This moves the once code from crc32.c to zutil.c, and uses it also
for building the inflate fixed tables when BUILDFIXED is defined.
The fixed tables are now housed in inftrees.c, shared by inflate.c
and infback.c. The once() function is now external, and so is
renamed to z_once() to avoid name collisions.
If either BUILDFIXED or DYNAMIC_CRC_TABLE is defined, and atomics
are not available, then a warning is issued noting that zlib is not
thread-safe.
C2X has removed K&R definitions from the C function syntax.
Though the standard has not yet been approved, some high-profile
compilers are now issuing warnings when such definitions are
encountered.
This patch allows zlib to compile cleanly with the -Wcast-qual gcc
warning enabled, but only if ZLIB_CONST is defined, which adds
const to next_in and msg in z_stream and in the in_func prototype.
A --const option is added to ./configure which adds -DZLIB_CONST
to the compile flags, and adds -Wcast-qual to the compile flags
when ZLIBGCCWARN is set in the environment.
During coverage testing it was discovered that these two lines could
never pull more bits, since the immediately preceding for loop assures
that all of the code's bits are already pulled.
A common request has been the ability to compile zlib to require no
other libraries. This --solo option provides that ability. The price
is that the gz*, compress*, and uncompress functions are eliminated,
and that the user must provide memory allocation and free routines to
deflate and inflate when initializing.
Mark Adler