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|
#include "fitz.h"
#include "mupdf.h"
static inline int iswhite(int ch)
{
return
ch == '\000' || ch == '\011' || ch == '\012' ||
ch == '\014' || ch == '\015' || ch == '\040';
}
/*
* magic version tag and startxref
*/
static void
pdf_load_version(pdf_xref *xref)
{
char buf[20];
fz_seek(xref->file, 0, 0);
fz_read_line(xref->file, buf, sizeof buf);
if (memcmp(buf, "%PDF-", 5) != 0)
fz_throw(xref->ctx, "cannot recognize version marker");
xref->version = atoi(buf + 5) * 10 + atoi(buf + 7);
}
static void
pdf_read_start_xref(pdf_xref *xref)
{
unsigned char buf[1024];
int t, n;
int i;
fz_seek(xref->file, 0, 2);
xref->file_size = fz_tell(xref->file);
t = MAX(0, xref->file_size - (int)sizeof buf);
fz_seek(xref->file, t, 0);
n = fz_read(xref->file, buf, sizeof buf);
if (n < 0)
fz_throw(xref->ctx, "cannot read from file");
for (i = n - 9; i >= 0; i--)
{
if (memcmp(buf + i, "startxref", 9) == 0)
{
i += 9;
while (iswhite(buf[i]) && i < n)
i ++;
xref->startxref = atoi((char*)(buf + i));
return;
}
}
fz_throw(xref->ctx, "cannot find startxref");
}
/*
* trailer dictionary
*/
static void
pdf_read_old_trailer(pdf_xref *xref, char *buf, int cap)
{
int len;
char *s;
int n;
int t;
int tok;
int c;
fz_read_line(xref->file, buf, cap);
if (strncmp(buf, "xref", 4) != 0)
fz_throw(xref->ctx, "cannot find xref marker");
while (1)
{
c = fz_peek_byte(xref->file);
if (!(c >= '0' && c <= '9'))
break;
fz_read_line(xref->file, buf, cap);
s = buf;
fz_strsep(&s, " "); /* ignore ofs */
if (!s)
fz_throw(xref->ctx, "invalid range marker in xref");
len = atoi(fz_strsep(&s, " "));
/* broken pdfs where the section is not on a separate line */
if (s && *s != '\0')
fz_seek(xref->file, -(2 + (int)strlen(s)), 1);
t = fz_tell(xref->file);
if (t < 0)
fz_throw(xref->ctx, "cannot tell in file");
fz_seek(xref->file, t + 20 * len, 0);
}
fz_try(xref->ctx)
{
tok = pdf_lex(xref->file, buf, cap, &n);
if (tok != PDF_TOK_TRAILER)
fz_throw(xref->ctx, "expected trailer marker");
tok = pdf_lex(xref->file, buf, cap, &n);
if (tok != PDF_TOK_OPEN_DICT)
fz_throw(xref->ctx, "expected trailer dictionary");
xref->trailer = pdf_parse_dict(xref, xref->file, buf, cap);
}
fz_catch(xref->ctx)
{
fz_throw(xref->ctx, "cannot parse trailer");
}
}
static void
pdf_read_new_trailer(pdf_xref *xref, char *buf, int cap)
{
fz_try(xref->ctx)
{
xref->trailer = pdf_parse_ind_obj(xref, xref->file, buf, cap, NULL, NULL, NULL);
}
fz_catch(xref->ctx)
{
fz_throw(xref->ctx, "cannot parse trailer (compressed)");
}
}
static void
pdf_read_trailer(pdf_xref *xref, char *buf, int cap)
{
int c;
fz_seek(xref->file, xref->startxref, 0);
while (iswhite(fz_peek_byte(xref->file)))
fz_read_byte(xref->file);
fz_try(xref->ctx)
{
c = fz_peek_byte(xref->file);
if (c == 'x')
pdf_read_old_trailer(xref, buf, cap);
else if (c >= '0' && c <= '9')
pdf_read_new_trailer(xref, buf, cap);
else
fz_throw(xref->ctx, "cannot recognize xref format: '%c'", c);
}
fz_catch(xref->ctx)
{
fz_throw(xref->ctx, "cannot read trailer");
}
}
/*
* xref tables
*/
void
pdf_resize_xref(pdf_xref *xref, int newlen)
{
int i;
xref->table = fz_resize_array(xref->ctx, xref->table, newlen, sizeof(pdf_xref_entry));
for (i = xref->len; i < newlen; i++)
{
xref->table[i].type = 0;
xref->table[i].ofs = 0;
xref->table[i].gen = 0;
xref->table[i].stm_ofs = 0;
xref->table[i].obj = NULL;
}
xref->len = newlen;
}
static fz_obj *
pdf_read_old_xref(pdf_xref *xref, char *buf, int cap)
{
int ofs, len;
char *s;
int n;
int tok;
int i;
int c;
fz_obj *trailer;
fz_read_line(xref->file, buf, cap);
if (strncmp(buf, "xref", 4) != 0)
fz_throw(xref->ctx, "cannot find xref marker");
while (1)
{
c = fz_peek_byte(xref->file);
if (!(c >= '0' && c <= '9'))
break;
fz_read_line(xref->file, buf, cap);
s = buf;
ofs = atoi(fz_strsep(&s, " "));
len = atoi(fz_strsep(&s, " "));
/* broken pdfs where the section is not on a separate line */
if (s && *s != '\0')
{
fz_warn(xref->ctx, "broken xref section. proceeding anyway.");
fz_seek(xref->file, -(2 + (int)strlen(s)), 1);
}
/* broken pdfs where size in trailer undershoots entries in xref sections */
if (ofs + len > xref->len)
{
fz_warn(xref->ctx, "broken xref section, proceeding anyway.");
pdf_resize_xref(xref, ofs + len);
}
for (i = ofs; i < ofs + len; i++)
{
n = fz_read(xref->file, (unsigned char *) buf, 20);
if (n < 0)
fz_throw(xref->ctx, "cannot read xref table");
if (!xref->table[i].type)
{
s = buf;
/* broken pdfs where line start with white space */
while (*s != '\0' && iswhite(*s))
s++;
xref->table[i].ofs = atoi(s);
xref->table[i].gen = atoi(s + 11);
xref->table[i].type = s[17];
if (s[17] != 'f' && s[17] != 'n' && s[17] != 'o')
fz_throw(xref->ctx, "unexpected xref type: %#x (%d %d R)", s[17], i, xref->table[i].gen);
}
}
}
fz_try(xref->ctx)
{
tok = pdf_lex(xref->file, buf, cap, &n);
if (tok != PDF_TOK_TRAILER)
fz_throw(xref->ctx, "expected trailer marker");
tok = pdf_lex(xref->file, buf, cap, &n);
if (tok != PDF_TOK_OPEN_DICT)
fz_throw(xref->ctx, "expected trailer dictionary");
trailer = pdf_parse_dict(xref, xref->file, buf, cap);
}
fz_catch(xref->ctx)
{
fz_throw(xref->ctx, "cannot parse trailer");
}
return trailer;
}
static void
pdf_read_new_xref_section(pdf_xref *xref, fz_stream *stm, int i0, int i1, int w0, int w1, int w2)
{
int i, n;
if (i0 < 0 || i0 + i1 > xref->len)
fz_throw(xref->ctx, "xref stream has too many entries");
for (i = i0; i < i0 + i1; i++)
{
int a = 0;
int b = 0;
int c = 0;
if (fz_is_eof(stm))
fz_throw(xref->ctx, "truncated xref stream");
for (n = 0; n < w0; n++)
a = (a << 8) + fz_read_byte(stm);
for (n = 0; n < w1; n++)
b = (b << 8) + fz_read_byte(stm);
for (n = 0; n < w2; n++)
c = (c << 8) + fz_read_byte(stm);
if (!xref->table[i].type)
{
int t = w0 ? a : 1;
xref->table[i].type = t == 0 ? 'f' : t == 1 ? 'n' : t == 2 ? 'o' : 0;
xref->table[i].ofs = w1 ? b : 0;
xref->table[i].gen = w2 ? c : 0;
}
}
}
static fz_obj *
pdf_read_new_xref(pdf_xref *xref, char *buf, int cap)
{
fz_stream *stm;
fz_obj * volatile trailer = NULL;
fz_obj *index = NULL;
fz_obj *obj = NULL;
int num, gen, stm_ofs;
int size, w0, w1, w2;
int t;
fz_context *ctx = xref->ctx;
fz_try(ctx)
{
trailer = pdf_parse_ind_obj(xref, xref->file, buf, cap, &num, &gen, &stm_ofs);
}
fz_catch(ctx)
{
fz_throw(ctx, "cannot parse compressed xref stream object");
}
fz_try(ctx)
{
obj = fz_dict_gets(trailer, "Size");
if (!obj)
fz_throw(ctx, "xref stream missing Size entry (%d %d R)", num, gen);
size = fz_to_int(obj);
if (size > xref->len)
pdf_resize_xref(xref, size);
if (num < 0 || num >= xref->len)
fz_throw(ctx, "object id (%d %d R) out of range (0..%d)", num, gen, xref->len - 1);
obj = fz_dict_gets(trailer, "W");
if (!obj)
fz_throw(ctx, "xref stream missing W entry (%d %d R)", num, gen);
w0 = fz_to_int(fz_array_get(obj, 0));
w1 = fz_to_int(fz_array_get(obj, 1));
w2 = fz_to_int(fz_array_get(obj, 2));
index = fz_dict_gets(trailer, "Index");
stm = pdf_open_stream_at(xref, num, gen, trailer, stm_ofs);
/* RJW: Ensure pdf_open_stream does fz_throw(ctx, "cannot open compressed xref stream (%d %d R)", num, gen); */
if (!index)
{
pdf_read_new_xref_section(xref, stm, 0, size, w0, w1, w2);
/* RJW: Ensure above does fz_throw(ctx, "cannot read xref stream (%d %d R)", num, gen); */
}
else
{
int n = fz_array_len(index);
for (t = 0; t < n; t += 2)
{
int i0 = fz_to_int(fz_array_get(index, t + 0));
int i1 = fz_to_int(fz_array_get(index, t + 1));
pdf_read_new_xref_section(xref, stm, i0, i1, w0, w1, w2);
}
}
}
fz_catch(ctx)
{
fz_close(stm);
fz_drop_obj(trailer);
fz_drop_obj(index);
fz_drop_obj(obj);
fz_rethrow(ctx);
}
fz_close(stm);
return trailer;
}
static fz_obj *
pdf_read_xref(pdf_xref *xref, int ofs, char *buf, int cap)
{
int c;
fz_context *ctx = xref->ctx;
fz_obj *trailer;
fz_seek(xref->file, ofs, 0);
while (iswhite(fz_peek_byte(xref->file)))
fz_read_byte(xref->file);
fz_try(ctx)
{
c = fz_peek_byte(xref->file);
if (c == 'x')
trailer = pdf_read_old_xref(xref, buf, cap);
else if (c >= '0' && c <= '9')
trailer = pdf_read_new_xref(xref, buf, cap);
else
fz_throw(ctx, "cannot recognize xref format");
}
fz_catch(ctx)
{
fz_throw(ctx, "cannot read xref (ofs=%d)", ofs);
}
return trailer;
}
static void
pdf_read_xref_sections(pdf_xref *xref, int ofs, char *buf, int cap)
{
fz_obj *trailer = NULL;
fz_obj *xrefstm = NULL;
fz_obj *prev = NULL;
fz_context *ctx = xref->ctx;
fz_try(ctx)
{
trailer = pdf_read_xref(xref, ofs, buf, cap);
/* FIXME: do we overwrite free entries properly? */
xrefstm = fz_dict_gets(trailer, "XRefStm");
if (xrefstm)
pdf_read_xref_sections(xref, fz_to_int(xrefstm), buf, cap);
prev = fz_dict_gets(trailer, "Prev");
if (prev)
pdf_read_xref_sections(xref, fz_to_int(prev), buf, cap);
}
fz_catch(ctx)
{
fz_drop_obj(trailer);
fz_throw(ctx, "Failed to read xref at offset %d", ofs);
}
fz_drop_obj(trailer);
}
/*
* load xref tables from pdf
*/
static void
pdf_load_xref(pdf_xref *xref, char *buf, int bufsize)
{
fz_obj *size;
int i;
fz_context *ctx = xref->ctx;
pdf_load_version(xref);
pdf_read_start_xref(xref);
pdf_read_trailer(xref, buf, bufsize);
size = fz_dict_gets(xref->trailer, "Size");
if (!size)
fz_throw(ctx, "trailer missing Size entry");
pdf_resize_xref(xref, fz_to_int(size));
pdf_read_xref_sections(xref, xref->startxref, buf, bufsize);
/* broken pdfs where first object is not free */
if (xref->table[0].type != 'f')
fz_throw(ctx, "first object in xref is not free");
/* broken pdfs where object offsets are out of range */
for (i = 0; i < xref->len; i++)
{
if (xref->table[i].type == 'n')
if (xref->table[i].ofs <= 0 || xref->table[i].ofs >= xref->file_size)
fz_throw(ctx, "object offset out of range: %d (%d 0 R)", xref->table[i].ofs, i);
if (xref->table[i].type == 'o')
if (xref->table[i].ofs <= 0 || xref->table[i].ofs >= xref->len || xref->table[xref->table[i].ofs].type != 'n')
fz_throw(ctx, "invalid reference to an objstm that does not exist: %d (%d 0 R)", xref->table[i].ofs, i);
}
}
/*
* Initialize and load xref tables.
* If password is not null, try to decrypt.
*/
pdf_xref *
pdf_open_xref_with_stream(fz_stream *file, char *password)
{
pdf_xref *xref;
fz_obj *encrypt, *id;
fz_obj *dict = NULL;
fz_obj *obj;
fz_obj *nobj;
int i, repaired = 0;
fz_context *ctx = file->ctx;
//fz_var(dict);
/* install pdf specific callback */
fz_resolve_indirect = pdf_resolve_indirect;
xref = fz_calloc(ctx, 1, sizeof(pdf_xref));
xref->file = fz_keep_stream(file);
xref->ctx = ctx;
fz_try(ctx)
{
pdf_load_xref(xref, xref->scratch, sizeof xref->scratch);
}
fz_catch(ctx)
{
if (xref->table)
{
fz_free(xref->ctx, xref->table);
xref->table = NULL;
xref->len = 0;
}
if (xref->trailer)
{
fz_drop_obj(xref->trailer);
xref->trailer = NULL;
}
pdf_repair_xref(xref, xref->scratch, sizeof xref->scratch);
repaired = 1;
}
fz_try(ctx)
{
int hasroot, hasinfo;
encrypt = fz_dict_gets(xref->trailer, "Encrypt");
id = fz_dict_gets(xref->trailer, "ID");
if (fz_is_dict(encrypt))
xref->crypt = pdf_new_crypt(ctx, encrypt, id);
if (pdf_needs_password(xref))
{
/* Only care if we have a password */
if (password)
{
pdf_authenticate_password(xref, password);
}
}
if (repaired)
{
pdf_repair_obj_stms(xref);
}
hasroot = fz_dict_gets(xref->trailer, "Root") != NULL;
hasinfo = fz_dict_gets(xref->trailer, "Info") != NULL;
for (i = 1; i < xref->len; i++)
{
if (xref->table[i].type == 0 || xref->table[i].type == 'f')
continue;
fz_try(ctx)
{
dict = pdf_load_object(xref, i, 0);
}
fz_catch(ctx)
{
fz_warn(ctx, "ignoring broken object (%d 0 R)", i);
continue;
}
if (!hasroot)
{
obj = fz_dict_gets(dict, "Type");
if (fz_is_name(obj) && !strcmp(fz_to_name(obj), "Catalog"))
{
nobj = fz_new_indirect(ctx, i, 0, xref);
fz_dict_puts(xref->trailer, "Root", nobj);
fz_drop_obj(nobj);
nobj = NULL;
}
}
if (!hasinfo)
{
if (fz_dict_gets(dict, "Creator") || fz_dict_gets(dict, "Producer"))
{
nobj = fz_new_indirect(ctx, i, 0, xref);
fz_dict_puts(xref->trailer, "Info", nobj);
fz_drop_obj(nobj);
nobj = NULL;
}
}
fz_drop_obj(dict);
dict = NULL;
}
}
fz_catch(ctx)
{
fz_drop_obj(dict);
fz_drop_obj(nobj);
pdf_free_xref(xref);
fz_throw(ctx, "cannot open document");
}
return xref;
}
void
pdf_free_xref(pdf_xref *xref)
{
int i;
fz_context *ctx = xref->ctx;
if (xref->store)
pdf_free_store(ctx, xref->store);
if (xref->table)
{
for (i = 0; i < xref->len; i++)
{
if (xref->table[i].obj)
{
fz_drop_obj(xref->table[i].obj);
xref->table[i].obj = NULL;
}
}
fz_free(xref->ctx, xref->table);
}
if (xref->page_objs)
{
for (i = 0; i < xref->page_len; i++)
fz_drop_obj(xref->page_objs[i]);
fz_free(ctx, xref->page_objs);
}
if (xref->page_refs)
{
for (i = 0; i < xref->page_len; i++)
fz_drop_obj(xref->page_refs[i]);
fz_free(ctx, xref->page_refs);
}
if (xref->file)
fz_close(xref->file);
if (xref->trailer)
fz_drop_obj(xref->trailer);
if (xref->crypt)
pdf_free_crypt(ctx, xref->crypt);
fz_free(ctx, xref);
}
void
pdf_debug_xref(pdf_xref *xref)
{
int i;
printf("xref\n0 %d\n", xref->len);
for (i = 0; i < xref->len; i++)
{
printf("%05d: %010d %05d %c (stm_ofs=%d)\n", i,
xref->table[i].ofs,
xref->table[i].gen,
xref->table[i].type ? xref->table[i].type : '-',
xref->table[i].stm_ofs);
}
}
/*
* compressed object streams
*/
static void
pdf_load_obj_stm(pdf_xref *xref, int num, int gen, char *buf, int cap)
{
fz_stream *stm;
fz_obj *objstm;
int * volatile numbuf = NULL;
int * volatile ofsbuf = NULL;
fz_obj *obj;
int first;
int count;
int i, n;
int tok;
fz_context *ctx = xref->ctx;
//fz_var(numbuf);
//fz_var(ofsbuf);
fz_try(ctx)
{
objstm = pdf_load_object(xref, num, gen);
count = fz_to_int(fz_dict_gets(objstm, "N"));
first = fz_to_int(fz_dict_gets(objstm, "First"));
numbuf = fz_calloc(ctx, count, sizeof(int));
ofsbuf = fz_calloc(ctx, count, sizeof(int));
stm = pdf_open_stream(xref, num, gen);
for (i = 0; i < count; i++)
{
tok = pdf_lex(stm, buf, cap, &n);
if (tok != PDF_TOK_INT)
fz_throw(ctx, "corrupt object stream (%d %d R)", num, gen);
numbuf[i] = atoi(buf);
tok = pdf_lex(stm, buf, cap, &n);
if (tok != PDF_TOK_INT)
fz_throw(ctx, "corrupt object stream (%d %d R)", num, gen);
ofsbuf[i] = atoi(buf);
}
fz_seek(stm, first, 0);
for (i = 0; i < count; i++)
{
fz_seek(stm, first + ofsbuf[i], 0);
obj = pdf_parse_stm_obj(xref, stm, buf, cap);
/* RJW: Ensure above does fz_throw(ctx, "cannot parse object %d in stream (%d %d R)", i, num, gen); */
if (numbuf[i] < 1 || numbuf[i] >= xref->len)
{
fz_drop_obj(obj);
fz_throw(ctx, "object id (%d 0 R) out of range (0..%d)", numbuf[i], xref->len - 1);
}
if (xref->table[numbuf[i]].type == 'o' && xref->table[numbuf[i]].ofs == num)
{
if (xref->table[numbuf[i]].obj)
fz_drop_obj(xref->table[numbuf[i]].obj);
xref->table[numbuf[i]].obj = obj;
}
else
{
fz_drop_obj(obj);
}
}
}
fz_catch(ctx)
{
fz_close(stm);
fz_free(xref->ctx, ofsbuf);
fz_free(xref->ctx, numbuf);
fz_drop_obj(objstm);
fz_throw(ctx, "cannot open object stream (%d %d R)", num, gen);
}
fz_close(stm);
fz_free(xref->ctx, ofsbuf);
fz_free(xref->ctx, numbuf);
fz_drop_obj(objstm);
}
/*
* object loading
*/
void
pdf_cache_object(pdf_xref *xref, int num, int gen)
{
pdf_xref_entry *x;
int rnum, rgen;
fz_context *ctx = xref->ctx;
if (num < 0 || num >= xref->len)
fz_throw(ctx, "object out of range (%d %d R); xref size %d", num, gen, xref->len);
x = &xref->table[num];
if (x->obj)
return;
if (x->type == 'f')
{
x->obj = fz_new_null(ctx);
return;
}
else if (x->type == 'n')
{
fz_seek(xref->file, x->ofs, 0);
fz_try(ctx)
{
x->obj = pdf_parse_ind_obj(xref, xref->file, xref->scratch, sizeof xref->scratch,
&rnum, &rgen, &x->stm_ofs);
}
fz_catch(ctx)
{
fz_throw(ctx, "cannot parse object (%d %d R)", num, gen);
}
if (rnum != num)
fz_throw(ctx, "found object (%d %d R) instead of (%d %d R)", rnum, rgen, num, gen);
if (xref->crypt)
pdf_crypt_obj(ctx, xref->crypt, x->obj, num, gen);
}
else if (x->type == 'o')
{
if (!x->obj)
{
fz_try(ctx)
{
pdf_load_obj_stm(xref, x->ofs, 0, xref->scratch, sizeof xref->scratch);
}
fz_catch(ctx)
{
fz_throw(ctx, "cannot load object stream containing object (%d %d R)", num, gen);
}
if (!x->obj)
fz_throw(ctx, "object (%d %d R) was not found in its object stream", num, gen);
}
}
else
{
fz_throw(ctx, "assert: corrupt xref struct");
}
}
fz_obj *
pdf_load_object(pdf_xref *xref, int num, int gen)
{
fz_context *ctx = xref->ctx;
fz_try(ctx)
{
pdf_cache_object(xref, num, gen);
}
fz_catch(ctx)
{
fz_throw(ctx, "cannot load object (%d %d R) into cache", num, gen);
}
assert(xref->table[num].obj);
return fz_keep_obj(xref->table[num].obj);
}
fz_obj *
pdf_resolve_indirect(fz_obj *ref)
{
if (fz_is_indirect(ref))
{
pdf_xref *xref = fz_get_indirect_xref(ref);
fz_context *ctx = xref->ctx;
int num = fz_to_num(ref);
int gen = fz_to_gen(ref);
if (xref)
{
fz_try(ctx)
{
pdf_cache_object(xref, num, gen);
}
fz_catch(ctx)
{
fz_warn(ctx, "cannot load object (%d %d R) into cache", num, gen);
return ref;
}
if (xref->table[num].obj)
return xref->table[num].obj;
}
}
return ref;
}
/* Replace numbered object -- for use by pdfclean and similar tools */
void
pdf_update_object(pdf_xref *xref, int num, int gen, fz_obj *newobj)
{
pdf_xref_entry *x;
if (num < 0 || num >= xref->len)
{
fz_warn(xref->ctx, "object out of range (%d %d R); xref size %d", num, gen, xref->len);
return;
}
x = &xref->table[num];
if (x->obj)
fz_drop_obj(x->obj);
x->obj = fz_keep_obj(newobj);
x->type = 'n';
x->ofs = 0;
}
/*
* Convenience function to open a file then call pdf_open_xref_with_stream.
*/
pdf_xref *
pdf_open_xref(fz_context *ctx, const char *filename, char *password)
{
fz_stream *file = NULL;
pdf_xref *xref;
//fz_var(file);
fz_try(ctx)
{
file = fz_open_file(ctx, filename);
xref = pdf_open_xref_with_stream(file, password);
}
fz_catch(ctx)
{
fz_close(file);
fz_throw(ctx, "cannot load document '%s'", filename);
}
fz_close(file);
return xref;
}
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