src/libudev/libudev-list.c

   1 /*
   2  * libudev - interface to udev device information
   3  *
   4  * Copyright (C) 2008 Kay Sievers <kay.sievers@vrfy.org>
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <stdio.h>
  13 #include <stdlib.h>
  14 #include <stddef.h>
  15 #include <unistd.h>
  16 #include <errno.h>
  17 #include <string.h>
  18
  19 #include "libudev.h"
  20 #include "libudev-private.h"
  21
  22 /**
  23  * SECTION:libudev-list
  24  * @short_description: list operation
  25  *
  26  * Libudev list operations.
  27  */
  28
  29 /**
  30  * udev_list_entry:
  31  *
  32  * Opaque object representing one entry in a list. An entry contains
  33  * contains a name, and optionally a value.
  34  */
  35 struct udev_list_entry {
  36         struct udev_list_node node;
  37         struct udev_list *list;
  38         char *name;
  39         char *value;
  40         int num;
  41 };
  42
  43 /* the list's head points to itself if empty */
  44 void udev_list_node_init(struct udev_list_node *list)
  45 {
  46         list->next = list;
  47         list->prev = list;
  48 }
  49
  50 int udev_list_node_is_empty(struct udev_list_node *list)
  51 {
  52         return list->next == list;
  53 }
  54
  55 static void udev_list_node_insert_between(struct udev_list_node *new,
  56                                           struct udev_list_node *prev,
  57                                           struct udev_list_node *next)
  58 {
  59         next->prev = new;
  60         new->next = next;
  61         new->prev = prev;
  62         prev->next = new;
  63 }
  64
  65 void udev_list_node_append(struct udev_list_node *new, struct udev_list_node *list)
  66 {
  67         udev_list_node_insert_between(new, list->prev, list);
  68 }
  69
  70 void udev_list_node_remove(struct udev_list_node *entry)
  71 {
  72         struct udev_list_node *prev = entry->prev;
  73         struct udev_list_node *next = entry->next;
  74
  75         next->prev = prev;
  76         prev->next = next;
  77
  78         entry->prev = NULL;
  79         entry->next = NULL;
  80 }
  81
  82 /* return list entry which embeds this node */
  83 static struct udev_list_entry *list_node_to_entry(struct udev_list_node *node)
  84 {
  85         char *list;
  86
  87         list = (char *)node;
  88         list -= offsetof(struct udev_list_entry, node);
  89         return (struct udev_list_entry *)list;
  90 }
  91
  92 void udev_list_init(struct udev *udev, struct udev_list *list, bool unique)
  93 {
  94         memset(list, 0x00, sizeof(struct udev_list));
  95         list->udev = udev;
  96         list->unique = unique;
  97         udev_list_node_init(&list->node);
  98 }
  99
 100 /* insert entry into a list as the last element  */
 101 void udev_list_entry_append(struct udev_list_entry *new, struct udev_list *list)
 102 {
 103         /* inserting before the list head make the node the last node in the list */
 104         udev_list_node_insert_between(&new->node, list->node.prev, &list->node);
 105         new->list = list;
 106 }
 107
 108 /* insert entry into a list, before a given existing entry */
 109 void udev_list_entry_insert_before(struct udev_list_entry *new, struct udev_list_entry *entry)
 110 {
 111         udev_list_node_insert_between(&new->node, entry->node.prev, &entry->node);
 112         new->list = entry->list;
 113 }
 114
 115 /* binary search in sorted array */
 116 static int list_search(struct udev_list *list, const char *name)
 117 {
 118         unsigned int first, last;
 119
 120         first = 0;
 121         last = list->entries_cur;
 122         while (first < last) {
 123                 unsigned int i;
 124                 int cmp;
 125
 126                 i = (first + last)/2;
 127                 cmp = strcmp(name, list->entries[i]->name);
 128                 if (cmp < 0)
 129                         last = i;
 130                 else if (cmp > 0)
 131                         first = i+1;
 132                 else
 133                         return i;
 134         }
 135
 136         /* not found, return negative insertion-index+1 */
 137         return -(first+1);
 138 }
 139
 140 struct udev_list_entry *udev_list_entry_add(struct udev_list *list, const char *name, const char *value)
 141 {
 142         struct udev_list_entry *entry;
 143         int i = 0;
 144
 145         if (list->unique) {
 146                 /* lookup existing name or insertion-index */
 147                 i = list_search(list, name);
 148                 if (i >= 0) {
 149                         entry = list->entries[i];
 150
 151                         free(entry->value);
 152                         if (value == NULL) {
 153                                 entry->value = NULL;
 154                                 return entry;
 155                         }
 156                         entry->value = strdup(value);
 157                         if (entry->value == NULL)
 158                                 return NULL;
 159                         return entry;
 160                 }
 161         }
 162
 163         /* add new name */
 164         entry = calloc(1, sizeof(struct udev_list_entry));
 165         if (entry == NULL)
 166                 return NULL;
 167         entry->name = strdup(name);
 168         if (entry->name == NULL) {
 169                 free(entry);
 170                 return NULL;
 171         }
 172         if (value != NULL) {
 173                 entry->value = strdup(value);
 174                 if (entry->value == NULL) {
 175                         free(entry->name);
 176                         free(entry);
 177                         return NULL;
 178                 }
 179         }
 180
 181         if (list->unique) {
 182                 /* allocate or enlarge sorted array if needed */
 183                 if (list->entries_cur >= list->entries_max) {
 184                         unsigned int add;
 185
 186                         add = list->entries_max;
 187                         if (add < 1)
 188                                 add = 64;
 189                         list->entries = realloc(list->entries, (list->entries_max + add) * sizeof(struct udev_list_entry *));
 190                         if (list->entries == NULL) {
 191                                 free(entry->name);
 192                                 free(entry->value);
 193                                 return NULL;
 194                         }
 195                         list->entries_max += add;
 196                 }
 197
 198                 /* the negative i returned the insertion index */
 199                 i = (-i)-1;
 200
 201                 /* insert into sorted list */
 202                 if ((unsigned int)i < list->entries_cur)
 203                         udev_list_entry_insert_before(entry, list->entries[i]);
 204                 else
 205                         udev_list_entry_append(entry, list);
 206
 207                 /* insert into sorted array */
 208                 memmove(&list->entries[i+1], &list->entries[i],
 209                         (list->entries_cur - i) * sizeof(struct udev_list_entry *));
 210                 list->entries[i] = entry;
 211                 list->entries_cur++;
 212         } else {
 213                 udev_list_entry_append(entry, list);
 214         }
 215
 216         return entry;
 217 }
 218
 219 void udev_list_entry_delete(struct udev_list_entry *entry)
 220 {
 221         if (entry->list->entries != NULL) {
 222                 int i;
 223                 struct udev_list *list = entry->list;
 224
 225                 /* remove entry from sorted array */
 226                 i = list_search(list, entry->name);
 227                 if (i >= 0) {
 228                         memmove(&list->entries[i], &list->entries[i+1],
 229                                 ((list->entries_cur-1) - i) * sizeof(struct udev_list_entry *));
 230                         list->entries_cur--;
 231                 }
 232         }
 233
 234         udev_list_node_remove(&entry->node);
 235         free(entry->name);
 236         free(entry->value);
 237         free(entry);
 238 }
 239
 240 void udev_list_cleanup(struct udev_list *list)
 241 {
 242         struct udev_list_entry *entry_loop;
 243         struct udev_list_entry *entry_tmp;
 244
 245         free(list->entries);
 246         list->entries = NULL;
 247         list->entries_cur = 0;
 248         list->entries_max = 0;
 249         udev_list_entry_foreach_safe(entry_loop, entry_tmp, udev_list_get_entry(list))
 250                 udev_list_entry_delete(entry_loop);
 251 }
 252
 253 struct udev_list_entry *udev_list_get_entry(struct udev_list *list)
 254 {
 255         if (udev_list_node_is_empty(&list->node))
 256                 return NULL;
 257         return list_node_to_entry(list->node.next);
 258 }
 259
 260 /**
 261  * udev_list_entry_get_next:
 262  * @list_entry: current entry
 263  *
 264  * Get the next entry from the list.
 265  *
 266  * Returns: udev_list_entry, #NULL if no more entries are available.
 267  */
 268 _public_ struct udev_list_entry *udev_list_entry_get_next(struct udev_list_entry *list_entry)
 269 {
 270         struct udev_list_node *next;
 271
 272         if (list_entry == NULL)
 273                 return NULL;
 274         next = list_entry->node.next;
 275         /* empty list or no more entries */
 276         if (next == &list_entry->list->node)
 277                 return NULL;
 278         return list_node_to_entry(next);
 279 }
 280
 281 /**
 282  * udev_list_entry_get_by_name:
 283  * @list_entry: current entry
 284  * @name: name string to match
 285  *
 286  * Lookup an entry in the list with a certain name.
 287  *
 288  * Returns: udev_list_entry, #NULL if no matching entry is found.
 289  */
 290 _public_ struct udev_list_entry *udev_list_entry_get_by_name(struct udev_list_entry *list_entry, const char *name)
 291 {
 292         int i;
 293
 294         if (list_entry == NULL)
 295                 return NULL;
 296
 297         if (!list_entry->list->unique)
 298                 return NULL;
 299
 300         i = list_search(list_entry->list, name);
 301         if (i < 0)
 302                 return NULL;
 303         return list_entry->list->entries[i];
 304 }
 305
 306 /**
 307  * udev_list_entry_get_name:
 308  * @list_entry: current entry
 309  *
 310  * Get the name of a list entry.
 311  *
 312  * Returns: the name string of this entry.
 313  */
 314 _public_ const char *udev_list_entry_get_name(struct udev_list_entry *list_entry)
 315 {
 316         if (list_entry == NULL)
 317                 return NULL;
 318         return list_entry->name;
 319 }
 320
 321 /**
 322  * udev_list_entry_get_value:
 323  * @list_entry: current entry
 324  *
 325  * Get the value of list entry.
 326  *
 327  * Returns: the value string of this entry.
 328  */
 329 _public_ const char *udev_list_entry_get_value(struct udev_list_entry *list_entry)
 330 {
 331         if (list_entry == NULL)
 332                 return NULL;
 333         return list_entry->value;
 334 }
 335
 336 int udev_list_entry_get_num(struct udev_list_entry *list_entry)
 337 {
 338         if (list_entry == NULL)
 339                 return -EINVAL;
 340         return list_entry->num;
 341 }
 342
 343 void udev_list_entry_set_num(struct udev_list_entry *list_entry, int num)
 344 {
 345         if (list_entry == NULL)
 346                 return;
 347         list_entry->num = num;
 348 }