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[libpng16] Unknown handling fixes and clean up. This adds more correct option

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control of the unknown handling, corrects the pre-existing bug where
the per-chunk 'keep' setting is ignored and makes it possible to skip
IDAT chunks in the sequential reader (broken in earlier 1.6 versions).
There is a new test program, test-unknown.c, which is a work in progress
(not currently part of the test suite).  Comments in the header files now
explain how the unknown handling works.
This commit is contained in:
John Bowler
2012-08-15 22:53:00 -05:00
committed by Glenn Randers-Pehrson
parent b593b3f035
commit e9567514dd
15 changed files with 1498 additions and 443 deletions
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72
pngpread.c
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@@ -185,6 +185,9 @@ void /* PRIVATE */
png_push_read_chunk(png_structrp png_ptr, png_inforp info_ptr)
{
png_uint_32 chunk_name;
#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
int keep; /* unknown handling method */
#endif
/* 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
@@ -216,14 +219,28 @@ png_push_read_chunk(png_structrp png_ptr, png_inforp info_ptr)
if (chunk_name == png_IDAT)
{
/* This is here above the if/else case statement below because if the
* unknown handling marks 'IDAT' as unknown then the IDAT handling case is
* completely skipped.
*
* TODO: there must be a better way of doing this.
*/
if (png_ptr->mode & PNG_AFTER_IDAT)
png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_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
* is called after the image has been read - we have an error).
*/
if (!(png_ptr->mode & PNG_HAVE_IHDR))
png_error(png_ptr, "Missing IHDR before IDAT");
else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
!(png_ptr->mode & PNG_HAVE_PLTE))
png_error(png_ptr, "Missing PLTE before IDAT");
png_ptr->mode |= PNG_HAVE_IDAT;
if (!(png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT))
if (png_ptr->push_length == 0)
return;
if (png_ptr->mode & PNG_AFTER_IDAT)
png_benign_error(png_ptr, "Too many IDATs found");
}
if (chunk_name == png_IHDR)
@@ -255,7 +272,7 @@ png_push_read_chunk(png_structrp png_ptr, png_inforp info_ptr)
}
#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
else if (png_chunk_unknown_handling(png_ptr, chunk_name))
else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)))
{
if (png_ptr->push_length + 4 > png_ptr->buffer_size)
{
@@ -263,23 +280,10 @@ png_push_read_chunk(png_structrp png_ptr, png_inforp info_ptr)
return;
}
if (chunk_name == png_IDAT)
png_ptr->mode |= PNG_HAVE_IDAT;
png_handle_unknown(png_ptr, info_ptr, png_ptr->push_length);
png_handle_unknown(png_ptr, info_ptr, png_ptr->push_length, keep);
if (chunk_name == png_PLTE)
png_ptr->mode |= PNG_HAVE_PLTE;
else if (chunk_name == png_IDAT)
{
if (!(png_ptr->mode & PNG_HAVE_IHDR))
png_error(png_ptr, "Missing IHDR before IDAT");
else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
!(png_ptr->mode & PNG_HAVE_PLTE))
png_error(png_ptr, "Missing PLTE before IDAT");
}
}
#endif
@@ -295,30 +299,7 @@ png_push_read_chunk(png_structrp png_ptr, png_inforp info_ptr)
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
* is called after the image has been read - we have an error).
*/
if (!(png_ptr->mode & PNG_HAVE_IHDR))
png_error(png_ptr, "Missing IHDR before IDAT");
else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
!(png_ptr->mode & PNG_HAVE_PLTE))
png_error(png_ptr, "Missing PLTE before IDAT");
if (png_ptr->mode & PNG_HAVE_IDAT)
{
if (!(png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT))
if (png_ptr->push_length == 0)
return;
if (png_ptr->mode & PNG_AFTER_IDAT)
png_benign_error(png_ptr, "Too many IDATs found");
}
png_ptr->idat_size = png_ptr->push_length;
png_ptr->mode |= PNG_HAVE_IDAT;
png_ptr->process_mode = PNG_READ_IDAT_MODE;
png_push_have_info(png_ptr, info_ptr);
png_ptr->zstream.avail_out =
@@ -556,7 +537,8 @@ png_push_read_chunk(png_structrp png_ptr, png_inforp info_ptr)
png_push_save_buffer(png_ptr);
return;
}
png_handle_unknown(png_ptr, info_ptr, png_ptr->push_length);
png_handle_unknown(png_ptr, info_ptr, png_ptr->push_length,
PNG_HANDLE_CHUNK_AS_DEFAULT);
}
png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;