Revert "Update libpng from 1.6.22 -> 1.6.34"chromium/3543

This reverts commit 6b2e2f0ec7c5f629c5270d14c2339197af7392d8.

Reason for revert: Broke Chromium integration.

Original change's description:
> Update libpng from 1.6.22 -> 1.6.34
> 
> Updates third_party/libpng16 to Chromium's third_party/libpng @
> e87a02987101e2dbe319a4aba6b52470f7624b4a and applies PDFium specific
> patches.
> 
> BUG=chromium:880322
> 
> Change-Id: I6724f55099c70a79da6d6e4863b9c6c9157ec571
> Reviewed-on: https://pdfium-review.googlesource.com/41910
> Reviewed-by: Lei Zhang <thestig@chromium.org>
> Commit-Queue: Ryan Harrison <rharrison@chromium.org>

TBR=thestig@chromium.org,rharrison@chromium.org

Change-Id: I2fd1f78e5d07ca983b2430bf078544185292ee1d
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:880322
Reviewed-on: https://pdfium-review.googlesource.com/41970
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>

1 files changed, 18 insertions, 33 deletions

diff --git a/third_party/libpng16/pngtrans.c b/third_party/libpng16/pngtrans.c
index 6882f0fd7b..7f8cc455d3 100644
--- a/third_party/libpng16/pngtrans.c
+++ b/third_party/libpng16/pngtrans.c
@@ -1,8 +1,8 @@
 
 /* pngtrans.c - transforms the data in a row (used by both readers and writers)
  *
- * Last changed in libpng 1.6.33 [September 28, 2017]
- * Copyright (c) 1998-2002,2004,2006-2017 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.18 [July 23, 2015]
+ * Copyright (c) 1998-2002,2004,2006-2015 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.)
  *
@@ -172,14 +172,13 @@ png_set_filler(png_structrp png_ptr, png_uint_32 filler, int filler_loc)
                    * size!
                    */
                   png_app_error(png_ptr,
-                      "png_set_filler is invalid for"
-                      " low bit depth gray output");
+                     "png_set_filler is invalid for low bit depth gray output");
                   return;
                }
 
             default:
                png_app_error(png_ptr,
-                   "png_set_filler: inappropriate color type");
+                  "png_set_filler: inappropriate color type");
                return;
          }
 #     else
@@ -514,15 +513,11 @@ png_do_strip_channel(png_row_infop row_info, png_bytep row, int at_start)
          if (at_start != 0) /* Skip initial filler */
             ++sp;
          else          /* Skip initial channel and, for sp, the filler */
-         {
-            sp += 2; ++dp;
-         }
+            sp += 2, ++dp;
 
          /* For a 1 pixel wide image there is nothing to do */
          while (sp < ep)
-         {
-            *dp++ = *sp; sp += 2;
-         }
+            *dp++ = *sp, sp += 2;
 
          row_info->pixel_depth = 8;
       }
@@ -532,14 +527,10 @@ png_do_strip_channel(png_row_infop row_info, png_bytep row, int at_start)
          if (at_start != 0) /* Skip initial filler */
             sp += 2;
          else          /* Skip initial channel and, for sp, the filler */
-         {
-            sp += 4; dp += 2;
-         }
+            sp += 4, dp += 2;
 
          while (sp < ep)
-         {
-            *dp++ = *sp++; *dp++ = *sp; sp += 3;
-         }
+            *dp++ = *sp++, *dp++ = *sp, sp += 3;
 
          row_info->pixel_depth = 16;
       }
@@ -562,15 +553,11 @@ png_do_strip_channel(png_row_infop row_info, png_bytep row, int at_start)
          if (at_start != 0) /* Skip initial filler */
             ++sp;
          else          /* Skip initial channels and, for sp, the filler */
-         {
-            sp += 4; dp += 3;
-         }
+            sp += 4, dp += 3;
 
          /* Note that the loop adds 3 to dp and 4 to sp each time. */
          while (sp < ep)
-         {
-            *dp++ = *sp++; *dp++ = *sp++; *dp++ = *sp; sp += 2;
-         }
+            *dp++ = *sp++, *dp++ = *sp++, *dp++ = *sp, sp += 2;
 
          row_info->pixel_depth = 24;
       }
@@ -580,16 +567,14 @@ png_do_strip_channel(png_row_infop row_info, png_bytep row, int at_start)
          if (at_start != 0) /* Skip initial filler */
             sp += 2;
          else          /* Skip initial channels and, for sp, the filler */
-         {
-            sp += 8; dp += 6;
-         }
+            sp += 8, dp += 6;
 
          while (sp < ep)
          {
             /* Copy 6 bytes, skip 2 */
-            *dp++ = *sp++; *dp++ = *sp++;
-            *dp++ = *sp++; *dp++ = *sp++;
-            *dp++ = *sp++; *dp++ = *sp; sp += 3;
+            *dp++ = *sp++, *dp++ = *sp++;
+            *dp++ = *sp++, *dp++ = *sp++;
+            *dp++ = *sp++, *dp++ = *sp, sp += 3;
          }
 
          row_info->pixel_depth = 48;
@@ -609,7 +594,7 @@ png_do_strip_channel(png_row_infop row_info, png_bytep row, int at_start)
       return; /* The filler channel has gone already */
 
    /* Fix the rowbytes value. */
-   row_info->rowbytes = (png_size_t)(dp-row);
+   row_info->rowbytes = dp-row;
 }
 #endif
 
@@ -707,8 +692,8 @@ png_do_check_palette_indexes(png_structrp png_ptr, png_row_infop row_info)
        * and this calculation is used because it avoids warnings that other
        * forms produced on either GCC or MSVC.
        */
-      int padding = PNG_PADBITS(row_info->pixel_depth, row_info->width);
-      png_bytep rp = png_ptr->row_buf + row_info->rowbytes - 1;
+      int padding = (-row_info->pixel_depth * row_info->width) & 7;
+      png_bytep rp = png_ptr->row_buf + row_info->rowbytes;
 
       switch (row_info->bit_depth)
       {
@@ -812,7 +797,7 @@ png_set_user_transform_info(png_structrp png_ptr, png_voidp
       (png_ptr->flags & PNG_FLAG_ROW_INIT) != 0)
    {
       png_app_error(png_ptr,
-          "info change after png_start_read_image or png_read_update_info");
+            "info change after png_start_read_image or png_read_update_info");
       return;
    }
 #endif