makepkg: add PACMAN_AUTH configurable setting for sudo elevation

If specified, this will be used no matter what. If not, then we check if
sudo exists and use that, or else fall back on su.

Implements FS#32621

Signed-off-by: Eli Schwartz <eschwartz@archlinux.org>
Signed-off-by: Allan McRae <allan@archlinux.org>

doc/makepkg.conf.5.asciidoc

@@ -278,6 +278,14 @@ Options
 	`.tar.lzo`, `.tar.lrz`, `.tar.lz4`, `.tar.lz` and `.tar.Z`, or
 	simply `.tar` to disable compression entirely.
 
+**PACMAN_AUTH=()**::
+	Specify a command prefix for running pacman as root. If unset, makepkg will
+	check for the presence of sudo(8) and su(1) in turn, and try the first one
+	it finds.
+	+
+	If present, `%c` will be replaced with the shell-quoted form of the command
+	to run. Otherwise, the command to run is appended to the auth command.
+
 
 
 See Also

etc/makepkg.conf.in

@@ -147,3 +147,10 @@ COMPRESSLZ=(lzip -c -f)
 #
 PKGEXT='@PKGEXT@'
 SRCEXT='@SRCEXT@'
+
+#########################################################################
+# OTHER
+#########################################################################
+#
+#-- Command used to run pacman as root, instead of trying sudo and su
+PACMAN_AUTH=()

scripts/libmakepkg/executable/sudo.sh.in

@@ -29,7 +29,7 @@ executable_functions+=('executable_sudo')
 
 executable_sudo() {
     if (( DEP_BIN || RMDEPS || INSTALL )); then
-        if ! type -p sudo >/dev/null; then
+        if (( ${#PACMAN_AUTH[@]} == 0 )) && ! type -p sudo >/dev/null; then
             warning "$(gettext "Cannot find the %s binary. Will use %s to acquire root privileges.")" "sudo" "su"
         fi
     fi

scripts/makepkg.sh.in

@@ -225,15 +225,22 @@ missing_source_file() {
 }
 
 run_pacman() {
-	local cmd
+	local cmd cmdescape
 	if [[ $1 = -@(T|Q)*([[:alpha:]]) ]]; then
 		cmd=("$PACMAN_PATH" "$@")
 	else
 		cmd=("$PACMAN_PATH" "${PACMAN_OPTS[@]}" "$@")
-		if type -p sudo >/dev/null; then
+		cmdescape="$(printf '%q ' "${cmd[@]}")"
+		if (( ${#PACMAN_AUTH[@]} )); then
+			if in_array '%c' "${PACMAN_AUTH[@]}"; then
+				cmd=("${PACMAN_AUTH[@]/\%c/$cmdescape}")
+			else
+				cmd=("${PACMAN_AUTH[@]}" "${cmd[@]}")
+			fi
+		elif type -p sudo >/dev/null; then
 			cmd=(sudo "${cmd[@]}")
 		else
-			cmd=(su root -c "$(printf '%q ' "${cmd[@]}")")
+			cmd=(su root -c "$cmdescape")
 		fi
 		local lockfile="$(pacman-conf DBPath)/db.lck"
 		while [[ -f $lockfile ]]; do