Opens a gzip (.gz) file for reading or 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". (See the description of deflateInit2 in zlib.h
for more information about the strategy parameter.)
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.
gzopen() returns a file pointer
to the file opened, after that, everything you read from this
file descriptor will be transparently decompressed and what
you write gets compressed.
If the open fails, the function returns FALSE.
You can use the optional third parameter and set it to
"1", if you want to search for the file in the
include_path, too.
See also gzclose().