[libpng15] Bump version to libpng-1.5.6beta02

pngpread.c

@@ -1,7 +1,7 @@
 
 /* pngpread.c - read a png file in push mode
  *
- * Last changed in libpng 1.5.2 [March 31, 2011]
+ * Last changed in libpng 1.5.6 [(PENDING RELEASE)]
  * Copyright (c) 1998-2011 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.)
@@ -208,61 +208,7 @@ png_push_read_sig(png_structp png_ptr, png_infop info_ptr)
 void /* PRIVATE */
 png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 {
-      PNG_IHDR;
-      PNG_IDAT;
-      PNG_IEND;
-      PNG_PLTE;
-#ifdef PNG_READ_bKGD_SUPPORTED
-      PNG_bKGD;
-#endif
-#ifdef PNG_READ_cHRM_SUPPORTED
-      PNG_cHRM;
-#endif
-#ifdef PNG_READ_gAMA_SUPPORTED
-      PNG_gAMA;
-#endif
-#ifdef PNG_READ_hIST_SUPPORTED
-      PNG_hIST;
-#endif
-#ifdef PNG_READ_iCCP_SUPPORTED
-      PNG_iCCP;
-#endif
-#ifdef PNG_READ_iTXt_SUPPORTED
-      PNG_iTXt;
-#endif
-#ifdef PNG_READ_oFFs_SUPPORTED
-      PNG_oFFs;
-#endif
-#ifdef PNG_READ_pCAL_SUPPORTED
-      PNG_pCAL;
-#endif
-#ifdef PNG_READ_pHYs_SUPPORTED
-      PNG_pHYs;
-#endif
-#ifdef PNG_READ_sBIT_SUPPORTED
-      PNG_sBIT;
-#endif
-#ifdef PNG_READ_sCAL_SUPPORTED
-      PNG_sCAL;
-#endif
-#ifdef PNG_READ_sRGB_SUPPORTED
-      PNG_sRGB;
-#endif
-#ifdef PNG_READ_sPLT_SUPPORTED
-      PNG_sPLT;
-#endif
-#ifdef PNG_READ_tEXt_SUPPORTED
-      PNG_tEXt;
-#endif
-#ifdef PNG_READ_tIME_SUPPORTED
-      PNG_tIME;
-#endif
-#ifdef PNG_READ_tRNS_SUPPORTED
-      PNG_tRNS;
-#endif
-#ifdef PNG_READ_zTXt_SUPPORTED
-      PNG_zTXt;
-#endif
+   png_uint_32 chunk_name;
 
    /* First we make sure we have enough data for the 4 byte chunk name
     * and the 4 byte chunk length before proceeding with decoding the
@@ -273,6 +219,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
    if (!(png_ptr->mode & PNG_HAVE_CHUNK_HEADER))
    {
       png_byte chunk_length[4];
+      png_byte chunk_tag[4];
 
       if (png_ptr->buffer_size < 8)
       {
@@ -283,16 +230,19 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
       png_push_fill_buffer(png_ptr, chunk_length, 4);
       png_ptr->push_length = png_get_uint_31(png_ptr, chunk_length);
       png_reset_crc(png_ptr);
-      png_crc_read(png_ptr, png_ptr->chunk_name, 4);
+      png_crc_read(png_ptr, chunk_tag, 4);
+      png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(chunk_tag);
       png_check_chunk_name(png_ptr, png_ptr->chunk_name);
       png_ptr->mode |= PNG_HAVE_CHUNK_HEADER;
    }
 
-   if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
+   chunk_name = png_ptr->chunk_name;
+
+   if (chunk_name == png_IDAT)
       if (png_ptr->mode & PNG_AFTER_IDAT)
          png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
 
-   if (!png_memcmp(png_ptr->chunk_name, png_IHDR, 4))
+   if (chunk_name == png_IHDR)
    {
       if (png_ptr->push_length != 13)
          png_error(png_ptr, "Invalid IHDR length");
@@ -306,7 +256,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
       png_handle_IHDR(png_ptr, info_ptr, png_ptr->push_length);
    }
 
-   else if (!png_memcmp(png_ptr->chunk_name, png_IEND, 4))
+   else if (chunk_name == png_IEND)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
@@ -321,7 +271,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
    }
 
 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
-   else if (png_handle_as_unknown(png_ptr, png_ptr->chunk_name))
+   else if (png_chunk_unknown_handling(png_ptr, chunk_name))
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
@@ -329,15 +279,15 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
          return;
       }
 
-      if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
+      if (chunk_name == png_IDAT)
          png_ptr->mode |= PNG_HAVE_IDAT;
 
       png_handle_unknown(png_ptr, info_ptr, png_ptr->push_length);
 
-      if (!png_memcmp(png_ptr->chunk_name, png_PLTE, 4))
+      if (chunk_name == png_PLTE)
          png_ptr->mode |= PNG_HAVE_PLTE;
 
-      else if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
+      else if (chunk_name == png_IDAT)
       {
          if (!(png_ptr->mode & PNG_HAVE_IHDR))
             png_error(png_ptr, "Missing IHDR before IDAT");
@@ -349,7 +299,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
    }
 
 #endif
-   else if (!png_memcmp(png_ptr->chunk_name, png_PLTE, 4))
+   else if (chunk_name == png_PLTE)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
@@ -359,7 +309,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
       png_handle_PLTE(png_ptr, info_ptr, png_ptr->push_length);
    }
 
-   else if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
+   else if (chunk_name == png_IDAT)
    {
       /* If we reach an IDAT chunk, this means we have read all of the
        * header chunks, and we can start reading the image (or if this
@@ -395,7 +345,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
    }
 
 #ifdef PNG_READ_gAMA_SUPPORTED
-   else if (!png_memcmp(png_ptr->chunk_name, png_gAMA, 4))
+   else if (png_ptr->chunk_name == png_gAMA)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
@@ -408,7 +358,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 
 #endif
 #ifdef PNG_READ_sBIT_SUPPORTED
-   else if (!png_memcmp(png_ptr->chunk_name, png_sBIT, 4))
+   else if (png_ptr->chunk_name == png_sBIT)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
@@ -421,7 +371,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 
 #endif
 #ifdef PNG_READ_cHRM_SUPPORTED
-   else if (!png_memcmp(png_ptr->chunk_name, png_cHRM, 4))
+   else if (png_ptr->chunk_name == png_cHRM)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
@@ -434,7 +384,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 
 #endif
 #ifdef PNG_READ_sRGB_SUPPORTED
-   else if (!png_memcmp(png_ptr->chunk_name, png_sRGB, 4))
+   else if (chunk_name == png_sRGB)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
@@ -447,7 +397,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 
 #endif
 #ifdef PNG_READ_iCCP_SUPPORTED
-   else if (!png_memcmp(png_ptr->chunk_name, png_iCCP, 4))
+   else if (png_ptr->chunk_name == png_iCCP)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
@@ -460,7 +410,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 
 #endif
 #ifdef PNG_READ_sPLT_SUPPORTED
-   else if (!png_memcmp(png_ptr->chunk_name, png_sPLT, 4))
+   else if (chunk_name == png_sPLT)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
@@ -473,7 +423,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 
 #endif
 #ifdef PNG_READ_tRNS_SUPPORTED
-   else if (!png_memcmp(png_ptr->chunk_name, png_tRNS, 4))
+   else if (chunk_name == png_tRNS)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
@@ -486,7 +436,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 
 #endif
 #ifdef PNG_READ_bKGD_SUPPORTED
-   else if (!png_memcmp(png_ptr->chunk_name, png_bKGD, 4))
+   else if (chunk_name == png_bKGD)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
@@ -499,7 +449,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 
 #endif
 #ifdef PNG_READ_hIST_SUPPORTED
-   else if (!png_memcmp(png_ptr->chunk_name, png_hIST, 4))
+   else if (chunk_name == png_hIST)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
@@ -512,7 +462,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 
 #endif
 #ifdef PNG_READ_pHYs_SUPPORTED
-   else if (!png_memcmp(png_ptr->chunk_name, png_pHYs, 4))
+   else if (chunk_name == png_pHYs)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
@@ -525,7 +475,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 
 #endif
 #ifdef PNG_READ_oFFs_SUPPORTED
-   else if (!png_memcmp(png_ptr->chunk_name, png_oFFs, 4))
+   else if (chunk_name == png_oFFs)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
@@ -538,7 +488,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 #endif
 
 #ifdef PNG_READ_pCAL_SUPPORTED
-   else if (!png_memcmp(png_ptr->chunk_name, png_pCAL, 4))
+   else if (chunk_name == png_pCAL)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
@@ -551,7 +501,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 
 #endif
 #ifdef PNG_READ_sCAL_SUPPORTED
-   else if (!png_memcmp(png_ptr->chunk_name, png_sCAL, 4))
+   else if (chunk_name == png_sCAL)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
@@ -564,7 +514,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 
 #endif
 #ifdef PNG_READ_tIME_SUPPORTED
-   else if (!png_memcmp(png_ptr->chunk_name, png_tIME, 4))
+   else if (chunk_name == png_tIME)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
@@ -577,7 +527,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 
 #endif
 #ifdef PNG_READ_tEXt_SUPPORTED
-   else if (!png_memcmp(png_ptr->chunk_name, png_tEXt, 4))
+   else if (chunk_name == png_tEXt)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
@@ -590,7 +540,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 
 #endif
 #ifdef PNG_READ_zTXt_SUPPORTED
-   else if (!png_memcmp(png_ptr->chunk_name, png_zTXt, 4))
+   else if (chunk_name == png_zTXt)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
@@ -603,7 +553,7 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 
 #endif
 #ifdef PNG_READ_iTXt_SUPPORTED
-   else if (!png_memcmp(png_ptr->chunk_name, png_iTXt, 4))
+   else if (chunk_name == png_iTXt)
    {
       if (png_ptr->push_length + 4 > png_ptr->buffer_size)
       {
@@ -809,11 +759,12 @@ png_push_restore_buffer(png_structp png_ptr, png_bytep buffer,
 void /* PRIVATE */
 png_push_read_IDAT(png_structp png_ptr)
 {
-   PNG_IDAT;
    if (!(png_ptr->mode & PNG_HAVE_CHUNK_HEADER))
    {
       png_byte chunk_length[4];
+      png_byte chunk_tag[4];
 
+      /* TODO: this code can be commoned up with the same code in push_read */
       if (png_ptr->buffer_size < 8)
       {
          png_push_save_buffer(png_ptr);
@@ -823,10 +774,11 @@ png_push_read_IDAT(png_structp png_ptr)
       png_push_fill_buffer(png_ptr, chunk_length, 4);
       png_ptr->push_length = png_get_uint_31(png_ptr, chunk_length);
       png_reset_crc(png_ptr);
-      png_crc_read(png_ptr, png_ptr->chunk_name, 4);
+      png_crc_read(png_ptr, chunk_tag, 4);
+      png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(chunk_tag);
       png_ptr->mode |= PNG_HAVE_CHUNK_HEADER;
 
-      if (png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
+      if (png_ptr->chunk_name != png_IDAT)
       {
          png_ptr->process_mode = PNG_READ_CHUNK_MODE;
 
@@ -838,6 +790,7 @@ png_push_read_IDAT(png_structp png_ptr)
 
       png_ptr->idat_size = png_ptr->push_length;
    }
+
    if (png_ptr->idat_size && png_ptr->save_buffer_size)
    {
       png_size_t save_size = png_ptr->save_buffer_size;
@@ -1011,36 +964,56 @@ png_process_IDAT_data(png_structp png_ptr, png_bytep buffer,
 void /* PRIVATE */
 png_push_process_row(png_structp png_ptr)
 {
-   png_ptr->row_info.color_type = png_ptr->color_type;
-   png_ptr->row_info.width = png_ptr->iwidth;
-   png_ptr->row_info.channels = png_ptr->channels;
-   png_ptr->row_info.bit_depth = png_ptr->bit_depth;
-   png_ptr->row_info.pixel_depth = png_ptr->pixel_depth;
+   /* 1.5.6: row_info moved out of png_struct to a local here. */
+   png_row_info row_info;
 
-   png_ptr->row_info.rowbytes = PNG_ROWBYTES(png_ptr->row_info.pixel_depth,
-       png_ptr->row_info.width);
+   row_info.width = png_ptr->iwidth; /* NOTE: width of current interlaced row */
+   row_info.color_type = png_ptr->color_type;
+   row_info.bit_depth = png_ptr->bit_depth;
+   row_info.channels = png_ptr->channels;
+   row_info.pixel_depth = png_ptr->pixel_depth;
+   row_info.rowbytes = PNG_ROWBYTES(row_info.pixel_depth, row_info.width);
 
-   png_read_filter_row(png_ptr, &(png_ptr->row_info),
-       png_ptr->row_buf + 1, png_ptr->prev_row + 1,
-       (int)(png_ptr->row_buf[0]));
+   if (png_ptr->row_buf[0] > PNG_FILTER_VALUE_NONE)
+   {
+      if (png_ptr->row_buf[0] < PNG_FILTER_VALUE_LAST)
+         png_read_filter_row(&row_info, png_ptr->row_buf + 1,
+            png_ptr->prev_row + 1, png_ptr->row_buf[0]);
+      else
+         png_error(png_ptr, "bad adaptive filter value");
+   }
 
-   png_memcpy(png_ptr->prev_row, png_ptr->row_buf, png_ptr->rowbytes + 1);
+   /* libpng 1.5.6: the following line was copying png_ptr->rowbytes before
+    * 1.5.6, while the buffer really is this big in current versions of libpng
+    * it may not be in the future, so this was changed just to copy the
+    * interlaced row count:
+    */
+   png_memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info.rowbytes + 1);
 
 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
    if (png_ptr->transformations)
-      png_do_read_transformations(png_ptr);
+      png_do_read_transformations(png_ptr, &row_info);
 #endif
 
+   /* The transformed pixel depth should match the depth now in row_info. */
+   if (png_ptr->transformed_pixel_depth == 0)
+   {
+      png_ptr->transformed_pixel_depth = row_info.pixel_depth;
+      if (row_info.pixel_depth > png_ptr->maximum_pixel_depth)
+         png_error(png_ptr, "progressive row overflow");
+   }
+
+   else if (png_ptr->transformed_pixel_depth != row_info.pixel_depth)
+      png_error(png_ptr, "internal progressive row size calculation error");
+
+
 #ifdef PNG_READ_INTERLACING_SUPPORTED
    /* Blow up interlaced rows to full size */
    if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE))
    {
       if (png_ptr->pass < 6)
-/*       old interface (pre-1.0.9):
-         png_do_read_interlace(&(png_ptr->row_info),
-             png_ptr->row_buf + 1, png_ptr->pass, png_ptr->transformations);
- */
-         png_do_read_interlace(png_ptr);
+         png_do_read_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass,
+            png_ptr->transformations);
 
     switch (png_ptr->pass)
     {
@@ -1223,20 +1196,20 @@ png_read_push_finish_row(png_structp png_ptr)
    /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
 
    /* Start of interlace block */
-   PNG_CONST int FARDATA png_pass_start[] = {0, 4, 0, 2, 0, 1, 0};
+   static PNG_CONST png_byte FARDATA png_pass_start[] = {0, 4, 0, 2, 0, 1, 0};
 
    /* Offset to next interlace block */
-   PNG_CONST int FARDATA png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1};
+   static PNG_CONST png_byte FARDATA png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1};
 
    /* Start of interlace block in the y direction */
-   PNG_CONST int FARDATA png_pass_ystart[] = {0, 0, 4, 0, 2, 0, 1};
+   static PNG_CONST png_byte FARDATA png_pass_ystart[] = {0, 0, 4, 0, 2, 0, 1};
 
    /* Offset to next interlace block in the y direction */
-   PNG_CONST int FARDATA png_pass_yinc[] = {8, 8, 8, 4, 4, 2, 2};
+   static PNG_CONST png_byte FARDATA png_pass_yinc[] = {8, 8, 8, 4, 4, 2, 2};
 
    /* Height of interlace block.  This is not currently used - if you need
     * it, uncomment it here and in png.h
-   PNG_CONST int FARDATA png_pass_height[] = {8, 8, 4, 4, 2, 2, 1};
+   static PNG_CONST png_byte FARDATA png_pass_height[] = {8, 8, 4, 4, 2, 2, 1};
    */
 
    png_ptr->row_number++;
@@ -1714,11 +1687,12 @@ png_push_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32
     length)
 {
    png_uint_32 skip = 0;
+   png_uint_32 chunk_name = png_ptr->chunk_name;
 
-   if (!(png_ptr->chunk_name[0] & 0x20))
+   if (PNG_CHUNK_CRITICAL(chunk_name))
    {
 #ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
-      if (png_handle_as_unknown(png_ptr, png_ptr->chunk_name) !=
+      if (png_chunk_unknown_handling(png_ptr, chunk_name) !=
           PNG_HANDLE_CHUNK_ALWAYS
 #ifdef PNG_READ_USER_CHUNKS_SUPPORTED
           && png_ptr->read_user_chunk_fn == NULL
@@ -1731,22 +1705,26 @@ png_push_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32
    }
 
 #ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
+   /* TODO: the code below is apparently just using the
+    * png_struct::unknown_chunk member as a temporarily variable, it should be
+    * possible to eliminate both it and the temporary buffer.
+    */
    if (png_ptr->flags & PNG_FLAG_KEEP_UNKNOWN_CHUNKS)
    {
 #ifdef PNG_MAX_MALLOC_64K
-      if (length > (png_uint_32)65535L)
+      if (length > 65535)
       {
          png_warning(png_ptr, "unknown chunk too large to fit in memory");
-         skip = length - (png_uint_32)65535L;
-         length = (png_uint_32)65535L;
+         skip = length - 65535;
+         length = 65535;
       }
 #endif
-      png_memcpy((png_charp)png_ptr->unknown_chunk.name,
-          (png_charp)png_ptr->chunk_name,
-          png_sizeof(png_ptr->unknown_chunk.name));
-      png_ptr->unknown_chunk.name[png_sizeof(png_ptr->unknown_chunk.name) - 1]
-          = '\0';
+      /* This is just a record for the user; libpng doesn't use the character
+       * form of the name.
+       */
+      PNG_CSTRING_FROM_CHUNK(png_ptr->unknown_chunk.name, png_ptr->chunk_name);
 
+      /* The following cast should be safe because of the check above. */
       png_ptr->unknown_chunk.size = (png_size_t)length;
 
       if (length == 0)
@@ -1755,8 +1733,9 @@ png_push_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32
       else
       {
          png_ptr->unknown_chunk.data = (png_bytep)png_malloc(png_ptr,
-             (png_size_t)length);
-         png_crc_read(png_ptr, (png_bytep)png_ptr->unknown_chunk.data, length);
+            png_ptr->unknown_chunk.size);
+         png_crc_read(png_ptr, (png_bytep)png_ptr->unknown_chunk.data,
+            png_ptr->unknown_chunk.size);
       }
 
 #ifdef PNG_READ_USER_CHUNKS_SUPPORTED
@@ -1772,8 +1751,8 @@ png_push_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32
 
          if (ret == 0)
          {
-            if (!(png_ptr->chunk_name[0] & 0x20))
-               if (png_handle_as_unknown(png_ptr, png_ptr->chunk_name) !=
+            if (PNG_CHUNK_CRITICAL(png_ptr->chunk_name))
+               if (png_chunk_unknown_handling(png_ptr, chunk_name) !=
                    PNG_HANDLE_CHUNK_ALWAYS)
                   png_chunk_error(png_ptr, "unknown critical chunk");
             png_set_unknown_chunks(png_ptr, info_ptr,
@@ -1820,7 +1799,7 @@ void PNGAPI
 png_progressive_combine_row (png_structp png_ptr, png_bytep old_row,
     png_const_bytep new_row)
 {
-   PNG_CONST int FARDATA png_pass_dsp_mask[7] =
+   static PNG_CONST png_byte FARDATA png_pass_dsp_mask[7] =
       {0xff, 0x0f, 0xff, 0x33, 0xff, 0x55, 0xff};
 
    if (png_ptr == NULL)