[PATCH v2 4/4] Remove unnecessary cpio_init function

[David Gibson <david@gibson.dropbear.id.au>]

The cpio_init function is now only every called with the "discard" option.
But, moreover, what it does is create an initial mostly empty archive which
will just get overwritten by the final archive.

So, it's entirely unnecessary except for one subtlety.  Our use of realpath
when generating the final output requires that a file already exist in the
output location.  We can fix that by shuffling some things out of a
subshell, removing the need for realpath.

This removes functionality to modify an existing initramfs image.  However
that was already broken in a several ways.  Just remove it, and update the
help messages to match.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 mbuto | 39 +++++++--------------------------------
 1 file changed, 7 insertions(+), 32 deletions(-)

diff --git a/mbuto b/mbuto
index eb559fb..247b63d 100755
--- a/mbuto
+++ b/mbuto
@@ -544,28 +544,6 @@ subopts_get() {
 
 ### CPIO #######################################################################
 
-# cpio_init() - Source existing CPIO archive, or create if needed
-# $1:	Path to CPIO archive, might exist, might be discarded if existing
-cpio_init() {
-	if [ -f "${OUT}" ] && [ "${1}" != "discard" ]; then
-		info "Sourcing CPIO archive from ${OUT}"
-
-		if ! "${GZIP}" -dfc "${OUT}" |
-		   "${CPIO}" --quiet -iD "${wd}"; then
-			err "Invalid CPIO archive ${OUT}"
-		fi
-	else
-		info "Creating new CPIO archive"
-
-		if [ -z "${OUT}" ]; then
-			OUT="$("${MKTEMP}")"
-			notice "Creating image: ${OUT}"
-		else
-			OUT="$("${REALPATH}" "${OUT}")"
-		fi
-	fi
-}
-
 # compress_select() - Try compressors and pick the fastest to decompress image
 # $1:	Existing CPIO archive
 compress_select() {
@@ -987,7 +965,6 @@ pkg_add() {
 
 # build() - Build a new image, sourcing contents
 build() {
-	cpio_init discard
 	kmod_init
 
 	for __d in ${DIRS}; do
@@ -1083,11 +1060,11 @@ cmds() {
 
 	[ "${NOSTRIP}" != "y" ] && strip_all
 
-	( __out="$("${REALPATH}" "${OUT}")"
+	(
 		"${CD}" "${wd}"
-		"${FIND}" . | "${CPIO}" --create -H newc --quiet > "${OUT}"
-		cpio_compress "${__out}"
-	)
+		"${FIND}" . | "${CPIO}" --create -H newc --quiet
+	) > "${OUT}"
+	cpio_compress "${OUT}"
 
 	stats
 
@@ -1139,9 +1116,9 @@ usage() {
 	echo "	-v: verbose"
 	echo "	-h: show this help"
 	echo
-	echo "Build initramfs image unless an existing one is passed."
-	echo "Additional programs, kernel modules, device nodes, generic files"
-	echo "can be passed as a list of ADD_ON parameters."
+	echo "Build initramfs image.  Additional programs, kernel modules,"
+	echo "device nodes, generic files can be passed as a list of ADD_ON"
+	echo "parameters."
 	echo
 	echo "Distribution packages (deb and RPM currently supported) can be"
 	echo "added too, but they will simply be extracted, not installed."
@@ -1173,8 +1150,6 @@ usage() {
 	echo "		Build a base image as a temporary file"
 	echo "	${0} grep"
 	echo "		Build a new image including grep and needed libraries"
-	echo "	${0} -f kata.img zsh_5.6.2-3_amd64.deb"
-	echo "		Install zsh package to pre-existing kata.img"
 	echo "	${0} -v -f kata.img -p kata_debug -c lz4"
 	echo "		Use lz4 compression, run a shell before proceeding"
 	exit 1
-- 
@@ -544,28 +544,6 @@ subopts_get() {
 
 ### CPIO #######################################################################
 
-# cpio_init() - Source existing CPIO archive, or create if needed
-# $1:	Path to CPIO archive, might exist, might be discarded if existing
-cpio_init() {
-	if [ -f "${OUT}" ] && [ "${1}" != "discard" ]; then
-		info "Sourcing CPIO archive from ${OUT}"
-
-		if ! "${GZIP}" -dfc "${OUT}" |
-		   "${CPIO}" --quiet -iD "${wd}"; then
-			err "Invalid CPIO archive ${OUT}"
-		fi
-	else
-		info "Creating new CPIO archive"
-
-		if [ -z "${OUT}" ]; then
-			OUT="$("${MKTEMP}")"
-			notice "Creating image: ${OUT}"
-		else
-			OUT="$("${REALPATH}" "${OUT}")"
-		fi
-	fi
-}
-
 # compress_select() - Try compressors and pick the fastest to decompress image
 # $1:	Existing CPIO archive
 compress_select() {
@@ -987,7 +965,6 @@ pkg_add() {
 
 # build() - Build a new image, sourcing contents
 build() {
-	cpio_init discard
 	kmod_init
 
 	for __d in ${DIRS}; do
@@ -1083,11 +1060,11 @@ cmds() {
 
 	[ "${NOSTRIP}" != "y" ] && strip_all
 
-	( __out="$("${REALPATH}" "${OUT}")"
+	(
 		"${CD}" "${wd}"
-		"${FIND}" . | "${CPIO}" --create -H newc --quiet > "${OUT}"
-		cpio_compress "${__out}"
-	)
+		"${FIND}" . | "${CPIO}" --create -H newc --quiet
+	) > "${OUT}"
+	cpio_compress "${OUT}"
 
 	stats
 
@@ -1139,9 +1116,9 @@ usage() {
 	echo "	-v: verbose"
 	echo "	-h: show this help"
 	echo
-	echo "Build initramfs image unless an existing one is passed."
-	echo "Additional programs, kernel modules, device nodes, generic files"
-	echo "can be passed as a list of ADD_ON parameters."
+	echo "Build initramfs image.  Additional programs, kernel modules,"
+	echo "device nodes, generic files can be passed as a list of ADD_ON"
+	echo "parameters."
 	echo
 	echo "Distribution packages (deb and RPM currently supported) can be"
 	echo "added too, but they will simply be extracted, not installed."
@@ -1173,8 +1150,6 @@ usage() {
 	echo "		Build a base image as a temporary file"
 	echo "	${0} grep"
 	echo "		Build a new image including grep and needed libraries"
-	echo "	${0} -f kata.img zsh_5.6.2-3_amd64.deb"
-	echo "		Install zsh package to pre-existing kata.img"
 	echo "	${0} -v -f kata.img -p kata_debug -c lz4"
 	echo "		Use lz4 compression, run a shell before proceeding"
 	exit 1
-- 
2.44.0