Add generic, reusable menu code

This will be used first by the pxe code, but is intended to be generic and reusable for other jobs in U-boot. Signed-off-by: Jason Hobbs <jason.hobbs@calxeda.com>

Add generic, reusable menu code
This will be used first by the pxe code, but is intended to be generic and reusable for other jobs in U-boot. Signed-off-by: Jason Hobbs <jason.hobbs@calxeda.com>
Jason Hobbs · Wolfgang Denk
1 parent 5c1d082b14
Showing 4 changed files with 543 additions and 0 deletions Side-by-side Diff
common/Makefile
common/menu.c
doc/README.menu
include/menu.h
@@ -177,6 +177,7 @@
 COBJS-$(CONFIG_KALLSYMS) += kallsyms.o
 COBJS-$(CONFIG_LCD) += lcd.o
 COBJS-$(CONFIG_LYNXKDI) += lynxkdi.o
+COBJS-$(CONFIG_MENU) += menu.o
 COBJS-$(CONFIG_MODEM_SUPPORT) += modem.o
 COBJS-$(CONFIG_UPDATE_TFTP) += update.o
 COBJS-$(CONFIG_USB_KEYBOARD) += usb_kbd.o
+/*
+ * Copyright 2010-2011 Calxeda, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <common.h>
+#include <malloc.h>
+#include <errno.h>
+#include <linux/list.h>
+
+#include "menu.h"
+
+/*
+ * Internally, each item in a menu is represented by a struct menu_item.
+ *
+ * These items will be alloc'd and initialized by menu_item_add and destroyed
+ * by menu_item_destroy, and the consumer of the interface never sees that
+ * this struct is used at all.
+ */
+struct menu_item {
+	char *key;
+	void *data;
+	struct list_head list;
+};
+
+/*
+ * The menu is composed of a list of items along with settings and callbacks
+ * provided by the user. An incomplete definition of this struct is available
+ * in menu.h, but the full definition is here to prevent consumers from
+ * relying on its contents.
+ */
+struct menu {
+	struct menu_item *default_item;
+	char *title;
+	int prompt;
+	void (*item_data_print)(void *);
+	struct list_head items;
+};
+
+/*
+ * An iterator function for menu items. callback will be called for each item
+ * in m, with m, a pointer to the item, and extra being passed to callback. If
+ * callback returns a value other than NULL, iteration stops and the value
+ * return by callback is returned from menu_items_iter.  This allows it to be
+ * used for search type operations. It is also safe for callback to remove the
+ * item from the list of items.
+ */
+static inline void *menu_items_iter(struct menu *m,
+		void *(*callback)(struct menu *, struct menu_item *, void *),
+		void *extra)
+{
+	struct list_head *pos, *n;
+	struct menu_item *item;
+	void *ret;
+
+	list_for_each_safe(pos, n, &m->items) {
+		item = list_entry(pos, struct menu_item, list);
+
+		ret = callback(m, item, extra);
+
+		if (ret)
+			return ret;
+	}
+
+	return NULL;
+}
+
+/*
+ * Print a menu_item. If the consumer provided an item_data_print function
+ * when creating the menu, call it with a pointer to the item's private data.
+ * Otherwise, print the key of the item.
+ */
+static inline void *menu_item_print(struct menu *m,
+				struct menu_item *item,
+				void *extra)
+{
+	if (!m->item_data_print)
+		printf("%s\n", item->key);
+	else
+		m->item_data_print(item->data);
+
+	return NULL;
+}
+
+/*
+ * Free the memory used by a menu item. This includes the memory used by its
+ * key.
+ */
+static inline void *menu_item_destroy(struct menu *m,
+				struct menu_item *item,
+				void *extra)
+{
+	if (item->key)
+		free(item->key);
+
+	free(item);
+
+	return NULL;
+}
+
+/*
+ * Display a menu so the user can make a choice of an item. First display its
+ * title, if any, and then each item in the menu.
+ */
+static inline void menu_display(struct menu *m)
+{
+	if (m->title)
+		printf("%s:\n", m->title);
+
+	menu_items_iter(m, menu_item_print, NULL);
+}
+
+/*
+ * Check if an item's key matches a provided string, pointed to by extra. If
+ * extra is NULL, an item with a NULL key will match. Otherwise, the item's
+ * key has to match according to strcmp.
+ *
+ * This is called via menu_items_iter, so it returns a pointer to the item if
+ * the key matches, and returns NULL otherwise.
+ */
+static inline void *menu_item_key_match(struct menu *m,
+			struct menu_item *item, void *extra)
+{
+	char *item_key = extra;
+
+	if (!item_key || !item->key) {
+		if (item_key == item->key)
+			return item;
+
+		return NULL;
+	}
+
+	if (strcmp(item->key, item_key) == 0)
+		return item;
+
+	return NULL;
+}
+
+/*
+ * Find the first item with a key matching item_key, if any exists.
+ */
+static inline struct menu_item *menu_item_by_key(struct menu *m,
+							char *item_key)
+{
+	return menu_items_iter(m, menu_item_key_match, item_key);
+}
+
+/*
+ * Checks whether or not the default menu item should be used without
+ * prompting for a user choice.  If the menu is set to always prompt, return
+ * 0. Otherwise, return 1 to indicate we should use the default menu item.
+ */
+static inline int menu_use_default(struct menu *m)
+{
+	return !m->prompt;
+}
+
+/*
+ * Set *choice to point to the default item's data, if any default item was
+ * set, and returns 1. If no default item was set, returns -ENOENT.
+ */
+static inline int menu_default_choice(struct menu *m, void **choice)
+{
+	if (m->default_item) {
+		*choice = m->default_item->data;
+		return 1;
+	}
+
+	return -ENOENT;
+}
+
+/*
+ * Displays the menu and asks the user to choose an item. *choice will point
+ * to the private data of the item the user chooses. The user makes a choice
+ * by inputting a string matching the key of an item. Invalid choices will
+ * cause the user to be prompted again, repeatedly, until the user makes a
+ * valid choice. The user can exit the menu without making a choice via ^c.
+ *
+ * Returns 1 if the user made a choice, or -EINTR if they bail via ^c.
+ */
+static inline int menu_interactive_choice(struct menu *m, void **choice)
+{
+	char cbuf[CONFIG_SYS_CBSIZE];
+	struct menu_item *choice_item = NULL;
+	int readret;
+
+	while (!choice_item) {
+		cbuf[0] = '\0';
+
+		menu_display(m);
+
+		readret = readline_into_buffer("Enter choice: ", cbuf);
+
+		if (readret >= 0) {
+			choice_item = menu_item_by_key(m, cbuf);
+
+			if (!choice_item)
+				printf("%s not found\n", cbuf);
+		} else {
+			printf("^C\n");
+			return -EINTR;
+		}
+	}
+
+	*choice = choice_item->data;
+
+	return 1;
+}
+
+/*
+ * menu_default_set() - Sets the default choice for the menu. This is safe to
+ * call more than once on a menu.
+ *
+ * m - Points to a menu created by menu_create().
+ *
+ * item_key - Points to a string that, when compared using strcmp, matches the
+ * key for an existing item in the menu.
+ *
+ * Returns 1 if successful, -EINVAL if m is NULL, or -ENOENT if no item with a
+ * key matching item_key is found.
+ */
+int menu_default_set(struct menu *m, char *item_key)
+{
+	struct menu_item *item;
+
+	if (!m)
+		return -EINVAL;
+
+	item = menu_item_by_key(m, item_key);
+
+	if (!item)
+		return -ENOENT;
+
+	m->default_item = item;
+
+	return 1;
+}
+
+/*
+ * menu_get_choice() - Returns the user's selected menu entry, or the default
+ * if the menu is set to not prompt. This is safe to call more than once.
+ *
+ * m - Points to a menu created by menu_create().
+ *
+ * choice - Points to a location that will store a pointer to the selected
+ * menu item. If no item is selected or there is an error, no value will be
+ * written at the location it points to.
+ *
+ * Returns 1 if successful, -EINVAL if m or choice is NULL, -ENOENT if no
+ * default has been set and the menu is set to not prompt, or -EINTR if the
+ * user exits the menu via ^c.
+ */
+int menu_get_choice(struct menu *m, void **choice)
+{
+	if (!m || !choice)
+		return -EINVAL;
+
+	if (menu_use_default(m))
+		return menu_default_choice(m, choice);
+
+	return menu_interactive_choice(m, choice);
+}
+
+/*
+ * menu_item_add() - Adds or replaces a menu item. Note that this replaces the
+ * data of an item if it already exists, but doesn't change the order of the
+ * item.
+ *
+ * m - Points to a menu created by menu_create().
+ *
+ * item_key - Points to a string that will uniquely identify the item.  The
+ * string will be copied to internal storage, and is safe to discard after
+ * passing to menu_item_add.
+ *
+ * item_data - An opaque pointer associated with an item. It is never
+ * dereferenced internally, but will be passed to the item_data_print, and
+ * will be returned from menu_get_choice if the menu item is selected.
+ *
+ * Returns 1 if successful, -EINVAL if m is NULL, or -ENOMEM if there is
+ * insufficient memory to add the menu item.
+ */
+int menu_item_add(struct menu *m, char *item_key, void *item_data)
+{
+	struct menu_item *item;
+
+	if (!m)
+		return -EINVAL;
+
+	item = menu_item_by_key(m, item_key);
+
+	if (item) {
+		item->data = item_data;
+		return 1;
+	}
+
+	item = malloc(sizeof *item);
+	if (!item)
+		return -ENOMEM;
+
+	item->key = strdup(item_key);
+
+	if (!item->key) {
+		free(item);
+		return -ENOMEM;
+	}
+
+	item->data = item_data;
+
+	list_add_tail(&item->list, &m->items);
+
+	return 1;
+}
+
+/*
+ * menu_create() - Creates a menu handle with default settings
+ *
+ * title - If not NULL, points to a string that will be displayed before the
+ * list of menu items. It will be copied to internal storage, and is safe to
+ * discard after passing to menu_create().
+ *
+ * prompt - If 0, don't ask for user input.
+ *
+ * item_data_print - If not NULL, will be called for each item when the menu
+ * is displayed, with the pointer to the item's data passed as the argument.
+ * If NULL, each item's key will be printed instead.  Since an item's key is
+ * what must be entered to select an item, the item_data_print function should
+ * make it obvious what the key for each entry is.
+ *
+ * Returns a pointer to the menu if successful, or NULL if there is
+ * insufficient memory available to create the menu.
+ */
+struct menu *menu_create(char *title, int prompt,
+				void (*item_data_print)(void *))
+{
+	struct menu *m;
+
+	m = malloc(sizeof *m);
+
+	if (!m)
+		return NULL;
+
+	m->default_item = NULL;
+	m->prompt = prompt;
+	m->item_data_print = item_data_print;
+
+	if (title) {
+		m->title = strdup(title);
+		if (!m->title) {
+			free(m);
+			return NULL;
+		}
+	} else
+		m->title = NULL;
+
+
+	INIT_LIST_HEAD(&m->items);
+
+	return m;
+}
+
+/*
+ * menu_destroy() - frees the memory used by a menu and its items.
+ *
+ * m - Points to a menu created by menu_create().
+ *
+ * Returns 1 if successful, or -EINVAL if m is NULL.
+ */
+int menu_destroy(struct menu *m)
+{
+	if (!m)
+		return -EINVAL;
+
+	menu_items_iter(m, menu_item_destroy, NULL);
+
+	if (m->title)
+		free(m->title);
+
+	free(m);
+
+	return 1;
+}
+/*
+ * Copyright 2010-2011 Calxeda, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+U-boot provides a set of interfaces for creating and using simple, text
+based menus. Menus are displayed as lists of labeled entries on the
+console, and an entry can be selected by entering its label.
+
+To use the menu code, enable CONFIG_MENU, and include "menu.h" where
+the interfaces should be available.
+
+Menus are composed of items. Each item has a key used to identify it in
+the menu, and an opaque pointer to data controlled by the consumer.
+
+Interfaces
+----------
+#include "menu.h"
+
+/*
+ * Consumers of the menu interfaces will use a struct menu * as the
+ * handle for a menu. struct menu is only fully defined in menu.c,
+ * preventing consumers of the menu interfaces from accessing its
+ * contents directly.
+ */
+struct menu;
+
+/*
+ * NOTE: See comments in common/menu.c for more detailed documentation on
+ * these interfaces.
+ */
+
+/*
+ * menu_create() - Creates a menu handle with default settings
+ */
+struct menu *menu_create(char *title, int prompt,
+				void (*item_data_print)(void *));
+
+/*
+ * menu_item_add() - Adds or replaces a menu item
+ */
+int menu_item_add(struct menu *m, char *item_key, void *item_data);
+
+/*
+ * menu_default_set() - Sets the default choice for the menu
+ */
+int menu_default_set(struct menu *m, char *item_key);
+
+/*
+ * menu_get_choice() - Returns the user's selected menu entry, or the
+ * default if the menu is set to not prompt.
+ */
+int menu_get_choice(struct menu *m, void **choice);
+
+/*
+ * menu_destroy() - frees the memory used by a menu and its items.
+ */
+int menu_destroy(struct menu *m);
+
+
+Example Code
+------------
+This example creates a menu that always prompts, and allows the user
+to pick from a list of tools.  The item key and data are the same.
+
+#include "menu.h"
+
+char *tools[] = {
+	"Hammer",
+	"Screwdriver",
+	"Nail gun",
+	NULL
+};
+
+char *pick_a_tool(void)
+{
+	struct menu *m;
+	int i;
+	char *tool = NULL;
+
+	m = menu_create("Tools", 1, NULL);
+
+	for(i = 0; tools[i]; i++) {
+		if (menu_item_add(m, tools[i], tools[i]) != 1) {
+			printf("failed to add item!");
+			menu_destroy(m);
+			return NULL;
+                }
+	}
+
+	if (menu_get_choice(m, (void **)&tool) != 1)
+		printf("Problem picking tool!\n");
+
+	menu_destroy(m);
+
+	return tool;
+}
+
+void caller(void)
+{
+	char *tool = pick_a_tool();
+
+	if (tool) {
+		printf("picked a tool: %s\n", tool);
+		use_tool(tool);
+	}
+}
+/*
+ * Copyright 2010-2011 Calxeda, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef __MENU_H__
+#define __MENU_H__
+
+struct menu;
+
+struct menu *menu_create(char *title, int prompt,
+				void (*item_data_print)(void *));
+int menu_default_set(struct menu *m, char *item_key);
+int menu_get_choice(struct menu *m, void **choice);
+int menu_item_add(struct menu *m, char *item_key, void *item_data);
+int menu_destroy(struct menu *m);
+
+#endif /* __MENU_H__ */
...	...	@@ -177,6 +177,7 @@
177	177	COBJS-$(CONFIG_KALLSYMS) += kallsyms.o
178	178	COBJS-$(CONFIG_LCD) += lcd.o
179	179	COBJS-$(CONFIG_LYNXKDI) += lynxkdi.o
	180	+COBJS-$(CONFIG_MENU) += menu.o
180	181	COBJS-$(CONFIG_MODEM_SUPPORT) += modem.o
181	182	COBJS-$(CONFIG_UPDATE_TFTP) += update.o
182	183	COBJS-$(CONFIG_USB_KEYBOARD) += usb_kbd.o
	1	+/*
	2	+ * Copyright 2010-2011 Calxeda, Inc.
	3	+ *
	4	+ * This program is free software; you can redistribute it and/or modify it
	5	+ * under the terms of the GNU General Public License as published by the Free
	6	+ * Software Foundation; either version 2 of the License, or (at your option)
	7	+ * any later version.
	8	+ *
	9	+ * This program is distributed in the hope it will be useful, but WITHOUT
	10	+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	11	+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
	12	+ * more details.
	13	+ *
	14	+ * You should have received a copy of the GNU General Public License along with
	15	+ * this program. If not, see <http://www.gnu.org/licenses/>.
	16	+ */
	17	+
	18	+#include <common.h>
	19	+#include <malloc.h>
	20	+#include <errno.h>
	21	+#include <linux/list.h>
	22	+
	23	+#include "menu.h"
	24	+
	25	+/*
	26	+ * Internally, each item in a menu is represented by a struct menu_item.
	27	+ *
	28	+ * These items will be alloc'd and initialized by menu_item_add and destroyed
	29	+ * by menu_item_destroy, and the consumer of the interface never sees that
	30	+ * this struct is used at all.
	31	+ */
	32	+struct menu_item {
	33	+ char *key;
	34	+ void *data;
	35	+ struct list_head list;
	36	+};
	37	+
	38	+/*
	39	+ * The menu is composed of a list of items along with settings and callbacks
	40	+ * provided by the user. An incomplete definition of this struct is available
	41	+ * in menu.h, but the full definition is here to prevent consumers from
	42	+ * relying on its contents.
	43	+ */
	44	+struct menu {
	45	+ struct menu_item *default_item;
	46	+ char *title;
	47	+ int prompt;
	48	+ void (item_data_print)(void );
	49	+ struct list_head items;
	50	+};
	51	+
	52	+/*
	53	+ * An iterator function for menu items. callback will be called for each item
	54	+ * in m, with m, a pointer to the item, and extra being passed to callback. If
	55	+ * callback returns a value other than NULL, iteration stops and the value
	56	+ * return by callback is returned from menu_items_iter. This allows it to be
	57	+ * used for search type operations. It is also safe for callback to remove the
	58	+ * item from the list of items.
	59	+ */
	60	+static inline void menu_items_iter(struct menu m,
	61	+ void (callback)(struct menu , struct menu_item , void *),
	62	+ void *extra)
	63	+{
	64	+ struct list_head pos, n;
	65	+ struct menu_item *item;
	66	+ void *ret;
	67	+
	68	+ list_for_each_safe(pos, n, &m->items) {
	69	+ item = list_entry(pos, struct menu_item, list);
	70	+
	71	+ ret = callback(m, item, extra);
	72	+
	73	+ if (ret)
	74	+ return ret;
	75	+ }
	76	+
	77	+ return NULL;
	78	+}
	79	+
	80	+/*
	81	+ * Print a menu_item. If the consumer provided an item_data_print function
	82	+ * when creating the menu, call it with a pointer to the item's private data.
	83	+ * Otherwise, print the key of the item.
	84	+ */
	85	+static inline void menu_item_print(struct menu m,
	86	+ struct menu_item *item,
	87	+ void *extra)
	88	+{
	89	+ if (!m->item_data_print)
	90	+ printf("%s\n", item->key);
	91	+ else
	92	+ m->item_data_print(item->data);
	93	+
	94	+ return NULL;
	95	+}
	96	+
	97	+/*
	98	+ * Free the memory used by a menu item. This includes the memory used by its
	99	+ * key.
	100	+ */
	101	+static inline void menu_item_destroy(struct menu m,
	102	+ struct menu_item *item,
	103	+ void *extra)
	104	+{
	105	+ if (item->key)
	106	+ free(item->key);
	107	+
	108	+ free(item);
	109	+
	110	+ return NULL;
	111	+}
	112	+
	113	+/*
	114	+ * Display a menu so the user can make a choice of an item. First display its
	115	+ * title, if any, and then each item in the menu.
	116	+ */
	117	+static inline void menu_display(struct menu *m)
	118	+{
	119	+ if (m->title)
	120	+ printf("%s:\n", m->title);
	121	+
	122	+ menu_items_iter(m, menu_item_print, NULL);
	123	+}
	124	+
	125	+/*
	126	+ * Check if an item's key matches a provided string, pointed to by extra. If
	127	+ * extra is NULL, an item with a NULL key will match. Otherwise, the item's
	128	+ * key has to match according to strcmp.
	129	+ *
	130	+ * This is called via menu_items_iter, so it returns a pointer to the item if
	131	+ * the key matches, and returns NULL otherwise.
	132	+ */
	133	+static inline void menu_item_key_match(struct menu m,
	134	+ struct menu_item item, void extra)
	135	+{
	136	+ char *item_key = extra;
	137	+
	138	+ if (!item_key \|\| !item->key) {
	139	+ if (item_key == item->key)
	140	+ return item;
	141	+
	142	+ return NULL;
	143	+ }
	144	+
	145	+ if (strcmp(item->key, item_key) == 0)
	146	+ return item;
	147	+
	148	+ return NULL;
	149	+}
	150	+
	151	+/*
	152	+ * Find the first item with a key matching item_key, if any exists.
	153	+ */
	154	+static inline struct menu_item menu_item_by_key(struct menu m,
	155	+ char *item_key)
	156	+{
	157	+ return menu_items_iter(m, menu_item_key_match, item_key);
	158	+}
	159	+
	160	+/*
	161	+ * Checks whether or not the default menu item should be used without
	162	+ * prompting for a user choice. If the menu is set to always prompt, return
	163	+ * 0. Otherwise, return 1 to indicate we should use the default menu item.
	164	+ */
	165	+static inline int menu_use_default(struct menu *m)
	166	+{
	167	+ return !m->prompt;
	168	+}
	169	+
	170	+/*
	171	+ * Set *choice to point to the default item's data, if any default item was
	172	+ * set, and returns 1. If no default item was set, returns -ENOENT.
	173	+ */
	174	+static inline int menu_default_choice(struct menu m, void *choice)
	175	+{
	176	+ if (m->default_item) {
	177	+ *choice = m->default_item->data;
	178	+ return 1;
	179	+ }
	180	+
	181	+ return -ENOENT;
	182	+}
	183	+
	184	+/*
	185	+ * Displays the menu and asks the user to choose an item. *choice will point
	186	+ * to the private data of the item the user chooses. The user makes a choice
	187	+ * by inputting a string matching the key of an item. Invalid choices will
	188	+ * cause the user to be prompted again, repeatedly, until the user makes a
	189	+ * valid choice. The user can exit the menu without making a choice via ^c.
	190	+ *
	191	+ * Returns 1 if the user made a choice, or -EINTR if they bail via ^c.
	192	+ */
	193	+static inline int menu_interactive_choice(struct menu m, void *choice)
	194	+{
	195	+ char cbuf[CONFIG_SYS_CBSIZE];
	196	+ struct menu_item *choice_item = NULL;
	197	+ int readret;
	198	+
	199	+ while (!choice_item) {
	200	+ cbuf[0] = '\0';
	201	+
	202	+ menu_display(m);
	203	+
	204	+ readret = readline_into_buffer("Enter choice: ", cbuf);
	205	+
	206	+ if (readret >= 0) {
	207	+ choice_item = menu_item_by_key(m, cbuf);
	208	+
	209	+ if (!choice_item)
	210	+ printf("%s not found\n", cbuf);
	211	+ } else {
	212	+ printf("^C\n");
	213	+ return -EINTR;
	214	+ }
	215	+ }
	216	+
	217	+ *choice = choice_item->data;
	218	+
	219	+ return 1;
	220	+}
	221	+
	222	+/*
	223	+ * menu_default_set() - Sets the default choice for the menu. This is safe to
	224	+ * call more than once on a menu.
	225	+ *
	226	+ * m - Points to a menu created by menu_create().
	227	+ *
	228	+ * item_key - Points to a string that, when compared using strcmp, matches the
	229	+ * key for an existing item in the menu.
	230	+ *
	231	+ * Returns 1 if successful, -EINVAL if m is NULL, or -ENOENT if no item with a
	232	+ * key matching item_key is found.
	233	+ */
	234	+int menu_default_set(struct menu m, char item_key)
	235	+{
	236	+ struct menu_item *item;
	237	+
	238	+ if (!m)
	239	+ return -EINVAL;
	240	+
	241	+ item = menu_item_by_key(m, item_key);
	242	+
	243	+ if (!item)
	244	+ return -ENOENT;
	245	+
	246	+ m->default_item = item;
	247	+
	248	+ return 1;
	249	+}
	250	+
	251	+/*
	252	+ * menu_get_choice() - Returns the user's selected menu entry, or the default
	253	+ * if the menu is set to not prompt. This is safe to call more than once.
	254	+ *
	255	+ * m - Points to a menu created by menu_create().
	256	+ *
	257	+ * choice - Points to a location that will store a pointer to the selected
	258	+ * menu item. If no item is selected or there is an error, no value will be
	259	+ * written at the location it points to.
	260	+ *
	261	+ * Returns 1 if successful, -EINVAL if m or choice is NULL, -ENOENT if no
	262	+ * default has been set and the menu is set to not prompt, or -EINTR if the
	263	+ * user exits the menu via ^c.
	264	+ */
	265	+int menu_get_choice(struct menu m, void *choice)
	266	+{
	267	+ if (!m \|\| !choice)
	268	+ return -EINVAL;
	269	+
	270	+ if (menu_use_default(m))
	271	+ return menu_default_choice(m, choice);
	272	+
	273	+ return menu_interactive_choice(m, choice);
	274	+}
	275	+
	276	+/*
	277	+ * menu_item_add() - Adds or replaces a menu item. Note that this replaces the
	278	+ * data of an item if it already exists, but doesn't change the order of the
	279	+ * item.
	280	+ *
	281	+ * m - Points to a menu created by menu_create().
	282	+ *
	283	+ * item_key - Points to a string that will uniquely identify the item. The
	284	+ * string will be copied to internal storage, and is safe to discard after
	285	+ * passing to menu_item_add.
	286	+ *
	287	+ * item_data - An opaque pointer associated with an item. It is never
	288	+ * dereferenced internally, but will be passed to the item_data_print, and
	289	+ * will be returned from menu_get_choice if the menu item is selected.
	290	+ *
	291	+ * Returns 1 if successful, -EINVAL if m is NULL, or -ENOMEM if there is
	292	+ * insufficient memory to add the menu item.
	293	+ */
	294	+int menu_item_add(struct menu m, char item_key, void *item_data)
	295	+{
	296	+ struct menu_item *item;
	297	+
	298	+ if (!m)
	299	+ return -EINVAL;
	300	+
	301	+ item = menu_item_by_key(m, item_key);
	302	+
	303	+ if (item) {
	304	+ item->data = item_data;
	305	+ return 1;
	306	+ }
	307	+
	308	+ item = malloc(sizeof *item);
	309	+ if (!item)
	310	+ return -ENOMEM;
	311	+
	312	+ item->key = strdup(item_key);
	313	+
	314	+ if (!item->key) {
	315	+ free(item);
	316	+ return -ENOMEM;
	317	+ }
	318	+
	319	+ item->data = item_data;
	320	+
	321	+ list_add_tail(&item->list, &m->items);
	322	+
	323	+ return 1;
	324	+}
	325	+
	326	+/*
	327	+ * menu_create() - Creates a menu handle with default settings
	328	+ *
	329	+ * title - If not NULL, points to a string that will be displayed before the
	330	+ * list of menu items. It will be copied to internal storage, and is safe to
	331	+ * discard after passing to menu_create().
	332	+ *
	333	+ * prompt - If 0, don't ask for user input.
	334	+ *
	335	+ * item_data_print - If not NULL, will be called for each item when the menu
	336	+ * is displayed, with the pointer to the item's data passed as the argument.
	337	+ * If NULL, each item's key will be printed instead. Since an item's key is
	338	+ * what must be entered to select an item, the item_data_print function should
	339	+ * make it obvious what the key for each entry is.
	340	+ *
	341	+ * Returns a pointer to the menu if successful, or NULL if there is
	342	+ * insufficient memory available to create the menu.
	343	+ */
	344	+struct menu menu_create(char title, int prompt,
	345	+ void (item_data_print)(void ))
	346	+{
	347	+ struct menu *m;
	348	+
	349	+ m = malloc(sizeof *m);
	350	+
	351	+ if (!m)
	352	+ return NULL;
	353	+
	354	+ m->default_item = NULL;
	355	+ m->prompt = prompt;
	356	+ m->item_data_print = item_data_print;
	357	+
	358	+ if (title) {
	359	+ m->title = strdup(title);
	360	+ if (!m->title) {
	361	+ free(m);
	362	+ return NULL;
	363	+ }
	364	+ } else
	365	+ m->title = NULL;
	366	+
	367	+
	368	+ INIT_LIST_HEAD(&m->items);
	369	+
	370	+ return m;
	371	+}
	372	+
	373	+/*
	374	+ * menu_destroy() - frees the memory used by a menu and its items.
	375	+ *
	376	+ * m - Points to a menu created by menu_create().
	377	+ *
	378	+ * Returns 1 if successful, or -EINVAL if m is NULL.
	379	+ */
	380	+int menu_destroy(struct menu *m)
	381	+{
	382	+ if (!m)
	383	+ return -EINVAL;
	384	+
	385	+ menu_items_iter(m, menu_item_destroy, NULL);
	386	+
	387	+ if (m->title)
	388	+ free(m->title);
	389	+
	390	+ free(m);
	391	+
	392	+ return 1;
	393	+}