Util.killall: add utility for killing unwanted processes

Since we have to use pkill, kludgily, for the right combination of
portability and featurefulness, put the code in one place rather than
duplicating it everywhere.

https://bugzilla.gnome.org/show_bug.cgi?id=635089

js/misc/util.js

@@ -148,3 +148,28 @@ function _handleSpawnError(command, err) {
     notification.setTransient(true);
     source.notify(notification);
 }
+
+// killall:
+// @processName: a process name
+//
+// Kills @processName. If no process with the given name is found,
+// this will fail silently.
+function killall(processName) {
+    try {
+        // pkill is more portable than killall, but on Linux at least
+        // it won't match if you pass more than 15 characters of the
+        // process name... However, if you use the '-f' flag to match
+        // the entire command line, it will work, but we have to be
+        // careful in that case that we can match
+        // '/usr/bin/processName' but not 'gedit processName.c' or
+        // whatever...
+
+        let argv = ['pkill', '-f', '^([^ ]*/)?' + processName + '($| )'];
+        GLib.spawn_sync(null, argv, null, GLib.SpawnFlags.SEARCH_PATH, null, null);
+        // It might be useful to return success/failure, but we'd need
+        // a wrapper around WIFEXITED and WEXITSTATUS. Since none of
+        // the current callers care, we don't bother.
+    } catch (e) {
+        logError(e, 'Failed to kill ' + processName);
+    }
+}