libudev/libudev.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 <stdarg.h>
  16 #include <unistd.h>
  17 #include <errno.h>
  18 #include <string.h>
  19 #include <ctype.h>
  20
  21 #include "libudev.h"
  22 #include "libudev-private.h"
  23
  24 struct udev {
  25         int refcount;
  26         void (*log_fn)(struct udev *udev,
  27                        int priority, const char *file, int line, const char *fn,
  28                        const char *format, va_list args);
  29         void *userdata;
  30         char *sys_path;
  31         char *dev_path;
  32         char *rules_path;
  33         struct udev_list_node properties_list;
  34         int log_priority;
  35         int run;
  36 };
  37
  38 void udev_log(struct udev *udev,
  39               int priority, const char *file, int line, const char *fn,
  40               const char *format, ...)
  41 {
  42         va_list args;
  43
  44         va_start(args, format);
  45         udev->log_fn(udev, priority, file, line, fn, format, args);
  46         va_end(args);
  47 }
  48
  49 static void log_stderr(struct udev *udev,
  50                        int priority, const char *file, int line, const char *fn,
  51                        const char *format, va_list args)
  52 {
  53         fprintf(stderr, "libudev: %s: ", fn);
  54         vfprintf(stderr, format, args);
  55 }
  56
  57 void *udev_get_userdata(struct udev *udev)
  58 {
  59         if (udev == NULL)
  60                 return NULL;
  61         return udev->userdata;
  62 }
  63
  64 void udev_set_userdata(struct udev *udev, void *userdata)
  65 {
  66         if (udev == NULL)
  67                 return;
  68         udev->userdata = userdata;
  69 }
  70
  71 /**
  72  * udev_new:
  73  *
  74  * Create udev library context.
  75  *
  76  * The initial refcount is 1, and needs to be decremented to
  77  * release the resources of the udev library context.
  78  *
  79  * Returns: a new udev library context
  80  **/
  81 struct udev *udev_new(void)
  82 {
  83         struct udev *udev;
  84         const char *env;
  85         char *config_file;
  86         FILE *f;
  87
  88         udev = calloc(1, sizeof(struct udev));
  89         if (udev == NULL)
  90                 return NULL;
  91         udev->refcount = 1;
  92         udev->log_fn = log_stderr;
  93         udev->log_priority = LOG_ERR;
  94         udev_list_init(&udev->properties_list);
  95         udev->run = 1;
  96         udev->dev_path = strdup(UDEV_PREFIX "/dev");
  97         udev->sys_path = strdup("/sys");
  98         config_file = strdup(SYSCONFDIR "/udev/udev.conf");
  99         if (udev->dev_path == NULL ||
 100             udev->sys_path == NULL ||
 101             config_file == NULL)
 102                 goto err;
 103
 104         /* settings by environment and config file */
 105         env = getenv("SYSFS_PATH");
 106         if (env != NULL) {
 107                 free(udev->sys_path);
 108                 udev->sys_path = strdup(env);
 109                 util_remove_trailing_chars(udev->sys_path, '/');
 110                 udev_add_property(udev, "SYSFS_PATH", udev->sys_path);
 111         }
 112
 113         env = getenv("UDEV_RUN");
 114         if (env != NULL && strcmp(env, "0") == 0)
 115                 udev->run = 0;
 116
 117         env = getenv("UDEV_CONFIG_FILE");
 118         if (env != NULL) {
 119                 free(config_file);
 120                 config_file = strdup(env);
 121                 util_remove_trailing_chars(config_file, '/');
 122         }
 123         if (config_file == NULL)
 124                 goto err;
 125         f = fopen(config_file, "r");
 126         if (f != NULL) {
 127                 char line[UTIL_LINE_SIZE];
 128                 int line_nr = 0;
 129
 130                 while (fgets(line, sizeof(line), f)) {
 131                         size_t len;
 132                         char *key;
 133                         char *val;
 134
 135                         line_nr++;
 136
 137                         /* find key */
 138                         key = line;
 139                         while (isspace(key[0]))
 140                                 key++;
 141
 142                         /* comment or empty line */
 143                         if (key[0] == '#' || key[0] == '\0')
 144                                 continue;
 145
 146                         /* split key/value */
 147                         val = strchr(key, '=');
 148                         if (val == NULL) {
 149                                 err(udev, "missing <key>=<value> in '%s'[%i], skip line\n", config_file, line_nr);
 150                                 continue;
 151                         }
 152                         val[0] = '\0';
 153                         val++;
 154
 155                         /* find value */
 156                         while (isspace(val[0]))
 157                                 val++;
 158
 159                         /* terminate key */
 160                         len = strlen(key);
 161                         if (len == 0)
 162                                 continue;
 163                         while (isspace(key[len-1]))
 164                                 len--;
 165                         key[len] = '\0';
 166
 167                         /* terminate value */
 168                         len = strlen(val);
 169                         if (len == 0)
 170                                 continue;
 171                         while (isspace(val[len-1]))
 172                                 len--;
 173                         val[len] = '\0';
 174
 175                         if (len == 0)
 176                                 continue;
 177
 178                         /* unquote */
 179                         if (val[0] == '"' || val[0] == '\'') {
 180                                 if (val[len-1] != val[0]) {
 181                                         err(udev, "inconsistent quoting in '%s'[%i], skip line\n", config_file, line_nr);
 182                                         continue;
 183                                 }
 184                                 val[len-1] = '\0';
 185                                 val++;
 186                         }
 187
 188                         if (strcmp(key, "udev_log") == 0) {
 189                                 udev_set_log_priority(udev, util_log_priority(val));
 190                                 continue;
 191                         }
 192                         if (strcmp(key, "udev_root") == 0) {
 193                                 free(udev->dev_path);
 194                                 udev->dev_path = strdup(val);
 195                                 util_remove_trailing_chars(udev->dev_path, '/');
 196                                 continue;
 197                         }
 198                         if (strcmp(key, "udev_rules") == 0) {
 199                                 free(udev->rules_path);
 200                                 udev->rules_path = strdup(val);
 201                                 util_remove_trailing_chars(udev->rules_path, '/');
 202                                 continue;
 203                         }
 204                 }
 205                 fclose(f);
 206         }
 207
 208         env = getenv("UDEV_ROOT");
 209         if (env != NULL) {
 210                 free(udev->dev_path);
 211                 udev->dev_path = strdup(env);
 212                 util_remove_trailing_chars(udev->dev_path, '/');
 213                 udev_add_property(udev, "UDEV_ROOT", udev->dev_path);
 214         }
 215
 216         env = getenv("UDEV_LOG");
 217         if (env != NULL)
 218                 udev_set_log_priority(udev, util_log_priority(env));
 219
 220         if (udev->dev_path == NULL || udev->sys_path == NULL)
 221                 goto err;
 222         dbg(udev, "context %p created\n", udev);
 223         dbg(udev, "log_priority=%d\n", udev->log_priority);
 224         dbg(udev, "config_file='%s'\n", config_file);
 225         dbg(udev, "dev_path='%s'\n", udev->dev_path);
 226         dbg(udev, "sys_path='%s'\n", udev->sys_path);
 227         if (udev->rules_path != NULL)
 228                 dbg(udev, "rules_path='%s'\n", udev->rules_path);
 229         free(config_file);
 230         return udev;
 231 err:
 232         free(config_file);
 233         err(udev, "context creation failed\n");
 234         udev_unref(udev);
 235         return NULL;
 236 }
 237
 238 /**
 239  * udev_ref:
 240  * @udev: udev library context
 241  *
 242  * Take a reference of the udev library context.
 243  *
 244  * Returns: the passed udev library context
 245  **/
 246 struct udev *udev_ref(struct udev *udev)
 247 {
 248         if (udev == NULL)
 249                 return NULL;
 250         udev->refcount++;
 251         return udev;
 252 }
 253
 254 /**
 255  * udev_unref:
 256  * @udev: udev library context
 257  *
 258  * Drop a reference of the udev library context. If the refcount
 259  * reaches zero, the resources of the context will be released.
 260  *
 261  **/
 262 void udev_unref(struct udev *udev)
 263 {
 264         if (udev == NULL)
 265                 return;
 266         udev->refcount--;
 267         if (udev->refcount > 0)
 268                 return;
 269         udev_list_cleanup_entries(udev, &udev->properties_list);
 270         free(udev->dev_path);
 271         free(udev->sys_path);
 272         free(udev->rules_path);
 273         dbg(udev, "context %p released\n", udev);
 274         free(udev);
 275 }
 276
 277 /**
 278  * udev_set_log_fn:
 279  * @udev: udev library context
 280  * @log_fn: function to be called for logging messages
 281  *
 282  * The built-in logging writes to stderr. It can be
 283  * overridden by a custom function, to plug log messages
 284  * into the users' logging functionality.
 285  *
 286  **/
 287 void udev_set_log_fn(struct udev *udev,
 288                      void (*log_fn)(struct udev *udev,
 289                                     int priority, const char *file, int line, const char *fn,
 290                                     const char *format, va_list args))
 291 {
 292         udev->log_fn = log_fn;
 293         info(udev, "custom logging function %p registered\n", udev);
 294 }
 295
 296 int udev_get_log_priority(struct udev *udev)
 297 {
 298         return udev->log_priority;
 299 }
 300
 301 void udev_set_log_priority(struct udev *udev, int priority)
 302 {
 303         char num[32];
 304
 305         udev->log_priority = priority;
 306         snprintf(num, sizeof(num), "%u", udev->log_priority);
 307         udev_add_property(udev, "UDEV_LOG", num);
 308 }
 309
 310 const char *udev_get_rules_path(struct udev *udev)
 311 {
 312         return udev->rules_path;
 313 }
 314
 315 int udev_get_run(struct udev *udev)
 316 {
 317         return udev->run;
 318 }
 319
 320 /**
 321  * udev_get_sys_path:
 322  * @udev: udev library context
 323  *
 324  * Retrieve the sysfs mount point. The default is "/sys". For
 325  * testing purposes, it can be overridden with the environment
 326  * variable SYSFS_PATH.
 327  *
 328  * Returns: the sys mount point
 329  **/
 330 const char *udev_get_sys_path(struct udev *udev)
 331 {
 332         if (udev == NULL)
 333                 return NULL;
 334         return udev->sys_path;
 335 }
 336
 337 /**
 338  * udev_get_dev_path:
 339  * @udev: udev library context
 340  *
 341  * Retrieve the device directory path. The default value is "/dev",
 342  * the actual value may be overridden in the udev configuration
 343  * file.
 344  *
 345  * Returns: the device directory path
 346  **/
 347 const char *udev_get_dev_path(struct udev *udev)
 348 {
 349         if (udev == NULL)
 350                 return NULL;
 351         return udev->dev_path;
 352 }
 353
 354 struct udev_list_entry *udev_add_property(struct udev *udev, const char *key, const char *value)
 355 {
 356         if (value == NULL) {
 357                 struct udev_list_entry *list_entry;
 358
 359                 list_entry = udev_get_properties_list_entry(udev);
 360                 list_entry = udev_list_entry_get_by_name(list_entry, key);
 361                 if (list_entry != NULL)
 362                         udev_list_entry_delete(list_entry);
 363                 return NULL;
 364         }
 365         return udev_list_entry_add(udev, &udev->properties_list, key, value, 1, 0);
 366 }
 367
 368 struct udev_list_entry *udev_get_properties_list_entry(struct udev *udev)
 369 {
 370         return udev_list_get_entry(&udev->properties_list);
 371 }