116 lines
3.2 KiB
Bash
Executable File
116 lines
3.2 KiB
Bash
Executable File
#!/bin/bash
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#
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#############################################################################
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#
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# 7z2lzma.bash is very primitive .7z to .lzma converter. The input file must
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# have exactly one LZMA compressed stream, which has been created with the
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# default lc, lp, and pb values. The CRC32 in the .7z archive is not checked,
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# and the script may seem to succeed while it actually created a corrupt .lzma
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# file. You should always try uncompressing both the original .7z and the
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# created .lzma and compare that the output is identical.
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#
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# This script requires basic GNU tools and 7z or 7za tool from p7zip.
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#
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# Last modified: 2009-01-15 14:25+0200
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#
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#############################################################################
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#
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# Author: Lasse Collin <lasse.collin@tukaani.org>
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#
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# This file has been put into the public domain.
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# You can do whatever you want with this file.
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#
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#############################################################################
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# You can use 7z or 7za, both will work.
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SEVENZIP=7za
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if [ $# != 2 -o -z "$1" -o -z "$2" ]; then
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echo "Usage: $0 input.7z output.lzma"
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exit 1
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fi
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# Converts an integer variable to little endian binary integer.
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int2bin()
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{
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local LEN=$1
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local NUM=$2
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local HEX=(0 1 2 3 4 5 6 7 8 9 A B C D E F)
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local I
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for ((I=0; I < "$LEN"; ++I)); do
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printf "\\x${HEX[(NUM >> 4) & 0x0F]}${HEX[NUM & 0x0F]}"
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NUM=$((NUM >> 8))
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done
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}
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# Make sure we get possible errors from pipes.
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set -o pipefail
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# Get information about the input file. At least older 7z and 7za versions
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# may return with zero exit status even when an error occurred, so check
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# if the output has any lines beginning with "Error".
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INFO=$("$SEVENZIP" l -slt "$1")
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if [ $? != 0 ] || printf '%s\n' "$INFO" | grep -q ^Error; then
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printf '%s\n' "$INFO"
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exit 1
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fi
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# Check if the input file has more than one compressed block.
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if printf '%s\n' "$INFO" | grep -q '^Block = 1'; then
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echo "Cannot convert, because the input file has more than"
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echo "one compressed block."
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exit 1
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fi
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# Get compressed, uncompressed, and dictionary size.
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CSIZE=$(printf '%s\n' "$INFO" | sed -rn 's|^Packed Size = ([0-9]+$)|\1|p')
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USIZE=$(printf '%s\n' "$INFO" | sed -rn 's|^Size = ([0-9]+$)|\1|p')
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DICT=$(printf '%s\n' "$INFO" | sed -rn 's|^Method = LZMA:([0-9]+[bkm]?)$|\1|p')
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if [ -z "$CSIZE" -o -z "$USIZE" -o -z "$DICT" ]; then
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echo "Parsing output of $SEVENZIP failed. Maybe the file uses some"
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echo "other compression method than plain LZMA."
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exit 1
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fi
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# The following assumes that the default lc, lp, and pb settings were used.
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# Otherwise the output will be corrupt.
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printf '\x5D' > "$2"
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# Dictionary size can be either was power of two, bytes, kibibytes, or
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# mebibytes. We need to convert it to bytes.
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case $DICT in
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*b)
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DICT=${DICT%b}
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;;
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*k)
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DICT=${DICT%k}
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DICT=$((DICT << 10))
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;;
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*m)
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DICT=${DICT%m}
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DICT=$((DICT << 20))
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;;
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*)
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DICT=$((1 << DICT))
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;;
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esac
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int2bin 4 "$DICT" >> "$2"
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# Uncompressed size
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int2bin 8 "$USIZE" >> "$2"
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# Copy the actual compressed data. Using multiple dd commands to avoid
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# copying large amount of data with one-byte block size, which would be
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# annoyingly slow.
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BS=8192
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BIGSIZE=$((CSIZE / BS))
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CSIZE=$((CSIZE % BS))
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{
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dd of=/dev/null bs=32 count=1 \
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&& dd bs="$BS" count="$BIGSIZE" \
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&& dd bs=1 count="$CSIZE"
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} < "$1" >> "$2"
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exit $?
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