zlib(3) - phpMan

ZLIB(3) Library Functions Manual ZLIB(3)

NAME
zlib - compression/decompression library

SYNOPSIS
[see zlib.h for full description]

DESCRIPTION
The zlib library is a general purpose data compression library. The code is thread safe,
assuming that the standard library functions used are thread safe, such as memory alloca-
tion routines. It provides in-memory compression and decompression functions, including
integrity checks of the uncompressed data. This version of the library supports only one
compression method (deflation) but other algorithms may be added later with the same
stream interface.

Compression can be done in a single step if the buffers are large enough or can be done by
repeated calls of the compression function. In the latter case, the application must pro-
vide more input and/or consume the output (providing more output space) before each call.

The library also supports reading and writing files in gzip(1) (.gz) format with an inter-
face similar to that of stdio.

The library does not install any signal handler. The decoder checks the consistency of
the compressed data, so the library should never crash even in the case of corrupted in-
put.

All functions of the compression library are documented in the file zlib.h. The distribu-
tion source includes examples of use of the library in the files test/example.c and
test/minigzip.c, as well as other examples in the examples/ directory.

Changes to this version are documented in the file ChangeLog that accompanies the source.

zlib is built in to many languages and operating systems, including but not limited to
Java, Python, .NET, PHP, Perl, Ruby, Swift, and Go.

An experimental package to read and write files in the .zip format, written on top of zlib
by Gilles Vollant (info AT winimage.com), is available at:

http://www.winimage.com/zLibDll/minizip.html and also in the contrib/minizip direc-
tory of the main zlib source distribution.

SEE ALSO
The zlib web site can be found at:

http://zlib.net/

The data format used by the zlib library is described by RFC (Request for Comments) 1950
to 1952 in the files:

http://tools.ietf.org/html/rfc1950 (for the zlib header and trailer format)
http://tools.ietf.org/html/rfc1951 (for the deflate compressed data format)
http://tools.ietf.org/html/rfc1952 (for the gzip header and trailer format)

Mark Nelson wrote an article about zlib for the Jan. 1997 issue of Dr. Dobb's Journal; a
copy of the article is available at:

http://marknelson.us/1997/01/01/zlib-engine/

REPORTING PROBLEMS
Before reporting a problem, please check the zlib web site to verify that you have the
latest version of zlib; otherwise, obtain the latest version and see if the problem still
exists. Please read the zlib FAQ at:

http://zlib.net/zlib_faq.html

before asking for help. Send questions and/or comments to zlib AT gzip.org, or (for the Win-
dows DLL version) to Gilles Vollant (info AT winimage.com).

AUTHORS AND LICENSE
Version 1.2.11

This software is provided 'as-is', without any express or implied warranty. In no event
will the authors be held liable for any damages arising from the use of this software.

Permission is granted to anyone to use this software for any purpose, including commercial
applications, and to alter it and redistribute it freely, subject to the following re-
strictions:

1. The origin of this software must not be misrepresented; you must not claim that you
wrote the original software. If you use this software in a product, an acknowledgment
in the product documentation would be appreciated but is not required.

2. Altered source versions must be plainly marked as such, and must not be misrepresented
as being the original software.

3. This notice may not be removed or altered from any source distribution.

Jean-loup Gailly Mark Adler
jloup AT gzip.org madler AT alumni.edu

The deflate format used by zlib was defined by Phil Katz. The deflate and zlib specifica-
tions were written by L. Peter Deutsch. Thanks to all the people who reported problems
and suggested various improvements in zlib; who are too numerous to cite here.

UNIX manual page by R. P. C. Rodgers, U.S. National Library of Medicine
(rodgers AT nlm.gov).

15 Jan 2017 ZLIB(3)

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