This updates the documentation to reflect the behavior of
deflateParams() when it is not able to compress all of the input
data provided so far due to insufficient output space. It also
assures that data provided is compressed before the parameter
changes, even if at the beginning of the stream.
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.
crc_table is made using a four-byte integer (when that can be
determined). However get_crc_table() returned a pointer to an
unsigned long, which could be eight bytes. This fixes that by
creating a new z_crc_t type for the crc_table.
This type is also used for the BYFOUR crc calculations that depend
on a four-byte type. The four-byte type can now be determined by
./configure, which also solves a problem where ./configure --solo
would never use BYFOUR. No the Z_U4 #define indicates that four-
byte integer was found either by ./configure or by zconf.h.
gzflags() was put in gzwrite.c in order to be compiled exactly the
same as gzprintf(), so that it was guaranteed to return the correct
information. However that causes a static linkage to zlib to bring
in many routines that are often not used. All that is required to
duplicate the compilation environment of gzprintf() is to include
gzguts.h. So that is now done in zutil.c to assure that the correct
flags are returned.
Also since gzread() will no longer return an error for an incomplete
gzip file, have gzclose() return an error if the last gzread() ended
in the middle of a gzip stream.
inflate() avoided that allocation normally, until it was modified to
update the window on a normal completion so that inflateResetKeep()
could work. This patch restores that behavior, but only when
Z_FINISH is used successfully to complete an inflation of a stream in
a single call of inflate(). The comments in zlib.h have been updated
accordingly.
This patch adds the deflateResetKeep() function to retain the sliding
window for the next deflate operation, and fixes an inflateResetKeep()
problem that came from inflate() not updating the window when the
stream completed. This enables constructing and decompressing a series
of concatenated deflate streams where each can depend on the history of
uncompressed data that precedes it.
This generalizes deflateSetDictionary() and inflateSetDictionary() to
permit setting the dictionary in the middle of a stream for raw deflate
and inflate. This in combination with the Keep functions enables a
scheme for updating files block by block with the transmission of
compressed data, where blocks are sent with deflateResetKeep() to
retain history for better compression, and deflateSetDictionary() is
used for blocks already present at the receiver to skip compression but
insert that data in the history, again for better compression. The
corresponding inflate calls are done on the receiver side.