mirror of
https://salsa.debian.org/kernel-team/initramfs-tools.git
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Merge branch 'unmk-regression' into 'debian/latest'
unmkinitramfs: Restore split to "early" and "main" subdirectories See merge request kernel-team/initramfs-tools!162
This commit is contained in:
Ben Hutchings
commit
8722bb830a
143
unmkinitramfs
143
unmkinitramfs
@ -25,24 +25,28 @@ usage_error()
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# Extract a compressed cpio archive
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xcpio()
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{
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archive="$1"
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dir="$2"
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shift 2
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archive_uncomp="$1"
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archive="$2"
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dir="$3"
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shift 3
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if gzip -t "$archive" >/dev/null 2>&1 ; then
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gzip -c -d "$archive"
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elif zstd -q -c -t "$archive" >/dev/null 2>&1 ; then
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zstd -q -c -d "$archive"
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elif xzcat -t "$archive" >/dev/null 2>&1 ; then
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xzcat "$archive"
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elif lz4cat -t < "$archive" >/dev/null 2>&1 ; then
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lz4cat "$archive"
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elif bzip2 -t "$archive" >/dev/null 2>&1 ; then
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bzip2 -c -d "$archive"
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elif lzop -t "$archive" >/dev/null 2>&1 ; then
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lzop -c -d "$archive"
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# Ignoring other data, which may be garbage at the end of the file
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fi | (
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{
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cat "$archive_uncomp"
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if gzip -t "$archive" >/dev/null 2>&1 ; then
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gzip -c -d "$archive"
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elif zstd -q -c -t "$archive" >/dev/null 2>&1 ; then
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zstd -q -c -d "$archive"
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elif xzcat -t "$archive" >/dev/null 2>&1 ; then
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xzcat "$archive"
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elif lz4cat -t < "$archive" >/dev/null 2>&1 ; then
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lz4cat "$archive"
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elif bzip2 -t "$archive" >/dev/null 2>&1 ; then
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bzip2 -c -d "$archive"
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elif lzop -t "$archive" >/dev/null 2>&1 ; then
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lzop -c -d "$archive"
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# Ignoring other data, which may be garbage at the end of the file
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fi
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} | (
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if [ -n "$dir" ]; then
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mkdir -p -- "$dir"
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cd -- "$dir"
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@ -65,13 +69,16 @@ checkzero()
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LANG=C grep -q -z '^$'
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}
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# Split an initramfs into archives and call xcpio on each
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# Split an initramfs into archives and run cpio/xcpio to extract them
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splitinitramfs()
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{
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initramfs="$1"
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dir="$2"
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shift 2
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# Ensure this exists so we can use it unconditionally later
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touch "$tempdir/main-uncomp.cpio"
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count=0
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start=0
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while true; do
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@ -81,55 +88,92 @@ splitinitramfs()
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# very roughly based on linux/lib/earlycpio.c
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end=$start
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while true; do
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if checkzero "$initramfs" $end; then
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# This is the EOF marker. There might
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# be more zero padding before the next
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# archive, so read through all of it.
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end=$((end + 4))
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headoff=$end
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magic="$(readhex "$initramfs" $end 6)" || break
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test "$magic" = 070701 || test "$magic" = 070702 || break
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namesize=$((0x$(readhex "$initramfs" $((end + 94)) 8)))
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filesize=$((0x$(readhex "$initramfs" $((end + 54)) 8)))
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nameoff=$((end + 110))
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end=$(((nameoff + namesize + 3) & ~3))
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end=$(((end + filesize + 3) & ~3))
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# Check for EOF marker. Note that namesize
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# includes a null terminator.
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if [ $namesize = 11 ] \
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&& name="$(dd if="$initramfs" bs=1 skip=$nameoff count=$((namesize - 1)) 2> /dev/null)" \
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&& [ "$name" = 'TRAILER!!!' ]; then
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# There might be more zero padding
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# before the next archive, so read
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# through all of it.
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while checkzero "$initramfs" $end; do
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end=$((end + 4))
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done
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break
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fi
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magic="$(readhex "$initramfs" $end 6)" || break
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test "$magic" = 070701 || test "$magic" = 070702 || break
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namesize=0x$(readhex "$initramfs" $((end + 94)) 8)
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filesize=0x$(readhex "$initramfs" $((end + 54)) 8)
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end=$((end + 110))
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end=$(((end + namesize + 3) & ~3))
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end=$(((end + filesize + 3) & ~3))
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done
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if [ $end -eq $start ]; then
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break
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fi
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# Extract to cpio1, cpio2, ... subdirectories
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count=$((count + 1))
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subdir=cpio$count
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dd < "$initramfs" skip=$start count=$((end - start)) iflag=skip_bytes,count_bytes 2> /dev/null |
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(
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if [ -n "$dir" ]; then
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mkdir -p -- "$dir/$subdir"
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cd -- "$dir/$subdir"
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# Check whether this should be treated as an "early"
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# or "main" initramfs. Currently all filenames the
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# kernel looks for in an early initramfs begin with
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# kernel/ subdirectory, but we should never create
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# this in the main initramfs.
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if dd < "$initramfs" skip=$start count=$((end - start)) \
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iflag=skip_bytes,count_bytes 2> /dev/null |
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cpio -i --list 2> /dev/null |
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grep -q ^kernel/; then
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# Extract to early, early2, ... subdirectories
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count=$((count + 1))
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if [ $count -eq 1 ]; then
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subdir=early
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else
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subdir=early$count
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fi
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cpio -i "$@"
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)
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dd < "$initramfs" skip=$start count=$((end - start)) \
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iflag=skip_bytes,count_bytes 2> /dev/null |
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(
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if [ -n "$dir" ]; then
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mkdir -p -- "$dir/$subdir"
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cd -- "$dir/$subdir"
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fi
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cpio -i "$@"
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)
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else
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# Append to main-uncomp.cpio, excluding the
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# trailer so cpio won't stop before the
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# (de)compressed part.
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dd < "$initramfs" skip=$start \
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count=$((headoff - start)) \
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iflag=skip_bytes,count_bytes \
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>> "$tempdir/main-uncomp.cpio" 2> /dev/null
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fi
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start=$end
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done
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# Split out final archive if necessary
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if [ "$end" -gt 0 ]; then
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# Extract to main subdirectory
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subarchive=$(mktemp "${TMPDIR:-/var/tmp}/unmkinitramfs_XXXXXX")
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trap 'rm -f "$subarchive"' EXIT
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subarchive="$tempdir/main-comp.cpio"
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dd < "$initramfs" skip="$end" iflag=skip_bytes 2> /dev/null \
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> "$subarchive"
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count=$((count + 1))
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subdir=cpio$count
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xcpio "$subarchive" "${dir:+$dir/$subdir}" -i "$@"
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else
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# Don't use subdirectories (for backward compatibility)
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xcpio "$initramfs" "$dir" -i "$@"
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subarchive="$initramfs"
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fi
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# If we found an early initramfs, extract main initramfs to
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# main subdirectory. Otherwise don't use a subdirectory (for
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# backward compatibility).
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if [ "$count" -gt 0 ]; then
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subdir=main
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else
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subdir=.
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fi
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xcpio "$tempdir/main-uncomp.cpio" "$subarchive" \
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"${dir:+$dir/$subdir}" -i "$@"
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}
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OPTIONS=$(getopt -o hv --long help,list,verbose -n "$0" -- "$@") || usage_error
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@ -168,5 +212,8 @@ if [ $# -ne $expected_args ]; then
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usage_error
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fi
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tempdir="$(mktemp -d "${TMPDIR:-/var/tmp}/unmkinitramfs_XXXXXX")"
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trap 'rm -rf "$tempdir"' EXIT
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# shellcheck disable=SC2086
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splitinitramfs "$1" "${2:-}" $cpio_opts
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@ -1,4 +1,4 @@
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.TH UNMKINITRAMFS 8 "2016/12/15" "initramfs\-tools" "System Administration"
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.TH UNMKINITRAMFS 8 "2025/03/20" "initramfs\-tools" "System Administration"
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.SH NAME
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unmkinitramfs \- extract content from an initramfs image
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@ -14,10 +14,21 @@ unmkinitramfs \- extract content from an initramfs image
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The
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.B unmkinitramfs
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command extracts the content of a given initramfs image using
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.BR cpio .
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If the image contains multiple segments, each are passed to
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.B cpio
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in order.
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and the appropriate decompressor command.
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The initramfs image may be a single compressed cpio archive, or the
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concatenation of any number of uncompressed cpio archives followed by
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a compressed cpio archive.
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When the initramfs image includes one or more "early initramfs"
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archives, that is uncompressed archives with microcode or other files
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that the kernel uses directly, these are extracted to sub\-directories
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named "\fBearly\fR", "\fBearly2\fR", etc., and the other archives are
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extracted to a sub\-directory named "\fBmain\fR".
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In a future version of initramfs\-tools this behaviour may change so
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that all archives are extracted directly into the given directory.
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.SH OPTIONS
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@ -40,9 +51,8 @@ Extract initramfs content of current running kernel:
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.SH BUGS
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.BR unmkinitramfs
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cannot deal with multiple-segmented initramfs images, except where an
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early (uncompressed) initramfs with system firmware is prepended to
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the regular compressed initramfs.
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does not support initramfs images with more or less than one
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compressed cpio archive.
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.SH AUTHOR
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The initramfs-tools are written by Maximilian Attems <maks@debian.org>
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