From: glennrp <glennrp@git.imagemagick.org>
Date: Sun, 30 May 2010 01:56:35 +0000 (+0000)
Subject: Sometimes the png encoder would write an empty tRNS chunk.
X-Git-Tag: 7.0.1-0~9352
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=e9c26dc68fb7cff87adcf2677968737acc9d3d2c;p=imagemagick

Sometimes the png encoder would write an empty tRNS chunk.
---

diff --git a/ChangeLog b/ChangeLog
index 086055a10..d6d3abad9 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,6 @@
+2010-05-28  6.6.2.1 Glenn Randers-Pehrson <glennrp@image...>
+  * Prevent coders/png.c from attempting to write an empty tRNS chunk.
+
 2010-05-25  6.6.2.1 Anthony Thyssen <A.Thyssen@griffith...>
   * Finish for Square Array Rotates (off center origin rotate)
   * Added HitAndMiss kernel Ridges2 to find 2 pixel thick ridges
diff --git a/coders/png.c b/coders/png.c
index 0eefea8d6..48dac7645 100644
--- a/coders/png.c
+++ b/coders/png.c
@@ -2752,7 +2752,8 @@ static Image *ReadOnePNGImage(MngInfo *mng_info,
       {
          for (x=0; x < ping_num_trans; x++)
          {
-            image->colormap[x].opacity = ScaleCharToQuantum((unsigned char)(255-ping_trans_alpha[x]));
+            image->colormap[x].opacity =
+              ScaleCharToQuantum((unsigned char)(255-ping_trans_alpha[x]));
          }
       }
       else if (ping_color_type == PNG_COLOR_TYPE_GRAY)
@@ -6344,8 +6345,8 @@ static MagickBooleanType WriteOnePNGImage(MngInfo *mng_info,
     num_passes,
     pass;
 
-  png_bytep
-     ping_trans_alpha;
+  png_byte
+     ping_trans_alpha[256];
 
   png_colorp
      palette;
@@ -6431,8 +6432,6 @@ static MagickBooleanType WriteOnePNGImage(MngInfo *mng_info,
   ping_trans_color.blue=0;
   ping_trans_color.gray=0;
 
-  ping_trans_alpha = NULL;
-
   quantum_info = (QuantumInfo *) NULL;
   image_colors=image->colors;
   image_depth=image->depth;
@@ -7217,11 +7216,6 @@ static MagickBooleanType WriteOnePNGImage(MngInfo *mng_info,
                 ping_num_trans=0;
               if (ping_num_trans != 0)
               {
-                ping_trans_alpha=(unsigned char *) AcquireQuantumMemory(
-                  number_colors,sizeof(*ping_trans_alpha));
-                if (ping_trans_alpha == (unsigned char *) NULL)
-                  ThrowWriterException(ResourceLimitError,
-                     "MemoryAllocationFailed");
                 for (i=0; i < (ssize_t) number_colors; i++)
                     ping_trans_alpha[i]=(png_byte) trans[i];
               }
@@ -7513,6 +7507,22 @@ static MagickBooleanType WriteOnePNGImage(MngInfo *mng_info,
           "  Added an opaque matte channel");
     }
 
+  if (image->matte == MagickTrue && ping_color_type < 4)
+    {
+      if (ping_color_type == 3 && ping_num_trans == 0)
+        {
+          png_set_invalid(ping,ping_info,PNG_INFO_tRNS);
+          if (logging != MagickFalse)
+            (void) LogMagickEvent(CoderEvent,GetMagickModule(),
+              "  Ignoring request to write tRNS chunk with num_trans==0");
+        }
+      else
+        (void) png_set_tRNS(ping, ping_info,
+                            ping_trans_alpha,
+                            ping_num_trans,
+                            &ping_trans_color);
+    }
+
   if (logging != MagickFalse)
     (void) LogMagickEvent(CoderEvent,GetMagickModule(),
       "  Writing PNG header chunks");
@@ -7772,7 +7782,7 @@ static MagickBooleanType WriteOnePNGImage(MngInfo *mng_info,
             }
           for (y=0; y < (ssize_t) image->rows; y++)
           {
-            if (logging)
+            if (logging && y == 0)
               (void) LogMagickEvent(CoderEvent,GetMagickModule(),
                 "  pass %d, Image Is RGB, 16-bit GRAY, or GRAY_ALPHA",pass);
             p=GetVirtualPixels(image,0,y,image->columns,1,&image->exception);