lib/blkid/tag.c

   1 /*
   2  * tag.c - allocation/initialization/free routines for tag structs
   3  *
   4  * Copyright (C) 2001 Andreas Dilger
   5  * Copyright (C) 2003 Theodore Ts'o
   6  *
   7  * %Begin-Header%
   8  * This file may be redistributed under the terms of the
   9  * GNU Lesser General Public License.
  10  * %End-Header%
  11  */
  12
  13 #include <stdlib.h>
  14 #include <string.h>
  15 #include <stdio.h>
  16
  17 #include "blkidP.h"
  18
  19 static blkid_tag blkid_new_tag(void)
  20 {
  21         blkid_tag tag;
  22
  23         if (!(tag = (blkid_tag) calloc(1, sizeof(struct blkid_struct_tag))))
  24                 return NULL;
  25
  26         INIT_LIST_HEAD(&tag->bit_tags);
  27         INIT_LIST_HEAD(&tag->bit_names);
  28
  29         return tag;
  30 }
  31
  32 void blkid_free_tag(blkid_tag tag)
  33 {
  34         if (!tag)
  35                 return;
  36
  37         DBG(DEBUG_TAG, printf("    freeing tag %s=%s\n", tag->bit_name,
  38                    tag->bit_val ? tag->bit_val : "(NULL)"));
  39         DEB_DUMP_TAG(DEBUG_TAG, tag);
  40
  41         list_del(&tag->bit_tags);       /* list of tags for this device */
  42         list_del(&tag->bit_names);      /* list of tags with this type */
  43
  44         if (tag->bit_name)
  45                 free(tag->bit_name);
  46         if (tag->bit_val)
  47                 free(tag->bit_val);
  48
  49         free(tag);
  50 }
  51
  52 /*
  53  * Find the desired tag on a device.  If value is NULL, then the
  54  * first such tag is returned, otherwise return only exact tag if found.
  55  */
  56 blkid_tag blkid_find_tag_dev(blkid_dev dev, const char *type)
  57 {
  58         struct list_head *p;
  59
  60         if (!dev || !type)
  61                 return NULL;
  62
  63         list_for_each(p, &dev->bid_tags) {
  64                 blkid_tag tmp = list_entry(p, struct blkid_struct_tag,
  65                                            bit_tags);
  66
  67                 if (!strcmp(tmp->bit_name, type))
  68                         return tmp;
  69         }
  70         return NULL;
  71 }
  72
  73 /*
  74  * Find the desired tag type in the cache.
  75  * We return the head tag for this tag type.
  76  */
  77 static blkid_tag blkid_find_head_cache(blkid_cache cache, const char *type)
  78 {
  79         blkid_tag head = NULL, tmp;
  80         struct list_head *p;
  81
  82         if (!cache || !type)
  83                 return NULL;
  84
  85         list_for_each(p, &cache->bic_tags) {
  86                 tmp = list_entry(p, struct blkid_struct_tag, bit_tags);
  87                 if (!strcmp(tmp->bit_name, type)) {
  88                         DBG(DEBUG_TAG,
  89                             printf("    found cache tag head %s\n", type));
  90                         head = tmp;
  91                         break;
  92                 }
  93         }
  94         return head;
  95 }
  96
  97 /*
  98  * Set a tag on an existing device.
  99  *
 100  * If value is NULL, then delete the tagsfrom the device.
 101  */
 102 int blkid_set_tag(blkid_dev dev, const char *name,
 103                   const char *value, const int vlength)
 104 {
 105         blkid_tag       t = 0, head = 0;
 106         char            *val = 0;
 107
 108         if (!dev || !name)
 109                 return -BLKID_ERR_PARAM;
 110
 111         if (!(val = blkid_strndup(value, vlength)) && value)
 112                 return -BLKID_ERR_MEM;
 113         t = blkid_find_tag_dev(dev, name);
 114         if (!value) {
 115                 if (t)
 116                         blkid_free_tag(t);
 117         } else if (t) {
 118                 if (!strcmp(t->bit_val, val)) {
 119                         /* Same thing, exit */
 120                         free(val);
 121                         return 0;
 122                 }
 123                 free(t->bit_val);
 124                 t->bit_val = val;
 125         } else {
 126                 /* Existing tag not present, add to device */
 127                 if (!(t = blkid_new_tag()))
 128                         goto errout;
 129                 t->bit_name = blkid_strdup(name);
 130                 t->bit_val = val;
 131                 t->bit_dev = dev;
 132
 133                 list_add_tail(&t->bit_tags, &dev->bid_tags);
 134
 135                 if (dev->bid_cache) {
 136                         head = blkid_find_head_cache(dev->bid_cache,
 137                                                      t->bit_name);
 138                         if (!head) {
 139                                 head = blkid_new_tag();
 140                                 if (!head)
 141                                         goto errout;
 142
 143                                 DBG(DEBUG_TAG,
 144                                     printf("    creating new cache tag head %s\n", name));
 145                                 head->bit_name = blkid_strdup(name);
 146                                 if (!head->bit_name)
 147                                         goto errout;
 148                                 list_add_tail(&head->bit_tags,
 149                                               &dev->bid_cache->bic_tags);
 150                         }
 151                         list_add_tail(&t->bit_names, &head->bit_names);
 152                 }
 153         }
 154
 155         /* Link common tags directly to the device struct */
 156         if (!strcmp(name, "TYPE"))
 157                 dev->bid_type = val;
 158         else if (!strcmp(name, "LABEL"))
 159                 dev->bid_label = val;
 160         else if (!strcmp(name, "UUID"))
 161                 dev->bid_uuid = val;
 162
 163         if (dev->bid_cache)
 164                 dev->bid_cache->bic_flags |= BLKID_BIC_FL_CHANGED;
 165         return 0;
 166
 167 errout:
 168         if (t)
 169                 blkid_free_tag(t);
 170         else if (val)
 171                 free(val);
 172         if (head)
 173                 blkid_free_tag(head);
 174         return -BLKID_ERR_MEM;
 175 }
 176
 177
 178 /*
 179  * Parse a "NAME=value" string.  This is slightly different than
 180  * parse_token, because that will end an unquoted value at a space, while
 181  * this will assume that an unquoted value is the rest of the token (e.g.
 182  * if we are passed an already quoted string from the command-line we don't
 183  * have to both quote and escape quote so that the quotes make it to
 184  * us).
 185  *
 186  * Returns 0 on success, and -1 on failure.
 187  */
 188 int blkid_parse_tag_string(const char *token, char **ret_type, char **ret_val)
 189 {
 190         char *name, *value, *cp;
 191
 192         DBG(DEBUG_TAG, printf("trying to parse '%s' as a tag\n", token));
 193
 194         if (!token || !(cp = strchr(token, '=')))
 195                 return -1;
 196
 197         name = blkid_strdup(token);
 198         if (!name)
 199                 return -1;
 200         value = name + (cp - token);
 201         *value++ = '\0';
 202         if (*value == '"' || *value == '\'') {
 203                 char c = *value++;
 204                 if (!(cp = strrchr(value, c)))
 205                         goto errout; /* missing closing quote */
 206                 *cp = '\0';
 207         }
 208         value = blkid_strdup(value);
 209         if (!value)
 210                 goto errout;
 211
 212         *ret_type = name;
 213         *ret_val = value;
 214
 215         return 0;
 216
 217 errout:
 218         free(name);
 219         return -1;
 220 }
 221
 222 /*
 223  * Tag iteration routines for the public libblkid interface.
 224  *
 225  * These routines do not expose the list.h implementation, which are a
 226  * contamination of the namespace, and which force us to reveal far, far
 227  * too much of our internal implemenation.  I'm not convinced I want
 228  * to keep list.h in the long term, anyway.  It's fine for kernel
 229  * programming, but performance is not the #1 priority for this
 230  * library, and I really don't like the tradeoff of type-safety for
 231  * performance for this application.  [tytso:20030125.2007EST]
 232  */
 233
 234 /*
 235  * This series of functions iterate over all tags in a device
 236  */
 237 #define TAG_ITERATE_MAGIC       0x01a5284c
 238
 239 struct blkid_struct_tag_iterate {
 240         int                     magic;
 241         blkid_dev               dev;
 242         struct list_head        *p;
 243 };
 244
 245 extern blkid_tag_iterate blkid_tag_iterate_begin(blkid_dev dev)
 246 {
 247         blkid_tag_iterate       iter;
 248
 249         iter = malloc(sizeof(struct blkid_struct_tag_iterate));
 250         if (iter) {
 251                 iter->magic = TAG_ITERATE_MAGIC;
 252                 iter->dev = dev;
 253                 iter->p = dev->bid_tags.next;
 254         }
 255         return (iter);
 256 }
 257
 258 /*
 259  * Return 0 on success, -1 on error
 260  */
 261 extern int blkid_tag_next(blkid_tag_iterate iter,
 262                           const char **type, const char **value)
 263 {
 264         blkid_tag tag;
 265
 266         *type = 0;
 267         *value = 0;
 268         if (!iter || iter->magic != TAG_ITERATE_MAGIC ||
 269             iter->p == &iter->dev->bid_tags)
 270                 return -1;
 271         tag = list_entry(iter->p, struct blkid_struct_tag, bit_tags);
 272         *type = tag->bit_name;
 273         *value = tag->bit_val;
 274         iter->p = iter->p->next;
 275         return 0;
 276 }
 277
 278 extern void blkid_tag_iterate_end(blkid_tag_iterate iter)
 279 {
 280         if (!iter || iter->magic != TAG_ITERATE_MAGIC)
 281                 return;
 282         iter->magic = 0;
 283         free(iter);
 284 }
 285
 286 /*
 287  * This function returns a device which matches a particular
 288  * type/value pair.  If there is more than one device that matches the
 289  * search specification, it returns the one with the highest priority
 290  * value.  This allows us to give preference to EVMS or LVM devices.
 291  *
 292  * XXX there should also be an interface which uses an iterator so we
 293  * can get all of the devices which match a type/value search parameter.
 294  */
 295 extern blkid_dev blkid_find_dev_with_tag(blkid_cache cache,
 296                                          const char *type,
 297                                          const char *value)
 298 {
 299         blkid_tag       head;
 300         blkid_dev       dev;
 301         int             pri;
 302         struct list_head *p;
 303
 304         if (!cache || !type || !value)
 305                 return NULL;
 306
 307         blkid_read_cache(cache);
 308
 309         DBG(DEBUG_TAG, printf("looking for %s=%s in cache\n", type, value));
 310
 311 try_again:
 312         pri = -1;
 313         dev = 0;
 314         head = blkid_find_head_cache(cache, type);
 315
 316         if (head) {
 317                 list_for_each(p, &head->bit_names) {
 318                         blkid_tag tmp = list_entry(p, struct blkid_struct_tag,
 319                                                    bit_names);
 320
 321                         if (!strcmp(tmp->bit_val, value) &&
 322                             tmp->bit_dev->bid_pri > pri) {
 323                                 dev = tmp->bit_dev;
 324                                 pri = dev->bid_pri;
 325                         }
 326                 }
 327         }
 328         if (dev && !(dev->bid_flags & BLKID_BID_FL_VERIFIED)) {
 329                 dev = blkid_verify_devname(cache, dev);
 330                 if (dev && (dev->bid_flags & BLKID_BID_FL_VERIFIED))
 331                         goto try_again;
 332         }
 333
 334         if (!dev && !(cache->bic_flags & BLKID_BIC_FL_PROBED)) {
 335                 blkid_probe_all(cache);
 336                 goto try_again;
 337         }
 338         return dev;
 339 }