Changes since the last public release (1.6.9):
Backported changes from libpng-1.7.0beta30 and beta31:
Fixed a large number of instances where PNGCBAPI was omitted from
Added pngimage test program for png_read_png() and png_write_png()
with two new test scripts.
Removed dependence on !PNG_READ_EXPAND_SUPPORTED for calling
png_set_packing() in png_read_png().
Fixed combination of ~alpha with shift. On read invert alpha, processing
occurred after shift processing, which causes the final values to be
outside the range that should be produced by the shift. Reversing the
order on read makes the two transforms work together correctly and mirrors
the order used on write.
Do not read invalid sBIT chunks. Previously libpng only checked sBIT
values on write, so a malicious PNG writer could therefore cause
the read code to return an invalid sBIT chunk, which might lead to
application errors or crashes. Such chunks are now skipped (with
Make png_read_png() and png_write_png() prototypes in png.h depend
upon PNG_READ_SUPPORTED and PNG_WRITE_SUPPORTED.
Support builds with unsupported PNG_TRANSFORM_* values. All of the
PNG_TRANSFORM_* values are always defined in png.h and, because they
are used for both read and write in some cases, it is not reliable
to #if out ones that are totally unsupported. This change adds error
detection in png_read_image() and png_write_image() to do a
png_app_error() if the app requests something that cannot be done
and it adds corresponding code to pngimage.c to handle such options
by not attempting to test them.
Moved redefines of png_error(), png_warning(), png_chunk_error(),
and png_chunk_warning() from pngpriv.h to png.h to make them visible
to libpng-calling applications.
Moved OS dependent code from arm/arm_init.c, to allow the included
implementation of the ARM NEON discovery function to be set at
build-time and provide sample implementations from the current code in the
contrib/arm-neon subdirectory. The __linux__ code has also been changed to
compile and link on Android by using /proc/cpuinfo, and the old linux code
is in contrib/arm-neon/linux-auxv.c. The new code avoids POSIX and Linux
dependencies apart from opening /proc/cpuinfo and is C90 compliant.
Check for info_ptr == NULL early in png_read_end() so we don't need to
run all the png_handle_*() and depend on them to return if info_ptr == NULL.
This improves the performance of png_read_end(png_ptr, NULL) and makes
it more robust against future programming errors.
Check for __has_extension before using it in pngconf.h, to
support older Clang versions (Jeremy Sequoia).
Treat CRC error handling with png_set_crc_action(), instead of with
png_set_benign_errors(), which has been the case since libpng-1.6.0beta18.
Use a user warning handler in contrib/gregbook/readpng2.c instead of default,
so warnings will be put on stderr even if libpng has CONSOLE_IO disabled.
Added png_ptr->process_mode = PNG_READ_IDAT_MODE in png_push_read_chunk
after recognizing the IDAT chunk, which avoids an infinite loop while
reading a datastream whose first IDAT chunk is of zero-length.
This fixes CERT VU#684412 and CVE-2014-0333.
Don't recognize known sRGB profiles as sRGB if they have been hacked,
but don't reject them and don't issue a copyright violation warning.
Moved some documentation from png.h to libpng.3 and libpng-manual.txt
Minor editing of contrib/arm-neon/README and contrib/examples/*.c
Fixed typos in the manual and in scripts/pnglibconf.dfa (CFLAGS -> CPPFLAGS
and PNG_USR_CONFIG -> PNG_USER_CONFIG).