Make list-commands command show only one command if an argument is

given, from Ilya Grigoriev in GitHub issue 4352.

cmd-list-keys.c

@@ -321,34 +321,13 @@ out:
 	return (CMD_RETURN_NORMAL);
 }
 
-static enum cmd_retval
+static void
-cmd_list_keys_commands(struct cmd *self, struct cmdq_item *item)
+cmd_list_single_command(const struct cmd_entry *entry, struct format_tree *ft,
+    const char *template, struct cmdq_item *item)
 {
-	struct args		 *args = cmd_get_args(self);
+	const char	*s;
-	const struct cmd_entry	**entryp;
-	const struct cmd_entry	 *entry;
-	struct format_tree	 *ft;
-	const char		 *template, *s, *command;
 	char		*line;
 
-	if ((template = args_get(args, 'F')) == NULL) {
-		template = "#{command_list_name}"
-		    "#{?command_list_alias, (#{command_list_alias}),} "
-		    "#{command_list_usage}";
-	}
-
-	ft = format_create(cmdq_get_client(item), item, FORMAT_NONE, 0);
-	format_defaults(ft, NULL, NULL, NULL, NULL);
-
-	command = args_string(args, 0);
-	for (entryp = cmd_table; *entryp != NULL; entryp++) {
-		entry = *entryp;
-		if (command != NULL &&
-		    (strcmp(entry->name, command) != 0 &&
-		    (entry->alias == NULL ||
-		    strcmp(entry->alias, command) != 0)))
-		    continue;
-
 	format_add(ft, "command_list_name", "%s", entry->name);
 	if (entry->alias != NULL)
 		s = entry->alias;
@@ -367,6 +346,41 @@ cmd_list_keys_commands(struct cmd *self, struct cmdq_item *item)
 	free(line);
 }
 
+static enum cmd_retval
+cmd_list_keys_commands(struct cmd *self, struct cmdq_item *item)
+{
+	struct args		 *args = cmd_get_args(self);
+	const struct cmd_entry	**entryp;
+	const struct cmd_entry	 *entry;
+	struct format_tree	 *ft;
+	const char		 *template,  *command;
+	char			 *cause;
+
+	if ((template = args_get(args, 'F')) == NULL) {
+		template = "#{command_list_name}"
+		    "#{?command_list_alias, (#{command_list_alias}),} "
+		    "#{command_list_usage}";
+	}
+
+	ft = format_create(cmdq_get_client(item), item, FORMAT_NONE, 0);
+	format_defaults(ft, NULL, NULL, NULL, NULL);
+
+	command = args_string(args, 0);
+	if (command == NULL) {
+		for (entryp = cmd_table; *entryp != NULL; entryp++)
+			cmd_list_single_command(*entryp, ft, template, item);
+	} else {
+		entry = cmd_find(command, &cause);
+		if (entry != NULL)
+			cmd_list_single_command(entry, ft, template, item);
+		else {
+			cmdq_error(item, "%s", cause);
+			free(cause);
+			format_free(ft);
+			return (CMD_RETURN_ERROR);
+		}
+	}
+
 	format_free(ft);
 	return (CMD_RETURN_NORMAL);
 }

cmd.c

@@ -445,7 +445,7 @@ cmd_get_alias(const char *name)
 }
 
 /* Look up a command entry by name. */
-static const struct cmd_entry *
+const struct cmd_entry *
 cmd_find(const char *name, char **cause)
 {
 	const struct cmd_entry	**loop, *entry, *found = NULL;

tmux.h

@@ -2597,6 +2597,7 @@ int		 cmd_find_from_nothing(struct cmd_find_state *, int);
 
 /* cmd.c */
 extern const struct cmd_entry *cmd_table[];
+const struct cmd_entry *cmd_find(const char *, char **);
 void printflike(3, 4) cmd_log_argv(int, char **, const char *, ...);
 void		 cmd_prepend_argv(int *, char ***, const char *);
 void		 cmd_append_argv(int *, char ***, const char *);