77# This will create one or more out-dir/rootfs-N directories that contain the contents of the initramfs.
88
99set -euo pipefail
10- # check for unzstd. Will abort the script with an error message if the tool is not present.
11- unzstd -V > /dev/null
10+
11+ # check for xzcat. Will abort the script with an error message if the tool is not present.
12+ xzcat -V > /dev/null
13+
1214fail () {
1315 echo " ${* } " >&2
1416 exit 1
1517}
1618
17- # Stolen from extract-vmlinux and modified.
18- try_decompress () {
19- local header=" ${1} "
20- local no_idea=" ${2} "
21- local tool=" ${3} "
22- local image=" ${4} "
23- local tmp=" ${5} "
24- local output_basename=" ${6} "
25-
26- local pos
27- local tool_filename=$( echo " ${tool} " | cut -f1 -d' ' )
28- # The obscure use of the "tr" filter is to work around older versions of
29- # "grep" that report the byte offset of the line instead of the pattern.
19+ find_xz_headers () {
20+ grep --fixed-strings --text --byte-offset --only-matching $' \xFD\x37\x7A\x58\x5A\x00 ' " $1 " | cut -d: -f1
21+ }
3022
31- # Try to find the header and decompress from here.
32- for pos in $( tr " ${header} \n${no_idea} " " \n${no_idea} =" < " ${image} " |
33- grep --text --byte-offset --only-matching " ^${no_idea} " )
34- do
35- pos=${pos%%:* }
36- # Disable error handling, because we will be potentially
37- # giving the tool garbage or a valid archive with some garbage
38- # appended to it. So let the tool extract the valid archive
39- # and then complain about the garbage at the end, but don't
40- # fail the script because of it.
41- set +e; tail " -c+${pos} " " ${image} " | " ${tool} " > " ${tmp} /out" 2> /dev/null; set -e;
42- if [ -s " ${tmp} /out" ; then
43- mv " ${tmp} /out" " ${output_basename} -${tool_filename} -at-${pos} "
44- else
45- rm -f " ${tmp} /out"
46- fi
47- done
23+ decompress_at () {
24+ # Data may not really be a valid xz, so allow for errors.
25+ tail " -c+$(( ${2%:* } + 1 )) " " $1 " | xzcat 2> /dev/null || true
4826}
4927
50- try_unzstd_decompress () {
51- local image=" ${1} "
52- local tmp=" ${2} "
53- local output_basename=" ${3} "
54- try_decompress ' (\265/\375' " ${image} " " ${tmp} " " ${output_basename} "
28+ try_extract () {
29+ # cpio can do strange things when given garbage, so do a basic check.
30+ [[ $( head -c6 " $1 " ) == 070701 ]] || return 0
31+
32+ # There may be multiple concatenated archives so try cpio till it fails.
33+ while cpio --quiet --extract --make-directories --directory=" ${out} /rootfs-${ROOTFS_IDX} " ' dev/*' 2> /dev/null; do
34+ ROOTFS_IDX=$(( ROOTFS_IDX + 1 ))
35+ done < " $1 "
36+
37+ # Last cpio attempt may or may not leave an empty directory.
38+ rmdir " ${out} /rootfs-${ROOTFS_IDX} " 2> /dev/null || ROOTFS_IDX=$(( ROOTFS_IDX + 1 ))
5539}
5640
5741me=" ${0##*/ } "
@@ -65,37 +49,22 @@ if [[ ! -s "${image}" ]]; then
6549fi
6650mkdir -p " ${out} "
6751
68- tmp=$( mktemp --directory /tmp/eifv-XXXXXX)
69- trap " rm -rf ${tmp} "
52+ tmp=$( mktemp --directory eifv-XXXXXX)
53+ trap ' rm -rf -- "${tmp}"'
54+ ROOTFS_IDX=0
7055
71- tmp_dec=" ${tmp} /decompress"
72- mkdir " ${tmp_dec} "
73- fr_prefix=" ${tmp} /first-round"
56+ # arm64 kernels are not compressed, so try decompressing once.
57+ # Other kernels are compressed, so also try decompressing twice.
58+ for OFF1 in $( find_xz_headers " ${image} " )
59+ do
60+ decompress_at " ${image} " " ${OFF1} " > " ${tmp} /initrd.maybe_cpio_or_elf"
61+ try_extract " ${tmp} /initrd.maybe_cpio_or_elf"
7462
75- ROOTFS_IDX=0
76- perform_round () {
77- local image=" ${1} "
78- local tmp_dec=" ${2} "
79- local round_prefix=" ${3} "
80- try_unzstd_decompress " ${image} " " ${tmp_dec} " " ${round_prefix} "
81- for rnd in " ${round_prefix} " * ; do
82- if [[ $( file --brief " ${rnd} " ) =~ ' cpio archive' ; then
83- mkdir -p " ${out} /rootfs-${ROOTFS_IDX} "
84- # On Linux 6.10, the first rootfs is an extra ghost rootfs of 336K, that has a corrupted CPIO
85- cpio --quiet --extract --make-directories --directory=" ${out} /rootfs-${ROOTFS_IDX} " ' dev/*' < $rnd || true
86- ROOTFS_IDX=$(( ROOTFS_IDX + 1 ))
87- fi
63+ for OFF2 in $( find_xz_headers " ${tmp} /initrd.maybe_cpio_or_elf" )
64+ do
65+ decompress_at " ${tmp} /initrd.maybe_cpio_or_elf" " ${OFF2} " > " ${tmp} /initrd.maybe_cpio"
66+ try_extract " ${tmp} /initrd.maybe_cpio"
8867 done
89- }
90-
91- shopt -s nullglob
92- perform_round " ${image} " " ${tmp_dec} " " ${fr_prefix} "
93- for fr in " ${fr_prefix} " * ; do
94- fr_files=" ${fr} -files"
95- fr_dec=" ${fr_files} /decompress"
96- mkdir -p " ${fr_dec} "
97- sr_prefix=" ${fr_files} /second-round"
98- perform_round " ${fr} " " ${fr_dec} " " ${sr_prefix} "
9968done
10069
10170if [[ ${ROOTFS_IDX} -eq 0 ]]; then
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