extra/7z2lzma/7z2lzma.bash

   1 #!/bin/bash
   2 #
   3 #############################################################################
   4 #
   5 # 7z2lzma.bash is very primitive .7z to .lzma converter. The input file must
   6 # have exactly one LZMA compressed stream, which has been created with the
   7 # default lc, lp, and pb values. The CRC32 in the .7z archive is not checked,
   8 # and the script may seem to succeed while it actually created a corrupt .lzma
   9 # file. You should always try uncompressing both the original .7z and the
  10 # created .lzma and compare that the output is identical.
  11 #
  12 # This script requires basic GNU tools and 7z or 7za tool from p7zip.
  13 #
  14 # Last modified: 2009-01-15 14:25+0200
  15 #
  16 #############################################################################
  17 #
  18 # Author: Lasse Collin <lasse.collin@tukaani.org>
  19 #
  20 # This file has been put into the public domain.
  21 # You can do whatever you want with this file.
  22 #
  23 #############################################################################
  24
  25 # You can use 7z or 7za, both will work.
  26 SEVENZIP=7za
  27
  28 if [ $# != 2 -o -z "$1" -o -z "$2" ]; then
  29         echo "Usage: $0 input.7z output.lzma"
  30         exit 1
  31 fi
  32
  33 # Converts an integer variable to little endian binary integer.
  34 int2bin()
  35 {
  36         local LEN=$1
  37         local NUM=$2
  38         local HEX=(0 1 2 3 4 5 6 7 8 9 A B C D E F)
  39         local I
  40         for ((I=0; I < "$LEN"; ++I)); do
  41                 printf "\\x${HEX[(NUM >> 4) & 0x0F]}${HEX[NUM & 0x0F]}"
  42                 NUM=$((NUM >> 8))
  43         done
  44 }
  45
  46 # Make sure we get possible errors from pipes.
  47 set -o pipefail
  48
  49 # Get information about the input file. At least older 7z and 7za versions
  50 # may return with zero exit status even when an error occurred, so check
  51 # if the output has any lines beginning with "Error".
  52 INFO=$("$SEVENZIP" l -slt "$1")
  53 if [ $? != 0 ] || printf '%s\n' "$INFO" | grep -q ^Error; then
  54         printf '%s\n' "$INFO"
  55         exit 1
  56 fi
  57
  58 # Check if the input file has more than one compressed block.
  59 if printf '%s\n' "$INFO" | grep -q '^Block = 1'; then
  60         echo "Cannot convert, because the input file has more than"
  61         echo "one compressed block."
  62         exit 1
  63 fi
  64
  65 # Get compressed, uncompressed, and dictionary size.
  66 CSIZE=$(printf '%s\n' "$INFO" | sed -rn 's|^Packed Size = ([0-9]+$)|\1|p')
  67 USIZE=$(printf '%s\n' "$INFO" | sed -rn 's|^Size = ([0-9]+$)|\1|p')
  68 DICT=$(printf '%s\n' "$INFO" | sed -rn 's|^Method = LZMA:([0-9]+[bkm]?)$|\1|p')
  69
  70 if [ -z "$CSIZE" -o -z "$USIZE" -o -z "$DICT" ]; then
  71         echo "Parsing output of $SEVENZIP failed. Maybe the file uses some"
  72         echo "other compression method than plain LZMA."
  73         exit 1
  74 fi
  75
  76 # The following assumes that the default lc, lp, and pb settings were used.
  77 # Otherwise the output will be corrupt.
  78 printf '\x5D' > "$2"
  79
  80 # Dictionary size can be either was power of two, bytes, kibibytes, or
  81 # mebibytes. We need to convert it to bytes.
  82 case $DICT in
  83         *b)
  84                 DICT=${DICT%b}
  85                 ;;
  86         *k)
  87                 DICT=${DICT%k}
  88                 DICT=$((DICT << 10))
  89                 ;;
  90         *m)
  91                 DICT=${DICT%m}
  92                 DICT=$((DICT << 20))
  93                 ;;
  94         *)
  95                 DICT=$((1 << DICT))
  96                 ;;
  97 esac
  98 int2bin 4 "$DICT" >> "$2"
  99
 100 # Uncompressed size
 101 int2bin 8 "$USIZE" >> "$2"
 102
 103 # Copy the actual compressed data. Using multiple dd commands to avoid
 104 # copying large amount of data with one-byte block size, which would be
 105 # annoyingly slow.
 106 BS=8192
 107 BIGSIZE=$((CSIZE / BS))
 108 CSIZE=$((CSIZE % BS))
 109 {
 110         dd of=/dev/null bs=32 count=1 \
 111                 && dd bs="$BS" count="$BIGSIZE" \
 112                 && dd bs=1 count="$CSIZE"
 113 } < "$1" >> "$2"
 114
 115 exit $?