mirror of
https://github.com/php-win-ext/php-rar.git
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a88a995ca0
Added technote.txt. Added rar_file_t::entries_idx. It's a hashtable that stores the entries in rar_file_t::entries indexed by name. _rar_raw_entries_to_files uses it, if available. Added an extension global, a per-request cache that will be used when directory streams are implemented. Eliminated dependency on SPL. Substituted several legacy macro names for new ones. Stream close operation operates differently when close_handle is FALSE (not that I actually know what the correct behaviour would be...) Added rar stream stat operation. Added wrapper, not with only an opener. The syntax is "rar://<urlencoded path to RAR archive>#<urlencoded entry name>". Context options should be under "rar" and are "open_password", "file_password" and "volume_callback" extract() and the wrapper opener should support RAR files with header passwords different from file passwords (but WinRAR does not generate them, so not tested). Avoid test 46 infinite loop on resource opening failure. git-svn-id: http://svn.php.net/repository/pecl/rar/trunk@298704 c90b9560-bf6c-de11-be94-00142212c4b1
276 lines
8.7 KiB
Plaintext
276 lines
8.7 KiB
Plaintext
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RAR version 3.93 - Technical information
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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THE ARCHIVE FORMAT DESCRIBED BELOW IS ONLY VALID FOR VERSIONS SINCE 1.50
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==========================================================================
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RAR archive file format
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==========================================================================
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Archive file consists of variable length blocks. The order of these
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blocks may vary, but the first block must be a marker block followed by
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an archive header block.
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Each block begins with the following fields:
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HEAD_CRC 2 bytes CRC of total block or block part
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HEAD_TYPE 1 byte Block type
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HEAD_FLAGS 2 bytes Block flags
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HEAD_SIZE 2 bytes Block size
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ADD_SIZE 4 bytes Optional field - added block size
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Field ADD_SIZE present only if (HEAD_FLAGS & 0x8000) != 0
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Total block size is HEAD_SIZE if (HEAD_FLAGS & 0x8000) == 0
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and HEAD_SIZE+ADD_SIZE if the field ADD_SIZE is present - when
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(HEAD_FLAGS & 0x8000) != 0.
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In each block the followings bits in HEAD_FLAGS have the same meaning:
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0x4000 - if set, older RAR versions will ignore the block
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and remove it when the archive is updated.
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if clear, the block is copied to the new archive
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file when the archive is updated;
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0x8000 - if set, ADD_SIZE field is present and the full block
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size is HEAD_SIZE+ADD_SIZE.
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Declared block types:
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HEAD_TYPE=0x72 marker block
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HEAD_TYPE=0x73 archive header
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HEAD_TYPE=0x74 file header
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HEAD_TYPE=0x75 old style comment header
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HEAD_TYPE=0x76 old style authenticity information
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HEAD_TYPE=0x77 old style subblock
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HEAD_TYPE=0x78 old style recovery record
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HEAD_TYPE=0x79 old style authenticity information
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HEAD_TYPE=0x7a subblock
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Comment block is actually used only within other blocks and doesn't
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exist separately.
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Archive processing is made in the following manner:
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1. Read and check marker block
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2. Read archive header
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3. Read or skip HEAD_SIZE-sizeof(MAIN_HEAD) bytes
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4. If end of archive encountered then terminate archive processing,
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else read 7 bytes into fields HEAD_CRC, HEAD_TYPE, HEAD_FLAGS,
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HEAD_SIZE.
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5. Check HEAD_TYPE.
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if HEAD_TYPE==0x74
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read file header ( first 7 bytes already read )
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read or skip HEAD_SIZE-sizeof(FILE_HEAD) bytes
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if (HEAD_FLAGS & 0x100)
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read or skip HIGH_PACK_SIZE*0x100000000+PACK_SIZE bytes
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else
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read or skip PACK_SIZE bytes
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else
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read corresponding HEAD_TYPE block:
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read HEAD_SIZE-7 bytes
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if (HEAD_FLAGS & 0x8000)
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read ADD_SIZE bytes
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6. go to 4.
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==========================================================================
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Block Formats
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==========================================================================
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Marker block ( MARK_HEAD )
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HEAD_CRC Always 0x6152
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2 bytes
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HEAD_TYPE Header type: 0x72
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1 byte
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HEAD_FLAGS Always 0x1a21
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2 bytes
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HEAD_SIZE Block size = 0x0007
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2 bytes
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The marker block is actually considered as a fixed byte
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sequence: 0x52 0x61 0x72 0x21 0x1a 0x07 0x00
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Archive header ( MAIN_HEAD )
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HEAD_CRC CRC of fields HEAD_TYPE to RESERVED2
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2 bytes
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HEAD_TYPE Header type: 0x73
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1 byte
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HEAD_FLAGS Bit flags:
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2 bytes
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0x0001 - Volume attribute (archive volume)
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0x0002 - Archive comment present
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RAR 3.x uses the separate comment block
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and does not set this flag.
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0x0004 - Archive lock attribute
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0x0008 - Solid attribute (solid archive)
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0x0010 - New volume naming scheme ('volname.partN.rar')
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0x0020 - Authenticity information present
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RAR 3.x does not set this flag.
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0x0040 - Recovery record present
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0x0080 - Block headers are encrypted
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0x0100 - First volume (set only by RAR 3.0 and later)
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other bits in HEAD_FLAGS are reserved for
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internal use
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HEAD_SIZE Archive header total size including archive comments
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2 bytes
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RESERVED1 Reserved
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2 bytes
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RESERVED2 Reserved
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4 bytes
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File header (File in archive)
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HEAD_CRC CRC of fields from HEAD_TYPE to FILEATTR
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2 bytes and file name
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HEAD_TYPE Header type: 0x74
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1 byte
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HEAD_FLAGS Bit flags:
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2 bytes
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0x01 - file continued from previous volume
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0x02 - file continued in next volume
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0x04 - file encrypted with password
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0x08 - file comment present
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RAR 3.x uses the separate comment block
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and does not set this flag.
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0x10 - information from previous files is used (solid flag)
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(for RAR 2.0 and later)
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bits 7 6 5 (for RAR 2.0 and later)
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0 0 0 - dictionary size 64 KB
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0 0 1 - dictionary size 128 KB
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0 1 0 - dictionary size 256 KB
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0 1 1 - dictionary size 512 KB
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1 0 0 - dictionary size 1024 KB
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1 0 1 - dictionary size 2048 KB
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1 1 0 - dictionary size 4096 KB
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1 1 1 - file is directory
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0x100 - HIGH_PACK_SIZE and HIGH_UNP_SIZE fields
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are present. These fields are used to archive
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only very large files (larger than 2Gb),
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for smaller files these fields are absent.
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0x200 - FILE_NAME contains both usual and encoded
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Unicode name separated by zero. In this case
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NAME_SIZE field is equal to the length
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of usual name plus encoded Unicode name plus 1.
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If this flag is present, but FILE_NAME does not
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contain zero bytes, it means that file name
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is encoded using UTF-8.
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0x400 - the header contains additional 8 bytes
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after the file name, which are required to
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increase encryption security (so called 'salt').
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0x800 - Version flag. It is an old file version,
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a version number is appended to file name as ';n'.
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0x1000 - Extended time field present.
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0x8000 - this bit always is set, so the complete
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block size is HEAD_SIZE + PACK_SIZE
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(and plus HIGH_PACK_SIZE, if bit 0x100 is set)
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HEAD_SIZE File header full size including file name and comments
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2 bytes
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PACK_SIZE Compressed file size
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4 bytes
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UNP_SIZE Uncompressed file size
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4 bytes
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HOST_OS Operating system used for archiving
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1 byte 0 - MS DOS
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1 - OS/2
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2 - Win32
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3 - Unix
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4 - Mac OS
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5 - BeOS
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FILE_CRC File CRC
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4 bytes
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FTIME Date and time in standard MS DOS format
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4 bytes
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UNP_VER RAR version needed to extract file
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1 byte
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Version number is encoded as
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10 * Major version + minor version.
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METHOD Packing method
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1 byte
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0x30 - storing
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0x31 - fastest compression
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0x32 - fast compression
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0x33 - normal compression
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0x34 - good compression
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0x35 - best compression
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NAME_SIZE File name size
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2 bytes
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ATTR File attributes
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4 bytes
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HIGH_PACK_SIZE High 4 bytes of 64 bit value of compressed file size.
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4 bytes Optional value, presents only if bit 0x100 in HEAD_FLAGS
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is set.
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HIGH_UNP_SIZE High 4 bytes of 64 bit value of uncompressed file size.
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4 bytes Optional value, presents only if bit 0x100 in HEAD_FLAGS
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is set.
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FILE_NAME File name - string of NAME_SIZE bytes size
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SALT present if (HEAD_FLAGS & 0x400) != 0
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8 bytes
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EXT_TIME present if (HEAD_FLAGS & 0x1000) != 0
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variable size
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other new fields may appear here.
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==========================================================================
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Application notes
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==========================================================================
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1. To process an SFX archive you need to skip the SFX module searching
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for the marker block in the archive. There is no marker block sequence (0x52
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0x61 0x72 0x21 0x1a 0x07 0x00) in the SFX module itself.
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2. The CRC is calculated using the standard polynomial 0xEDB88320. In
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case the size of the CRC is less than 4 bytes, only the low order bytes
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are used.
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