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108 lines
2.6 KiB
108 lines
2.6 KiB
#!/bin/sh |
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# img-lib.sh: utilities for dealing with archives and filesystem images. |
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# |
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# TODO: identify/unpack rpm, deb, maybe others? |
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# super-simple "file" that only identifies archives. |
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# works with stdin if $1 is not set. |
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det_archive() { |
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# NOTE: internal echo -e works in ash and bash, but not dash |
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local bz xz gz zs |
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local headerblock |
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bz="BZh" |
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# shellcheck disable=SC3037 |
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xz="$(/bin/echo -e '\xfd7zXZ')" |
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# shellcheck disable=SC3037 |
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gz="$(/bin/echo -e '\x1f\x8b')" |
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# shellcheck disable=SC3037 |
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zs="$(/bin/echo -e '\x28\xB5\x2F\xFD')" |
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headerblock="$(dd ${1:+if=$1} bs=262 count=1 2> /dev/null | tr -d '\0')" |
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case "$headerblock" in |
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$xz*) echo "xz" ;; |
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$gz*) echo "gzip" ;; |
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$bz*) echo "bzip2" ;; |
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$zs*) echo "zstd" ;; |
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07070*) echo "cpio" ;; |
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*ustar) echo "tar" ;; |
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esac |
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} |
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# determine filesystem type for a filesystem image |
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det_fs_img() { |
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local dev |
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dev=$(losetup --find --show "$1") rv="" |
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det_fs "$dev" |
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rv=$? |
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losetup -d "$dev" |
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return $rv |
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} |
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# unpack_archive ARCHIVE OUTDIR |
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# unpack a (possibly compressed) cpio/tar archive |
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unpack_archive() { |
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local img="$1" outdir="$2" archiver="" decompr="" |
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local ft |
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ft="$(det_archive "$img")" |
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case "$ft" in |
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xz | gzip | bzip2 | zstd) decompr="$ft -dc" ;; |
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cpio | tar) decompr="cat" ;; |
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*) return 1 ;; |
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esac |
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ft="$($decompr "$img" | det_archive)" |
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case "$ft" in |
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cpio) archiver="cpio -iumd" ;; |
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tar) archiver="tar -xf -" ;; |
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*) return 2 ;; |
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esac |
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mkdir -p "$outdir" |
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( |
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cd "$outdir" || exit |
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$decompr | $archiver 2> /dev/null |
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) < "$img" |
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} |
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# unpack_fs FSIMAGE OUTDIR |
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# unpack a filesystem image |
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unpack_fs() { |
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local img="$1" outdir="$2" |
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local mnt |
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mnt="$(mkuniqdir /tmp unpack_fs.)" |
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mount -o loop "$img" "$mnt" || { |
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rmdir "$mnt" |
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return 1 |
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} |
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mkdir -p "$outdir" |
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outdir="$( |
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cd "$outdir" || exit |
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pwd |
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)" |
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copytree "$mnt" "$outdir" |
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umount "$mnt" |
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rmdir "$mnt" |
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} |
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# unpack an image file - compressed/uncompressed cpio/tar, filesystem, whatever |
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# unpack_img IMAGEFILE OUTDIR |
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unpack_img() { |
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local img="$1" outdir="$2" |
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[ -r "$img" ] || { |
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warn "can't read img!" |
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return 1 |
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} |
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[ -n "$outdir" ] || { |
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warn "unpack_img: no output dir given" |
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return 1 |
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} |
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if [ "$(det_archive "$img")" ]; then |
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unpack_archive "$@" || { |
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warn "can't unpack archive file!" |
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return 1 |
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} |
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else |
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unpack_fs "$@" || { |
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warn "can't unpack filesystem image!" |
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return 1 |
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} |
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fi |
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}
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