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Diffstat (limited to 'doc/lzip.info')
| -rw-r--r-- | doc/lzip.info | 66 |
1 files changed, 36 insertions, 30 deletions
diff --git a/doc/lzip.info b/doc/lzip.info index 5c4cf81..9c4e874 100644 --- a/doc/lzip.info +++ b/doc/lzip.info @@ -11,7 +11,7 @@ File: lzip.info, Node: Top, Next: Introduction, Up: (dir) Lzip Manual *********** -This manual is for Lzip (version 1.15-pre1, 21 March 2013). +This manual is for Lzip (version 1.15-pre2, 11 May 2013). * Menu: @@ -43,6 +43,10 @@ gzip or bzip2. Lzip decompresses almost as fast as gzip and compresses better than bzip2, which makes it well suited for software distribution and data archiving. + Lzip 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. + If you ever need to recover data from a damaged lzip file, try the lziprecover program. @@ -93,20 +97,16 @@ filename.tlz becomes filename.tar anyothername becomes anyothername.out As a self-check for your protection, lzip 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 lzip (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 lzip to panic. +trailer 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 lzip (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. File: lzip.info, Node: Algorithm, Next: Invoking Lzip, Prev: Introduction, Up: Top @@ -325,6 +325,12 @@ E exabyte (10^18) | Ei exbibyte (2^60) Z zettabyte (10^21) | Zi zebibyte (2^70) Y yottabyte (10^24) | Yi yobibyte (2^80) + + 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 lzip to panic. + File: lzip.info, Node: File Format, Next: Stream Format, Prev: Invoking Lzip, Up: Top @@ -392,8 +398,9 @@ additional information before, between, or after them. `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. + acts as a distributed index, allows the verification of stream + integrity, and facilitates safe recovery of undamaged members from + multi-member files. @@ -535,8 +542,8 @@ bm_align reverse bit tree for distances >= 128, after fixed probability bits - There are two separated sets of length contexts (`Len_model' in the -source). One for normal matches, the other for repeated matches. The + There are two separate sets of contexts for lengths (`Len_model' in +the source). One for normal matches, the other for repeated matches. The contexts in each Len_model are (see `decode_len' in the source): Name Indices Used when @@ -747,7 +754,6 @@ struct Bit_model Bit_model() : probability( bit_model_total / 2 ) {} }; - struct Len_model { Bit_model choice1; @@ -1057,7 +1063,7 @@ typedef uint8_t File_trailer[20]; // 12-19 member size including header and trailer -/* Return values: 0 for a normal exit, 1 for environmental problems +/* 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. */ @@ -1156,15 +1162,15 @@ Concept Index Tag Table: Node: Top224 -Node: Introduction1067 -Node: Algorithm4732 -Node: Invoking Lzip7250 -Node: File Format12602 -Node: Stream Format14985 -Node: Examples23695 -Node: Problems25644 -Node: Reference source code26174 -Node: Concept Index39424 +Node: Introduction1065 +Node: Algorithm4786 +Node: Invoking Lzip7304 +Node: File Format12895 +Node: Stream Format15328 +Node: Examples24042 +Node: Problems25991 +Node: Reference source code26521 +Node: Concept Index39768 End Tag Table |