GZIP file format specification version 4.3
RFC 1952
| Document | Type |
RFC - Informational
(May 1996; No errata)
Was draft-deutsch-gzip-spec (individual)
|
|
|---|---|---|---|
| Last updated | 2013-03-02 | ||
| Stream | Legacy | ||
| Formats | plain text pdf ps html bibtex | ||
| Stream | Legacy state | (None) | |
| Consensus Boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | RFC 1952 (Informational) | |
| Telechat date | |||
| Responsible AD | (None) | ||
| Send notices to | (None) | ||
Network Working Group P. Deutsch
Request for Comments: 1952 Aladdin Enterprises
Category: Informational May 1996
GZIP file format specification version 4.3
Status of This Memo
This memo provides information for the Internet community. This memo
does not specify an Internet standard of any kind. Distribution of
this memo is unlimited.
IESG Note:
The IESG takes no position on the validity of any Intellectual
Property Rights statements contained in this document.
Notices
Copyright (c) 1996 L. Peter Deutsch
Permission is granted to copy and distribute this document for any
purpose and without charge, including translations into other
languages and incorporation into compilations, provided that the
copyright notice and this notice are preserved, and that any
substantive changes or deletions from the original are clearly
marked.
A pointer to the latest version of this and related documentation in
HTML format can be found at the URL
<ftp://ftp.uu.net/graphics/png/documents/zlib/zdoc-index.html>.
Abstract
This specification defines a lossless compressed data format that is
compatible with the widely used GZIP utility. The format includes a
cyclic redundancy check value for detecting data corruption. The
format presently uses the DEFLATE method of compression but can be
easily extended to use other compression methods. The format can be
implemented readily in a manner not covered by patents.
Deutsch Informational [Page 1]
RFC 1952 GZIP File Format Specification May 1996
Table of Contents
1. Introduction ................................................... 2
1.1. Purpose ................................................... 2
1.2. Intended audience ......................................... 3
1.3. Scope ..................................................... 3
1.4. Compliance ................................................ 3
1.5. Definitions of terms and conventions used ................. 3
1.6. Changes from previous versions ............................ 3
2. Detailed specification ......................................... 4
2.1. Overall conventions ....................................... 4
2.2. File format ............................................... 5
2.3. Member format ............................................. 5
2.3.1. Member header and trailer ........................... 6
2.3.1.1. Extra field ................................... 8
2.3.1.2. Compliance .................................... 9
3. References .................................................. 9
4. Security Considerations .................................... 10
5. Acknowledgements ........................................... 10
6. Author's Address ........................................... 10
7. Appendix: Jean-Loup Gailly's gzip utility .................. 11
8. Appendix: Sample CRC Code .................................. 11
1. Introduction
1.1. Purpose
The purpose of this specification is to define a lossless
compressed data format that:
* Is independent of CPU type, operating system, file system,
and character set, and hence can be used for interchange;
* Can compress or decompress a data stream (as opposed to a
randomly accessible file) to produce another data stream,
using only an a priori bounded amount of intermediate
storage, and hence can be used in data communications or
similar structures such as Unix filters;
* Compresses data with efficiency comparable to the best
currently available general-purpose compression methods,
and in particular considerably better than the "compress"
program;
* Can be implemented readily in a manner not covered by
patents, and hence can be practiced freely;
* Is compatible with the file format produced by the current
widely used gzip utility, in that conforming decompressors
will be able to read data produced by the existing gzip
compressor.
Deutsch Informational [Page 2]
RFC 1952 GZIP File Format Specification May 1996
The data format defined by this specification does not attempt to:
* Provide random access to compressed data;
* Compress specialized data (e.g., raster graphics) as well as
Show full document text