common/menu.c

   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         int timeout;
  47         char *title;
  48         int prompt;
  49         void (*item_data_print)(void *);
  50         struct list_head items;
  51 };
  52
  53 /*
  54  * An iterator function for menu items. callback will be called for each item
  55  * in m, with m, a pointer to the item, and extra being passed to callback. If
  56  * callback returns a value other than NULL, iteration stops and the value
  57  * return by callback is returned from menu_items_iter.  This allows it to be
  58  * used for search type operations. It is also safe for callback to remove the
  59  * item from the list of items.
  60  */
  61 static inline void *menu_items_iter(struct menu *m,
  62                 void *(*callback)(struct menu *, struct menu_item *, void *),
  63                 void *extra)
  64 {
  65         struct list_head *pos, *n;
  66         struct menu_item *item;
  67         void *ret;
  68
  69         list_for_each_safe(pos, n, &m->items) {
  70                 item = list_entry(pos, struct menu_item, list);
  71
  72                 ret = callback(m, item, extra);
  73
  74                 if (ret)
  75                         return ret;
  76         }
  77
  78         return NULL;
  79 }
  80
  81 /*
  82  * Print a menu_item. If the consumer provided an item_data_print function
  83  * when creating the menu, call it with a pointer to the item's private data.
  84  * Otherwise, print the key of the item.
  85  */
  86 static inline void *menu_item_print(struct menu *m,
  87                                 struct menu_item *item,
  88                                 void *extra)
  89 {
  90         if (!m->item_data_print)
  91                 printf("%s\n", item->key);
  92         else
  93                 m->item_data_print(item->data);
  94
  95         return NULL;
  96 }
  97
  98 /*
  99  * Free the memory used by a menu item. This includes the memory used by its
 100  * key.
 101  */
 102 static inline void *menu_item_destroy(struct menu *m,
 103                                 struct menu_item *item,
 104                                 void *extra)
 105 {
 106         if (item->key)
 107                 free(item->key);
 108
 109         free(item);
 110
 111         return NULL;
 112 }
 113
 114 /*
 115  * Display a menu so the user can make a choice of an item. First display its
 116  * title, if any, and then each item in the menu.
 117  */
 118 static inline void menu_display(struct menu *m)
 119 {
 120         if (m->title)
 121                 printf("%s:\n", m->title);
 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  * Wait for the user to hit a key according to the timeout set for the menu.
 163  * Returns 1 if the user hit a key, or 0 if the timeout expired.
 164  */
 165 static inline int menu_interrupted(struct menu *m)
 166 {
 167         if (!m->timeout)
 168                 return 0;
 169
 170         if (abortboot(m->timeout/10))
 171                 return 1;
 172
 173         return 0;
 174 }
 175
 176 /*
 177  * Checks whether or not the default menu item should be used without
 178  * prompting for a user choice. If the menu is set to always prompt, or the
 179  * user hits a key during the timeout period, return 0. Otherwise, return 1 to
 180  * indicate we should use the default menu item.
 181  */
 182 static inline int menu_use_default(struct menu *m)
 183 {
 184         return !m->prompt && !menu_interrupted(m);
 185 }
 186
 187 /*
 188  * Set *choice to point to the default item's data, if any default item was
 189  * set, and returns 1. If no default item was set, returns -ENOENT.
 190  */
 191 static inline int menu_default_choice(struct menu *m, void **choice)
 192 {
 193         if (m->default_item) {
 194                 *choice = m->default_item->data;
 195                 return 1;
 196         }
 197
 198         return -ENOENT;
 199 }
 200
 201 /*
 202  * Displays the menu and asks the user to choose an item. *choice will point
 203  * to the private data of the item the user chooses. The user makes a choice
 204  * by inputting a string matching the key of an item. Invalid choices will
 205  * cause the user to be prompted again, repeatedly, until the user makes a
 206  * valid choice. The user can exit the menu without making a choice via ^c.
 207  *
 208  * Returns 1 if the user made a choice, or -EINTR if they bail via ^c.
 209  */
 210 static inline int menu_interactive_choice(struct menu *m, void **choice)
 211 {
 212         char cbuf[CONFIG_SYS_CBSIZE];
 213         struct menu_item *choice_item = NULL;
 214         int readret;
 215
 216         while (!choice_item) {
 217                 cbuf[0] = '\0';
 218
 219                 menu_display(m);
 220
 221                 readret = readline_into_buffer("Enter choice: ", cbuf);
 222
 223                 if (readret >= 0) {
 224                         choice_item = menu_item_by_key(m, cbuf);
 225
 226                         if (!choice_item)
 227                                 printf("%s not found\n", cbuf);
 228                 } else {
 229                         printf("^C\n");
 230                         return -EINTR;
 231                 }
 232         }
 233
 234         *choice = choice_item->data;
 235
 236         return 1;
 237 }
 238
 239 /*
 240  * menu_default_set() - Sets the default choice for the menu. This is safe to
 241  * call more than once on a menu.
 242  *
 243  * m - Points to a menu created by menu_create().
 244  *
 245  * item_key - Points to a string that, when compared using strcmp, matches the
 246  * key for an existing item in the menu.
 247  *
 248  * Returns 1 if successful, -EINVAL if m is NULL, or -ENOENT if no item with a
 249  * key matching item_key is found.
 250  */
 251 int menu_default_set(struct menu *m, char *item_key)
 252 {
 253         struct menu_item *item;
 254
 255         if (!m)
 256                 return -EINVAL;
 257
 258         item = menu_item_by_key(m, item_key);
 259
 260         if (!item)
 261                 return -ENOENT;
 262
 263         m->default_item = item;
 264
 265         return 1;
 266 }
 267
 268 /*
 269  * menu_get_choice() - Returns the user's selected menu entry, or the default
 270  * if the menu is set to not prompt or the timeout expires. This is safe to
 271  * call more than once.
 272  *
 273  * m - Points to a menu created by menu_create().
 274  *
 275  * choice - Points to a location that will store a pointer to the selected
 276  * menu item. If no item is selected or there is an error, no value will be
 277  * written at the location it points to.
 278  *
 279  * Returns 1 if successful, -EINVAL if m or choice is NULL, -ENOENT if no
 280  * default has been set and the menu is set to not prompt or the timeout
 281  * expires, or -EINTR if the user exits the menu via ^c.
 282  */
 283 int menu_get_choice(struct menu *m, void **choice)
 284 {
 285         if (!m || !choice)
 286                 return -EINVAL;
 287
 288         if (menu_use_default(m))
 289                 return menu_default_choice(m, choice);
 290
 291         return menu_interactive_choice(m, choice);
 292 }
 293
 294 /*
 295  * menu_item_add() - Adds or replaces a menu item. Note that this replaces the
 296  * data of an item if it already exists, but doesn't change the order of the
 297  * item.
 298  *
 299  * m - Points to a menu created by menu_create().
 300  *
 301  * item_key - Points to a string that will uniquely identify the item.  The
 302  * string will be copied to internal storage, and is safe to discard after
 303  * passing to menu_item_add.
 304  *
 305  * item_data - An opaque pointer associated with an item. It is never
 306  * dereferenced internally, but will be passed to the item_data_print, and
 307  * will be returned from menu_get_choice if the menu item is selected.
 308  *
 309  * Returns 1 if successful, -EINVAL if m is NULL, or -ENOMEM if there is
 310  * insufficient memory to add the menu item.
 311  */
 312 int menu_item_add(struct menu *m, char *item_key, void *item_data)
 313 {
 314         struct menu_item *item;
 315
 316         if (!m)
 317                 return -EINVAL;
 318
 319         item = menu_item_by_key(m, item_key);
 320
 321         if (item) {
 322                 item->data = item_data;
 323                 return 1;
 324         }
 325
 326         item = malloc(sizeof *item);
 327         if (!item)
 328                 return -ENOMEM;
 329
 330         item->key = strdup(item_key);
 331
 332         if (!item->key) {
 333                 free(item);
 334                 return -ENOMEM;
 335         }
 336
 337         item->data = item_data;
 338
 339         list_add_tail(&item->list, &m->items);
 340
 341         return 1;
 342 }
 343
 344 /*
 345  * menu_create() - Creates a menu handle with default settings
 346  *
 347  * title - If not NULL, points to a string that will be displayed before the
 348  * list of menu items. It will be copied to internal storage, and is safe to
 349  * discard after passing to menu_create().
 350  *
 351  * timeout - A delay in seconds to wait for user input. If 0, timeout is
 352  * disabled, and the default choice will be returned unless prompt is 1.
 353  *
 354  * prompt - If 0, don't ask for user input unless there is an interrupted
 355  * timeout. If 1, the user will be prompted for input regardless of the value
 356  * of timeout.
 357  *
 358  * item_data_print - If not NULL, will be called for each item when the menu
 359  * is displayed, with the pointer to the item's data passed as the argument.
 360  * If NULL, each item's key will be printed instead.  Since an item's key is
 361  * what must be entered to select an item, the item_data_print function should
 362  * make it obvious what the key for each entry is.
 363  *
 364  * Returns a pointer to the menu if successful, or NULL if there is
 365  * insufficient memory available to create the menu.
 366  */
 367 struct menu *menu_create(char *title, int timeout, int prompt,
 368                                 void (*item_data_print)(void *))
 369 {
 370         struct menu *m;
 371
 372         m = malloc(sizeof *m);
 373
 374         if (!m)
 375                 return NULL;
 376
 377         m->default_item = NULL;
 378         m->prompt = prompt;
 379         m->timeout = timeout;
 380         m->item_data_print = item_data_print;
 381
 382         if (title) {
 383                 m->title = strdup(title);
 384                 if (!m->title) {
 385                         free(m);
 386                         return NULL;
 387                 }
 388         } else
 389                 m->title = NULL;
 390
 391
 392         INIT_LIST_HEAD(&m->items);
 393
 394         return m;
 395 }
 396
 397 /*
 398  * menu_destroy() - frees the memory used by a menu and its items.
 399  *
 400  * m - Points to a menu created by menu_create().
 401  *
 402  * Returns 1 if successful, or -EINVAL if m is NULL.
 403  */
 404 int menu_destroy(struct menu *m)
 405 {
 406         if (!m)
 407                 return -EINVAL;
 408
 409         menu_items_iter(m, menu_item_destroy, NULL);
 410
 411         if (m->title)
 412                 free(m->title);
 413
 414         free(m);
 415
 416         return 1;
 417 }