From 71a80751257f11a64e6035cf91fc6b23e6c31863 Mon Sep 17 00:00:00 2001
From: Thierry Laurion <insurgo@riseup.net>
Date: Fri, 22 Nov 2024 16:40:40 -0500
Subject: [PATCH 1/2] initrd/bin/unpack_initramfs.sh: no functional change,
 just format with tabs

Signed-off-by: Thierry Laurion <insurgo@riseup.net>
---
 initrd/bin/unpack_initramfs.sh | 131 +++++++++++++++++----------------
 1 file changed, 67 insertions(+), 64 deletions(-)

diff --git a/initrd/bin/unpack_initramfs.sh b/initrd/bin/unpack_initramfs.sh
index db176fd6..12ce32b8 100755
--- a/initrd/bin/unpack_initramfs.sh
+++ b/initrd/bin/unpack_initramfs.sh
@@ -31,78 +31,81 @@ CPIO_ARGS=("$@")
 
 # Consume zero bytes, the first nonzero byte read (if any) is repeated on stdout
 consume_zeros() {
-    TRACE_FUNC
-    next_byte='00'
-    while [ "$next_byte" = "00" ]; do
-        # if we reach EOF, next_byte becomes empty (dd does not fail)
-        next_byte="$(dd bs=1 count=1 status=none | xxd -p | tr -d ' ')"
-    done
-    # if we finished due to nonzero byte (not EOF), then carry that byte
-    if [ -n "$next_byte" ]; then
-        echo -n "$next_byte" | xxd -p -r
-    fi
+	TRACE_FUNC
+	next_byte='00'
+	while [ "$next_byte" = "00" ]; do
+		# if we reach EOF, next_byte becomes empty (dd does not fail)
+		next_byte="$(dd bs=1 count=1 status=none | xxd -p | tr -d ' ')"
+	done
+	# if we finished due to nonzero byte (not EOF), then carry that byte
+	if [ -n "$next_byte" ]; then
+		echo -n "$next_byte" | xxd -p -r
+	fi
 }
 
 unpack_cpio() {
-    TRACE_FUNC
-    (cd "$dest_dir"; cpio -i "${CPIO_ARGS[@]}" 2>/dev/null)
+	TRACE_FUNC
+	(
+		cd "$dest_dir"
+		cpio -i "${CPIO_ARGS[@]}" 2>/dev/null
+	)
 }
 
 # unpack the first segment of an archive, then write the rest to another file
 unpack_first_segment() {
-    TRACE_FUNC
-    unpack_archive="$1"
-    dest_dir="$2"
-    rest_archive="$3"
+	TRACE_FUNC
+	unpack_archive="$1"
+	dest_dir="$2"
+	rest_archive="$3"
 
-    mkdir -p "$dest_dir"
+	mkdir -p "$dest_dir"
 
-    # peek the beginning of the file to determine what type of content is next
-    magic="$(dd if="$unpack_archive" bs=6 count=1 status=none | xxd -p)"
+	# peek the beginning of the file to determine what type of content is next
+	magic="$(dd if="$unpack_archive" bs=6 count=1 status=none | xxd -p)"
 
-    # read this segment of the archive, then write the rest to the next file
-    (
-        # Magic values correspond to Linux init/initramfs.c (zero, cpio) and
-        # lib/decompress.c (gzip)
-        case "$magic" in
-            00*)
-                DEBUG "archive segment $magic: uncompressed cpio"
-                # Skip zero bytes and copy the first nonzero byte
-                consume_zeros
-                # Copy the remaining data
-                cat
-                ;;
-            303730373031*|303730373032*)    # plain cpio
-                DEBUG "archive segment $magic: plain cpio"
-                # Unpack the plain cpio, this stops reading after the trailer
-                unpack_cpio
-                # Copy the remaining data
-                cat
-                ;;
-            1f8b*|1f9e*)    # gzip
-                DEBUG "archive segment $magic: gzip"
-                # gunzip won't stop when reaching the end of the gzipped member,
-                # so we can't read another segment after this.  We can't
-                # reasonably determine the member length either, this requires
-                # walking all the compressed blocks.
-                gunzip | unpack_cpio
-                ;;
-            28b5*)  # zstd
-                DEBUG "archive segment $magic: zstd"
-                # Like gunzip, this will not stop when reaching the end of the
-                # frame, and determining the frame length requires walking all
-                # of its blocks.
-                (zstd-decompress -d || true) | unpack_cpio
-                ;;
-            *)  # unknown
-                die "Can't decompress initramfs archive, unknown type: $magic"
-                ;;
-        esac
-    ) <"$unpack_archive" >"$rest_archive"
+	# read this segment of the archive, then write the rest to the next file
+	(
+		# Magic values correspond to Linux init/initramfs.c (zero, cpio) and
+		# lib/decompress.c (gzip)
+		case "$magic" in
+		00*)
+			DEBUG "archive segment $magic: uncompressed cpio"
+			# Skip zero bytes and copy the first nonzero byte
+			consume_zeros
+			# Copy the remaining data
+			cat
+			;;
+		303730373031* | 303730373032*) # plain cpio
+			DEBUG "archive segment $magic: plain cpio"
+			# Unpack the plain cpio, this stops reading after the trailer
+			unpack_cpio
+			# Copy the remaining data
+			cat
+			;;
+		1f8b* | 1f9e*) # gzip
+			DEBUG "archive segment $magic: gzip"
+			# gunzip won't stop when reaching the end of the gzipped member,
+			# so we can't read another segment after this.  We can't
+			# reasonably determine the member length either, this requires
+			# walking all the compressed blocks.
+			gunzip | unpack_cpio
+			;;
+		28b5*) # zstd
+			DEBUG "archive segment $magic: zstd"
+			# Like gunzip, this will not stop when reaching the end of the
+			# frame, and determining the frame length requires walking all
+			# of its blocks.
+			(zstd-decompress -d || true) | unpack_cpio
+			;;
+		*) # unknown
+			die "Can't decompress initramfs archive, unknown type: $magic"
+			;;
+		esac
+	) <"$unpack_archive" >"$rest_archive"
 
-    orig_size="$(stat -c %s "$unpack_archive")"
-    rest_size="$(stat -c %s "$rest_archive")"
-    DEBUG "archive segment $magic: $((orig_size - rest_size)) bytes"
+	orig_size="$(stat -c %s "$unpack_archive")"
+	rest_size="$(stat -c %s "$rest_archive")"
+	DEBUG "archive segment $magic: $((orig_size - rest_size)) bytes"
 }
 
 DEBUG "Unpacking $INITRAMFS_ARCHIVE to $DEST_DIR"
@@ -112,7 +115,7 @@ rest_archive="/tmp/unpack_initramfs_rest"
 
 # Break when there is no remaining data
 while [ -s "$next_archive" ]; do
-    unpack_first_segment "$next_archive" "$DEST_DIR" "$rest_archive"
-    next_archive="/tmp/unpack_initramfs_next"
-    mv "$rest_archive" "$next_archive"
+	unpack_first_segment "$next_archive" "$DEST_DIR" "$rest_archive"
+	next_archive="/tmp/unpack_initramfs_next"
+	mv "$rest_archive" "$next_archive"
 done

From 95c6eb5c498bebc028cd92d62c83e33c2be3ed2e Mon Sep 17 00:00:00 2001
From: Thierry Laurion <insurgo@riseup.net>
Date: Fri, 22 Nov 2024 16:43:12 -0500
Subject: [PATCH 2/2] initrd/bin/unpack_initramfs.sh: add xz to unpack logic
 (add commented: bzip2, lzma, lzo and lz4)

xz: tested working with tails test build and 6.8.1's initrd
latest ubuntu 24.10: switched back to zstd, works as expected (tested)

Magic numbers referred at:
- https://github.com/torvalds/linux/blob/28eb75e178d389d325f1666e422bc13bbbb9804c/scripts/extract-vmlinux#L52C1-L58C43
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/lib/decompress.c#n51

Signed-off-by: Thierry Laurion <insurgo@riseup.net>
---
 initrd/bin/unpack_initramfs.sh | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/initrd/bin/unpack_initramfs.sh b/initrd/bin/unpack_initramfs.sh
index 12ce32b8..77213118 100755
--- a/initrd/bin/unpack_initramfs.sh
+++ b/initrd/bin/unpack_initramfs.sh
@@ -90,6 +90,10 @@ unpack_first_segment() {
 			# walking all the compressed blocks.
 			gunzip | unpack_cpio
 			;;
+		fd37*) # xz
+			DEBUG "archive segment $magic: xz"
+			unxz | unpack_cpio
+			;;
 		28b5*) # zstd
 			DEBUG "archive segment $magic: zstd"
 			# Like gunzip, this will not stop when reaching the end of the
@@ -99,6 +103,26 @@ unpack_first_segment() {
 			;;
 		*) # unknown
 			die "Can't decompress initramfs archive, unknown type: $magic"
+			# The following are magic values for other compression formats
+			#  but not added because not tested.
+			# TODO: open an issue for unsupported magic number reported on die.
+			# 
+			#425a*) # bzip2
+			#	DEBUG "archive segment $magic: bzip2"
+			#	bunzip2 | unpack_cpio
+			#;;
+			#5d00*) # lzma
+			#	DEBUG "archive segment $magic: lzma"
+			#	unlzma | unpack_cpio
+			#;;
+			#894c*) # lzo
+			#	DEBUG "archive segment $magic: lzo"
+			#	lzop -d | unpack_cpio
+			#;;
+			#0221*) # lz4
+			#	DEBUG "archive segment $magic: lz4"
+			#	lz4 -d | unpack_cpio
+			#	;;
 			;;
 		esac
 	) <"$unpack_archive" >"$rest_archive"