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Make png_struct palette, trans_alpha private

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This removes the side-effect on the png_struct palette of calling png_set_PLTE
or png_set_tRNS.  NOTE: this is a quiet API change, it was possible before to
alter the palette on a PNG image by using png_set_PLTE, but this was unintended
and inconsistent with the other png_set APIs.

Fix a bug in palette index checking; png_struct::num_palette could, in
principle, get changed by the transformations (e.g. png_set_quantize) and this
would invalidate the check.  The palette checking init function now makes a copy
of png_struct::num_palette.

Fix a bug in pngvalid error handling.  A png_error in png_write_info is not
continuable (a valid image cannot necessarily be written afterward) because the
png_error aborts the write of subsequent pre-IDAT chunks.  In particular an
abort as a result of a bogus colorspace information (gAMA, cHRM, sBIT etc)
prevents the write of the PLTE chunk.

Signed-off-by: John Bowler <jbowler@acm.org>
This commit is contained in:
John Bowler
2015-12-01 08:16:53 -08:00
parent 8fe2eac47f
commit 84a8bb8244
8 changed files with 137 additions and 139 deletions
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91
contrib/libtests/pngvalid.c
View File

@@ -4276,62 +4276,71 @@ make_error(png_store* const ps, png_byte const colour_type,
#undef exception__env
/* And clear these flags */
ps->expect_error = 0;
ps->expect_warning = 0;
/* Now write the whole image, just to make sure that the detected, or
* undetected, errro has not created problems inside libpng.
*/
if (png_get_rowbytes(pp, pi) !=
transform_rowsize(pp, colour_type, bit_depth))
png_error(pp, "row size incorrect");
if (ps->expect_error)
ps->expect_error = 0;
else
{
int npasses = set_write_interlace_handling(pp, interlace_type);
int pass;
/* Now write the whole image, just to make sure that the detected, or
* undetected, errro has not created problems inside libpng. This
* doesn't work if there was a png_error in png_write_info because that
* can abort before PLTE was written.
*/
if (png_get_rowbytes(pp, pi) !=
transform_rowsize(pp, colour_type, bit_depth))
png_error(pp, "row size incorrect");
if (npasses != npasses_from_interlace_type(pp, interlace_type))
png_error(pp, "write: png_set_interlace_handling failed");
for (pass=0; pass<npasses; ++pass)
else
{
png_uint_32 y;
int npasses = set_write_interlace_handling(pp, interlace_type);
int pass;
for (y=0; y<h; ++y)
if (npasses != npasses_from_interlace_type(pp, interlace_type))
png_error(pp, "write: png_set_interlace_handling failed");
for (pass=0; pass<npasses; ++pass)
{
png_byte buffer[TRANSFORM_ROWMAX];
png_uint_32 y;
transform_row(pp, buffer, colour_type, bit_depth, y);
for (y=0; y<h; ++y)
{
png_byte buffer[TRANSFORM_ROWMAX];
# if do_own_interlace
/* If do_own_interlace *and* the image is interlaced we need a
* reduced interlace row; this may be reduced to empty.
*/
if (interlace_type == PNG_INTERLACE_ADAM7)
{
/* The row must not be written if it doesn't exist, notice
* that there are two conditions here, either the row isn't
* ever in the pass or the row would be but isn't wide
* enough to contribute any pixels. In fact the wPass test
* can be used to skip the whole y loop in this case.
transform_row(pp, buffer, colour_type, bit_depth, y);
# if do_own_interlace
/* If do_own_interlace *and* the image is interlaced we
* need a reduced interlace row; this may be reduced to
* empty.
*/
if (PNG_ROW_IN_INTERLACE_PASS(y, pass) &&
PNG_PASS_COLS(w, pass) > 0)
interlace_row(buffer, buffer,
bit_size(pp, colour_type, bit_depth), w, pass,
0/*data always bigendian*/);
else
continue;
}
# endif /* do_own_interlace */
if (interlace_type == PNG_INTERLACE_ADAM7)
{
/* The row must not be written if it doesn't exist,
* notice that there are two conditions here, either the
* row isn't ever in the pass or the row would be but
* isn't wide enough to contribute any pixels. In fact
* the wPass test can be used to skip the whole y loop
* in this case.
*/
if (PNG_ROW_IN_INTERLACE_PASS(y, pass) &&
PNG_PASS_COLS(w, pass) > 0)
interlace_row(buffer, buffer,
bit_size(pp, colour_type, bit_depth), w, pass,
0/*data always bigendian*/);
else
continue;
}
# endif /* do_own_interlace */
png_write_row(pp, buffer);
png_write_row(pp, buffer);
}
}
}
}
} /* image writing */
png_write_end(pp, pi);
png_write_end(pp, pi);
}
/* The following deletes the file that was just written. */
store_write_reset(ps);