Create unmkinitramfs command

This command supports extracting files from an initramfs image.  It is
designed to be a drop-in for cpio wherever an initramfs may be present.

It is implemented using the code from lsinitramfs, which now delegates
to uninitramfs instead of cpio.

Signed-off-by: Kevin Locke <kevin@kevinlocke.name>
[bwh: Rename it from uninitramfs to unmkinitramfs; add to .install list]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

1 files changed, 2 insertions, 69 deletions

diff --git a/lsinitramfs b/lsinitramfs
index 34d84e4..14705ad 100755
--- a/lsinitramfs
+++ b/lsinitramfs
@@ -12,7 +12,7 @@ if [ "$#" -eq 0 ] ; then
 	exit 1
 fi
 
-cpio_args="--extract --quiet --list"
+cpio_args="--quiet --list"
 
 OPTIONS=`getopt -o hl --long help,long -n "$0" -- "$@"`
 # Check for non-GNU getopt
@@ -40,73 +40,6 @@ while true; do
 	esac
 done
 
-listarchive()
-{
-	archive="$1"
-	if zcat -t "${archive}" >/dev/null 2>&1 ; then
-		zcat "${archive}" | cpio ${cpio_args}
-	elif xzcat -t "${archive}" >/dev/null 2>&1 ; then
-		xzcat "${archive}" | cpio ${cpio_args}
-	elif bzip2 -t "${archive}" >/dev/null 2>&1 ; then
-		bzip2 -c -d "${archive}" | cpio ${cpio_args}
-	elif lzop -t "${archive}" >/dev/null 2>&1 ; then
-		lzop -c -d "${archive}" | cpio ${cpio_args}
-	fi
-}
-
-# 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="$2" count=1 2> /dev/null | \
-		LANG=C grep -q -z '^$'
-}
-
 for initramfs in "$@" ; do
-	if ! [ -r "${initramfs}" ] ; then
-		echo "Specified file could not be read." >&2
-		exit 1
-	else
-		echo "${initramfs}"
-
-		# There may be a prepended uncompressed archive.  cpio
-		# won't tell us the true size of this so we have to
-		# parse the headers and padding ourselves.  This is
-		# very roughly based on linux/lib/earlycpio.c
-		offset=0
-		while true; do
-			if checkzero "$initramfs" $offset; then
-				offset=$((offset + 4))
-				continue
-			fi
-			magic="$(readhex "$initramfs" $offset 6)" || break
-			test $magic = 070701 || test $magic = 070702 || break
-			namesize=0x$(readhex "$initramfs" $((offset + 94)) 8)
-			filesize=0x$(readhex "$initramfs" $((offset + 54)) 8)
-			offset=$(((offset + 110)))
-			offset=$(((offset + $namesize + 3) & ~3))
-			offset=$(((offset + $filesize + 3) & ~3))
-		done
-
-		if [ $offset -ne 0 ]; then
-			# List uncompressed archive
-			cpio ${cpio_args} < "$initramfs"
-
-			# List main archive
-			subarchive=$(mktemp ${TMPDIR:-/var/tmp}/lsinitramfs_XXXXXX)
-			trap "rm -f $subarchive" EXIT
-			dd < "$initramfs" bs="$offset" skip=1 2> /dev/null \
-				> $subarchive
-			listarchive $subarchive
-		else
-			listarchive "${initramfs}"
-		fi
-
-	fi
+	unmkinitramfs $cpio_args < "$initramfs"
 done