alpm-hooks: add Description field

The "Description" field allows a hook to provide a some text for frontends
to use in describing what the hook is doing.  For example:

Description = updating info page directory

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

doc/alpm-hooks.5.txt

@@ -19,6 +19,7 @@ Type = File|Package (Required)
 Target = <Path|PkgName> (Required, Repeatable)
 
 [Action] (Required)
+Description = ... (Optional)
 When = PreTransaction|PostTransaction (Required)
 Exec = <Command> (Required)
 Depends = <PkgName> (Optional)
@@ -63,6 +64,10 @@ defined the hook will run if the transaction matches *any* of the triggers.
 ACTIONS
 -------
 
+* Description =* ...::
+	An optional description that describes the action being taken by the
+	hook for use in front-end output.
+
 *Exec =* <command>::
 	Command to run.  Command arguments are split on whitespace.  Values
 	containing whitespace should be enclosed in quotes.  Required.

lib/libalpm/alpm.h

@@ -568,6 +568,8 @@ typedef struct _alpm_event_hook_run_t {
 	alpm_event_type_t type;
 	/** Name of hook */
 	const char *name;
+	/** Description of hook to be outputted */
+	const char *desc;
 	/** position of hook being run */
 	size_t position;
 	/** total hooks being run */

lib/libalpm/hook.c

@@ -48,6 +48,7 @@ struct _alpm_trigger_t {
 
 struct _alpm_hook_t {
 	char *name;
+	char *desc;
 	alpm_list_t *triggers;
 	alpm_list_t *depends;
 	char **cmd;
@@ -84,6 +85,7 @@ static void _alpm_hook_free(struct _alpm_hook_t *hook)
 {
 	if(hook) {
 		free(hook->name);
+		free(hook->desc);
 		_alpm_wordsplit_free(hook->cmd);
 		alpm_list_free_inner(hook->triggers, (alpm_list_fn_free) _alpm_trigger_free);
 		alpm_list_free(hook->triggers);
@@ -316,6 +318,8 @@ static int _alpm_hook_parse_cb(const char *file, int line,
 			} else {
 				error(_("hook %s line %d: invalid value %s\n"), file, line, value);
 			}
+		} else if(strcmp(key, "Description") == 0) {
+			STRDUP(hook->desc, value, return 1);
 		} else if(strcmp(key, "Depends") == 0) {
 			char *val;
 			STRDUP(val, value, return 1);
@@ -732,6 +736,7 @@ int _alpm_hook_run(alpm_handle_t *handle, alpm_hook_when_t when)
 
 			hook_event.type = ALPM_EVENT_HOOK_RUN_START;
 			hook_event.name = hook->name;
+			hook_event.desc = hook->desc;
 			EVENT(handle, &hook_event);
 
 			if(_alpm_hook_run_hook(handle, hook) != 0 && hook->abort_on_fail) {

src/pacman/callback.c

@@ -189,7 +189,8 @@ void cb_event(alpm_event_t *event)
 				alpm_event_hook_run_t *e = &event->hook_run;
 				int digits = number_length(e->total);
 				printf("(%*zu/%*zu) %s\n", digits, e->position,
-						digits, e->total, e->name);
+						digits, e->total, 
+						e->desc ? e->desc : e->name);
 			}
 			break;
 		case ALPM_EVENT_CHECKDEPS_START: