src/udev/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                         dbg(list->udev, "'%s' is already in the list\n", name);
 152                         free(entry->value);
 153                         if (value == NULL) {
 154                                 entry->value = NULL;
 155                                 dbg(list->udev, "'%s' value unset\n", name);
 156                                 return entry;
 157                         }
 158                         entry->value = strdup(value);
 159                         if (entry->value == NULL)
 160                                 return NULL;
 161                         dbg(list->udev, "'%s' value replaced with '%s'\n", name, value);
 162                         return entry;
 163                 }
 164         }
 165
 166         /* add new name */
 167         entry = calloc(1, sizeof(struct udev_list_entry));
 168         if (entry == NULL)
 169                 return NULL;
 170         entry->name = strdup(name);
 171         if (entry->name == NULL) {
 172                 free(entry);
 173                 return NULL;
 174         }
 175         if (value != NULL) {
 176                 entry->value = strdup(value);
 177                 if (entry->value == NULL) {
 178                         free(entry->name);
 179                         free(entry);
 180                         return NULL;
 181                 }
 182         }
 183
 184         if (list->unique) {
 185                 /* allocate or enlarge sorted array if needed */
 186                 if (list->entries_cur >= list->entries_max) {
 187                         unsigned int add;
 188
 189                         add = list->entries_max;
 190                         if (add < 1)
 191                                 add = 64;
 192                         list->entries = realloc(list->entries, (list->entries_max + add) * sizeof(struct udev_list_entry *));
 193                         if (list->entries == NULL) {
 194                                 free(entry->name);
 195                                 free(entry->value);
 196                                 return NULL;
 197                         }
 198                         list->entries_max += add;
 199                 }
 200
 201                 /* the negative i returned the insertion index */
 202                 i = (-i)-1;
 203
 204                 /* insert into sorted list */
 205                 if ((unsigned int)i < list->entries_cur)
 206                         udev_list_entry_insert_before(entry, list->entries[i]);
 207                 else
 208                         udev_list_entry_append(entry, list);
 209
 210                 /* insert into sorted array */
 211                 memmove(&list->entries[i+1], &list->entries[i],
 212                         (list->entries_cur - i) * sizeof(struct udev_list_entry *));
 213                 list->entries[i] = entry;
 214                 list->entries_cur++;
 215         } else {
 216                 udev_list_entry_append(entry, list);
 217         }
 218
 219         dbg(list->udev, "'%s=%s' added\n", entry->name, entry->value);
 220         return entry;
 221 }
 222
 223 void udev_list_entry_delete(struct udev_list_entry *entry)
 224 {
 225         if (entry->list->entries != NULL) {
 226                 int i;
 227                 struct udev_list *list = entry->list;
 228
 229                 /* remove entry from sorted array */
 230                 i = list_search(list, entry->name);
 231                 if (i >= 0) {
 232                         memmove(&list->entries[i], &list->entries[i+1],
 233                                 ((list->entries_cur-1) - i) * sizeof(struct udev_list_entry *));
 234                         list->entries_cur--;
 235                 }
 236         }
 237
 238         udev_list_node_remove(&entry->node);
 239         free(entry->name);
 240         free(entry->value);
 241         free(entry);
 242 }
 243
 244 void udev_list_cleanup(struct udev_list *list)
 245 {
 246         struct udev_list_entry *entry_loop;
 247         struct udev_list_entry *entry_tmp;
 248
 249         free(list->entries);
 250         list->entries = NULL;
 251         list->entries_cur = 0;
 252         list->entries_max = 0;
 253         udev_list_entry_foreach_safe(entry_loop, entry_tmp, udev_list_get_entry(list))
 254                 udev_list_entry_delete(entry_loop);
 255 }
 256
 257 struct udev_list_entry *udev_list_get_entry(struct udev_list *list)
 258 {
 259         if (udev_list_node_is_empty(&list->node))
 260                 return NULL;
 261         return list_node_to_entry(list->node.next);
 262 }
 263
 264 /**
 265  * udev_list_entry_get_next:
 266  * @list_entry: current entry
 267  *
 268  * Returns: the next entry from the list, #NULL is no more entries are found.
 269  */
 270 UDEV_EXPORT struct udev_list_entry *udev_list_entry_get_next(struct udev_list_entry *list_entry)
 271 {
 272         struct udev_list_node *next;
 273
 274         if (list_entry == NULL)
 275                 return NULL;
 276         next = list_entry->node.next;
 277         /* empty list or no more entries */
 278         if (next == &list_entry->list->node)
 279                 return NULL;
 280         return list_node_to_entry(next);
 281 }
 282
 283 /**
 284  * udev_list_entry_get_by_name:
 285  * @list_entry: current entry
 286  * @name: name string to match
 287  *
 288  * Returns: the entry where @name matched, #NULL if no matching entry is found.
 289  */
 290 UDEV_EXPORT 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  * Returns: the name string of this entry.
 311  */
 312 UDEV_EXPORT const char *udev_list_entry_get_name(struct udev_list_entry *list_entry)
 313 {
 314         if (list_entry == NULL)
 315                 return NULL;
 316         return list_entry->name;
 317 }
 318
 319 /**
 320  * udev_list_entry_get_value:
 321  * @list_entry: current entry
 322  *
 323  * Returns: the value string of this entry.
 324  */
 325 UDEV_EXPORT const char *udev_list_entry_get_value(struct udev_list_entry *list_entry)
 326 {
 327         if (list_entry == NULL)
 328                 return NULL;
 329         return list_entry->value;
 330 }
 331
 332 int udev_list_entry_get_num(struct udev_list_entry *list_entry)
 333 {
 334         if (list_entry == NULL)
 335                 return -EINVAL;
 336         return list_entry->num;
 337 }
 338
 339 void udev_list_entry_set_num(struct udev_list_entry *list_entry, int num)
 340 {
 341         if (list_entry == NULL)
 342                 return;
 343         list_entry->num = num;
 344 }