libudev/libudev.c

   1 /*
   2  * libudev - interface to udev device information
   3  *
   4  * Copyright (C) 2008-2010 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 <stdarg.h>
  16 #include <unistd.h>
  17 #include <errno.h>
  18 #include <string.h>
  19 #include <ctype.h>
  20 #include <time.h>
  21
  22 #include "libudev.h"
  23 #include "libudev-private.h"
  24
  25 /**
  26  * SECTION:libudev
  27  * @short_description: libudev context
  28  *
  29  * The context contains the default values read from the udev config file,
  30  * and is passed to all library operations.
  31  */
  32
  33 /**
  34  * udev:
  35  *
  36  * Opaque object representing the library context.
  37  */
  38 struct udev {
  39         int refcount;
  40         void (*log_fn)(struct udev *udev,
  41                        int priority, const char *file, int line, const char *fn,
  42                        const char *format, va_list args);
  43         void *userdata;
  44         char *sys_path;
  45         char *dev_path;
  46         char *rules_path[4];
  47         unsigned long long rules_path_ts[4];
  48         int rules_path_count;
  49         char *run_path;
  50         struct udev_list properties_list;
  51         int log_priority;
  52 };
  53
  54 void udev_log(struct udev *udev,
  55               int priority, const char *file, int line, const char *fn,
  56               const char *format, ...)
  57 {
  58         va_list args;
  59
  60         va_start(args, format);
  61         udev->log_fn(udev, priority, file, line, fn, format, args);
  62         va_end(args);
  63 }
  64
  65 static void log_stderr(struct udev *udev,
  66                        int priority, const char *file, int line, const char *fn,
  67                        const char *format, va_list args)
  68 {
  69         fprintf(stderr, "libudev: %s: ", fn);
  70         vfprintf(stderr, format, args);
  71 }
  72
  73 /**
  74  * udev_get_userdata:
  75  * @udev: udev library context
  76  *
  77  * Retrieve stored data pointer from library context. This might be useful
  78  * to access from callbacks like a custom logging function.
  79  *
  80  * Returns: stored userdata
  81  **/
  82 UDEV_EXPORT void *udev_get_userdata(struct udev *udev)
  83 {
  84         if (udev == NULL)
  85                 return NULL;
  86         return udev->userdata;
  87 }
  88
  89 /**
  90  * udev_set_userdata:
  91  * @udev: udev library context
  92  * @userdata: data pointer
  93  *
  94  * Store custom @userdata in the library context.
  95  **/
  96 UDEV_EXPORT void udev_set_userdata(struct udev *udev, void *userdata)
  97 {
  98         if (udev == NULL)
  99                 return;
 100         udev->userdata = userdata;
 101 }
 102
 103 static char *set_value(char **s, const char *v)
 104 {
 105         free(*s);
 106         *s = strdup(v);
 107         util_remove_trailing_chars(*s, '/');
 108         return *s;
 109 }
 110
 111 /**
 112  * udev_new:
 113  *
 114  * Create udev library context. This reads the udev configuration
 115  * file, and fills in the default values.
 116  *
 117  * The initial refcount is 1, and needs to be decremented to
 118  * release the resources of the udev library context.
 119  *
 120  * Returns: a new udev library context
 121  **/
 122 UDEV_EXPORT struct udev *udev_new(void)
 123 {
 124         struct udev *udev;
 125         const char *env;
 126         char *config_file = NULL;
 127         FILE *f;
 128
 129         udev = calloc(1, sizeof(struct udev));
 130         if (udev == NULL)
 131                 return NULL;
 132         udev->refcount = 1;
 133         udev->log_fn = log_stderr;
 134         udev->log_priority = LOG_ERR;
 135         udev_list_init(udev, &udev->properties_list, true);
 136
 137         /* custom config file */
 138         env = getenv("UDEV_CONFIG_FILE");
 139         if (env != NULL) {
 140                 if (set_value(&config_file, env) == NULL)
 141                         goto err;
 142                 udev_add_property(udev, "UDEV_CONFIG_FILE", config_file);
 143         }
 144
 145         /* default config file */
 146         if (config_file == NULL)
 147                 config_file = strdup(SYSCONFDIR "/udev/udev.conf");
 148         if (config_file == NULL)
 149                 goto err;
 150
 151         f = fopen(config_file, "re");
 152         if (f != NULL) {
 153                 char line[UTIL_LINE_SIZE];
 154                 int line_nr = 0;
 155
 156                 while (fgets(line, sizeof(line), f)) {
 157                         size_t len;
 158                         char *key;
 159                         char *val;
 160
 161                         line_nr++;
 162
 163                         /* find key */
 164                         key = line;
 165                         while (isspace(key[0]))
 166                                 key++;
 167
 168                         /* comment or empty line */
 169                         if (key[0] == '#' || key[0] == '\0')
 170                                 continue;
 171
 172                         /* split key/value */
 173                         val = strchr(key, '=');
 174                         if (val == NULL) {
 175                                 err(udev, "missing <key>=<value> in '%s'[%i], skip line\n", config_file, line_nr);
 176                                 continue;
 177                         }
 178                         val[0] = '\0';
 179                         val++;
 180
 181                         /* find value */
 182                         while (isspace(val[0]))
 183                                 val++;
 184
 185                         /* terminate key */
 186                         len = strlen(key);
 187                         if (len == 0)
 188                                 continue;
 189                         while (isspace(key[len-1]))
 190                                 len--;
 191                         key[len] = '\0';
 192
 193                         /* terminate value */
 194                         len = strlen(val);
 195                         if (len == 0)
 196                                 continue;
 197                         while (isspace(val[len-1]))
 198                                 len--;
 199                         val[len] = '\0';
 200
 201                         if (len == 0)
 202                                 continue;
 203
 204                         /* unquote */
 205                         if (val[0] == '"' || val[0] == '\'') {
 206                                 if (val[len-1] != val[0]) {
 207                                         err(udev, "inconsistent quoting in '%s'[%i], skip line\n", config_file, line_nr);
 208                                         continue;
 209                                 }
 210                                 val[len-1] = '\0';
 211                                 val++;
 212                         }
 213
 214                         if (strcmp(key, "udev_log") == 0) {
 215                                 udev_set_log_priority(udev, util_log_priority(val));
 216                                 continue;
 217                         }
 218                         if (strcmp(key, "udev_root") == 0) {
 219                                 set_value(&udev->dev_path, val);
 220                                 continue;
 221                         }
 222                         if (strcmp(key, "udev_run") == 0) {
 223                                 set_value(&udev->run_path, val);
 224                                 continue;
 225                         }
 226                         if (strcmp(key, "udev_rules") == 0) {
 227                                 set_value(&udev->rules_path[0], val);
 228                                 udev->rules_path_count = 1;
 229                                 continue;
 230                         }
 231                 }
 232                 fclose(f);
 233         }
 234
 235         /* environment overwrites config */
 236         env = getenv("UDEV_LOG");
 237         if (env != NULL)
 238                 udev_set_log_priority(udev, util_log_priority(env));
 239
 240         env = getenv("UDEV_ROOT");
 241         if (env != NULL) {
 242                 set_value(&udev->dev_path, env);
 243                 udev_add_property(udev, "UDEV_ROOT", udev->dev_path);
 244         }
 245
 246         env = getenv("SYSFS_PATH");
 247         if (env != NULL) {
 248                 set_value(&udev->sys_path, env);
 249                 udev_add_property(udev, "SYSFS_PATH", udev->sys_path);
 250         }
 251
 252         /* set defaults */
 253         if (udev->dev_path == NULL)
 254                 if (set_value(&udev->dev_path, "/dev") == NULL)
 255                         goto err;
 256
 257         if (udev->sys_path == NULL)
 258                 if (set_value(&udev->sys_path, "/sys") == NULL)
 259                         goto err;
 260
 261         if (udev->run_path == NULL)
 262                 if (set_value(&udev->run_path, "/run/udev") == NULL)
 263                         goto err;
 264
 265         if (udev->rules_path[0] == NULL) {
 266                 /* /usr/lib/udev -- system rules */
 267                 udev->rules_path[0] = strdup(LIBEXECDIR "/rules.d");
 268                 if (!udev->rules_path[0])
 269                         goto err;
 270
 271                 /* /etc/udev -- local administration rules */
 272                 udev->rules_path[1] = strdup(SYSCONFDIR "/udev/rules.d");
 273                 if (!udev->rules_path[1])
 274                         goto err;
 275
 276                 /* /run/udev -- runtime rules */
 277                 if (asprintf(&udev->rules_path[2], "%s/rules.d", udev->run_path) < 0)
 278                         goto err;
 279
 280                 udev->rules_path_count = 3;
 281         }
 282
 283         dbg(udev, "context %p created\n", udev);
 284         dbg(udev, "log_priority=%d\n", udev->log_priority);
 285         dbg(udev, "config_file='%s'\n", config_file);
 286         dbg(udev, "dev_path='%s'\n", udev->dev_path);
 287         dbg(udev, "sys_path='%s'\n", udev->sys_path);
 288         dbg(udev, "run_path='%s'\n", udev->run_path);
 289         dbg(udev, "rules_path='%s':'%s':'%s'\n", udev->rules_path[0], udev->rules_path[1], udev->rules_path[2]);
 290         free(config_file);
 291         return udev;
 292 err:
 293         free(config_file);
 294         err(udev, "context creation failed\n");
 295         udev_unref(udev);
 296         return NULL;
 297 }
 298
 299 /**
 300  * udev_ref:
 301  * @udev: udev library context
 302  *
 303  * Take a reference of the udev library context.
 304  *
 305  * Returns: the passed udev library context
 306  **/
 307 UDEV_EXPORT struct udev *udev_ref(struct udev *udev)
 308 {
 309         if (udev == NULL)
 310                 return NULL;
 311         udev->refcount++;
 312         return udev;
 313 }
 314
 315 /**
 316  * udev_unref:
 317  * @udev: udev library context
 318  *
 319  * Drop a reference of the udev library context. If the refcount
 320  * reaches zero, the resources of the context will be released.
 321  *
 322  **/
 323 UDEV_EXPORT void udev_unref(struct udev *udev)
 324 {
 325         if (udev == NULL)
 326                 return;
 327         udev->refcount--;
 328         if (udev->refcount > 0)
 329                 return;
 330         udev_list_cleanup(&udev->properties_list);
 331         free(udev->dev_path);
 332         free(udev->sys_path);
 333         free(udev->rules_path[0]);
 334         free(udev->rules_path[1]);
 335         free(udev->rules_path[2]);
 336         free(udev->run_path);
 337         dbg(udev, "context %p released\n", udev);
 338         free(udev);
 339 }
 340
 341 /**
 342  * udev_set_log_fn:
 343  * @udev: udev library context
 344  * @log_fn: function to be called for logging messages
 345  *
 346  * The built-in logging writes to stderr. It can be
 347  * overridden by a custom function, to plug log messages
 348  * into the users' logging functionality.
 349  *
 350  **/
 351 UDEV_EXPORT void udev_set_log_fn(struct udev *udev,
 352                      void (*log_fn)(struct udev *udev,
 353                                     int priority, const char *file, int line, const char *fn,
 354                                     const char *format, va_list args))
 355 {
 356         udev->log_fn = log_fn;
 357         info(udev, "custom logging function %p registered\n", log_fn);
 358 }
 359
 360 /**
 361  * udev_get_log_priority:
 362  * @udev: udev library context
 363  *
 364  * The initial logging priority is read from the udev config file
 365  * at startup.
 366  *
 367  * Returns: the current logging priority
 368  **/
 369 UDEV_EXPORT int udev_get_log_priority(struct udev *udev)
 370 {
 371         return udev->log_priority;
 372 }
 373
 374 /**
 375  * udev_set_log_priority:
 376  * @udev: udev library context
 377  * @priority: the new logging priority
 378  *
 379  * Set the current logging priority. The value controls which messages
 380  * are logged.
 381  **/
 382 UDEV_EXPORT void udev_set_log_priority(struct udev *udev, int priority)
 383 {
 384         char num[32];
 385
 386         udev->log_priority = priority;
 387         snprintf(num, sizeof(num), "%u", udev->log_priority);
 388         udev_add_property(udev, "UDEV_LOG", num);
 389 }
 390
 391 int udev_get_rules_path(struct udev *udev, char **path[], unsigned long long *stamp_usec[])
 392 {
 393         *path = udev->rules_path;
 394         if (stamp_usec)
 395                 *stamp_usec = udev->rules_path_ts;
 396         return udev->rules_path_count;
 397 }
 398
 399 /**
 400  * udev_get_sys_path:
 401  * @udev: udev library context
 402  *
 403  * Retrieve the sysfs mount point. The default is "/sys". For
 404  * testing purposes, it can be overridden with the environment
 405  * variable SYSFS_PATH.
 406  *
 407  * Returns: the sys mount point
 408  **/
 409 UDEV_EXPORT const char *udev_get_sys_path(struct udev *udev)
 410 {
 411         if (udev == NULL)
 412                 return NULL;
 413         return udev->sys_path;
 414 }
 415
 416 /**
 417  * udev_get_dev_path:
 418  * @udev: udev library context
 419  *
 420  * Retrieve the device directory path. The default value is "/dev",
 421  * the actual value may be overridden in the udev configuration
 422  * file.
 423  *
 424  * Returns: the device directory path
 425  **/
 426 UDEV_EXPORT const char *udev_get_dev_path(struct udev *udev)
 427 {
 428         if (udev == NULL)
 429                 return NULL;
 430         return udev->dev_path;
 431 }
 432
 433 /**
 434  * udev_get_run_path:
 435  * @udev: udev library context
 436  *
 437  * Retrieve the udev runtime directory path. The default is "/run/udev".
 438  *
 439  * Returns: the runtime directory path
 440  **/
 441 UDEV_EXPORT const char *udev_get_run_path(struct udev *udev)
 442 {
 443         if (udev == NULL)
 444                 return NULL;
 445         return udev->run_path;
 446 }
 447
 448 struct udev_list_entry *udev_add_property(struct udev *udev, const char *key, const char *value)
 449 {
 450         if (value == NULL) {
 451                 struct udev_list_entry *list_entry;
 452
 453                 list_entry = udev_get_properties_list_entry(udev);
 454                 list_entry = udev_list_entry_get_by_name(list_entry, key);
 455                 if (list_entry != NULL)
 456                         udev_list_entry_delete(list_entry);
 457                 return NULL;
 458         }
 459         return udev_list_entry_add(&udev->properties_list, key, value);
 460 }
 461
 462 struct udev_list_entry *udev_get_properties_list_entry(struct udev *udev)
 463 {
 464         return udev_list_get_entry(&udev->properties_list);
 465 }