common/menu.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Copyright 2010-2011 Calxeda, Inc.
   4  */
   5
   6 #include <common.h>
   7 #include <cli.h>
   8 #include <malloc.h>
   9 #include <errno.h>
  10 #include <linux/list.h>
  11
  12 #include "menu.h"
  13
  14 /*
  15  * Internally, each item in a menu is represented by a struct menu_item.
  16  *
  17  * These items will be alloc'd and initialized by menu_item_add and destroyed
  18  * by menu_item_destroy, and the consumer of the interface never sees that
  19  * this struct is used at all.
  20  */
  21 struct menu_item {
  22         char *key;
  23         void *data;
  24         struct list_head list;
  25 };
  26
  27 /*
  28  * The menu is composed of a list of items along with settings and callbacks
  29  * provided by the user. An incomplete definition of this struct is available
  30  * in menu.h, but the full definition is here to prevent consumers from
  31  * relying on its contents.
  32  */
  33 struct menu {
  34         struct menu_item *default_item;
  35         int timeout;
  36         char *title;
  37         int prompt;
  38         void (*item_data_print)(void *);
  39         char *(*item_choice)(void *);
  40         void *item_choice_data;
  41         struct list_head items;
  42 };
  43
  44 /*
  45  * An iterator function for menu items. callback will be called for each item
  46  * in m, with m, a pointer to the item, and extra being passed to callback. If
  47  * callback returns a value other than NULL, iteration stops and the value
  48  * return by callback is returned from menu_items_iter.  This allows it to be
  49  * used for search type operations. It is also safe for callback to remove the
  50  * item from the list of items.
  51  */
  52 static inline void *menu_items_iter(struct menu *m,
  53                 void *(*callback)(struct menu *, struct menu_item *, void *),
  54                 void *extra)
  55 {
  56         struct list_head *pos, *n;
  57         struct menu_item *item;
  58         void *ret;
  59
  60         list_for_each_safe(pos, n, &m->items) {
  61                 item = list_entry(pos, struct menu_item, list);
  62
  63                 ret = callback(m, item, extra);
  64
  65                 if (ret)
  66                         return ret;
  67         }
  68
  69         return NULL;
  70 }
  71
  72 /*
  73  * Print a menu_item. If the consumer provided an item_data_print function
  74  * when creating the menu, call it with a pointer to the item's private data.
  75  * Otherwise, print the key of the item.
  76  */
  77 static inline void *menu_item_print(struct menu *m,
  78                                 struct menu_item *item,
  79                                 void *extra)
  80 {
  81         if (!m->item_data_print) {
  82                 puts(item->key);
  83                 putc('\n');
  84         } else {
  85                 m->item_data_print(item->data);
  86         }
  87
  88         return NULL;
  89 }
  90
  91 /*
  92  * Free the memory used by a menu item. This includes the memory used by its
  93  * key.
  94  */
  95 static inline void *menu_item_destroy(struct menu *m,
  96                                 struct menu_item *item,
  97                                 void *extra)
  98 {
  99         if (item->key)
 100                 free(item->key);
 101
 102         free(item);
 103
 104         return NULL;
 105 }
 106
 107 __weak void menu_display_statusline(struct menu *m)
 108 {
 109 }
 110
 111 /*
 112  * Display a menu so the user can make a choice of an item. First display its
 113  * title, if any, and then each item in the menu.
 114  */
 115 static inline void menu_display(struct menu *m)
 116 {
 117         if (m->title) {
 118                 puts(m->title);
 119                 putc('\n');
 120         }
 121         menu_display_statusline(m);
 122
 123         menu_items_iter(m, menu_item_print, NULL);
 124 }
 125
 126 /*
 127  * Check if an item's key matches a provided string, pointed to by extra. If
 128  * extra is NULL, an item with a NULL key will match. Otherwise, the item's
 129  * key has to match according to strcmp.
 130  *
 131  * This is called via menu_items_iter, so it returns a pointer to the item if
 132  * the key matches, and returns NULL otherwise.
 133  */
 134 static inline void *menu_item_key_match(struct menu *m,
 135                         struct menu_item *item, void *extra)
 136 {
 137         char *item_key = extra;
 138
 139         if (!item_key || !item->key) {
 140                 if (item_key == item->key)
 141                         return item;
 142
 143                 return NULL;
 144         }
 145
 146         if (strcmp(item->key, item_key) == 0)
 147                 return item;
 148
 149         return NULL;
 150 }
 151
 152 /*
 153  * Find the first item with a key matching item_key, if any exists.
 154  */
 155 static inline struct menu_item *menu_item_by_key(struct menu *m,
 156                                                         char *item_key)
 157 {
 158         return menu_items_iter(m, menu_item_key_match, item_key);
 159 }
 160
 161 /*
 162  * Set *choice to point to the default item's data, if any default item was
 163  * set, and returns 1. If no default item was set, returns -ENOENT.
 164  */
 165 int menu_default_choice(struct menu *m, void **choice)
 166 {
 167         if (m->default_item) {
 168                 *choice = m->default_item->data;
 169                 return 1;
 170         }
 171
 172         return -ENOENT;
 173 }
 174
 175 /*
 176  * Displays the menu and asks the user to choose an item. *choice will point
 177  * to the private data of the item the user chooses. The user makes a choice
 178  * by inputting a string matching the key of an item. Invalid choices will
 179  * cause the user to be prompted again, repeatedly, until the user makes a
 180  * valid choice. The user can exit the menu without making a choice via ^c.
 181  *
 182  * Returns 1 if the user made a choice, or -EINTR if they bail via ^c.
 183  */
 184 static inline int menu_interactive_choice(struct menu *m, void **choice)
 185 {
 186         char cbuf[CONFIG_SYS_CBSIZE];
 187         struct menu_item *choice_item = NULL;
 188         int readret;
 189
 190         while (!choice_item) {
 191                 cbuf[0] = '\0';
 192
 193                 menu_display(m);
 194
 195                 if (!m->item_choice) {
 196                         readret = cli_readline_into_buffer("Enter choice: ",
 197                                                            cbuf, m->timeout);
 198
 199                         if (readret >= 0) {
 200                                 choice_item = menu_item_by_key(m, cbuf);
 201                                 if (!choice_item)
 202                                         printf("%s not found\n", cbuf);
 203                         } else if (readret == -1)  {
 204                                 printf("<INTERRUPT>\n");
 205                                 return -EINTR;
 206                         } else {
 207                                 return menu_default_choice(m, choice);
 208                         }
 209                 } else {
 210                         char *key = m->item_choice(m->item_choice_data);
 211
 212                         if (key)
 213                                 choice_item = menu_item_by_key(m, key);
 214                 }
 215
 216                 if (!choice_item)
 217                         m->timeout = 0;
 218         }
 219
 220         *choice = choice_item->data;
 221
 222         return 1;
 223 }
 224
 225 /*
 226  * menu_default_set() - Sets the default choice for the menu. This is safe to
 227  * call more than once on a menu.
 228  *
 229  * m - Points to a menu created by menu_create().
 230  *
 231  * item_key - Points to a string that, when compared using strcmp, matches the
 232  * key for an existing item in the menu.
 233  *
 234  * Returns 1 if successful, -EINVAL if m is NULL, or -ENOENT if no item with a
 235  * key matching item_key is found.
 236  */
 237 int menu_default_set(struct menu *m, char *item_key)
 238 {
 239         struct menu_item *item;
 240
 241         if (!m)
 242                 return -EINVAL;
 243
 244         item = menu_item_by_key(m, item_key);
 245
 246         if (!item)
 247                 return -ENOENT;
 248
 249         m->default_item = item;
 250
 251         return 1;
 252 }
 253
 254 /*
 255  * menu_get_choice() - Returns the user's selected menu entry, or the default
 256  * if the menu is set to not prompt or the timeout expires. This is safe to
 257  * call more than once.
 258  *
 259  * m - Points to a menu created by menu_create().
 260  *
 261  * choice - Points to a location that will store a pointer to the selected
 262  * menu item. If no item is selected or there is an error, no value will be
 263  * written at the location it points to.
 264  *
 265  * Returns 1 if successful, -EINVAL if m or choice is NULL, -ENOENT if no
 266  * default has been set and the menu is set to not prompt or the timeout
 267  * expires, or -EINTR if the user exits the menu via ^c.
 268  */
 269 int menu_get_choice(struct menu *m, void **choice)
 270 {
 271         if (!m || !choice)
 272                 return -EINVAL;
 273
 274         if (!m->prompt)
 275                 return menu_default_choice(m, choice);
 276
 277         return menu_interactive_choice(m, choice);
 278 }
 279
 280 /*
 281  * menu_item_add() - Adds or replaces a menu item. Note that this replaces the
 282  * data of an item if it already exists, but doesn't change the order of the
 283  * item.
 284  *
 285  * m - Points to a menu created by menu_create().
 286  *
 287  * item_key - Points to a string that will uniquely identify the item.  The
 288  * string will be copied to internal storage, and is safe to discard after
 289  * passing to menu_item_add.
 290  *
 291  * item_data - An opaque pointer associated with an item. It is never
 292  * dereferenced internally, but will be passed to the item_data_print, and
 293  * will be returned from menu_get_choice if the menu item is selected.
 294  *
 295  * Returns 1 if successful, -EINVAL if m is NULL, or -ENOMEM if there is
 296  * insufficient memory to add the menu item.
 297  */
 298 int menu_item_add(struct menu *m, char *item_key, void *item_data)
 299 {
 300         struct menu_item *item;
 301
 302         if (!m)
 303                 return -EINVAL;
 304
 305         item = menu_item_by_key(m, item_key);
 306
 307         if (item) {
 308                 item->data = item_data;
 309                 return 1;
 310         }
 311
 312         item = malloc(sizeof *item);
 313         if (!item)
 314                 return -ENOMEM;
 315
 316         item->key = strdup(item_key);
 317
 318         if (!item->key) {
 319                 free(item);
 320                 return -ENOMEM;
 321         }
 322
 323         item->data = item_data;
 324
 325         list_add_tail(&item->list, &m->items);
 326
 327         return 1;
 328 }
 329
 330 /*
 331  * menu_create() - Creates a menu handle with default settings
 332  *
 333  * title - If not NULL, points to a string that will be displayed before the
 334  * list of menu items. It will be copied to internal storage, and is safe to
 335  * discard after passing to menu_create().
 336  *
 337  * timeout - A delay in seconds to wait for user input. If 0, timeout is
 338  * disabled, and the default choice will be returned unless prompt is 1.
 339  *
 340  * prompt - If 0, don't ask for user input unless there is an interrupted
 341  * timeout. If 1, the user will be prompted for input regardless of the value
 342  * of timeout.
 343  *
 344  * item_data_print - If not NULL, will be called for each item when the menu
 345  * is displayed, with the pointer to the item's data passed as the argument.
 346  * If NULL, each item's key will be printed instead.  Since an item's key is
 347  * what must be entered to select an item, the item_data_print function should
 348  * make it obvious what the key for each entry is.
 349  *
 350  * item_choice - If not NULL, will be called when asking the user to choose an
 351  * item. Returns a key string corresponding to the chosen item or NULL if
 352  * no item has been selected.
 353  *
 354  * item_choice_data - Will be passed as the argument to the item_choice function
 355  *
 356  * Returns a pointer to the menu if successful, or NULL if there is
 357  * insufficient memory available to create the menu.
 358  */
 359 struct menu *menu_create(char *title, int timeout, int prompt,
 360                                 void (*item_data_print)(void *),
 361                                 char *(*item_choice)(void *),
 362                                 void *item_choice_data)
 363 {
 364         struct menu *m;
 365
 366         m = malloc(sizeof *m);
 367
 368         if (!m)
 369                 return NULL;
 370
 371         m->default_item = NULL;
 372         m->prompt = prompt;
 373         m->timeout = timeout;
 374         m->item_data_print = item_data_print;
 375         m->item_choice = item_choice;
 376         m->item_choice_data = item_choice_data;
 377
 378         if (title) {
 379                 m->title = strdup(title);
 380                 if (!m->title) {
 381                         free(m);
 382                         return NULL;
 383                 }
 384         } else
 385                 m->title = NULL;
 386
 387
 388         INIT_LIST_HEAD(&m->items);
 389
 390         return m;
 391 }
 392
 393 /*
 394  * menu_destroy() - frees the memory used by a menu and its items.
 395  *
 396  * m - Points to a menu created by menu_create().
 397  *
 398  * Returns 1 if successful, or -EINVAL if m is NULL.
 399  */
 400 int menu_destroy(struct menu *m)
 401 {
 402         if (!m)
 403                 return -EINVAL;
 404
 405         menu_items_iter(m, menu_item_destroy, NULL);
 406
 407         if (m->title)
 408                 free(m->title);
 409
 410         free(m);
 411
 412         return 1;
 413 }