shell: make detecting help option optional

Shell will not "steal" by default "-h" and "--help" each time
help functions are enabled.
This change is necessary to implement and use the getopt library.

Signed-off-by: Jakub Rzeszutko <jakub.rzeszutko@nordicsemi.no>

subsys/shell/Kconfig

@@ -121,7 +121,17 @@ config SHELL_HELP
 	bool "Enable help message"
 	default y if !SHELL_MINIMAL
 	help
-	  Enables formatting help message when requested with '-h' or '--help'.
+	  Enables shell functions for printing formatted help message.
+
+config SHELL_HELP_OPT_PARSE
+	bool "Parse -h and --help options"
+	depends on SHELL_HELP
+	depends on !SHELL_GETOPT
+	default y
+	help
+	  Shell parses command to find '-h' or '--help' string. If the shell
+	  finds the string, it will automatically print a help message
+	  for a command.
 
 config SHELL_HELP_ON_WRONG_ARGUMENT_COUNT
 	bool "Enable printing help on wrong argument count"

subsys/shell/shell.c

@@ -662,8 +662,7 @@ static int execute(const struct shell *shell)
 		}
 
 		if (IS_ENABLED(CONFIG_SHELL_HELP) && (cmd_lvl > 0) &&
-		    (!strcmp(argvp[0], "-h") ||
-		     !strcmp(argvp[0], "--help"))) {
+		    z_shell_help_request(argvp[0])) {
 			/* Command called with help option so it makes no sense
 			 * to search deeper commands.
 			 */

subsys/shell/shell_help.c

@@ -187,3 +187,16 @@ void z_shell_help_cmd_print(const struct shell *shell,
 
 	formatted_text_print(shell, cmd->help, field_width, false);
 }
+
+bool z_shell_help_request(const char *str)
+{
+	if (!IS_ENABLED(CONFIG_SHELL_HELP_OPT_PARSE)) {
+		return false;
+	}
+
+	if (!strcmp(str, "-h") || !strcmp(str, "--help")) {
+		return true;
+	}
+
+	return false;
+}

subsys/shell/shell_help.h

@@ -22,6 +22,9 @@ void z_shell_help_subcmd_print(const struct shell *shell,
 			       const struct shell_static_entry *cmd,
 			       const char *description);
 
+/* Function returns true if str == -h or --help */
+bool z_shell_help_request(const char *str);
+
 /**
  * @}
  */