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zlib-src/zlib.h  view on Meta::CPAN

*/

ZEXTERN uLong ZEXPORT compressBound(uLong sourceLen);
ZEXTERN z_size_t ZEXPORT compressBound_z(z_size_t sourceLen);
/*
     compressBound() returns an upper bound on the compressed size after
   compress() or compress2() on sourceLen bytes.  It would be used before a
   compress() or compress2() call to allocate the destination buffer.
*/

ZEXTERN int ZEXPORT uncompress(Bytef *dest, uLongf *destLen,
                               const Bytef *source, uLong sourceLen);
ZEXTERN int ZEXPORT uncompress_z(Bytef *dest, z_size_t *destLen,
                                 const Bytef *source, z_size_t sourceLen);
/*
     Decompresses the source buffer into the destination buffer.  sourceLen is
   the byte length of the source buffer.  On entry, *destLen is the total size
   of the destination buffer, which must be large enough to hold the entire
   uncompressed data.  (The size of the uncompressed data must have been saved
   previously by the compressor and transmitted to the decompressor by some
   mechanism outside the scope of this compression library.)  On exit, *destLen
   is the actual size of the uncompressed data.

     uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
   enough memory, Z_BUF_ERROR if there was not enough room in the output
   buffer, or Z_DATA_ERROR if the input data was corrupted or incomplete.  In
   the case where there is not enough room, uncompress() will fill the output
   buffer with the uncompressed data up to that point.
*/

ZEXTERN int ZEXPORT uncompress2(Bytef *dest, uLongf *destLen,
                                const Bytef *source, uLong *sourceLen);
ZEXTERN int ZEXPORT uncompress2_z(Bytef *dest, z_size_t *destLen,
                                  const Bytef *source, z_size_t *sourceLen);
/*
     Same as uncompress, except that sourceLen is a pointer, where the
   length of the source is *sourceLen.  On return, *sourceLen is the number of
   source bytes consumed.
*/

                        /* gzip file access functions */

/*
     This library supports reading and writing files in gzip (.gz) format with
   an interface similar to that of stdio, using the functions that start with
   "gz".  The gzip format is different from the zlib format.  gzip is a gzip
   wrapper, documented in RFC 1952, wrapped around a deflate stream.
*/

typedef struct gzFile_s *gzFile;    /* semi-opaque gzip file descriptor */

/*
ZEXTERN gzFile ZEXPORT gzopen(const char *path, const char *mode);

     Open the gzip (.gz) file at path for reading and decompressing, or
   compressing and writing.  The mode parameter is as in fopen ("rb" or "wb")
   but can also include a compression level ("wb9") or a strategy: 'f' for
   filtered data as in "wb6f", 'h' for Huffman-only compression as in "wb1h",
   'R' for run-length encoding as in "wb1R", or 'F' for fixed code compression
   as in "wb9F".  (See the description of deflateInit2 for more information
   about the strategy parameter.)  'T' will request transparent writing or
   appending with no compression and not using the gzip format. 'T' cannot be
   used to force transparent reading. Transparent reading is automatically
   performed if there is no gzip header at the start. Transparent reading can
   be disabled with the 'G' option, which will instead return an error if there
   is no gzip header. 'N' will open the file in non-blocking mode.

     'a' can be used instead of 'w' to request that the gzip stream that will
   be written be appended to the file.  '+' will result in an error, since
   reading and writing to the same gzip file is not supported.  The addition of
   'x' when writing will create the file exclusively, which fails if the file
   already exists.  On systems that support it, the addition of 'e' when
   reading or writing will set the flag to close the file on an execve() call.

     These functions, as well as gzip, will read and decode a sequence of gzip
   streams in a file.  The append function of gzopen() can be used to create
   such a file.  (Also see gzflush() for another way to do this.)  When
   appending, gzopen does not test whether the file begins with a gzip stream,
   nor does it look for the end of the gzip streams to begin appending.  gzopen
   will simply append a gzip stream to the existing file.

     gzopen can be used to read a file which is not in gzip format; in this
   case gzread will directly read from the file without decompression.  When
   reading, this will be detected automatically by looking for the magic two-
   byte gzip header.

     gzopen returns NULL if the file could not be opened, if there was
   insufficient memory to allocate the gzFile state, or if an invalid mode was
   specified (an 'r', 'w', or 'a' was not provided, or '+' was provided).
   errno can be checked to determine if the reason gzopen failed was that the
   file could not be opened. Note that if 'N' is in mode for non-blocking, the
   open() itself can fail in order to not block. In that case gzopen() will
   return NULL and errno will be EAGAIN or ENONBLOCK. The call to gzopen() can
   then be re-tried. If the application would like to block on opening the
   file, then it can use open() without O_NONBLOCK, and then gzdopen() with the
   resulting file descriptor and 'N' in the mode, which will set it to non-
   blocking.
*/

ZEXTERN gzFile ZEXPORT gzdopen(int fd, const char *mode);
/*
     Associate a gzFile with the file descriptor fd.  File descriptors are
   obtained from calls like open, dup, creat, pipe or fileno (if the file has
   been previously opened with fopen).  The mode parameter is as in gzopen. An
   'e' in mode will set fd's flag to close the file on an execve() call. An 'N'
   in mode will set fd's non-blocking flag.

     The next call of gzclose on the returned gzFile will also close the file
   descriptor fd, just like fclose(fdopen(fd, mode)) closes the file descriptor
   fd.  If you want to keep fd open, use fd = dup(fd_keep); gz = gzdopen(fd,
   mode);.  The duplicated descriptor should be saved to avoid a leak, since
   gzdopen does not close fd if it fails.  If you are using fileno() to get the
   file descriptor from a FILE *, then you will have to use dup() to avoid
   double-close()ing the file descriptor.  Both gzclose() and fclose() will
   close the associated file descriptor, so they need to have different file
   descriptors.

     gzdopen returns NULL if there was insufficient memory to allocate the
   gzFile state, if an invalid mode was specified (an 'r', 'w', or 'a' was not
   provided, or '+' was provided), or if fd is -1.  The file descriptor is not
   used until the next gz* read, write, seek, or close operation, so gzdopen
   will not detect if fd is invalid (unless fd is -1).
*/

zlib-src/zlib.h  view on Meta::CPAN

ZEXTERN int ZEXPORT gzrewind(gzFile file);
/*
     Rewind file. This function is supported only for reading.

     gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET).
*/

/*
ZEXTERN z_off_t ZEXPORT gztell(gzFile file);

     Return the starting position for the next gzread or gzwrite on file.
   This position represents a number of bytes in the uncompressed data stream,
   and is zero when starting, even if appending or reading a gzip stream from
   the middle of a file using gzdopen().

     gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
*/

/*
ZEXTERN z_off_t ZEXPORT gzoffset(gzFile file);

     Return the current compressed (actual) read or write offset of file.  This
   offset includes the count of bytes that precede the gzip stream, for example
   when appending or when using gzdopen() for reading.  When reading, the
   offset does not include as yet unused buffered input.  This information can
   be used for a progress indicator.  On error, gzoffset() returns -1.
*/

ZEXTERN int ZEXPORT gzeof(gzFile file);
/*
     Return true (1) if the end-of-file indicator for file has been set while
   reading, false (0) otherwise.  Note that the end-of-file indicator is set
   only if the read tried to go past the end of the input, but came up short.
   Therefore, just like feof(), gzeof() may return false even if there is no
   more data to read, in the event that the last read request was for the exact
   number of bytes remaining in the input file.  This will happen if the input
   file size is an exact multiple of the buffer size.

     If gzeof() returns true, then the read functions will return no more data,
   unless the end-of-file indicator is reset by gzclearerr() and the input file
   has grown since the previous end of file was detected.
*/

ZEXTERN int ZEXPORT gzdirect(gzFile file);
/*
     Return true (1) if file is being copied directly while reading, or false
   (0) if file is a gzip stream being decompressed.

     If the input file is empty, gzdirect() will return true, since the input
   does not contain a gzip stream.

     If gzdirect() is used immediately after gzopen() or gzdopen() it will
   cause buffers to be allocated to allow reading the file to determine if it
   is a gzip file. Therefore if gzbuffer() is used, it should be called before
   gzdirect(). If the input is being written concurrently or the device is non-
   blocking, then gzdirect() may give a different answer once four bytes of
   input have been accumulated, which is what is needed to confirm or deny a
   gzip header. Before this, gzdirect() will return true (1).

     When writing, gzdirect() returns true (1) if transparent writing was
   requested ("wT" for the gzopen() mode), or false (0) otherwise.  (Note:
   gzdirect() is not needed when writing.  Transparent writing must be
   explicitly requested, so the application already knows the answer.  When
   linking statically, using gzdirect() will include all of the zlib code for
   gzip file reading and decompression, which may not be desired.)
*/

ZEXTERN int ZEXPORT gzclose(gzFile file);
/*
     Flush all pending output for file, if necessary, close file and
   deallocate the (de)compression state.  Note that once file is closed, you
   cannot call gzerror with file, since its structures have been deallocated.
   gzclose must not be called more than once on the same file, just as free
   must not be called more than once on the same allocation.

     gzclose will return Z_STREAM_ERROR if file is not valid, Z_ERRNO on a
   file operation error, Z_MEM_ERROR if out of memory, Z_BUF_ERROR if the
   last read ended in the middle of a gzip stream, or Z_OK on success.
*/

ZEXTERN int ZEXPORT gzclose_r(gzFile file);
ZEXTERN int ZEXPORT gzclose_w(gzFile file);
/*
     Same as gzclose(), but gzclose_r() is only for use when reading, and
   gzclose_w() is only for use when writing or appending.  The advantage to
   using these instead of gzclose() is that they avoid linking in zlib
   compression or decompression code that is not used when only reading or only
   writing respectively.  If gzclose() is used, then both compression and
   decompression code will be included the application when linking to a static
   zlib library.
*/

ZEXTERN const char * ZEXPORT gzerror(gzFile file, int *errnum);
/*
     Return the error message for the last error which occurred on file.
   If errnum is not NULL, *errnum is set to zlib error number.  If an error
   occurred in the file system and not in the compression library, *errnum is
   set to Z_ERRNO and the application may consult errno to get the exact error
   code.

     The application must not modify the returned string.  Future calls to
   this function may invalidate the previously returned string.  If file is
   closed, then the string previously returned by gzerror will no longer be
   available.

     gzerror() should be used to distinguish errors from end-of-file for those
   functions above that do not distinguish those cases in their return values.
*/

ZEXTERN void ZEXPORT gzclearerr(gzFile file);
/*
     Clear the error and end-of-file flags for file.  This is analogous to the
   clearerr() function in stdio.  This is useful for continuing to read a gzip
   file that is being written concurrently.
*/

#endif /* !Z_SOLO */

                        /* checksum functions */