This implements an API and provides a number of assist macros to allow an
application which uses the simplified API write to bypass stdio and write
directly to memory.
It also includes some warnings (png.h) and some check code to detect *possible*
overflow in the ROW_STRIDE and simplified image SIZE macros. This disallows
image width/height/format that *might* overflow. A quiet API change that limits
in-memory image size (uncompressed) to less that 4GByte and image row size
(stride) to less than 2GByte.
Signed-off-by: John Bowler <jbowler@acm.org>
Undefined because (png_byte) << shift is undefined if it changes the signed bit
(because png_byte is promoted to int). The libpng exported functions
png_get_uint_32 and png_get_uint_16 handle this.
Bug reported by David Drysdale as a result of reports from UBSAN in clang 3.8.
This changes pngvalid to use BE random numbers; this used to produce errors but
these should not be fixed as a result of the previous changes.
Signed-off-by: John Bowler <jbowler@acm.org>
This widens the 'limit' check on the internally calculated error limits in the
'DIGITIZE' case (the code used prior to 1.7 for rgb_to_gray error checks) and it
changes the check to only operate in non-release builds (base build type not RC
or RELEASE.)
Signed-off-by: John Bowler <jbowler@acm.org>
Fixes to pngvalid for various reduced build configurations (eliminate unused
statics) and a fix for the case in rgb_to_gray when the digitize option reduces
graylo to 0, producing a large error.
Signed-off-by: John Bowler <jbowler@acm.org>
This 'fixes' the current problem in the BE tests by not testing it, making the
BE code the same as the LE version.
Signed-off-by: John Bowler <jbowler@acm.org>
In libpng 1.6 zlib initialization was changed to use the window size in the zlib
stream, not a fixed value. This causes some invalid images, ones where CINFO is
too large, to display 'correctly' if the rest of the data is valid. This
provides a work-round for zlib versions where the error arises (ones that
support the API change to use the window size in the stream).
Signed-off-by: John Bowler <jbowler@acm.org>
