#------------------------------------------------------------------------------ # compress: file(1) magic for pure-compression formats (no archives) # # compress, gzip, pack, compact, huf, squeeze, crunch, freeze, yabba, etc. # # Formats for various forms of compressed data # Formats for "compress" proper have been moved into "compress.c", # because it tries to uncompress it to figure out what's inside. # standard unix compress 0 string \037\235 compress'd data >2 byte&0x80 >0 block compressed >2 byte&0x1f x %d bits # gzip (GNU zip, not to be confused with Info-ZIP or PKWARE zip archiver) 0 string \037\213 gzip compressed data >2 byte <8 \b, reserved method, >2 byte 8 \b, deflated, >3 byte &0x01 ASCII, >3 byte &0x02 continuation, >3 byte &0x04 extra field, >3 byte &0x08 original filename, >3 byte &0x10 comment, >3 byte &0x20 encrypted, >4 ledate x last modified: %s, >8 byte 2 max compression, >8 byte 4 max speed, >9 byte =0x00 os: MS-DOS >9 byte =0x01 os: Amiga >9 byte =0x02 os: VMS >9 byte =0x03 os: Unix >9 byte =0x05 os: Atari >9 byte =0x06 os: OS/2 >9 byte =0x07 os: MacOS >9 byte =0x0A os: Tops/20 >9 byte =0x0B os: Win/32 # packed data, Huffman (minimum redundancy) codes on a byte-by-byte basis 0 string \037\036 packed data >2 belong >1 \b, %d characters originally >2 belong =1 \b, %d character originally # # This magic number is byte-order-independent. XXX - Does that mean this # is big-endian, little-endian, either, or that you can't tell? # this short is valid for SunOS 0 short 017437 old packed data # XXX - why *two* entries for "compacted data", one of which is # byte-order independent, and one of which is byte-order dependent? # 0 short 0x1fff compacted data # This string is valid for SunOS (BE) and a matching "short" is listed # in the Ultrix (LE) magic file. 0 string \377\037 compacted data 0 short 0145405 huf output # Squeeze and Crunch... # These numbers were gleaned from the Unix versions of the programs to # handle these formats. Note that I can only uncrunch, not crunch, and # I didn't have a crunched file handy, so the crunch number is untested. # Keith Waclena <keith@cerberus.uchicago.edu> 0 leshort 0x76FF squeezed data (CP/M, DOS) 0 leshort 0x76FE crunched data (CP/M, DOS) # Freeze 0 string \037\237 frozen file 2.1 0 string \037\236 frozen file 1.0 (or gzip 0.5) # SCO compress -H (LZH) 0 string \037\240 SCO compress -H (LZH) data # European GSM 06.10 is a provisional standard for full-rate speech # transcoding, prI-ETS 300 036, which uses RPE/LTP (residual pulse # excitation/long term prediction) coding at 13 kbit/s. # # There's only a magic nibble (4 bits); that nibble repeats every 33 # bytes. This isn't suited for use, but maybe we can use it someday. # # This will cause very short GSM files to be declared as data and # mismatches to be declared as data too! #0 byte&0xF0 0xd0 data #>33 byte&0xF0 0xd0 #>66 byte&0xF0 0xd0 #>99 byte&0xF0 0xd0 #>132 byte&0xF0 0xd0 GSM 06.10 compressed audio # Bzip from ulmo@Q.Net 0 string BZ bzip compressed data, >2 byte x format v. %c, >3 byte x block size indicator %c