summaryrefslogtreecommitdiffstats
path: root/unmkinitramfs
diff options
context:
space:
mode:
authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 15:45:07 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 15:45:07 +0000
commit3b043b08c9b52424072db56be6636ff44c737e83 (patch)
treed64185acc33a046c8bb297641a16b01ec167eaa5 /unmkinitramfs
parentInitial commit. (diff)
downloadinitramfs-tools-3b043b08c9b52424072db56be6636ff44c737e83.tar.xz
initramfs-tools-3b043b08c9b52424072db56be6636ff44c737e83.zip
Adding upstream version 0.142.upstream/0.142upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'unmkinitramfs')
-rwxr-xr-xunmkinitramfs174
1 files changed, 174 insertions, 0 deletions
diff --git a/unmkinitramfs b/unmkinitramfs
new file mode 100755
index 0000000..d1226c3
--- /dev/null
+++ b/unmkinitramfs
@@ -0,0 +1,174 @@
+#!/bin/sh
+
+set -eu
+
+usage()
+{
+ cat << EOF
+
+Usage: unmkinitramfs [-v] initramfs-file directory
+
+Options:
+ -v Display verbose messages about extraction
+
+See unmkinitramfs(8) for further details.
+
+EOF
+}
+
+usage_error()
+{
+ usage >&2
+ exit 2
+}
+
+# Extract a compressed cpio archive
+xcpio()
+{
+ archive="$1"
+ dir="$2"
+ shift 2
+
+ if gzip -t "$archive" >/dev/null 2>&1 ; then
+ gzip -c -d "$archive"
+ elif zstd -q -c -t "$archive" >/dev/null 2>&1 ; then
+ zstd -q -c -d "$archive"
+ elif xzcat -t "$archive" >/dev/null 2>&1 ; then
+ xzcat "$archive"
+ elif lz4cat -t < "$archive" >/dev/null 2>&1 ; then
+ lz4cat "$archive"
+ elif bzip2 -t "$archive" >/dev/null 2>&1 ; then
+ bzip2 -c -d "$archive"
+ elif lzop -t "$archive" >/dev/null 2>&1 ; then
+ lzop -c -d "$archive"
+ # Ignoring other data, which may be garbage at the end of the file
+ fi | (
+ if [ -n "$dir" ]; then
+ mkdir -p -- "$dir"
+ cd -- "$dir"
+ fi
+ cpio "$@"
+ )
+}
+
+# Read bytes out of a file, checking that they are valid hex digits
+readhex()
+{
+ dd < "$1" bs=1 skip="$2" count="$3" 2> /dev/null | \
+ LANG=C grep -E "^[0-9A-Fa-f]{$3}\$"
+}
+
+# Check for a zero byte in a file
+checkzero()
+{
+ dd < "$1" bs=1 skip="$2" count=1 2> /dev/null | \
+ LANG=C grep -q -z '^$'
+}
+
+# Split an initramfs into archives and call xcpio on each
+splitinitramfs()
+{
+ initramfs="$1"
+ dir="$2"
+ shift 2
+
+ count=0
+ start=0
+ while true; do
+ # There may be prepended uncompressed archives. cpio
+ # won't tell us the true size of these so we have to
+ # parse the headers and padding ourselves. This is
+ # very roughly based on linux/lib/earlycpio.c
+ end=$start
+ while true; do
+ if checkzero "$initramfs" $end; then
+ # This is the EOF marker. There might
+ # be more zero padding before the next
+ # archive, so read through all of it.
+ end=$((end + 4))
+ while checkzero "$initramfs" $end; do
+ end=$((end + 4))
+ done
+ break
+ fi
+ magic="$(readhex "$initramfs" $end 6)" || break
+ test "$magic" = 070701 || test "$magic" = 070702 || break
+ namesize=0x$(readhex "$initramfs" $((end + 94)) 8)
+ filesize=0x$(readhex "$initramfs" $((end + 54)) 8)
+ end=$(((end + 110)))
+ end=$(((end + namesize + 3) & ~3))
+ end=$(((end + filesize + 3) & ~3))
+ done
+ if [ $end -eq $start ]; then
+ break
+ fi
+
+ # Extract to early, early2, ... subdirectories
+ count=$((count + 1))
+ if [ $count -eq 1 ]; then
+ subdir=early
+ else
+ subdir=early$count
+ fi
+ dd < "$initramfs" skip=$start count=$((end - start)) iflag=skip_bytes 2> /dev/null |
+ (
+ if [ -n "$dir" ]; then
+ mkdir -p -- "$dir/$subdir"
+ cd -- "$dir/$subdir"
+ fi
+ cpio -i "$@"
+ )
+ start=$end
+ done
+
+ if [ $end -gt 0 ]; then
+ # Extract to main subdirectory
+ subarchive=$(mktemp "${TMPDIR:-/var/tmp}/unmkinitramfs_XXXXXX")
+ trap 'rm -f "$subarchive"' EXIT
+ dd < "$initramfs" skip=$end iflag=skip_bytes 2> /dev/null \
+ > "$subarchive"
+ xcpio "$subarchive" "${dir:+$dir/main}" -i "$@"
+ else
+ # Don't use subdirectories (for backward compatibility)
+ xcpio "$initramfs" "$dir" -i "$@"
+ fi
+}
+
+OPTIONS=$(getopt -o hv --long help,list,verbose -n "$0" -- "$@") || usage_error
+
+cpio_opts="--preserve-modification-time --no-absolute-filenames --quiet"
+expected_args=2
+eval set -- "$OPTIONS"
+
+while true; do
+ case "$1" in
+ -h|--help)
+ usage
+ exit 0
+ ;;
+ --list)
+ # For lsinitramfs
+ cpio_opts="${cpio_opts:+${cpio_opts} --list}"
+ expected_args=1
+ shift
+ ;;
+ -v|--verbose)
+ cpio_opts="${cpio_opts:+${cpio_opts} --verbose}"
+ shift
+ ;;
+ --)
+ shift
+ break
+ ;;
+ *)
+ echo "Internal error!" >&2
+ exit 1
+ esac
+done
+
+if [ $# -ne $expected_args ]; then
+ usage_error
+fi
+
+# shellcheck disable=SC2086
+splitinitramfs "$1" "${2:-}" $cpio_opts