shell: add getopt library support

This functionality is is enabled by setting CONFIG_SHELL_GETOPT.
It is not active by default.

User can call following functions inside command handlers:
 - shell_getopt - getopt function based on freebsd implementation
 - shell_getopt_status_get - returns getopt status

Beware when getopt functionality is enabled shell will not parse
command handler to look for "-h" or "--help" options and print
help message automatically.

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

include/shell/shell.h

@@ -16,6 +16,10 @@
 #include <logging/log.h>
 #include <sys/util.h>
 
+#if defined CONFIG_SHELL_GETOPT
+#include <shell/shell_getopt.h>
+#endif
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -67,6 +71,7 @@ extern "C" {
  * @{
  */
 
+struct getopt_state;
 struct shell_static_entry;
 
 /**
@@ -649,6 +654,11 @@ struct shell_ctx {
 	/*!< VT100 color and cursor position, terminal width.*/
 	struct shell_vt100_ctx vt100_ctx;
 
+#if defined CONFIG_SHELL_GETOPT
+	/*!< getopt context for a shell backend. */
+	struct getopt_state getopt_state;
+#endif
+
 	uint16_t cmd_buff_len; /*!< Command length.*/
 	uint16_t cmd_buff_pos; /*!< Command buffer cursor position.*/
 
@@ -958,6 +968,40 @@ void shell_help(const struct shell *shell);
 /* @brief Command's help has been printed */
 #define SHELL_CMD_HELP_PRINTED	(1)
 
+#if defined CONFIG_SHELL_GETOPT
+/**
+ * @brief Parses the command-line arguments.
+ *
+ * It is based on FreeBSD implementation.
+ *
+ * @param[in] shell	Pointer to the shell instance.
+ * @param[in] argc	Arguments count.
+ * @param[in] argv	Arguments.
+ * @param[in] ostr	String containing the legitimate option characters.
+ *
+ * @return		If an option was successfully found, function returns
+ *			the option character.
+ * @return		If options have been detected that is not in @p ostr
+ *			function will return '?'.
+ *			If function encounters an option with a missing
+ *			argument, then the return value depends on the first
+ *			character in optstring: if it is ':', then ':' is
+ *			returned; otherwise '?' is returned.
+ * @return -1		If all options have been parsed.
+ */
+int shell_getopt(const struct shell *shell, int argc, char *const argv[],
+		 const char *ostr);
+
+/**
+ * @brief Returns shell_getopt state.
+ *
+ * @param[in] shell	Pointer to the shell instance.
+ *
+ * @return		Pointer to struct getopt_state.
+ */
+struct getopt_state *shell_getopt_state_get(const struct shell *shell);
+#endif /* CONFIG_SHELL_GETOPT */
+
 /** @brief Execute command.
  *
  * Pass command line to shell to execute.
@@ -973,7 +1017,7 @@ void shell_help(const struct shell *shell);
  *			@option{CONFIG_SHELL_BACKEND_DUMMY} option is enabled.
  * @param[in] cmd	Command to be executed.
  *
- * @returns		Result of the execution
+ * @return		Result of the execution
  */
 int shell_execute_cmd(const struct shell *shell, const char *cmd);
 

include/shell/shell_getopt.h

@@ -0,0 +1,27 @@
+/*
+ * Copyright (c) 2021 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef SHELL_GETOPT_H__
+#define SHELL_GETOPT_H__
+
+#include <getopt.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+
+/* Initializing shell getopt module.
+ *
+ * @param[in] shell	Pointer to the shell instance.
+ */
+void z_shell_getopt_init(struct getopt_state *state);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* SHELL_GETOPT_H__ */

subsys/shell/CMakeLists.txt

@@ -35,6 +35,11 @@ zephyr_sources_ifdef(
   shell_help.c
   )
 
+zephyr_sources_ifdef(
+  CONFIG_SHELL_GETOPT
+  shell_getopt.c
+  )
+
 zephyr_sources_ifdef(
   CONFIG_SHELL_CMDS
   shell_cmds.c

subsys/shell/Kconfig

@@ -109,6 +109,12 @@ config SHELL_VT100_COLORS
 	help
 	  If enabled VT100 colors are used in shell (e.g. print errors in red).
 
+config SHELL_GETOPT
+	bool "Enable getopt support"
+	select GETOPT
+	help
+	  Enables getopt support in the shell.
+
 config SHELL_METAKEYS
 	bool "Enable metakeys"
 	default y if !SHELL_MINIMAL

subsys/shell/shell.c

@@ -533,6 +533,10 @@ static int exec_cmd(const struct shell *shell, size_t argc, const char **argv,
 	}
 
 	if (!ret_val) {
+#if CONFIG_SHELL_GETOPT
+		z_shell_getopt_init(&shell->ctx->getopt_state);
+#endif
+
 		z_flag_cmd_ctx_set(shell, true);
 		/* Unlock thread mutex in case command would like to borrow
 		 * shell context to other thread to avoid mutex deadlock.

subsys/shell/shell_getopt.c

@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2021 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr.h>
+#include <shell/shell.h>
+#include <shell/shell_getopt.h>
+
+void z_shell_getopt_init(struct getopt_state *state)
+{
+	getopt_init(state);
+}
+
+int shell_getopt(const struct shell *shell, int argc, char *const argv[],
+		 const char *ostr)
+{
+	if (!IS_ENABLED(CONFIG_SHELL_GETOPT)) {
+		return 0;
+	}
+
+	__ASSERT_NO_MSG(shell);
+
+	return getopt(&shell->ctx->getopt_state, argc, argv, ostr);
+}
+
+struct getopt_state *shell_getopt_state_get(const struct shell *shell)
+{
+	if (!IS_ENABLED(CONFIG_SHELL_GETOPT)) {
+		return NULL;
+	}
+
+	__ASSERT_NO_MSG(shell);
+
+	return &shell->ctx->getopt_state;
+}