GZip — Wrapper for gzip functions in zlib

Note

located in gzip.jl

This module provides a wrapper for the gzip related functions of (zlib), a free, general-purpose, legally unencumbered, lossless data-compression library. These functions allow the reading and writing of gzip files.

It is currently based on zlib 1.2.7.

Notes

• This interface is only for gzipped files, not the streaming zlib compression interface. Internally, it depends on/uses the streaming interface, but the gzip related functions are higher level functions pertaining to gzip files only.
• GZipStream is an implementation of IO and can be used virtually anywhere IO is used.
• This implementation mimics the IOStream implementation, and should be a drop-in replacement for IOStream, with some exceptions:
  • seek_end() and truncate() are not available
  • readuntil() is available, but is not very efficient. (But readline() works fine.)

In addition to gzopen() and gzfdio()/gzdopen(), the following IO/IOStream functions are supported:

close() flush() seek() skip() position() eof() read() readuntil() readline() write()

Due to limitations in zlib, seek_end() and truncate() are not available.

Functions

gzopen(fname[, gzmode[, buf_size]])

Opens a file with mode (default "r"), setting internal buffer size to buf_size (default Z_DEFAULT_BUFSIZE=8192), and returns a the file as a GZipStream.

gzmode must contain one of

r	read
w	write, create, truncate
a	write, create, append

In addition, gzmode may also contain

x	create the file exclusively (fails if file exists)
0-9	compression level

and/or a compression strategy:

f	filtered data
h	Huffman-only compression
R	run-length encoding
F	fixed code compression

Note that + is not allowed in gzmode.

If an error occurs, gzopen throws a GZError

gzdopen(fd[, gzmode[, buf_size]])

Create a GZipStream object from an integer file descriptor. See gzopen() for gzmode and buf_size descriptions.

gzdopen(s[, gzmode[, buf_size]])

Create a GZipStream object from IOStream s.

Types

type GZipStream(name, gz_file[, buf_size[, fd[, s]]])

Subtype of IO which wraps a gzip stream. Returned by gzopen() and gzdopen().

type GZError(err, err_str)

gzip error number and string. Possible error values:

Z_OK	No error
Z_ERRNO	Filesystem error (consult errno())
Z_STREAM_ERROR	Inconsistent stream state
Z_DATA_ERROR	Compressed data error
Z_MEM_ERROR	Out of memory
Z_BUF_ERROR	Input buffer full/output buffer empty
Z_VERSION_ERROR	zlib library version is incompatible with caller version