improve 'help' command

Rewrites 'help' command in C, using new 'cmd_help' for display.  Adds the
built-in 'help' COMMAND_HANDLER to provide better output than the
TCL-based script command (e.g. heirarchical listing of commands).

The help string is stored in the command structure, though it conitnues
to be pushed into the Jim environment.  The current idiomatic usage
suggests the addition of a usage field as well, to provide two levels
of detail for users to consume (i.e. terse usage list, or verbose help).

1 files changed, 54 insertions, 2 deletions

diff --git a/src/helper/command.c b/src/helper/command.c
index 87a898f2..f135bb03 100644
--- a/src/helper/command.c
+++ b/src/helper/command.c
@@ -250,6 +250,8 @@ static struct command *command_new(struct command_context *cmd_ctx,
 	memset(c, 0, sizeof(struct command));
 
 	c->name = strdup(name);
+	if (help)
+		c->help = strdup(help);
 	c->parent = parent;
 	c->handler = handler;
 	c->mode = mode;
@@ -273,6 +275,8 @@ static void command_free(struct command *c)
 
 	if (c->name)
 		free(c->name);
+	if (c->help)
+		free((void*)c->help);
 	free(c);
 }
 
@@ -721,6 +725,52 @@ static int jim_capture(Jim_Interp *interp, int argc, Jim_Obj *const *argv)
 	return retcode;
 }
 
+static COMMAND_HELPER(command_help_find, struct command *head,
+		struct command **out)
+{
+	if (0 == CMD_ARGC)
+		return ERROR_INVALID_ARGUMENTS;
+	*out = command_find(head, CMD_ARGV[0]);
+	if (NULL == *out)
+		return ERROR_INVALID_ARGUMENTS;
+	if (--CMD_ARGC == 0)
+		return ERROR_OK;
+	CMD_ARGV++;
+	return CALL_COMMAND_HANDLER(command_help_find, (*out)->children, out);
+}
+
+static COMMAND_HELPER(command_help_show, struct command *c, unsigned n);
+
+static COMMAND_HELPER(command_help_show_list, struct command *head, unsigned n)
+{
+	for (struct command *c = head; NULL != c; c = c->next)
+		CALL_COMMAND_HANDLER(command_help_show, c, n);
+	return ERROR_OK;
+}
+static COMMAND_HELPER(command_help_show, struct command *c, unsigned n)
+{
+	command_run_linef(CMD_CTX, "cmd_help {%s} {%s} %d", command_name(c, ' '),
+			c->help ? : "no help available", n);
+
+	if (++n >= 2)
+		return ERROR_OK;
+
+	return CALL_COMMAND_HANDLER(command_help_show_list, c->children, n);
+}
+COMMAND_HANDLER(handle_help_command)
+{
+	struct command *c = CMD_CTX->commands;
+
+	if (0 == CMD_ARGC)
+		return CALL_COMMAND_HANDLER(command_help_show_list, c, 0);
+
+	int retval = CALL_COMMAND_HANDLER(command_help_find, c, &c);
+	if (ERROR_OK != retval)
+		return retval;
+
+	return CALL_COMMAND_HANDLER(command_help_show, c, 0);
+}
+
 /* sleep command sleeps for <n> miliseconds
  * this is useful in target startup scripts
  */
@@ -831,6 +881,10 @@ struct command_context* command_init(const char *startup_tcl)
 			"<n> [busy] - sleep for n milliseconds. "
 			"\"busy\" means busy wait");
 
+	register_command(context, NULL, "help",
+			&handle_help_command, COMMAND_ANY,
+			"[<command_name> ...] - show built-in command help");
+
 	return context;
 }
 
@@ -977,5 +1031,3 @@ COMMAND_HELPER(handle_command_parse_bool, bool *out, const char *label)
 	}
 	return ERROR_OK;
 }
-
-