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         char *(*item_choice)(void *);
  51         void *item_choice_data;
  52         struct list_head items;
  53 };
  54
  55 /*
  56  * An iterator function for menu items. callback will be called for each item
  57  * in m, with m, a pointer to the item, and extra being passed to callback. If
  58  * callback returns a value other than NULL, iteration stops and the value
  59  * return by callback is returned from menu_items_iter.  This allows it to be
  60  * used for search type operations. It is also safe for callback to remove the
  61  * item from the list of items.
  62  */
  63 static inline void *menu_items_iter(struct menu *m,
  64                 void *(*callback)(struct menu *, struct menu_item *, void *),
  65                 void *extra)
  66 {
  67         struct list_head *pos, *n;
  68         struct menu_item *item;
  69         void *ret;
  70
  71         list_for_each_safe(pos, n, &m->items) {
  72                 item = list_entry(pos, struct menu_item, list);
  73
  74                 ret = callback(m, item, extra);
  75
  76                 if (ret)
  77                         return ret;
  78         }
  79
  80         return NULL;
  81 }
  82
  83 /*
  84  * Print a menu_item. If the consumer provided an item_data_print function
  85  * when creating the menu, call it with a pointer to the item's private data.
  86  * Otherwise, print the key of the item.
  87  */
  88 static inline void *menu_item_print(struct menu *m,
  89                                 struct menu_item *item,
  90                                 void *extra)
  91 {
  92         if (!m->item_data_print) {
  93                 puts(item->key);
  94                 putc('\n');
  95         } else {
  96                 m->item_data_print(item->data);
  97         }
  98
  99         return NULL;
 100 }
 101
 102 /*
 103  * Free the memory used by a menu item. This includes the memory used by its
 104  * key.
 105  */
 106 static inline void *menu_item_destroy(struct menu *m,
 107                                 struct menu_item *item,
 108                                 void *extra)
 109 {
 110         if (item->key)
 111                 free(item->key);
 112
 113         free(item);
 114
 115         return NULL;
 116 }
 117
 118 void __menu_display_statusline(struct menu *m)
 119 {
 120         return;
 121 }
 122 void menu_display_statusline(struct menu *m)
 123         __attribute__ ((weak, alias("__menu_display_statusline")));
 124
 125 /*
 126  * Display a menu so the user can make a choice of an item. First display its
 127  * title, if any, and then each item in the menu.
 128  */
 129 static inline void menu_display(struct menu *m)
 130 {
 131         if (m->title) {
 132                 puts(m->title);
 133                 putc('\n');
 134         }
 135         menu_display_statusline(m);
 136
 137         menu_items_iter(m, menu_item_print, NULL);
 138 }
 139
 140 /*
 141  * Check if an item's key matches a provided string, pointed to by extra. If
 142  * extra is NULL, an item with a NULL key will match. Otherwise, the item's
 143  * key has to match according to strcmp.
 144  *
 145  * This is called via menu_items_iter, so it returns a pointer to the item if
 146  * the key matches, and returns NULL otherwise.
 147  */
 148 static inline void *menu_item_key_match(struct menu *m,
 149                         struct menu_item *item, void *extra)
 150 {
 151         char *item_key = extra;
 152
 153         if (!item_key || !item->key) {
 154                 if (item_key == item->key)
 155                         return item;
 156
 157                 return NULL;
 158         }
 159
 160         if (strcmp(item->key, item_key) == 0)
 161                 return item;
 162
 163         return NULL;
 164 }
 165
 166 /*
 167  * Find the first item with a key matching item_key, if any exists.
 168  */
 169 static inline struct menu_item *menu_item_by_key(struct menu *m,
 170                                                         char *item_key)
 171 {
 172         return menu_items_iter(m, menu_item_key_match, item_key);
 173 }
 174
 175 /*
 176  * Set *choice to point to the default item's data, if any default item was
 177  * set, and returns 1. If no default item was set, returns -ENOENT.
 178  */
 179 int menu_default_choice(struct menu *m, void **choice)
 180 {
 181         if (m->default_item) {
 182                 *choice = m->default_item->data;
 183                 return 1;
 184         }
 185
 186         return -ENOENT;
 187 }
 188
 189 /*
 190  * Displays the menu and asks the user to choose an item. *choice will point
 191  * to the private data of the item the user chooses. The user makes a choice
 192  * by inputting a string matching the key of an item. Invalid choices will
 193  * cause the user to be prompted again, repeatedly, until the user makes a
 194  * valid choice. The user can exit the menu without making a choice via ^c.
 195  *
 196  * Returns 1 if the user made a choice, or -EINTR if they bail via ^c.
 197  */
 198 static inline int menu_interactive_choice(struct menu *m, void **choice)
 199 {
 200         char cbuf[CONFIG_SYS_CBSIZE];
 201         struct menu_item *choice_item = NULL;
 202         int readret;
 203
 204         while (!choice_item) {
 205                 cbuf[0] = '\0';
 206
 207                 menu_display(m);
 208
 209                 if (!m->item_choice) {
 210                         readret = readline_into_buffer("Enter choice: ", cbuf,
 211                                         m->timeout / 10);
 212
 213                         if (readret >= 0) {
 214                                 choice_item = menu_item_by_key(m, cbuf);
 215                                 if (!choice_item)
 216                                         printf("%s not found\n", cbuf);
 217                         } else {
 218                                 return menu_default_choice(m, choice);
 219                         }
 220                 } else {
 221                         char *key = m->item_choice(m->item_choice_data);
 222
 223                         if (key)
 224                                 choice_item = menu_item_by_key(m, key);
 225                 }
 226
 227                 if (!choice_item)
 228                         m->timeout = 0;
 229         }
 230
 231         *choice = choice_item->data;
 232
 233         return 1;
 234 }
 235
 236 /*
 237  * menu_default_set() - Sets the default choice for the menu. This is safe to
 238  * call more than once on a menu.
 239  *
 240  * m - Points to a menu created by menu_create().
 241  *
 242  * item_key - Points to a string that, when compared using strcmp, matches the
 243  * key for an existing item in the menu.
 244  *
 245  * Returns 1 if successful, -EINVAL if m is NULL, or -ENOENT if no item with a
 246  * key matching item_key is found.
 247  */
 248 int menu_default_set(struct menu *m, char *item_key)
 249 {
 250         struct menu_item *item;
 251
 252         if (!m)
 253                 return -EINVAL;
 254
 255         item = menu_item_by_key(m, item_key);
 256
 257         if (!item)
 258                 return -ENOENT;
 259
 260         m->default_item = item;
 261
 262         return 1;
 263 }
 264
 265 /*
 266  * menu_get_choice() - Returns the user's selected menu entry, or the default
 267  * if the menu is set to not prompt or the timeout expires. This is safe to
 268  * call more than once.
 269  *
 270  * m - Points to a menu created by menu_create().
 271  *
 272  * choice - Points to a location that will store a pointer to the selected
 273  * menu item. If no item is selected or there is an error, no value will be
 274  * written at the location it points to.
 275  *
 276  * Returns 1 if successful, -EINVAL if m or choice is NULL, -ENOENT if no
 277  * default has been set and the menu is set to not prompt or the timeout
 278  * expires, or -EINTR if the user exits the menu via ^c.
 279  */
 280 int menu_get_choice(struct menu *m, void **choice)
 281 {
 282         if (!m || !choice)
 283                 return -EINVAL;
 284
 285         if (!m->prompt)
 286                 return menu_default_choice(m, choice);
 287
 288         return menu_interactive_choice(m, choice);
 289 }
 290
 291 /*
 292  * menu_item_add() - Adds or replaces a menu item. Note that this replaces the
 293  * data of an item if it already exists, but doesn't change the order of the
 294  * item.
 295  *
 296  * m - Points to a menu created by menu_create().
 297  *
 298  * item_key - Points to a string that will uniquely identify the item.  The
 299  * string will be copied to internal storage, and is safe to discard after
 300  * passing to menu_item_add.
 301  *
 302  * item_data - An opaque pointer associated with an item. It is never
 303  * dereferenced internally, but will be passed to the item_data_print, and
 304  * will be returned from menu_get_choice if the menu item is selected.
 305  *
 306  * Returns 1 if successful, -EINVAL if m is NULL, or -ENOMEM if there is
 307  * insufficient memory to add the menu item.
 308  */
 309 int menu_item_add(struct menu *m, char *item_key, void *item_data)
 310 {
 311         struct menu_item *item;
 312
 313         if (!m)
 314                 return -EINVAL;
 315
 316         item = menu_item_by_key(m, item_key);
 317
 318         if (item) {
 319                 item->data = item_data;
 320                 return 1;
 321         }
 322
 323         item = malloc(sizeof *item);
 324         if (!item)
 325                 return -ENOMEM;
 326
 327         item->key = strdup(item_key);
 328
 329         if (!item->key) {
 330                 free(item);
 331                 return -ENOMEM;
 332         }
 333
 334         item->data = item_data;
 335
 336         list_add_tail(&item->list, &m->items);
 337
 338         return 1;
 339 }
 340
 341 /*
 342  * menu_create() - Creates a menu handle with default settings
 343  *
 344  * title - If not NULL, points to a string that will be displayed before the
 345  * list of menu items. It will be copied to internal storage, and is safe to
 346  * discard after passing to menu_create().
 347  *
 348  * timeout - A delay in seconds to wait for user input. If 0, timeout is
 349  * disabled, and the default choice will be returned unless prompt is 1.
 350  *
 351  * prompt - If 0, don't ask for user input unless there is an interrupted
 352  * timeout. If 1, the user will be prompted for input regardless of the value
 353  * of timeout.
 354  *
 355  * item_data_print - If not NULL, will be called for each item when the menu
 356  * is displayed, with the pointer to the item's data passed as the argument.
 357  * If NULL, each item's key will be printed instead.  Since an item's key is
 358  * what must be entered to select an item, the item_data_print function should
 359  * make it obvious what the key for each entry is.
 360  *
 361  * item_choice - If not NULL, will be called when asking the user to choose an
 362  * item. Returns a key string corresponding to the choosen item or NULL if
 363  * no item has been selected.
 364  *
 365  * item_choice_data - Will be passed as the argument to the item_choice function
 366  *
 367  * Returns a pointer to the menu if successful, or NULL if there is
 368  * insufficient memory available to create the menu.
 369  */
 370 struct menu *menu_create(char *title, int timeout, int prompt,
 371                                 void (*item_data_print)(void *),
 372                                 char *(*item_choice)(void *),
 373                                 void *item_choice_data)
 374 {
 375         struct menu *m;
 376
 377         m = malloc(sizeof *m);
 378
 379         if (!m)
 380                 return NULL;
 381
 382         m->default_item = NULL;
 383         m->prompt = prompt;
 384         m->timeout = timeout;
 385         m->item_data_print = item_data_print;
 386         m->item_choice = item_choice;
 387         m->item_choice_data = item_choice_data;
 388
 389         if (title) {
 390                 m->title = strdup(title);
 391                 if (!m->title) {
 392                         free(m);
 393                         return NULL;
 394                 }
 395         } else
 396                 m->title = NULL;
 397
 398
 399         INIT_LIST_HEAD(&m->items);
 400
 401         return m;
 402 }
 403
 404 /*
 405  * menu_destroy() - frees the memory used by a menu and its items.
 406  *
 407  * m - Points to a menu created by menu_create().
 408  *
 409  * Returns 1 if successful, or -EINVAL if m is NULL.
 410  */
 411 int menu_destroy(struct menu *m)
 412 {
 413         if (!m)
 414                 return -EINVAL;
 415
 416         menu_items_iter(m, menu_item_destroy, NULL);
 417
 418         if (m->title)
 419                 free(m->title);
 420
 421         free(m);
 422
 423         return 1;
 424 }