92 lines
1.8 KiB
Bash
92 lines
1.8 KiB
Bash
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#!/bin/bash
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ORIGFILE="$1"
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is_relative() {
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local path="$1"
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shift
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[ "${path:0:1}" != "/" ]
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return
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}
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set_offsets() {
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# This won't work with non-GNU stat.
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FILE_SIZE=`stat -L --format "%s" "$1"`
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local offset=$(($FILE_SIZE - 4))
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MAGIC_OFFSET=$offset
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offset=$(($offset - 4))
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CHECKSUM_OFFSET=$offset
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offset=$(($offset - 4))
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VERSION_OFFSET=$offset
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offset=$(($offset - 4))
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PREPAYLOAD_OFFSET=$offset
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offset=$(($offset - 4))
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PREPAYLOAD_SIZE_OFFSET=$offset
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offset=$(($offset - 4))
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LAUNCHER_SIZE_OFFSET=$offset
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offset=$(($offset - 4))
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PAYLOAD_OFFSET=$offset
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offset=$(($offset - 4))
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PAYLOAD_SIZE_OFFSET=$offset
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offset=$(($offset - 4))
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}
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set_lengths() {
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local file="$1"
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if [ ! -s "$file" ]; then
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echo "$file does not exist"
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exit 1
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fi
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# XXX: put extraction in its own function
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MAGIC_NUMBER=`od -An -t u4 -N 4 -j $MAGIC_OFFSET "$file" | tr -d ' '`
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if [ "$MAGIC_NUMBER" != "907380241" ]; then
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echo "magic number does not match"
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exit 1
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fi
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LAUNCHER_SIZE=`od -An -t u4 -N 4 -j $LAUNCHER_SIZE_OFFSET "$file" | tr -d ' '`
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PAYLOAD_SIZE=`od -An -t u4 -N 4 -j $PAYLOAD_SIZE_OFFSET "$file" | tr -d ' '`
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PREPAYLOAD_SIZE=`od -An -t u4 -N 4 -j $PREPAYLOAD_SIZE_OFFSET "$file" | tr -d ' '`
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SKIP_BYTES=$(($PREPAYLOAD_SIZE + $LAUNCHER_SIZE))
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return 0
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}
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if is_relative "${ORIGFILE}"; then
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ORIGFILE="`pwd`/${ORIGFILE}"
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fi
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set_offsets ${ORIGFILE}
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set_lengths ${ORIGFILE}
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echo "Unbundling" ${ORIGFILE}
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PREPAYLOAD="prepayload"
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PAYLOAD="payload"
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# Unpack the pre-payload file
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mkdir ${PREPAYLOAD}
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cd ${PREPAYLOAD}
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dd if="${ORIGFILE}" ibs=$LAUNCHER_SIZE obs=1024 skip=1 | tar -xzf - 2> /dev/null
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cd ..
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# Unpack the main file
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mkdir ${PAYLOAD}
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cd ${PAYLOAD}
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dd if="${ORIGFILE}" ibs=$SKIP_BYTES obs=1024 skip=1 | tar -xzf - 2> /dev/null
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cd ..
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