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authorDaniel Baumann <mail@daniel-baumann.ch>2015-11-06 11:37:40 +0000
committerDaniel Baumann <mail@daniel-baumann.ch>2015-11-06 11:37:40 +0000
commitc33e1de813af248d4249725ac859dd3a26393704 (patch)
tree2a277fd093d46566d11b96d68ee4b9ba950e96be /doc/clzip.texinfo
parentAdding upstream version 1.4. (diff)
downloadclzip-c33e1de813af248d4249725ac859dd3a26393704.tar.xz
clzip-c33e1de813af248d4249725ac859dd3a26393704.zip
Adding upstream version 1.5~pre1.upstream/1.5_pre1
Signed-off-by: Daniel Baumann <mail@daniel-baumann.ch>
Diffstat (limited to 'doc/clzip.texinfo')
-rw-r--r--doc/clzip.texinfo43
1 files changed, 25 insertions, 18 deletions
diff --git a/doc/clzip.texinfo b/doc/clzip.texinfo
index 1d0479f..e372d60 100644
--- a/doc/clzip.texinfo
+++ b/doc/clzip.texinfo
@@ -6,8 +6,8 @@
@finalout
@c %**end of header
-@set UPDATED 18 February 2013
-@set VERSION 1.4
+@set UPDATED 13 May 2013
+@set VERSION 1.5-pre1
@dircategory Data Compression
@direntry
@@ -61,6 +61,10 @@ gzip or bzip2. Clzip decompresses almost as fast as gzip and compresses
better than bzip2, which makes it well suited for software distribution
and data archiving.
+Clzip uses the same well-defined exit status values used by bzip2, which
+makes it safer when used in pipes or scripts than compressors returning
+ambiguous warning values, like gzip.
+
Clzip uses the lzip file format; the files produced by clzip are fully
compatible with lzip-1.4 or newer. Clzip is in fact a C language version
of lzip, intended for embedded devices or systems lacking a C++
@@ -117,20 +121,16 @@ file from that of the compressed file as follows:
@end multitable
As a self-check for your protection, clzip stores in the member trailer
-the 32-bit CRC of the original data and the size of the original data,
-to make sure that the decompressed version of the data is identical to
-the original. This guards against corruption of the compressed data, and
-against undetected bugs in clzip (hopefully very unlikely). The chances
-of data corruption going undetected are microscopic, less than one
-chance in 4000 million for each member processed. Be aware, though, that
-the check occurs upon decompression, so it can only tell you that
-something is wrong. It can't help you recover the original uncompressed
-data.
-
-Return values: 0 for a normal exit, 1 for environmental problems (file
-not found, invalid flags, I/O errors, etc), 2 to indicate a corrupt or
-invalid input file, 3 for an internal consistency error (eg, bug) which
-caused clzip to panic.
+the 32-bit CRC of the original data, the size of the original data and
+the size of the member. These values, together with the value remaining
+in the range decoder and the end-of-stream marker, provide a very safe 4
+factor integrity checking which guarantees that the decompressed version
+of the data is identical to the original. This guards against corruption
+of the compressed data, and against undetected bugs in clzip (hopefully
+very unlikely). The chances of data corruption going undetected are
+microscopic. Be aware, though, that the check occurs upon decompression,
+so it can only tell you that something is wrong. It can't help you
+recover the original uncompressed data.
@node Algorithm
@@ -349,6 +349,12 @@ Table of SI and binary prefixes (unit multipliers):
@item Y @tab yottabyte (10^24) @tab | @tab Yi @tab yobibyte (2^80)
@end multitable
+@sp 1
+Exit status: 0 for a normal exit, 1 for environmental problems (file not
+found, invalid flags, I/O errors, etc), 2 to indicate a corrupt or
+invalid input file, 3 for an internal consistency error (eg, bug) which
+caused clzip to panic.
+
@node File Format
@chapter File Format
@@ -404,6 +410,7 @@ wedges between 0 and 7. The size of a wedge is (base_size / 16).@*
Bits 4-0 contain the base 2 logarithm of the base size (12 to 29).@*
Bits 7-5 contain the number of wedges (0 to 7) to substract from the
base size to obtain the dictionary size.@*
+Example: 0xD3 = (2^19 - 6 * 2^15) = (512KiB - 6 * 32KiB) = 320KiB@*
Valid values for dictionary size range from 4KiB to 512MiB.
@item Lzma stream
@@ -418,8 +425,8 @@ Size of the uncompressed original data.
@item Member size (8 bytes)
Total size of the member, including header and trailer. This field acts
-as a distributed index, and facilitates safe recovery of undamaged
-members from multi-member files.
+as a distributed index, allows the verification of stream integrity, and
+facilitates safe recovery of undamaged members from multi-member files.
@end table