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[devel] IDAT compression failed if preceded by a compressed text chunk

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This was because the attempt to reset the zlib stream in png_write_IDAT
happened after the first IDAT chunk had been deflated - much too late.
In this change internal functions are added to claim/release the z_stream
and, hopefully, make the code more robust.  Also deflateEnd checking is
added - previously libpng would ignore an error at the end of the stream.
This commit is contained in:
John Bowler
2011-05-05 17:35:39 -05:00
committed by Glenn Randers-Pehrson
parent c559bb58ed
commit c5bef946b1
9 changed files with 203 additions and 104 deletions
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15
pngstruct.h
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@@ -66,11 +66,26 @@ struct png_struct_def
z_stream zstream; /* pointer to decompression structure (below) */
png_bytep zbuf; /* buffer for zlib */
uInt zbuf_size; /* size of zbuf (typically 65536) */
#ifdef PNG_WRITE_SUPPORTED
/* Added in 1.5.3: state to keep track of whether the zstream has been
* initialized and if so whether it is for IDAT or some other chunk.
*/
#define PNG_ZLIB_UNINITIALIZED 0
#define PNG_ZLIB_FOR_IDAT 1
#define PNG_ZLIB_FOR_TEXT 2 /* anything other than IDAT */
#define PNG_ZLIB_USE_MASK 3 /* bottom two bits */
#define PNG_ZLIB_IN_USE 4 /* a flag value */
png_uint_32 zlib_state; /* State of zlib initialization */
/* End of material added at libpng 1.5.3 */
int zlib_level; /* holds zlib compression level */
int zlib_method; /* holds zlib compression method */
int zlib_window_bits; /* holds zlib compression window bits */
int zlib_mem_level; /* holds zlib compression memory level */
int zlib_strategy; /* holds zlib compression strategy */
#endif
/* Added at libpng 1.5.3 */
#if defined(PNG_WRITE_COMPRESSED_TEXT_SUPPORTED) || \
defined(PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION)