When an input file contains a zero length IDAT and pngfix is not applying the
IDAT rechunking (--max) option pngfix will go into a loop writing the zero
length IDAT for ever.
This is a fairly minor issue for interactive use; zero length IDAT is very rare,
the problem is obvious (pngfix hangs) and the fix (use --max, or --max=4096
etc), while not obvious, is easy.
For non-interactive use, e.g. trying to automatically repair a PNG that cannot
be read by libpng, there are security consequences:
1) pngfix hangs. This may permit a DoS attack.
2) When the --out option is used pngfix will just keep writing. This is a very
likely DoS scenario.
Signed-off-by: John Bowler <jbowler@acm.org>
The fixed size buffer for the file name being processed could have a byte
written beyond the end; a bug where the test was updated without changing the
size of the buffer. This commit reduces the buffer to the system maximum.
png_getrowbytes could, in theory, return 0; probably only if there is a bug in
libpng but the code now checks.
Signed-off-by: John Bowler <jbowler@acm.org>
In libpng 1.7 pngimage needs to check PNG_WRITE_PNG_SUPPORTED (new in 1.7), not
PNG_WRITE_SUPPORTED because png_write_png can be disabled without disabling
PNG_WRITE_SUPPORTED. Copied the approach from 1.6 pngcp.c (so this still works
in 1.6 as well.)
If PNG_PNGCP_TIMING_SUPPORTED is defined maximal resolution CPU time logging of
png_read_png and png_write_png is enabled via the --time command line option.
This is not on by default but is enabled by contrib/conftests/pngcp.dfa
Signed-off-by: John Bowler <jbowler@acm.org>
This adds pngcp to the build together with a pngcp.dfa configuration test; the
test revealed some configuration bugs which are fixed by corrections to the
_SUPPORTED macros.
pngcp builds on all tested configurations and a number of bugs have been fixed
to make this happen relative to the version in libpng 1.7 contrib/examples.
pngcp.dfa will have to be different for 1.7 but pngcp.c should work fine (not
yet tested). pngcp itself is still missing a usage message; this is a
preliminary version, although since it behaves the same way as 'cp' most unoids
shouldn't have a problem using it correctly.
Signed-off-by: John Bowler <jbowler@acm.org>
The SKIP definition needs to come after the png.h include (see all the other .c
files in contrib/libtests) because it depends on PNG_LIBPNG_VER. This commit
puts it in the correct place.
Signed-off-by: John Bowler <jbowler@acm.org>
MSVC does not like (uInt) = -(unsigned) (i.e. as an initializer), but it is fine
with it if the conversion is explicitly invoked by a cast.
Signed-off-by: John Bowler <jbowler@acm.org>
Coverity rejects code where an array element count has type size_t, this
elminates the code in question from contrib/libtests/pngvalid.c
Signed-off-by: John Bowler <jbowler@acm.org>
The previous version of the code invariably passed just one byte at a time to
libpng. The intention was to pass a random number of bytes in the range 0..511
(and this is what happens now).
Signed-off-by: John Bowler <jbowler@acm.org>
