control of the unknown handling, corrects the pre-existing bug where
the per-chunk 'keep' setting is ignored and makes it possible to skip
IDAT chunks in the sequential reader (broken in earlier 1.6 versions).
There is a new test program, test-unknown.c, which is a work in progress
(not currently part of the test suite). Comments in the header files now
explain how the unknown handling works.
ignore all unknown chunks and all known chunks except for IHDR, PLTE, tRNS,
IDAT, and IEND. Previously it only meant ignore all unknown chunks, the
same as num_chunks == 0. Revised png_image_skip_unused_chunks() to
provide a list of chunks to be processed instead of a list of chunks to
ignore. Revised contrib/gregbook/readpng2.c accordingly.
functions [rw]util.c. A new shared keyword check routine was also added
and the 'zbuf' is no longer allocated on progressive read. It is now
possible to call png_inflate() incrementally.
those uses of png_memcpy that were doing a simple assignment to assignments
(all those cases where the thing being copied is a non-array C L-value.)
Added some error checking to png_set_*() routines and removed the
reference to the non-exported function png_memcpy() from example.c. Fixed
the Visual C 64-bit build - it requires jmp_buf to be aligned, but it had
become misaligned.
Added new "png_structrp" typedef. Because of the
way libpng works both png_info and png_struct are always accessed via a
single pointer. This means adding C99 'restrict' to the pointer gives
the compiler some opportunity to optimize the code. This change allows that.
changes alter how the tricky allocation of the initial png_struct and png_info
structures are handled. png_info is now handled in pretty much the same
way as everything else, except that the allocations handle NULL return
silently. png_struct is changed in a similar way on allocation and on
deallocation a 'safety' error handler is put in place (which should never
be required). The error handler itself is changed to permit mismatches
in the application and libpng error buffer size; however, this means a
silent change to the API to return the jmp_buf if the size doesn't match
the size from the libpng compilation; libpng now allocates the memory and
this may fail. Overall these changes result in slight code size
reductions; however, this is a reduction in code that is always executed
so is particularly valuable. Overall on a 64-bit system the libpng DLL
decreases in code size by 1733 bytes. pngerror.o increases in size by
about 465 bytes because of the new functionality.
to conditions where types that are 32 bits in the GCC 32-bit
world (uLong and png_size_t) become 64 bits in the 64-bit
world. This produces potential truncation errors which the
compiler correctly flags.
