Use common functions to handle file locking

 * lib/common.sh: implement
   - lock_open_write()
   - lock_open_read()
   - lock_close()
 * archbuild.in, makechrootpkg.in, mkarchroot.in: use said functions

This has two benefits:
 1. All programs using these methods gain the ability to inherit locks,
    something that only mkarchroot could do before.  This allows the
    commands to be more compos-able.
 2. It is more readable. File locking isn't obvious.

1 files changed, 2 insertions, 7 deletions

diff --git a/archbuild.in b/archbuild.in
index 7220391..9476415 100644
--- a/archbuild.in
+++ b/archbuild.in
@@ -43,17 +43,12 @@ if ${clean_first} || [[ ! -d "${chroots}/${repo}-${arch}" ]]; then
 		[[ -d $copy ]] || continue
 		msg2 "Deleting chroot copy '$(basename "${copy}")'..."
 
-		exec 9>"$copy.lock"
-		if ! flock -n 9; then
-			stat_busy "Locking chroot copy '$copy'"
-			flock 9
-			stat_done
-		fi
+		lock_open_write 9 "$copy.lock" "Locking chroot copy '$copy'"
 
 		{ type -P btrfs && btrfs subvolume delete "${copy}"; } &>/dev/null
 		rm -rf --one-file-system "${copy}"
 	done
-	exec 9>&-
+	lock_close 9
 
 	rm -rf --one-file-system "${chroots}/${repo}-${arch}"
 	mkdir -p "${chroots}/${repo}-${arch}"