create a lock file during builds

prevent duplicate main instances of the build
system from running

the lock file is deleted when the parent process
exits, alongside the tmpdir deletion

the build system must only ever be run ot one
instance at a time, per work directory

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

.gitignore

@@ -24,3 +24,4 @@
 /src/
 /CHANGELOG
 /todo.txt
+/lock

build

@@ -119,7 +119,8 @@ fetch_trees()
 
 fail()
 {
-	tmp_cleanup || printf "WARNING: can't rm tmpdir: %s\n" "$tmpdir" 1>&2
+	tmp_cleanup || printf "WARNING: can't rm tmp files: %s\n" "$tmpdir" \
+	    1>&2
 	err_ "${1}"
 }
 
@@ -127,6 +128,7 @@ tmp_cleanup()
 {
 	[ "$tmpdir_was_set" = "n" ] || return 0
 	rm -Rf "$tmpdir" || return 1
+	rm -f lock || return 1
 }
 
 main $@

include/lib.sh

@@ -65,27 +65,28 @@ install_packages()
 id -u 1>/dev/null 2>/dev/null || $err "suid check failed (id -u)"
 [ "$(id -u)" != "0" ] || $err "this command as root is not permitted"
 
-# if "y": a coreboot target won't be built if target.cfg says release="n"
-# (this is used to exclude certain build targets from releases)
-
-[ -z "${XBMK_RELEASE+x}" ] && xbmk_release="n"
-[ -z "$xbmk_release" ] && xbmk_release="$XBMK_RELEASE"
-[ "$xbmk_release" = "n" ] || [ "$xbmk_release" = "y" ] || xbmk_release="n"
-export XBMK_RELEASE="$xbmk_release"
-
 [ -z "${TMPDIR+x}" ] && tmpdir_was_set="n"
 if [ "$tmpdir_was_set" = "y" ]; then
 	[ "${TMPDIR%_*}" = "/tmp/xbmk" ] || tmpdir_was_set="n"
 fi
 if [ "$tmpdir_was_set" = "n" ]; then
+	[ -f "lock" ] && $err "The 'lock' file exists. Is a build running?"
 	export TMPDIR="/tmp"
 	tmpdir="$(mktemp -d -t xbmk_XXXXXXXX)"
 	export TMPDIR="$tmpdir"
+	touch lock || $err "cannot create 'lock' file"
 else
 	export TMPDIR="$TMPDIR"
 	tmpdir="$TMPDIR"
 fi
 
+# if "y": a coreboot target won't be built if target.cfg says release="n"
+# (this is used to exclude certain build targets from releases)
+[ -z "${XBMK_RELEASE+x}" ] && xbmk_release="n"
+[ -z "$xbmk_release" ] && xbmk_release="$XBMK_RELEASE"
+[ "$xbmk_release" = "n" ] || [ "$xbmk_release" = "y" ] || xbmk_release="n"
+export XBMK_RELEASE="$xbmk_release"
+
 [ -z "${XBMK_THREADS+x}" ] || threads="$XBMK_THREADS"
 [ -z "$threads" ] && threads=1
 expr "X$threads" : "X-\{0,1\}[0123456789][0123456789]*$" \