diffpkg: prefer to search inside the pool dir if available

On certain packaging machines where the pacman cache gets updated very
infrequently, the behavior of diffpkg may not function correctly as old
packages were to be downloaded as diff target. In such cases we look for
a pool directory first and search via a glob for an available pool
package sorted by version.

The pool search glob has three glob segments each disallowing the dash
delimiter to split across pkgrel, pkgver and arch. This will return the
correct package from the pool without considering overly eager wildcards
that potentially match different pkgnames.

The default pool search directory is /srv/ftp/pool

1 files changed, 26 insertions, 2 deletions

diff --git a/src/diffpkg.in b/src/diffpkg.in
index baeb546..5bae805 100644
--- a/src/diffpkg.in
+++ b/src/diffpkg.in
@@ -24,6 +24,7 @@ usage() {
 
 		OPTIONS
 		    -M, --makepkg-config Set an alternate makepkg configuration file
+		    -P, --pool=DIR       Search diff target in pool dir (default '/srv/ftp/pool')
 		    -v, --verbose        Provide more detailed/unfiltered output
 		    -h, --help           Show this help text
 
@@ -44,6 +45,8 @@ _EOF_
 }
 
 MAKEPKG_CONF=/etc/makepkg.conf
+POOLDIR=/srv/ftp/pool
+
 VERBOSE=0
 TARLIST=0
 DIFFOSCOPE=0
@@ -63,6 +66,7 @@ while (( $# )); do
 			exit 0
 			;;
 		-M|--makepkg-config)
+			(( $# <= 1 )) && die "missing argument for %s" "$1"
 			MAKEPKG_CONF="$2"
 			shift 2
 			;;
@@ -112,6 +116,15 @@ while (( $# )); do
 			DIFFWIDTH="$1"
 			shift
 			;;
+		-P|--pool)
+			(( $# <= 1 )) && die "missing argument for %s" "$1"
+			POOLDIR="$2"
+			shift 2
+			;;
+		--pool=*)
+			POOLDIR="${1#*=}"
+			shift
+			;;
 		--)
 			shift
 			break
@@ -248,8 +261,19 @@ fetch_pkg() {
 			pkg=$1 ;;
 	esac
 
-	[[ -n $pkgurl ]] || pkgurl=$(pacman -Spdd --print-format '%l' --noconfirm "$pkg") ||
-		die "Couldn't download previous package for %s." "$pkg"
+	if [[ -z ${pkgurl} ]]; then
+		# Try to find latest package in pool dir
+		if [[ -d ${POOLDIR} ]]; then
+			shopt -s extglob nullglob
+			pkgurl=$(printf "%s\n" "${POOLDIR}"/*/"${_pkgname}"-!(*-*)-!(*-*)-!(*-*).pkg.tar!(*.sig)|sort -Vr|head -1)
+			shopt -u extglob nullglob
+		fi
+		# Search via pacman database if no pool file exists
+		if [[ ! -f ${pkgurl} ]]; then
+			pkgurl=$(pacman -Spdd --print-format '%l' --noconfirm "$pkg") ||
+				die "Couldn't download previous package for %s." "$pkg"
+		fi
+	fi
 
 	pkg=${pkgurl##*/}
 	pkgdest=$(mktemp -t -d "${pkg}-XXXXXX")/${pkg}