result when integers appear on both sides of a compare. Worked around the
others by forcing the strict-overflow setting in the relevant functions to
a level where they are not reported.
Changed "FALL THROUGH" comments to "FALLTHROUGH" because GCC doesn't like
the space.
Worked around some C-style casts from (void*) because g++ 5.4.0 objects
to them.
Increased the buffer size for 'sprint' to pass the gcc 7.1.0 'sprint
overflow' check that is on by default with -Wall -Wextra.
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>
This updates libpng16 with all the test changes from libpng17,
including changes to pngvalid.c to ensure that the original,
distributed, version of contrib/visupng/cexcept.h can be used.
pngvalid contains the correction to the use of SAVE/STORE_
UNKNOWN_CHUNKS; a bug revealed by changes in libpng 1.7. More
tests contain the --strict option to detect warnings and the
pngvalid-standard test has been corrected so that it does not
turn on progresive-read (there is a separate test which does
that.)
Some signed/unsigned fixes have been made.
Signed-off-by: John Bowler <jbowler@acm.org>
strip option. pngfix relied on undefined behavior and even a simple change from
gcc to g++ caused it to fail. The new strip option 'unsafe' has been
implemented and is the default if --max is given. Option names have
been clarified, with --strip=transform now stripping the bKGD chunk,
which was stripped previously with --strip=unused.
Added all documented chunk types to pngpriv.h
