Libpng 1.5.28rc01 - December 27, 2016

This is not intended to be a public release.  It will be replaced
within a few weeks by a public version or by another test version.

Files available for download:

Source files with LF line endings (for Unix/Linux) and with a
"configure" script

   1.5.28rc01.tar.xz (LZMA-compressed, recommended)
   1.5.28rc01.tar.gz

Source files with CRLF line endings (for Windows), without the
"configure" script

   lp1528r01.7z  (LZMA-compressed, recommended)
   lp1528r01.zip

Other information:

   1.5.28rc01-README.txt
   1.5.28rc01-LICENSE.txt
   libpng-1.5.28rc01-*.asc (armored detached GPG signatures)

Changes since the last public release (1.5.27):

version 1.5.28rc01 [December 27, 2016]
  Merged with current libpng16 gregbook, pngvalid.c, pngtest.c, pngminim,
    pngminus
  Fixed undefined behavior in png_push_save_buffer(). Do not call
    memcpy() with a null source, even if count is zero (Leon Scroggins III).
  Added "Common linking failures" section to INSTALL.
  Merge contrib/pngminim/*/makefile with libpng-1.6.24
  Minor editing of INSTALL, (whitespace, added copyright line)
  Removed the use of a macro containing the pre-processor 'defined'
    operator.  It is unclear whether this is valid; a macro that
    "generates" 'defined' is not permitted, but the use of the word
    "generates" within the C90 standard seems to imply more than simple
    substitution of an expression itself containing a well-formed defined
    operation.
  Previously the pngtrans.c code always resulted in an unsigned arithmetic
    overflow. This is well defined but produces errors from clang with the
    option to detect unsigned overflow. As the expression only gets
    evaluated once per row in this version of libpng it is easier just
    to rewrite it.
  The previous version of png.c produced a signed overflow as a result of
    both the "& 0xffff" on the most significant bits of a negative argument;
    this converted (-1) into 65535 which resulted in a subsequent overflow.
    Since signed overflow is undefined in C90 the code has been modified to
    correctly calculate a signed result.  This requires changing the 'hi'
    result parameter to a signed value.

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