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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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7
pngwrite.c
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@@ -844,8 +844,6 @@ png_write_flush(png_structp png_ptr)
{
/* Write the IDAT and reset the zlib output buffer */
png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);
png_ptr->zstream.next_out = png_ptr->zbuf;
png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
wrote_IDAT = 1;
}
} while (wrote_IDAT == 1);
@@ -856,8 +854,6 @@ png_write_flush(png_structp png_ptr)
/* Write the IDAT and reset the zlib output buffer */
png_write_IDAT(png_ptr, png_ptr->zbuf,
png_ptr->zbuf_size - png_ptr->zstream.avail_out);
png_ptr->zstream.next_out = png_ptr->zbuf;
png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
}
png_ptr->flush_rows = 0;
png_flush(png_ptr);
@@ -954,7 +950,8 @@ png_write_destroy(png_structp png_ptr)
png_debug(1, "in png_write_destroy");
/* Free any memory zlib uses */
deflateEnd(&png_ptr->zstream);
if (png_ptr->zlib_state != PNG_ZLIB_UNINITIALIZED)
deflateEnd(&png_ptr->zstream);
/* Free our memory. png_free checks NULL for us. */
png_free(png_ptr, png_ptr->zbuf);