[libpng16] Added tests for invalid palette index while reading and writing

(work in progress, the latter isn't finished).

ANNOUNCE

@@ -250,6 +250,8 @@ Version 1.6.0beta15 [March 2, 2012]
     allow the error numbers in pngstest to be tuned and checked.  makepng
     also allows generation of images with extra chunks, although this is
     still work-in-progress.
+  Added tests for invalid palette index while reading and writing (work in
+    progress, the latter isn't finished).
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
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CHANGES

@@ -4002,6 +4002,8 @@ Version 1.6.0beta15 [March 2, 2012]
     allow the error numbers in pngstest to be tuned and checked.  makepng
     also allows generation of images with extra chunks, although this is
     still work-in-progress.
+  Added tests for invalid palette index while reading and writing (work in
+    progress, the latter isn't finished).
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit

pngrtran.c

@@ -2294,32 +2294,104 @@ png_do_read_transformations(png_structrp png_ptr, png_row_infop row_info)
       png_do_unpack(row_info, png_ptr->row_buf + 1);
 #endif
 
-/* Added at libpng-1.6.0 */
-#ifdef PNG_CHECK_FOR_INVALID_INDEX_SUPPORTED
-   /* To do: Fix does not check sub-8-bit rows that have not been unpacked. */
-   if (row_info->color_type == PNG_COLOR_TYPE_PALETTE &&
-      row_info->bit_depth == 8)
-     if (png_ptr->num_palette < (1 << png_ptr->bit_depth))
-     {
-        if ((png_ptr->interlaced && png_ptr->pass == 6) ||
-            (!png_ptr->interlaced && png_ptr->pass == 0))
-        {
-           png_uint_32 i;
-           png_bytep rp = png_ptr->row_buf+1; /* +1 to skip the filter byte */
-  
-           for (i = 0; i <= row_info->rowbytes; i++)
-           {
-              if (*rp >= png_ptr->num_palette)
-              {
-                 /* Should this be a benign error instead of a warning? */
-                 png_warning(png_ptr,"Found invalid palette index");
-                 break;
-              }
-  
-              rp++;
-           }
-        }
-     }
+#ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED
+   /* Added at libpng-1.5.10 */
+
+   if (row_info->color_type == PNG_COLOR_TYPE_PALETTE)
+   {
+      if (png_ptr->num_palette < (1 << png_ptr->bit_depth) &&
+         ((png_ptr->interlaced && png_ptr->pass == 6) ||
+         (!png_ptr->interlaced && png_ptr->pass == 0)))
+      {
+         png_bytep rp = png_ptr->row_buf + 1 + row_info->rowbytes;
+         int index, padding;
+
+         switch (row_info->bit_depth)
+         {
+            case 1:
+            {
+               /* in this case, all bytes must be 0 so we don't need
+                * to unpack the pixels except for the rightmost one.
+                */
+               padding = 8*row_info->rowbytes - png_ptr->width;
+
+               for (; rp > png_ptr->row_buf; rp--)
+               {
+                 if (*rp >> padding != 0)
+                    png_ptr->num_palette_max = 1;
+                 padding = 0;
+               }
+
+               break;
+            }
+
+            case 2:
+            {
+               padding = 2*(4*row_info->rowbytes - png_ptr->width);
+
+               for (; rp > png_ptr->row_buf; rp--)
+               {
+                 index = ((*rp >> padding) & 0x03);
+
+                 if (index > png_ptr->num_palette_max)
+                    png_ptr->num_palette_max = index;
+
+                 index = (((*rp >> padding) >> 2) & 0x03);
+
+                 if (index > png_ptr->num_palette_max)
+                    png_ptr->num_palette_max = index;
+
+                 index = (((*rp >> padding) >> 4) & 0x03);
+
+                 if (index > png_ptr->num_palette_max)
+                    png_ptr->num_palette_max = index;
+
+                 index = (((*rp >> padding) >> 6) & 0x03);
+
+                 if (index > png_ptr->num_palette_max)
+                    png_ptr->num_palette_max = index;
+
+                 padding = 0;
+               }
+
+               break;
+            }
+
+            case 4:
+            {
+               padding = 4*(2*row_info->rowbytes - png_ptr->width);
+
+               for (; rp > png_ptr->row_buf; rp--)
+               {
+                 index = ((*rp >> padding) & 0x0f);
+
+                 if (index > png_ptr->num_palette_max)
+                    png_ptr->num_palette_max = index;
+
+                 index = (((*rp >> padding) >> 4) & 0x0f);
+
+                 if (index > png_ptr->num_palette_max)
+                    png_ptr->num_palette_max = index;
+
+                 padding = 0;
+               }
+
+               break;
+            }
+
+            case 8:
+            {
+               for (; rp > png_ptr->row_buf; rp--)
+               {
+                  if (*rp >= png_ptr->num_palette_max)
+                     png_ptr->num_palette_max = *rp;
+               }
+
+               break;
+            }
+         }
+      }
+   }
 #endif
 
 #ifdef PNG_READ_BGR_SUPPORTED

pngstruct.h

@@ -123,6 +123,12 @@ struct png_struct_def
    png_uint_32 crc;           /* current chunk CRC value */
    png_colorp palette;        /* palette from the input file */
    png_uint_16 num_palette;   /* number of color entries in palette */
+
+/* Added at libpng-1.5.10 */
+#ifdef PNG_CHECK_FOR_INVALID_INDEX_SUPPORTED
+   png_uint_16 num_palette_max; /* maximum palette index found in IDAT */
+#endif
+
    png_uint_16 num_trans;     /* number of transparency values */
    png_byte compression;      /* file compression type (always 0) */
    png_byte filter;           /* file filter type (always 0) */
@@ -215,13 +221,6 @@ struct png_struct_def
    int process_mode;                 /* what push library is currently doing */
    int cur_palette;                  /* current push library palette index */
 
-#  ifdef PNG_TEXT_SUPPORTED
-     png_size_t current_text_size;   /* current size of text input data */
-     png_size_t current_text_left;   /* how much text left to read in input */
-     png_charp current_text;         /* current text chunk buffer */
-     png_charp current_text_ptr;     /* current location in current_text */
-#  endif /* PNG_PROGRESSIVE_READ_SUPPORTED && PNG_TEXT_SUPPORTED */
-
 #endif /* PNG_PROGRESSIVE_READ_SUPPORTED */
 
 #if defined(__TURBOC__) && !defined(_Windows) && !defined(__FLAT__)

pngwrite.c

@@ -731,12 +731,15 @@ png_write_row(png_structrp png_ptr, png_const_bytep row)
    }
 #endif
 
-#if 0 /* To do: implement png_do_check_palette_indexes() */
+/* Added at libpng-1.5.10 */
+#ifdef PNG_WRITE_CHECK_FOR_INVALID_INDEX_SUPPORTED
    /* Check for out-of-range palette index */
+#if 0 /* To do: implement png_do_check_palette_indexes() */
    if (png_ptr->num_palette < (1 << png_ptr->bit_depth))
       png_do_check_palette_indexes(&row_info, png_ptr->row_buf + 1,
         png_ptr->num_palette_max);
-   if (png_ptr->num_palette_max > num_palette + 1)
+#endif
+   if (png_ptr->num_palette_max > png_ptr->num_palette + 1)
       png_warning(png_ptr, "Palette index exceeded num_palette");
 #endif
 

scripts/pnglibconf.dfa

@@ -586,7 +586,15 @@ option WRITE_COMPRESSED_TEXT enables WRITE_TEXT
 
 option INFO_IMAGE
 
-# Simplified API options
+# added at libpng-1.5.10
+# Turn this off to disable warning about invalid palette index and
+# leave the num_palette_max member out of the png structure.
+
+option CHECK_FOR_INVALID_INDEX
+option READ_CHECK_FOR_INVALID_INDEX requires READ CHECK_FOR_INVALID_INDEX
+option WRITE_CHECK_FOR_INVALID_INDEX requires WRITE CHECK_FOR_INVALID_INDEX
+
+# Simplified API options (added at libpng-1.6.0)
 # Read:
 option SIMPLIFIED_READ requires SEQUENTIAL_READ READ_TRANSFORMS SETJMP
 option SIMPLIFIED_READ enables READ_EXPAND READ_16BIT READ_EXPAND_16

scripts/pnglibconf.h.prebuilt

@@ -3,7 +3,7 @@
 
 /* pnglibconf.h - library build configuration */
 
-/* Libpng 1.6.0beta15 - February 27, 2012 */
+/* Libpng 1.6.0beta15 - March 1, 2012 */
 
 /* Copyright (c) 1998-2012 Glenn Randers-Pehrson */
 
@@ -41,6 +41,7 @@
 #define PNG_bKGD_SUPPORTED
 #define PNG_BUILD_GRAYSCALE_PALETTE_SUPPORTED
 #define PNG_CHECK_cHRM_SUPPORTED
+#define PNG_CHECK_FOR_INVALID_INDEX_SUPPORTED
 #define PNG_cHRM_SUPPORTED
 #define PNG_CONSOLE_IO_SUPPORTED
 #define PNG_CONVERT_tIME_SUPPORTED
@@ -72,6 +73,7 @@
 #define PNG_READ_BACKGROUND_SUPPORTED
 #define PNG_READ_BGR_SUPPORTED
 #define PNG_READ_bKGD_SUPPORTED
+#define PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED
 #define PNG_READ_cHRM_SUPPORTED
 #define PNG_READ_COMPOSITE_NODIV_SUPPORTED
 #define PNG_READ_COMPRESSED_TEXT_SUPPORTED
@@ -149,6 +151,7 @@
 #define PNG_WRITE_ANCILLARY_CHUNKS_SUPPORTED
 #define PNG_WRITE_BGR_SUPPORTED
 #define PNG_WRITE_bKGD_SUPPORTED
+#define PNG_WRITE_CHECK_FOR_INVALID_INDEX_SUPPORTED
 #define PNG_WRITE_cHRM_SUPPORTED
 #define PNG_WRITE_COMPRESSED_TEXT_SUPPORTED
 #define PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED