2 * libudev - interface to udev device information
4 * Copyright (C) 2008 Kay Sievers <kay.sievers@vrfy.org>
5 * Copyright (C) 2009 Alan Jenkins <alan-jenkins@tuffmail.co.uk>
7 * This library is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
14 * DISCLAIMER - The file format mentioned here is private to udev/libudev,
15 * and may be changed without notice.
17 * The udev event queue is exported as a binary log file.
18 * Each log record consists of a sequence number followed by the device path.
20 * When a new event is queued, its details are appended to the log.
21 * When the event finishes, a second record is appended to the log
22 * with the same sequence number but a null devpath.
25 * {1, "/devices/virtual/mem/null" },
26 * {2, "/devices/virtual/mem/zero" },
28 * Event 2 is still queued, but event 1 has been finished
30 * The queue does not grow indefinitely. It is periodically re-created
31 * to remove finished events. Atomic rename() makes this transparent to readers.
33 * The queue file starts with a single sequence number which specifies the
34 * minimum sequence number in the log that follows. Any events prior to this
35 * sequence number have already finished.
46 #include <sys/types.h>
50 #include "libudev-private.h"
52 static int rebuild_queue_file(struct udev_queue_export *udev_queue_export);
54 struct udev_queue_export {
56 int failed_count; /* number of failed events exported */
57 int queued_count; /* number of unfinished events exported in queue file */
59 unsigned long long int seqnum_max; /* earliest sequence number in queue file */
60 unsigned long long int seqnum_min; /* latest sequence number in queue file */
61 int waste_bytes; /* queue file bytes wasted on finished events */
64 struct udev_queue_export *udev_queue_export_new(struct udev *udev)
66 struct udev_queue_export *udev_queue_export;
67 unsigned long long int initial_seqnum;
72 udev_queue_export = calloc(1, sizeof(struct udev_queue_export));
73 if (udev_queue_export == NULL)
75 udev_queue_export->udev = udev;
77 initial_seqnum = udev_get_kernel_seqnum(udev);
78 udev_queue_export->seqnum_min = initial_seqnum;
79 udev_queue_export->seqnum_max = initial_seqnum;
81 udev_queue_export_cleanup(udev_queue_export);
82 if (rebuild_queue_file(udev_queue_export) != 0) {
83 free(udev_queue_export);
87 return udev_queue_export;
90 void udev_queue_export_unref(struct udev_queue_export *udev_queue_export)
92 if (udev_queue_export == NULL)
94 if (udev_queue_export->queue_file != NULL)
95 fclose(udev_queue_export->queue_file);
96 free(udev_queue_export);
99 void udev_queue_export_cleanup(struct udev_queue_export *udev_queue_export)
101 char filename[UTIL_PATH_SIZE];
103 util_strscpyl(filename, sizeof(filename), udev_get_dev_path(udev_queue_export->udev), "/.udev/queue.tmp", NULL);
106 util_strscpyl(filename, sizeof(filename), udev_get_dev_path(udev_queue_export->udev), "/.udev/queue.bin", NULL);
110 static int skip_to(FILE *file, long offset)
114 /* fseek may drop buffered data, avoid it for small seeks */
115 old_offset = ftell(file);
116 if (offset > old_offset && offset - old_offset <= BUFSIZ) {
117 size_t skip_bytes = offset - old_offset;
118 char buf[skip_bytes];
120 if (fread(buf, skip_bytes, 1, file) != skip_bytes)
124 return fseek(file, offset, SEEK_SET);
127 struct queue_devpaths {
128 unsigned int devpaths_first; /* index of first queued event */
129 unsigned int devpaths_size;
130 long devpaths[]; /* seqnum -> offset of devpath in queue file (or 0) */
134 * Returns a table mapping seqnum to devpath file offset for currently queued events.
135 * devpaths[i] represents the event with seqnum = i + udev_queue_export->seqnum_min.
137 static struct queue_devpaths *build_index(struct udev_queue_export *udev_queue_export)
139 struct queue_devpaths *devpaths;
140 unsigned long long int range;
143 unsigned long long int seqnum;
144 unsigned long long int n;
147 /* seek to the first event in the file */
148 rewind(udev_queue_export->queue_file);
149 udev_queue_read_seqnum(udev_queue_export->queue_file, &seqnum);
151 /* allocate the table */
152 range = udev_queue_export->seqnum_min - udev_queue_export->seqnum_max;
153 if (range - 1 > INT_MAX) {
154 err(udev_queue_export->udev, "queue file overflow\n");
157 devpaths = calloc(1, sizeof(struct queue_devpaths) + (range + 1) * sizeof(long));
160 devpaths->devpaths_size = range + 1;
162 /* read all records and populate the table */
164 if (udev_queue_read_seqnum(udev_queue_export->queue_file, &seqnum) < 0)
166 n = seqnum - udev_queue_export->seqnum_max;
167 if (n >= devpaths->devpaths_size)
170 devpath_offset = ftell(udev_queue_export->queue_file);
171 devpath_len = udev_queue_skip_devpath(udev_queue_export->queue_file);
176 devpaths->devpaths[n] = devpath_offset;
178 devpaths->devpaths[n] = 0;
181 /* find first queued event */
182 for (i = 0; i < devpaths->devpaths_size; i++) {
183 if (devpaths->devpaths[i] != 0)
186 devpaths->devpaths_first = i;
191 err(udev_queue_export->udev, "queue file corrupted\n");
196 static int rebuild_queue_file(struct udev_queue_export *udev_queue_export)
198 unsigned long long int seqnum;
199 struct queue_devpaths *devpaths = NULL;
200 char filename[UTIL_PATH_SIZE];
201 char filename_tmp[UTIL_PATH_SIZE];
202 FILE *new_queue_file = NULL;
205 /* read old queue file */
206 if (udev_queue_export->queue_file != NULL) {
207 dbg(udev_queue_export->udev, "compacting queue file, freeing %d bytes\n",
208 udev_queue_export->waste_bytes);
210 devpaths = build_index(udev_queue_export);
211 if (devpaths != NULL)
212 udev_queue_export->seqnum_max += devpaths->devpaths_first;
214 if (devpaths == NULL) {
215 dbg(udev_queue_export->udev, "creating empty queue file\n");
216 udev_queue_export->queued_count = 0;
217 udev_queue_export->seqnum_max = udev_queue_export->seqnum_min;
220 /* create new queue file */
221 util_strscpyl(filename_tmp, sizeof(filename_tmp), udev_get_dev_path(udev_queue_export->udev), "/.udev/queue.tmp", NULL);
222 new_queue_file = fopen(filename_tmp, "w+");
223 if (new_queue_file == NULL)
225 seqnum = udev_queue_export->seqnum_max;
226 fwrite(&seqnum, 1, sizeof(unsigned long long int), new_queue_file);
228 /* copy unfinished events only to the new file */
229 if (devpaths != NULL) {
230 for (i = devpaths->devpaths_first; i < devpaths->devpaths_size; i++) {
231 char devpath[UTIL_PATH_SIZE];
233 unsigned short devpath_len;
235 if (devpaths->devpaths[i] != 0)
237 skip_to(udev_queue_export->queue_file, devpaths->devpaths[i]);
238 err = udev_queue_read_devpath(udev_queue_export->queue_file, devpath, sizeof(devpath));
241 fwrite(&seqnum, sizeof(unsigned long long int), 1, new_queue_file);
242 fwrite(&devpath_len, sizeof(unsigned short), 1, new_queue_file);
243 fwrite(devpath, 1, devpath_len, new_queue_file);
250 fflush(new_queue_file);
251 if (ferror(new_queue_file))
254 /* rename the new file on top of the old one */
255 util_strscpyl(filename, sizeof(filename), udev_get_dev_path(udev_queue_export->udev), "/.udev/queue.bin", NULL);
256 if (rename(filename_tmp, filename) != 0)
259 if (udev_queue_export->queue_file != NULL)
260 fclose(udev_queue_export->queue_file);
261 udev_queue_export->queue_file = new_queue_file;
262 udev_queue_export->waste_bytes = 0;
267 err(udev_queue_export->udev, "failed to create queue file: %m\n");
268 udev_queue_export_cleanup(udev_queue_export);
270 if (udev_queue_export->queue_file != NULL) {
271 fclose(udev_queue_export->queue_file);
272 udev_queue_export->queue_file = NULL;
274 if (new_queue_file != NULL)
275 fclose(new_queue_file);
277 if (devpaths != NULL)
279 udev_queue_export->queued_count = 0;
280 udev_queue_export->waste_bytes = 0;
281 udev_queue_export->seqnum_max = udev_queue_export->seqnum_min;
286 static int write_queue_record(struct udev_queue_export *udev_queue_export,
287 unsigned long long int seqnum, const char *devpath, size_t devpath_len)
291 if (udev_queue_export->queue_file == NULL) {
292 dbg(udev_queue_export->udev, "can't record event: queue file not available\n");
296 if (fwrite(&seqnum, sizeof(unsigned long long int), 1, udev_queue_export->queue_file) != 1)
299 len = (devpath_len < USHRT_MAX) ? devpath_len : USHRT_MAX;
300 if (fwrite(&len, sizeof(unsigned short), 1, udev_queue_export->queue_file) != 1)
302 if (fwrite(devpath, 1, len, udev_queue_export->queue_file) != len)
305 /* *must* flush output; caller may fork */
306 if (fflush(udev_queue_export->queue_file) != 0)
312 /* if we failed half way through writing a record to a file,
313 we should not try to write any further records to it. */
314 err(udev_queue_export->udev, "error writing to queue file: %m\n");
315 fclose(udev_queue_export->queue_file);
316 udev_queue_export->queue_file = NULL;
327 static inline size_t queue_record_size(size_t devpath_len)
329 return sizeof(unsigned long long int) + sizeof(unsigned short int) + devpath_len;
332 static int update_queue(struct udev_queue_export *udev_queue_export,
333 struct udev_device *udev_device, enum device_state state)
335 unsigned long long int seqnum = udev_device_get_seqnum(udev_device);
336 const char *devpath = NULL;
337 size_t devpath_len = 0;
341 if (state == DEVICE_QUEUED) {
342 devpath = udev_device_get_devpath(udev_device);
343 devpath_len = strlen(devpath);
346 /* recover from an earlier failed rebuild */
347 if (udev_queue_export->queue_file == NULL) {
348 if (rebuild_queue_file(udev_queue_export) != 0)
352 /* when the queue files grow too large, they must be garbage collected and rebuilt */
353 bytes = ftell(udev_queue_export->queue_file) + queue_record_size(devpath_len);
355 /* if we're removing the last event from the queue, that's the best time to rebuild it */
356 if (state != DEVICE_QUEUED && udev_queue_export->queued_count == 1 && bytes > 2048) {
357 /* because we don't need to read the old queue file */
358 fclose(udev_queue_export->queue_file);
359 udev_queue_export->queue_file = NULL;
360 rebuild_queue_file(udev_queue_export);
364 /* try to rebuild the queue files before they grow larger than one page. */
365 if ((udev_queue_export->waste_bytes > bytes / 2) && bytes > 4096)
366 rebuild_queue_file(udev_queue_export);
368 /* don't record a finished event, if we already dropped the event in a failed rebuild */
369 if (seqnum < udev_queue_export->seqnum_max)
372 /* now write to the queue */
373 if (state == DEVICE_QUEUED) {
374 udev_queue_export->queued_count++;
375 udev_queue_export->seqnum_min = seqnum;
377 udev_queue_export->waste_bytes += queue_record_size(devpath_len) + queue_record_size(0);
378 udev_queue_export->queued_count--;
380 err = write_queue_record(udev_queue_export, seqnum, devpath, devpath_len);
382 /* try to handle ENOSPC */
383 if (err != 0 && udev_queue_export->queued_count == 0) {
384 udev_queue_export_cleanup(udev_queue_export);
385 err = rebuild_queue_file(udev_queue_export);
391 static void update_failed(struct udev_queue_export *udev_queue_export,
392 struct udev_device *udev_device, enum device_state state)
394 struct udev *udev = udev_device_get_udev(udev_device);
395 char filename[UTIL_PATH_SIZE];
399 if (state != DEVICE_FAILED && udev_queue_export->failed_count == 0)
402 /* location of failed file */
404 l = util_strpcpyl(&s, sizeof(filename), udev_get_dev_path(udev_queue_export->udev), "/.udev/failed/", NULL);
405 util_path_encode(udev_device_get_devpath(udev_device), s, l);
409 /* record event in the failed directory */
410 if (udev_queue_export->failed_count == 0)
411 util_create_path(udev, filename);
412 udev_queue_export->failed_count++;
414 udev_selinux_setfscreatecon(udev, filename, S_IFLNK);
415 symlink(udev_device_get_devpath(udev_device), filename);
416 udev_selinux_resetfscreatecon(udev);
420 /* delete failed file */
421 if (unlink(filename) == 0) {
422 util_delete_path(udev, filename);
423 udev_queue_export->failed_count--;
427 case DEVICE_FINISHED:
428 if (udev_device_get_devpath_old(udev_device) != NULL) {
429 /* "move" event - rename failed file to current name, do not delete failed */
430 char filename_old[UTIL_PATH_SIZE];
433 l = util_strpcpyl(&s, sizeof(filename_old), udev_get_dev_path(udev_queue_export->udev), "/.udev/failed/", NULL);
434 util_path_encode(udev_device_get_devpath_old(udev_device), s, l);
436 if (rename(filename_old, filename) == 0)
437 info(udev, "renamed devpath, moved failed state of '%s' to %s'\n",
438 udev_device_get_devpath_old(udev_device), udev_device_get_devpath(udev_device));
446 static int update(struct udev_queue_export *udev_queue_export,
447 struct udev_device *udev_device, enum device_state state)
449 update_failed(udev_queue_export, udev_device, state);
451 if (update_queue(udev_queue_export, udev_device, state) != 0)
457 int udev_queue_export_device_queued(struct udev_queue_export *udev_queue_export, struct udev_device *udev_device)
459 return update(udev_queue_export, udev_device, DEVICE_QUEUED);
462 int udev_queue_export_device_finished(struct udev_queue_export *udev_queue_export, struct udev_device *udev_device)
464 return update(udev_queue_export, udev_device, DEVICE_FINISHED);
467 int udev_queue_export_device_failed(struct udev_queue_export *udev_queue_export, struct udev_device *udev_device)
469 return update(udev_queue_export, udev_device, DEVICE_FAILED);