Enable user-defined actions

Also fix pclose() handling within Info plugins,
and prevent them from screwing up the terminal with error output
on initialization.

This is still rather crude, but at least it's possible.

NEWS

@@ -2,6 +2,9 @@ Unreleased
 
  * Made global search indicate the search terms, and match on filenames
 
+ * Added ability to configure bindable user-defined actions;
+   these can launch arbitrary shell commands
+
  * X11: added support for font fallbacks to the editor as well
 
 

nncmpp.actions.awk

@@ -1,6 +1,6 @@
 # nncmpp.actions.awk: produce C code for a list of user actions
 #
-# Copyright (c) 2022, Přemysl Eric Janouch <p@janouch.name>
+# Copyright (c) 2022 - 2024, Přemysl Eric Janouch <p@janouch.name>
 # SPDX-License-Identifier: 0BSD
 #
 # Usage: env LC_ALL=C A=0 B=1 awk -f nncmpp.actions.awk \
@@ -91,7 +91,7 @@ END {
 	print "enum action {"
 	for (i in Constants)
 		print "\t" "ACTION_" Constants[i] ","
-	print "\t" "ACTION_COUNT"
+	print "\t" "ACTION_USER_0"
 	print "};"
 	print ""
 	print "static const char *g_action_names[] = {"

nncmpp.adoc

@@ -85,6 +85,18 @@ To adjust key bindings, put them within a *normal* or *editor* object.
 Run *nncmpp* with the *--debug* option to find out key combinations names.
 Press *?* in the help tab to learn the action identifiers to use.
 
+You may also define and bind your own actions, launching arbitrary
+shell commands.  Note that you cannot override internal actions in this manner.
+
+....
+actions = {
+  "pioneer-on-off" = {
+    description = "Pioneer amplifier: turn on/off"
+    command = "elksmart-comm --nec A538"
+  }
+}
+....
+
 Spectrum visualiser
 -------------------
 When built against the FFTW library, *nncmpp* can make use of MPD's "fifo"

nncmpp.c

@@ -1256,6 +1256,9 @@ static struct app_context
 	struct config config;               ///< Program configuration
 	struct strv streams;                ///< List of "name NUL URI NUL"
 	struct strv enqueue;                ///< Items to enqueue once connected
+	struct strv action_names;           ///< User-defined action names
+	struct strv action_descriptions;    ///< User-defined action descriptions
+	struct strv action_commands;        ///< User-defined action commands
 
 	struct tab *help_tab;               ///< Special help tab
 	struct tab *tabs;                   ///< All other tabs
@@ -1410,6 +1413,17 @@ static const struct config_schema g_config_colors[] =
 	{}
 };
 
+static const struct config_schema g_config_actions[] =
+{
+	{ .name      = "description",
+	  .comment   = "Human-readable description of the action",
+	  .type      = CONFIG_ITEM_STRING },
+	{ .name      = "command",
+	  .comment   = "Shell command to run",
+	  .type      = CONFIG_ITEM_STRING },
+	{}
+};
+
 static const char *
 get_config_string (struct config_item *root, const char *key)
 {
@@ -1484,6 +1498,35 @@ load_config_streams (struct config_item *subtree, void *user_data)
 		sizeof *g.streams.vector, strv_sort_utf8_cb);
 }
 
+static void
+load_config_actions (struct config_item *subtree, void *user_data)
+{
+	(void) user_data;
+
+	struct str_map_iter iter = str_map_iter_make (&subtree->value.object);
+	while (str_map_iter_next (&iter))
+		strv_append (&g.action_names, iter.link->key);
+	qsort (g.action_names.vector, g.action_names.len,
+		sizeof *g.action_names.vector, strv_sort_utf8_cb);
+
+	for (size_t i = 0; i < g.action_names.len; i++)
+	{
+		const char *name = g.action_names.vector[i];
+		struct config_item *item = config_item_get (subtree, name, NULL);
+		hard_assert (item != NULL);
+		if (item->type != CONFIG_ITEM_OBJECT)
+			exit_fatal ("`%s': invalid user action, expected an object", name);
+
+		config_schema_apply_to_object (g_config_actions, item, NULL);
+		config_schema_call_changed (item);
+
+		const char *description = get_config_string (item, "description");
+		const char *command =  get_config_string (item, "command");
+		strv_append (&g.action_descriptions, description ? description : name);
+		strv_append (&g.action_commands, command ? command : "");
+	}
+}
+
 static void
 app_load_configuration (void)
 {
@@ -1491,6 +1534,8 @@ app_load_configuration (void)
 	config_register_module (config, "settings", load_config_settings, NULL);
 	config_register_module (config, "colors",   load_config_colors,   NULL);
 	config_register_module (config, "streams",  load_config_streams,  NULL);
+	// This must run before bindings are parsed in app_init_ui().
+	config_register_module (config, "actions",  load_config_actions,  NULL);
 
 	// Bootstrap configuration, so that we can access schema items at all
 	config_load (config, config_item_object ());
@@ -1548,6 +1593,9 @@ app_init_context (void)
 	g.config = config_make ();
 	g.streams = strv_make ();
 	g.enqueue = strv_make ();
+	g.action_names = strv_make ();
+	g.action_descriptions = strv_make ();
+	g.action_commands = strv_make ();
 
 	g.playback_info = str_map_make (free);
 	g.playback_info.key_xfrm = tolower_ascii_strxfrm;
@@ -1570,6 +1618,9 @@ app_free_context (void)
 	str_map_free (&g.playback_info);
 	strv_free (&g.streams);
 	strv_free (&g.enqueue);
+	strv_free (&g.action_names);
+	strv_free (&g.action_descriptions);
+	strv_free (&g.action_commands);
 	item_list_free (&g.playlist);
 
 #ifdef WITH_FFTW
@@ -2379,12 +2430,52 @@ app_goto_tab (int tab_index)
 static int
 action_resolve (const char *name)
 {
-	for (int i = 0; i < ACTION_COUNT; i++)
+	for (int i = 0; i < ACTION_USER_0; i++)
 		if (!strcasecmp_ascii (g_action_names[i], name))
 			return i;
+
+	// We could put this lookup first, and accordingly adjust
+	// app_init_bindings() to do action_resolve(action_name(action)),
+	// however the ability to override internal actions seems pointless.
+	for (size_t i = 0; i < g.action_names.len; i++)
+		if (!strcasecmp_ascii (g.action_names.vector[i], name))
+			return ACTION_USER_0 + i;
 	return -1;
 }
 
+static const char *
+action_name (enum action action)
+{
+	if (action < ACTION_USER_0)
+		return g_action_names[action];
+
+	size_t user_action = action - ACTION_USER_0;
+	hard_assert (user_action < g.action_names.len);
+	return g.action_names.vector[user_action];
+}
+
+static const char *
+action_description (enum action action)
+{
+	if (action < ACTION_USER_0)
+		return g_action_descriptions[action];
+
+	size_t user_action = action - ACTION_USER_0;
+	hard_assert (user_action < g.action_descriptions.len);
+	return g.action_descriptions.vector[user_action];
+}
+
+static const char *
+action_command (enum action action)
+{
+	if (action < ACTION_USER_0)
+		return NULL;
+
+	size_t user_action = action - ACTION_USER_0;
+	hard_assert (user_action < g.action_commands.len);
+	return g.action_commands.vector[user_action];
+}
+
 // --- User input handling -----------------------------------------------------
 
 static void
@@ -2516,6 +2607,64 @@ incremental_search_on_end (bool confirmed)
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 
+static bool
+run_command (const char *command, struct str *output, struct error **e)
+{
+	char *adjusted = xstrdup_printf ("2>&1 %s", command);
+	print_debug ("running command: %s", adjusted);
+
+	FILE *fp = popen (adjusted, "r");
+	free (adjusted);
+	if (!fp)
+		return error_set (e, "%s", strerror (errno));
+
+	char buf[BUFSIZ];
+	size_t len;
+	while ((len = fread (buf, 1, sizeof buf, fp)) == sizeof buf)
+		str_append_data (output, buf, len);
+	str_append_data (output, buf, len);
+
+	int status = pclose (fp);
+	if (status < 0)
+		return error_set (e, "%s", strerror (errno));
+	if (WIFEXITED (status) && WEXITSTATUS (status))
+		return error_set (e, "exit status %d", WEXITSTATUS (status));
+	if (WIFSIGNALED (status))
+		return error_set (e, "terminated on signal %d", WTERMSIG (status));
+	if (WIFSTOPPED (status))
+		return error_set (e, "stopped on signal %d", WSTOPSIG (status));
+	return true;
+}
+
+static bool
+app_process_action_command (enum action action)
+{
+	const char *command = action_command (action);
+	if (!command)
+		return false;
+
+	struct str output = str_make ();
+	struct error *error = NULL;
+	(void) run_command (command, &output, &error);
+	str_enforce_utf8 (&output);
+
+	struct strv lines = strv_make ();
+	cstr_split (output.str, "\r\n", false, &lines);
+	str_free (&output);
+	while (lines.len && !*lines.vector[lines.len - 1])
+		free (strv_steal (&lines, lines.len - 1));
+	for (size_t i = 0; i < lines.len; i++)
+		print_debug ("output: %s", lines.vector[i]);
+	strv_free (&lines);
+
+	if (error)
+	{
+		print_error ("\"%s\": %s", action_description (action), error->message);
+		error_free (error);
+	}
+	return true;
+}
+
 static bool
 app_mpd_toggle (const char *name)
 {
@@ -2562,10 +2711,6 @@ app_process_action (enum action action)
 		xui_invalidate ();
 		app_hide_message ();
 		return true;
-	default:
-		print_error ("\"%s\" is not allowed here",
-			g_action_descriptions[action]);
-		return false;
 
 	case ACTION_MULTISELECT:
 		if (!tab->can_multiselect
@@ -2677,9 +2822,15 @@ app_process_action (enum action action)
 	case ACTION_GOTO_VIEW_BOTTOM:
 		g.active_tab->item_selected = g.active_tab->item_top;
 		return app_move_selection (MAX (0, app_visible_items () - 1));
-	}
+
+	default:
+		if (app_process_action_command (action))
+			return true;
+
+		print_error ("\"%s\" is not allowed here", action_description (action));
 		return false;
 	}
+}
 
 static bool
 app_editor_process_action (enum action action)
@@ -2696,8 +2847,7 @@ app_editor_process_action (enum action action)
 		g.editor.on_end = NULL;
 		return true;
 	default:
-		print_error ("\"%s\" is not allowed here",
-			g_action_descriptions[action]);
+		print_error ("\"%s\" is not allowed here", action_description (action));
 		return false;
 
 	case ACTION_EDITOR_B_CHAR:
@@ -4110,24 +4260,16 @@ info_tab_plugin_load (const char *path)
 	// Shell quoting is less annoying than process management.
 	struct str escaped = str_make ();
 	shell_quote (path, &escaped);
-	FILE *fp = popen (escaped.str, "r");
-	str_free (&escaped);
-	if (!fp)
-	{
-		print_error ("%s: %s", path, strerror (errno));
-		return NULL;
-	}
 
 	struct str description = str_make ();
-	char buf[BUFSIZ];
-	size_t len;
-	while ((len = fread (buf, 1, sizeof buf, fp)) == sizeof buf)
-		str_append_data (&description, buf, len);
-	str_append_data (&description, buf, len);
-	if (pclose (fp))
+	struct error *error = NULL;
+	(void) run_command (escaped.str, &description, &error);
+	str_free (&escaped);
+	if (error)
 	{
+		print_error ("%s: %s", path, error->message);
+		error_free (error);
 		str_free (&description);
-		print_error ("%s: %s", path, strerror (errno));
 		return NULL;
 	}
 
@@ -4140,8 +4282,8 @@ info_tab_plugin_load (const char *path)
 	str_enforce_utf8 (&description);
 	if (!description.len)
 	{
-		str_free (&description);
 		print_error ("%s: %s", path, "missing description");
+		str_free (&description);
 		return NULL;
 	}
 
@@ -4579,7 +4721,7 @@ help_tab_on_action (enum action action)
 	if (action == ACTION_DESCRIBE)
 	{
 		app_show_message (xstrdup ("Configuration name: "),
-			xstrdup (g_action_names[a]));
+			xstrdup (action_name (a)));
 		return true;
 	}
 	if (action != ACTION_CHOOSE || a == ACTION_CHOOSE /* avoid recursion */)
@@ -4604,9 +4746,9 @@ help_tab_assign_action (enum action action)
 
 static void
 help_tab_group (struct binding *keys, size_t len, struct strv *out,
-	bool bound[ACTION_COUNT])
+	bool bound[], size_t action_count)
 {
-	for (enum action i = 0; i < ACTION_COUNT; i++)
+	for (enum action i = 0; i < action_count; i++)
 	{
 		struct strv ass = strv_make ();
 		for (size_t k = 0; k < len; k++)
@@ -4616,7 +4758,7 @@ help_tab_group (struct binding *keys, size_t len, struct strv *out,
 		{
 			char *joined = strv_join (&ass, ", ");
 			strv_append_owned (out, xstrdup_printf
-				("  %s%c%s", g_action_descriptions[i], 0, joined));
+				("  %s%c%s", action_description (i), 0, joined));
 			free (joined);
 
 			bound[i] = true;
@@ -4627,13 +4769,13 @@ help_tab_group (struct binding *keys, size_t len, struct strv *out,
 }
 
 static void
-help_tab_unbound (struct strv *out, bool bound[ACTION_COUNT])
+help_tab_unbound (struct strv *out, bool bound[], size_t action_count)
 {
-	for (enum action i = 0; i < ACTION_COUNT; i++)
+	for (enum action i = 0; i < action_count; i++)
 		if (!bound[i])
 		{
 			strv_append_owned (out,
-				xstrdup_printf ("  %s%c", g_action_descriptions[i], 0));
+				xstrdup_printf ("  %s%c", action_description (i), 0));
 			help_tab_assign_action (i);
 		}
 }
@@ -4663,27 +4805,30 @@ help_tab_init (void)
 	struct strv *lines = &g_help_tab.lines;
 	*lines = strv_make ();
 
-	bool bound[ACTION_COUNT] = { [ACTION_NONE] = true };
+	size_t bound_len = ACTION_USER_0 + g.action_names.len;
+	bool *bound = xcalloc (bound_len, sizeof *bound);
+	bound[ACTION_NONE] = true;
 
 	strv_append (lines, "Normal mode actions");
-	help_tab_group (g_normal_keys, g_normal_keys_len, lines, bound);
+	help_tab_group (g_normal_keys, g_normal_keys_len, lines, bound, bound_len);
 	strv_append (lines, "");
 
 	strv_append (lines, "Editor mode actions");
-	help_tab_group (g_editor_keys, g_editor_keys_len, lines, bound);
+	help_tab_group (g_editor_keys, g_editor_keys_len, lines, bound, bound_len);
 	strv_append (lines, "");
 
 	bool have_unbound = false;
-	for (enum action i = 0; i < ACTION_COUNT; i++)
+	for (size_t i = 0; i < bound_len; i++)
 		if (!bound[i])
 			have_unbound = true;
 
 	if (have_unbound)
 	{
 		strv_append (lines, "Unbound actions");
-		help_tab_unbound (lines, bound);
+		help_tab_unbound (lines, bound, bound_len);
 		strv_append (lines, "");
 	}
+	free (bound);
 
 	struct tab *super = &g_help_tab.super;
 	tab_init (super, "Help");