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/ lib/ dracut/ modules.d/ 99img-lib/ |
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#!/bin/sh # img-lib.sh: utilities for dealing with archives and filesystem images. # # TODO: identify/unpack rpm, deb, maybe others? # super-simple "file" that only identifies archives. # works with stdin if $1 is not set. det_archive() { # NOTE: echo -e works in ash and bash, but not dash local bz="BZh" xz="$(echo -e '\xfd7zXZ')" gz="$(echo -e '\x1f\x8b')" zs="$(echo -e '\x28\xB5\x2F\xFD')" local headerblock="$(dd ${1:+if=$1} bs=262 count=1 2>/dev/null | tr -d '\0')" case "$headerblock" in $xz*) echo "xz" ;; $gz*) echo "gzip" ;; $bz*) echo "bzip2" ;; $zs*) echo "zstd" ;; 07070*) echo "cpio" ;; *ustar) echo "tar" ;; esac } # determine filesystem type for a filesystem image det_fs_img() { local dev=$(losetup --find --show "$1") rv="" det_fs $dev; rv=$? losetup -d $dev return $rv } # unpack_archive ARCHIVE OUTDIR # unpack a (possibly compressed) cpio/tar archive unpack_archive() { local img="$1" outdir="$2" archiver="" decompr="" local ft="$(det_archive $img)" case "$ft" in xz|gzip|bzip2|zstd) decompr="$ft -dc" ;; cpio|tar) decompr="cat";; *) return 1 ;; esac ft="$($decompr $img | det_archive)" case "$ft" in cpio) archiver="cpio -iumd" ;; tar) archiver="tar -xf -" ;; *) return 2 ;; esac mkdir -p $outdir ( cd $outdir; $decompr | $archiver 2>/dev/null ) < $img } # unpack_fs FSIMAGE OUTDIR # unpack a filesystem image unpack_fs() { local img="$1" outdir="$2" mnt="$(mkuniqdir /tmp unpack_fs.)" mount -o loop $img $mnt || { rmdir $mnt; return 1; } mkdir -p $outdir; outdir="$(cd $outdir; pwd)" copytree $mnt $outdir umount $mnt rmdir $mnt } # unpack an image file - compressed/uncompressed cpio/tar, filesystem, whatever # unpack_img IMAGEFILE OUTDIR unpack_img() { local img="$1" outdir="$2" [ -r "$img" ] || { warn "can't read img!"; return 1; } [ -n "$outdir" ] || { warn "unpack_img: no output dir given"; return 1; } if [ "$(det_archive $img)" ]; then unpack_archive "$@" || { warn "can't unpack archive file!"; return 1; } else unpack_fs "$@" || { warn "can't unpack filesystem image!"; return 1; } fi }