lib/common.sh: add 'lock_close'; use it as appropriate.

`lock_close FD` is easier to remember than 'exec FD>&-`; and is especially
easier if FD is a variable (though that isn't actually taken advantage of
here).

This uses Bash 4.1+ `exec {var}>&-`, rather than the clunkier
`eval exec "$var>&-"` that was necessary in older versions of Bash.
Thanks to Dave Reisner for pointing this new bit of syntax out to me
the last time I submitted this (back in 2014, 4.1 had just come out).

1 files changed, 8 insertions, 0 deletions

diff --git a/lib/common.sh b/lib/common.sh
index f6aea93..91a55dc 100644
--- a/lib/common.sh
+++ b/lib/common.sh
@@ -159,6 +159,14 @@ slock() {
 }
 
 ##
+#  usage : lock_close( $fd )
+##
+lock_close() {
+	local fd=$1
+	exec {fd}>&-
+}
+
+##
 # usage: pkgver_equal( $pkgver1, $pkgver2 )
 ##
 pkgver_equal() {