improved safety/error handling on multitree git-am

update/trees wasn't correctly returning non-zero status,
even though it was printing an error message, when git-am
failed. this is due to the way subshells work, and it was
overlooked in previous auditing.

additionally: don't directly copy trees to the destination,
instead patch/reset first, then copy only under normal
condition, just as with single-tree projects.

when running build/roms, the script would continue after
a bad git-am, without exit. this patch fixes it in the
most paranoid way possible. i'm now fairly confident that
lbmk will fail gracefully and efficiently, under error
conditions. this should prevent bad image builds.

Signed-off-by: Leah Rowe <leah@libreboot.org>

include/git.sh

@@ -4,7 +4,7 @@
 
 # This file is only used by update/project/trees
 
-eval "$(setvars "" _target rev _xm loc url bkup_url depend)"
+eval "$(setvars "" _target rev _xm loc url bkup_url depend patchfail)"
 tmp_git_dir="${PWD}/tmp/gitclone"
 
 fetch_project_trees()
@@ -58,16 +58,27 @@ prepare_new_tree()
 {
 	printf "Creating %s tree %s (%s)\n" "${project}" "${tree}" "${_target}"
 
-	x_ cp -R "src/${project}/${project}" "src/${project}/${tree}"
-	git_reset_rev "src/${project}/${tree}" "${rev}"
+	rm -Rf "${tmp_git_dir%/*}" || \
+	    err "prepare_new_tree ${project}/${tree}: can't rm tmpclone"
+	mkdir "${tmp_git_dir%/*}" || \
+	    err "prepare_new_tree ${project}/${tree}: can't mkdir tmp"
+	cp -R "src/${project}/${project}" "${tmp_git_dir}" || \
+	    err "prepare_new_tree ${project}/${tree}: can't make tmpclone"
+	git_reset_rev "${tmp_git_dir}" "${rev}"
 	(
-	x_ cd "src/${project}/${tree}"
+	cd "${tmp_git_dir}" || \
+	    err "prepare_new_tree ${project}/${tree}: can't cd tmpclone"
 	if [ -f ".gitmodules" ]; then
 		git submodule update --init --checkout || \
 		    err "prepare_new_tree ${project}/${tree}: !submodules"
 	fi
 	)
-	git_am_patches "$PWD/src/$project/$tree" "$PWD/$cfgsdir/$tree/patches"
+	git_am_patches "${tmp_git_dir}" "$PWD/$cfgsdir/$tree/patches" || \
+	    err "prepare_new_tree ${project}/${tree}: patch fail"
+	[ "${patchfail}" = "y" ] && err "PATCH FAIL"
+
+	mv "${tmp_git_dir}" "src/${project}/${tree}" || \
+	    err "prepare_new_tree ${project}/${tree}: can't copy tmpclone"
 }
 
 fetch_project_repo()
@@ -107,7 +118,9 @@ clone_project()
 	    git clone ${bkup_url} "${tmp_git_dir}" || \
 	    err "clone_project: could not download ${project}"
 	git_reset_rev "${tmp_git_dir}" "${rev}"
-	git_am_patches "${tmp_git_dir}" "${PWD}/config/${project}/patches"
+	git_am_patches "${tmp_git_dir}" "${PWD}/config/${project}/patches" \
+	    || err "clone_project ${project} ${loc}: patch fail"
+	[ "${patchfail}" = "y" ] && err "PATCH FAIL"
 
 	x_ rm -Rf "${loc}"
 	[ "${loc}" = "${loc%/*}" ] || x_ mkdir -p ${loc%/*}
@@ -137,17 +150,18 @@ git_am_patches()
 	for patch in "${patchdir}/"*; do
 		[ -L "${patch}" ] && continue
 		[ -f "${patch}" ] || continue
-		patchfail="n"
 		git am "${patch}" || patchfail="y"
 		if [ "${patchfail}" = "y" ]; then
 			git am --abort || err  "${sdir}: !git am --abort"
 			err  "!git am ${patch} -> ${sdir}"
 		fi
 	done
-	)
+	) || err "PATCH FAILURE"
 	for patches in "${patchdir}/"*; do
 		[ -L "${patches}" ] && continue
 		[ ! -d "${patches}" ] && continue
 		git_am_patches "${sdir}" "${patches}"
 	done
+	[ "${patchfail}" = "y" ] && return 1
+	return 0
 }