26,25,25,25,25,24,24,24,24,
+ 23,23,23,23,23,22,22,22,22,22,22,21,21,21,21,21,
+ 21,20,20,20,20,20,20,20,20,19,19,19,19,19,19,19,
+ 19,18,18,18,18,18,18,18,18,18,18,17,17,17,17,17,
+ 17,17,17,17,17,17,16,16,16,16,16,16,16,16,16,16,
+ 16,16,16,16,15,15,15,15,15,15,15,15,15,15,15,15,
+ 15,15,15,15,14,14,14,14,14,14,14,14,14,14,14,14,
+ 14,14,14,14,14,14,14,13,13,13,13,13,13,13,13,13,
+ 13,13,13,13,13,13,13,13,13,13,13,13,13,13,12,12,
+ 12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,
+ 12,12,12,12,12,12,12,12,12,12,12,12,11,11,11,11,
+ 11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,
+ 11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,
+ 11,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,
+ 10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,
+ 10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,
+ 10,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
+ 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
+ 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
+ 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
+ 9,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
+ 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
+ 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
+ 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
+ 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
+ 8,8,8,8,8,8,8,8,8,7,7,7,7,7,7,7,
+ 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
+ 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
+ 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7
+};
+#endif /* SIMPLIFIED READ/WRITE sRGB support */
+
+/* SIMPLIFIED READ/WRITE SUPPORT */
+#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\
+ defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
+static int
+png_image_free_function(png_voidp argument)
+{
+ png_imagep image = png_voidcast(png_imagep, argument);
+ png_controlp cp = image->opaque;
+ png_control c;
+
+ /* Double check that we have a png_ptr - it should be impossible to get here
+ * without one.
+ */
+ if (cp->png_ptr == NULL)
+ return 0;
+
+ /* First free any data held in the control structure. */
+# ifdef PNG_STDIO_SUPPORTED
+ if (cp->owned_file)
+ {
+ FILE *fp = png_voidcast(FILE*, cp->png_ptr->io_ptr);
+ cp->owned_file = 0;
+
+ /* Ignore errors here. */
+ if (fp != NULL)
+ {
+ cp->png_ptr->io_ptr = NULL;
+ (void)fclose(fp);
+ }
+ }
+# endif
+
+ /* Copy the control structure so that the original, allocated, version can be
+ * safely freed. Notice that a png_error here stops the remainder of the
+ * cleanup, but this is probably fine because that would indicate bad memory
+ * problems anyway.
+ */
+ c = *cp;
+ image->opaque = &c;
+ png_free(c.png_ptr, cp);
+
+ /* Then the structures, calling the correct API. */
+ if (c.for_write)
+ {
+# ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED
+ png_destroy_write_struct(&c.png_ptr, &c.info_ptr);
+# else
+ png_error(c.png_ptr, "simplified write not supported");
+# endif
+ }
+ else
+ {
+# ifdef PNG_SIMPLIFIED_READ_SUPPORTED
+ png_destroy_read_struct(&c.png_ptr, &c.info_ptr, NULL);
+# else
+ png_error(c.png_ptr, "simplified read not supported");
+# endif
+ }
+
+ /* Success. */
+ return 1;
+}
+
+void PNGAPI
+png_image_free(png_imagep image)
+{
+ /* Safely call the real function, but only if doing so is safe at this point
+ * (if not inside an error handling context). Otherwise assume
+ * png_safe_execute will call this API after the return.
+ */
+ if (image != NULL && image->opaque != NULL &&
+ image->opaque->error_buf == NULL)
+ {
+ /* Ignore errors here: */
+ (void)png_safe_execute(image, png_image_free_function, image);
+ image->opaque = NULL;
+ }
+}
+
+int /* PRIVATE */
+png_image_error(png_imagep image, png_const_charp error_message)
+{
+ /* Utility to log an error. */
+ png_safecat(image->message, (sizeof image->message), 0, error_message);
+ image->warning_or_error |= PNG_IMAGE_ERROR;
+ png_image_free(image);
+ return 0;
+}
+
+#endif /* SIMPLIFIED READ/WRITE */
+#endif /* defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) */
|