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Installing a zisofs uncompression filter on file from ISO image which bear

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a ZF entry. Storing ZF entries during image write if that filter is found
directly on a fsrc stream from the loaded image and content does not get
copied.
This commit is contained in:
Thomas Schmitt
2009-04-11 14:15:34 +02:00
parent 77591e4546
commit 6886777ea0
7 changed files with 187 additions and 25 deletions
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36
doc/zisofs_format.txt
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@ -1,11 +1,13 @@
Description of the zisofs Format
Description of the zisofs Format
as of zisofs-tools-1.0.8 by H. Peter Anvin
and cdrtools-2.01.01a39 by Joerg Schilling
as of zisofs-tools-1.0.8 by H. Peter Anvin
and cdrtools-2.01.01a39 by Joerg Schilling
For libburnia-project.org by Thomas Schmitt <scdbackup@gmx.net>
Apr 7 2009
For libburnia-project.org by Thomas Schmitt <scdbackup@gmx.net>
- distribute freely , please report any errors or ambiguities -
Apr 11 2009
The zisofs format was invented by H. Peter Anvin. It compresses data file
@ -30,7 +32,7 @@ So its size is 16.
7.3.1 means little endian 4-byte words. 7.1.1. means unsigned single bytes.
Readers shall be able to handle log2(block_size) values 15, 16 and 17
i.e. block sizes 32 kB, 64 kB, and 128 kB.
i.e. block sizes 32 kB, 64 kB, and 128 kB. Writers must not use other sizes.
Block Pointers
@ -80,17 +82,16 @@ Its fields are:
[4] "BP 5 to BP 6 - Algorithm" shall be (70)(7A) ("pz") to indicate
"paged zlib".
[5] "BP 7 - Header Size" shall specify as an 8-bit number the number of
[5] "BP 7 - Header Size Div 4" shall specify as an 8-bit number the number of
4-byte words in the header part of the file data recorded according
to ISO 9660:7.1.1.
(This is a copy of header byte 12, resp. header BP 13).
[6] "BP 8 - Block Size" shall specify as an 8-bit number the binary
[6] "BP 8 - Log2 of Block Size" shall specify as an 8-bit number the binary
logarithm of the compression block size recorded according to
ISO 9660:7.1.1.
(This is a copy of header byte 13, resp. header BP 14.)
Implementations shall be able to handle values 15, 16 and 17 i.e.
block sizes 32 kiB, 64 kiB, and 128 kiB.
(This is a copy of header byte 13, resp. header BP 14.
The value has to be 15, 16 or 17 i.e. 32 kiB, 64 kiB, or 128 kiB.)
[7] "BP 9 to BP 16 - Uncompressed Size" shall tell the number of uncompressed
bytes represented by the given extent. This field shall be recorded
@ -98,8 +99,8 @@ Its fields are:
(This number is the same as in header bytes 8 to 11, resp header BP 9
to BP 12.)
| 'Z' | 'F' | LENGTH | 1 | 'p' | 'z' | HEADER SIZE | BLOCK SIZE |
UNCOMPRESSED SIZE |
| 'Z' | 'F' | LENGTH | 1 | 'p' | 'z' | HEADER SIZE DIV 4 | LOG2 BLOCK SIZE
| UNCOMPRESSED SIZE |
ISO 9660:7.3.3 means 4-byte word in both byte orders, first little endian, then
big endian.
@ -107,13 +108,16 @@ Example (block size 32 kiB, uncompressed file size = 1,234,567 bytes):
{ 'Z', "F', 16, 1, 'p', 'z', 4, 15,
0x87, 0xD6, 0x12, 0x00, 0x00, 0x12, 0xD6, 0x87 }
-------------------------------------------------------------------------------
Revoked specification aspects:
The comments in zisofs-tools-1.0.8 indicate a special case of output block:
A comment in zisofs-tools-1.0.8 indicates a special case of output block:
"a block the length of which is equal to the block size is unencoded."
This is not implemented in zisofs-tools and in the Linux kernel.
Therefore that rule is not part of this description and must not be
This is not implemented in zisofs-tools and in the Linux kernel. Existing
zisofs enhanced ISO images might contain encoded blocks which could be
mistaken for unencoded blocks.
Therefore this rule is not part of this description and must not be
implemented.
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