2 This file is part of systemd.
4 Copyright 2008-2012 Kay Sievers <kay@vrfy.org>
6 systemd is free software; you can redistribute it and/or modify it
7 under the terms of the GNU Lesser General Public License as published by
8 the Free Software Foundation; either version 2.1 of the License, or
9 (at your option) any later version.
11 systemd is distributed in the hope that it will be useful, but
12 WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public License
17 along with systemd; If not, see <http://www.gnu.org/licenses/>.
30 #include <sys/param.h>
33 #include "libudev-private.h"
36 * SECTION:libudev-enumerate
37 * @short_description: lookup and sort sys devices
39 * Lookup devices in the sys filesystem, filter devices by properties,
40 * and return a sorted list of devices.
51 * Opaque object representing one device lookup/sort context.
53 struct udev_enumerate {
56 struct udev_list sysattr_match_list;
57 struct udev_list sysattr_nomatch_list;
58 struct udev_list subsystem_match_list;
59 struct udev_list subsystem_nomatch_list;
60 struct udev_list sysname_match_list;
61 struct udev_list properties_match_list;
62 struct udev_list tags_match_list;
63 struct udev_device *parent_match;
64 struct udev_list devices_list;
65 struct syspath *devices;
66 unsigned int devices_cur;
67 unsigned int devices_max;
68 bool devices_uptodate:1;
69 bool match_is_initialized;
74 * @udev: udev library context
76 * Create an enumeration context to scan /sys.
78 * Returns: an enumeration context.
80 _public_ struct udev_enumerate *udev_enumerate_new(struct udev *udev)
82 struct udev_enumerate *udev_enumerate;
86 udev_enumerate = new0(struct udev_enumerate, 1);
87 if (udev_enumerate == NULL)
89 udev_enumerate->refcount = 1;
90 udev_enumerate->udev = udev;
91 udev_list_init(udev, &udev_enumerate->sysattr_match_list, false);
92 udev_list_init(udev, &udev_enumerate->sysattr_nomatch_list, false);
93 udev_list_init(udev, &udev_enumerate->subsystem_match_list, true);
94 udev_list_init(udev, &udev_enumerate->subsystem_nomatch_list, true);
95 udev_list_init(udev, &udev_enumerate->sysname_match_list, true);
96 udev_list_init(udev, &udev_enumerate->properties_match_list, false);
97 udev_list_init(udev, &udev_enumerate->tags_match_list, true);
98 udev_list_init(udev, &udev_enumerate->devices_list, false);
99 return udev_enumerate;
103 * udev_enumerate_ref:
104 * @udev_enumerate: context
106 * Take a reference of a enumeration context.
108 * Returns: the passed enumeration context
110 _public_ struct udev_enumerate *udev_enumerate_ref(struct udev_enumerate *udev_enumerate)
112 if (udev_enumerate == NULL)
114 udev_enumerate->refcount++;
115 return udev_enumerate;
119 * udev_enumerate_unref:
120 * @udev_enumerate: context
122 * Drop a reference of an enumeration context. If the refcount reaches zero,
123 * all resources of the enumeration context will be released.
127 _public_ struct udev_enumerate *udev_enumerate_unref(struct udev_enumerate *udev_enumerate)
131 if (udev_enumerate == NULL)
133 udev_enumerate->refcount--;
134 if (udev_enumerate->refcount > 0)
136 udev_list_cleanup(&udev_enumerate->sysattr_match_list);
137 udev_list_cleanup(&udev_enumerate->sysattr_nomatch_list);
138 udev_list_cleanup(&udev_enumerate->subsystem_match_list);
139 udev_list_cleanup(&udev_enumerate->subsystem_nomatch_list);
140 udev_list_cleanup(&udev_enumerate->sysname_match_list);
141 udev_list_cleanup(&udev_enumerate->properties_match_list);
142 udev_list_cleanup(&udev_enumerate->tags_match_list);
143 udev_device_unref(udev_enumerate->parent_match);
144 udev_list_cleanup(&udev_enumerate->devices_list);
145 for (i = 0; i < udev_enumerate->devices_cur; i++)
146 free(udev_enumerate->devices[i].syspath);
147 free(udev_enumerate->devices);
148 free(udev_enumerate);
153 * udev_enumerate_get_udev:
154 * @udev_enumerate: context
156 * Get the udev library context.
158 * Returns: a pointer to the context.
160 _public_ struct udev *udev_enumerate_get_udev(struct udev_enumerate *udev_enumerate)
162 if (udev_enumerate == NULL)
164 return udev_enumerate->udev;
167 static int syspath_add(struct udev_enumerate *udev_enumerate, const char *syspath)
170 struct syspath *entry;
172 /* double array size if needed */
173 if (udev_enumerate->devices_cur >= udev_enumerate->devices_max) {
177 add = udev_enumerate->devices_max;
180 buf = realloc(udev_enumerate->devices, (udev_enumerate->devices_max + add) * sizeof(struct syspath));
183 udev_enumerate->devices = buf;
184 udev_enumerate->devices_max += add;
187 path = strdup(syspath);
190 entry = &udev_enumerate->devices[udev_enumerate->devices_cur];
191 entry->syspath = path;
192 entry->len = strlen(path);
193 udev_enumerate->devices_cur++;
194 udev_enumerate->devices_uptodate = false;
198 static int syspath_cmp(const void *p1, const void *p2)
200 const struct syspath *path1 = p1;
201 const struct syspath *path2 = p2;
205 len = MIN(path1->len, path2->len);
206 ret = memcmp(path1->syspath, path2->syspath, len);
208 if (path1->len < path2->len)
210 else if (path1->len > path2->len)
216 /* For devices that should be moved to the absolute end of the list */
217 static bool devices_delay_end(struct udev *udev, const char *syspath)
219 static const char *delay_device_list[] = {
226 for (i = 0; delay_device_list[i] != NULL; i++) {
227 if (strstr(syspath + strlen("/sys"), delay_device_list[i]) != NULL)
233 /* For devices that should just be moved a little bit later, just
234 * before the point where some common path prefix changes. Returns the
235 * number of characters that make up that common prefix */
236 static size_t devices_delay_later(struct udev *udev, const char *syspath)
240 /* For sound cards the control device must be enumerated last
241 * to make sure it's the final device node that gets ACLs
242 * applied. Applications rely on this fact and use ACL changes
243 * on the control node as an indicator that the ACL change of
244 * the entire sound card completed. The kernel makes this
245 * guarantee when creating those devices, and hence we should
246 * too when enumerating them. */
248 if ((c = strstr(syspath, "/sound/card"))) {
250 c += strcspn(c, "/");
252 if (startswith(c, "/controlC"))
253 return c - syspath + 1;
260 * udev_enumerate_get_list_entry:
261 * @udev_enumerate: context
263 * Get the first entry of the sorted list of device paths.
265 * Returns: a udev_list_entry.
267 _public_ struct udev_list_entry *udev_enumerate_get_list_entry(struct udev_enumerate *udev_enumerate)
269 if (udev_enumerate == NULL)
271 if (!udev_enumerate->devices_uptodate) {
275 struct syspath *prev = NULL;
276 size_t move_later_prefix = 0;
278 udev_list_cleanup(&udev_enumerate->devices_list);
279 qsort_safe(udev_enumerate->devices, udev_enumerate->devices_cur, sizeof(struct syspath), syspath_cmp);
281 max = udev_enumerate->devices_cur;
282 for (i = 0; i < max; i++) {
283 struct syspath *entry = &udev_enumerate->devices[i];
285 /* skip duplicated entries */
287 entry->len == prev->len &&
288 memcmp(entry->syspath, prev->syspath, entry->len) == 0)
292 /* skip to be delayed devices, and add them to the end of the list */
293 if (devices_delay_end(udev_enumerate->udev, entry->syspath)) {
294 syspath_add(udev_enumerate, entry->syspath);
295 /* need to update prev here for the case realloc() gives a different address */
296 prev = &udev_enumerate->devices[i];
300 /* skip to be delayed devices, and move the to
301 * the point where the prefix changes. We can
302 * only move one item at a time. */
303 if (move_later == -1) {
304 move_later_prefix = devices_delay_later(udev_enumerate->udev, entry->syspath);
306 if (move_later_prefix > 0) {
312 if ((move_later >= 0) &&
313 !strneq(entry->syspath, udev_enumerate->devices[move_later].syspath, move_later_prefix)) {
315 udev_list_entry_add(&udev_enumerate->devices_list,
316 udev_enumerate->devices[move_later].syspath, NULL);
320 udev_list_entry_add(&udev_enumerate->devices_list, entry->syspath, NULL);
324 udev_list_entry_add(&udev_enumerate->devices_list,
325 udev_enumerate->devices[move_later].syspath, NULL);
327 /* add and cleanup delayed devices from end of list */
328 for (i = max; i < udev_enumerate->devices_cur; i++) {
329 struct syspath *entry = &udev_enumerate->devices[i];
331 udev_list_entry_add(&udev_enumerate->devices_list, entry->syspath, NULL);
332 free(entry->syspath);
334 udev_enumerate->devices_cur = max;
336 udev_enumerate->devices_uptodate = true;
338 return udev_list_get_entry(&udev_enumerate->devices_list);
342 * udev_enumerate_add_match_subsystem:
343 * @udev_enumerate: context
344 * @subsystem: filter for a subsystem of the device to include in the list
346 * Match only devices belonging to a certain kernel subsystem.
348 * Returns: 0 on success, otherwise a negative error value.
350 _public_ int udev_enumerate_add_match_subsystem(struct udev_enumerate *udev_enumerate, const char *subsystem)
352 if (udev_enumerate == NULL)
354 if (subsystem == NULL)
356 if (udev_list_entry_add(&udev_enumerate->subsystem_match_list, subsystem, NULL) == NULL)
362 * udev_enumerate_add_nomatch_subsystem:
363 * @udev_enumerate: context
364 * @subsystem: filter for a subsystem of the device to exclude from the list
366 * Match only devices not belonging to a certain kernel subsystem.
368 * Returns: 0 on success, otherwise a negative error value.
370 _public_ int udev_enumerate_add_nomatch_subsystem(struct udev_enumerate *udev_enumerate, const char *subsystem)
372 if (udev_enumerate == NULL)
374 if (subsystem == NULL)
376 if (udev_list_entry_add(&udev_enumerate->subsystem_nomatch_list, subsystem, NULL) == NULL)
382 * udev_enumerate_add_match_sysattr:
383 * @udev_enumerate: context
384 * @sysattr: filter for a sys attribute at the device to include in the list
385 * @value: optional value of the sys attribute
387 * Match only devices with a certain /sys device attribute.
389 * Returns: 0 on success, otherwise a negative error value.
391 _public_ int udev_enumerate_add_match_sysattr(struct udev_enumerate *udev_enumerate, const char *sysattr, const char *value)
393 if (udev_enumerate == NULL)
397 if (udev_list_entry_add(&udev_enumerate->sysattr_match_list, sysattr, value) == NULL)
403 * udev_enumerate_add_nomatch_sysattr:
404 * @udev_enumerate: context
405 * @sysattr: filter for a sys attribute at the device to exclude from the list
406 * @value: optional value of the sys attribute
408 * Match only devices not having a certain /sys device attribute.
410 * Returns: 0 on success, otherwise a negative error value.
412 _public_ int udev_enumerate_add_nomatch_sysattr(struct udev_enumerate *udev_enumerate, const char *sysattr, const char *value)
414 if (udev_enumerate == NULL)
418 if (udev_list_entry_add(&udev_enumerate->sysattr_nomatch_list, sysattr, value) == NULL)
423 static int match_sysattr_value(struct udev_device *dev, const char *sysattr, const char *match_val)
425 const char *val = NULL;
428 val = udev_device_get_sysattr_value(dev, sysattr);
431 if (match_val == NULL) {
435 if (fnmatch(match_val, val, 0) == 0) {
444 * udev_enumerate_add_match_property:
445 * @udev_enumerate: context
446 * @property: filter for a property of the device to include in the list
447 * @value: value of the property
449 * Match only devices with a certain property.
451 * Returns: 0 on success, otherwise a negative error value.
453 _public_ int udev_enumerate_add_match_property(struct udev_enumerate *udev_enumerate, const char *property, const char *value)
455 if (udev_enumerate == NULL)
457 if (property == NULL)
459 if (udev_list_entry_add(&udev_enumerate->properties_match_list, property, value) == NULL)
465 * udev_enumerate_add_match_tag:
466 * @udev_enumerate: context
467 * @tag: filter for a tag of the device to include in the list
469 * Match only devices with a certain tag.
471 * Returns: 0 on success, otherwise a negative error value.
473 _public_ int udev_enumerate_add_match_tag(struct udev_enumerate *udev_enumerate, const char *tag)
475 if (udev_enumerate == NULL)
479 if (udev_list_entry_add(&udev_enumerate->tags_match_list, tag, NULL) == NULL)
485 * udev_enumerate_add_match_parent:
486 * @udev_enumerate: context
487 * @parent: parent device where to start searching
489 * Return the devices on the subtree of one given device. The parent
490 * itself is included in the list.
492 * A reference for the device is held until the udev_enumerate context
495 * Returns: 0 on success, otherwise a negative error value.
497 _public_ int udev_enumerate_add_match_parent(struct udev_enumerate *udev_enumerate, struct udev_device *parent)
499 if (udev_enumerate == NULL)
503 if (udev_enumerate->parent_match != NULL)
504 udev_device_unref(udev_enumerate->parent_match);
505 udev_enumerate->parent_match = udev_device_ref(parent);
510 * udev_enumerate_add_match_is_initialized:
511 * @udev_enumerate: context
513 * Match only devices which udev has set up already. This makes
514 * sure, that the device node permissions and context are properly set
515 * and that network devices are fully renamed.
517 * Usually, devices which are found in the kernel but not already
518 * handled by udev, have still pending events. Services should subscribe
519 * to monitor events and wait for these devices to become ready, instead
520 * of using uninitialized devices.
522 * For now, this will not affect devices which do not have a device node
523 * and are not network interfaces.
525 * Returns: 0 on success, otherwise a negative error value.
527 _public_ int udev_enumerate_add_match_is_initialized(struct udev_enumerate *udev_enumerate)
529 if (udev_enumerate == NULL)
531 udev_enumerate->match_is_initialized = true;
536 * udev_enumerate_add_match_sysname:
537 * @udev_enumerate: context
538 * @sysname: filter for the name of the device to include in the list
540 * Match only devices with a given /sys device name.
542 * Returns: 0 on success, otherwise a negative error value.
544 _public_ int udev_enumerate_add_match_sysname(struct udev_enumerate *udev_enumerate, const char *sysname)
546 if (udev_enumerate == NULL)
550 if (udev_list_entry_add(&udev_enumerate->sysname_match_list, sysname, NULL) == NULL)
555 static bool match_sysattr(struct udev_enumerate *udev_enumerate, struct udev_device *dev)
557 struct udev_list_entry *list_entry;
560 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_enumerate->sysattr_nomatch_list)) {
561 if (match_sysattr_value(dev, udev_list_entry_get_name(list_entry),
562 udev_list_entry_get_value(list_entry)))
566 if (udev_list_get_entry(&udev_enumerate->sysattr_match_list) != NULL) {
567 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_enumerate->sysattr_match_list)) {
568 /* anything that does not match, will make it FALSE */
569 if (!match_sysattr_value(dev, udev_list_entry_get_name(list_entry),
570 udev_list_entry_get_value(list_entry)))
578 static bool match_property(struct udev_enumerate *udev_enumerate, struct udev_device *dev)
580 struct udev_list_entry *list_entry;
583 /* no match always matches */
584 if (udev_list_get_entry(&udev_enumerate->properties_match_list) == NULL)
587 /* loop over matches */
588 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_enumerate->properties_match_list)) {
589 const char *match_key = udev_list_entry_get_name(list_entry);
590 const char *match_value = udev_list_entry_get_value(list_entry);
591 struct udev_list_entry *property_entry;
593 /* loop over device properties */
594 udev_list_entry_foreach(property_entry, udev_device_get_properties_list_entry(dev)) {
595 const char *dev_key = udev_list_entry_get_name(property_entry);
596 const char *dev_value = udev_list_entry_get_value(property_entry);
598 if (fnmatch(match_key, dev_key, 0) != 0)
600 if (match_value == NULL && dev_value == NULL) {
604 if (match_value == NULL || dev_value == NULL)
606 if (fnmatch(match_value, dev_value, 0) == 0) {
616 static bool match_tag(struct udev_enumerate *udev_enumerate, struct udev_device *dev)
618 struct udev_list_entry *list_entry;
620 /* no match always matches */
621 if (udev_list_get_entry(&udev_enumerate->tags_match_list) == NULL)
624 /* loop over matches */
625 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_enumerate->tags_match_list))
626 if (!udev_device_has_tag(dev, udev_list_entry_get_name(list_entry)))
632 static bool match_parent(struct udev_enumerate *udev_enumerate, struct udev_device *dev)
634 if (udev_enumerate->parent_match == NULL)
637 return startswith(udev_device_get_devpath(dev), udev_device_get_devpath(udev_enumerate->parent_match));
640 static bool match_sysname(struct udev_enumerate *udev_enumerate, const char *sysname)
642 struct udev_list_entry *list_entry;
644 if (udev_list_get_entry(&udev_enumerate->sysname_match_list) == NULL)
647 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_enumerate->sysname_match_list)) {
648 if (fnmatch(udev_list_entry_get_name(list_entry), sysname, 0) != 0)
655 static int scan_dir_and_add_devices(struct udev_enumerate *udev_enumerate,
656 const char *basedir, const char *subdir1, const char *subdir2)
658 char path[UTIL_PATH_SIZE];
665 l = strpcpyl(&s, sizeof(path), "/sys/", basedir, NULL);
667 l = strpcpyl(&s, l, "/", subdir1, NULL);
669 strpcpyl(&s, l, "/", subdir2, NULL);
673 for (dent = readdir(dir); dent != NULL; dent = readdir(dir)) {
674 char syspath[UTIL_PATH_SIZE];
675 struct udev_device *dev;
677 if (dent->d_name[0] == '.')
680 if (!match_sysname(udev_enumerate, dent->d_name))
683 strscpyl(syspath, sizeof(syspath), path, "/", dent->d_name, NULL);
684 dev = udev_device_new_from_syspath(udev_enumerate->udev, syspath);
688 if (udev_enumerate->match_is_initialized) {
690 * All devices with a device node or network interfaces
691 * possibly need udev to adjust the device node permission
692 * or context, or rename the interface before it can be
693 * reliably used from other processes.
695 * For now, we can only check these types of devices, we
696 * might not store a database, and have no way to find out
697 * for all other types of devices.
699 if (!udev_device_get_is_initialized(dev) &&
700 (major(udev_device_get_devnum(dev)) > 0 || udev_device_get_ifindex(dev) > 0))
703 if (!match_parent(udev_enumerate, dev))
705 if (!match_tag(udev_enumerate, dev))
707 if (!match_property(udev_enumerate, dev))
709 if (!match_sysattr(udev_enumerate, dev))
712 syspath_add(udev_enumerate, udev_device_get_syspath(dev));
714 udev_device_unref(dev);
720 static bool match_subsystem(struct udev_enumerate *udev_enumerate, const char *subsystem)
722 struct udev_list_entry *list_entry;
727 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_enumerate->subsystem_nomatch_list)) {
728 if (fnmatch(udev_list_entry_get_name(list_entry), subsystem, 0) == 0)
732 if (udev_list_get_entry(&udev_enumerate->subsystem_match_list) != NULL) {
733 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_enumerate->subsystem_match_list)) {
734 if (fnmatch(udev_list_entry_get_name(list_entry), subsystem, 0) == 0)
743 static int scan_dir(struct udev_enumerate *udev_enumerate, const char *basedir, const char *subdir, const char *subsystem)
745 char path[UTIL_PATH_SIZE];
749 strscpyl(path, sizeof(path), "/sys/", basedir, NULL);
753 for (dent = readdir(dir); dent != NULL; dent = readdir(dir)) {
754 if (dent->d_name[0] == '.')
756 if (!match_subsystem(udev_enumerate, subsystem != NULL ? subsystem : dent->d_name))
758 scan_dir_and_add_devices(udev_enumerate, basedir, dent->d_name, subdir);
765 * udev_enumerate_add_syspath:
766 * @udev_enumerate: context
767 * @syspath: path of a device
769 * Add a device to the list of devices, to retrieve it back sorted in dependency order.
771 * Returns: 0 on success, otherwise a negative error value.
773 _public_ int udev_enumerate_add_syspath(struct udev_enumerate *udev_enumerate, const char *syspath)
775 struct udev_device *udev_device;
777 if (udev_enumerate == NULL)
781 /* resolve to real syspath */
782 udev_device = udev_device_new_from_syspath(udev_enumerate->udev, syspath);
783 if (udev_device == NULL)
785 syspath_add(udev_enumerate, udev_device_get_syspath(udev_device));
786 udev_device_unref(udev_device);
790 static int scan_devices_tags(struct udev_enumerate *udev_enumerate)
792 struct udev_list_entry *list_entry;
794 /* scan only tagged devices, use tags reverse-index, instead of searching all devices in /sys */
795 udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_enumerate->tags_match_list)) {
798 char path[UTIL_PATH_SIZE];
800 strscpyl(path, sizeof(path), "/run/udev/tags/", udev_list_entry_get_name(list_entry), NULL);
804 for (dent = readdir(dir); dent != NULL; dent = readdir(dir)) {
805 struct udev_device *dev;
807 if (dent->d_name[0] == '.')
810 dev = udev_device_new_from_device_id(udev_enumerate->udev, dent->d_name);
814 if (!match_subsystem(udev_enumerate, udev_device_get_subsystem(dev)))
816 if (!match_sysname(udev_enumerate, udev_device_get_sysname(dev)))
818 if (!match_parent(udev_enumerate, dev))
820 if (!match_property(udev_enumerate, dev))
822 if (!match_sysattr(udev_enumerate, dev))
825 syspath_add(udev_enumerate, udev_device_get_syspath(dev));
827 udev_device_unref(dev);
834 static int parent_add_child(struct udev_enumerate *enumerate, const char *path)
836 struct udev_device *dev;
839 dev = udev_device_new_from_syspath(enumerate->udev, path);
843 if (!match_subsystem(enumerate, udev_device_get_subsystem(dev)))
845 if (!match_sysname(enumerate, udev_device_get_sysname(dev)))
847 if (!match_property(enumerate, dev))
849 if (!match_sysattr(enumerate, dev))
852 syspath_add(enumerate, udev_device_get_syspath(dev));
856 udev_device_unref(dev);
860 static int parent_crawl_children(struct udev_enumerate *enumerate, const char *path, int maxdepth)
869 for (dent = readdir(d); dent != NULL; dent = readdir(d)) {
872 if (dent->d_name[0] == '.')
874 if (dent->d_type != DT_DIR)
876 if (asprintf(&child, "%s/%s", path, dent->d_name) < 0)
878 parent_add_child(enumerate, child);
880 parent_crawl_children(enumerate, child, maxdepth-1);
888 static int scan_devices_children(struct udev_enumerate *enumerate)
892 path = udev_device_get_syspath(enumerate->parent_match);
893 parent_add_child(enumerate, path);
894 return parent_crawl_children(enumerate, path, 256);
897 static int scan_devices_all(struct udev_enumerate *udev_enumerate)
901 if (stat("/sys/subsystem", &statbuf) == 0) {
902 /* we have /subsystem/, forget all the old stuff */
903 scan_dir(udev_enumerate, "subsystem", "devices", NULL);
905 scan_dir(udev_enumerate, "bus", "devices", NULL);
906 scan_dir(udev_enumerate, "class", NULL, NULL);
912 * udev_enumerate_scan_devices:
913 * @udev_enumerate: udev enumeration context
915 * Scan /sys for all devices which match the given filters. No matches
916 * will return all currently available devices.
918 * Returns: 0 on success, otherwise a negative error value.
920 _public_ int udev_enumerate_scan_devices(struct udev_enumerate *udev_enumerate)
922 if (udev_enumerate == NULL)
925 /* efficiently lookup tags only, we maintain a reverse-index */
926 if (udev_list_get_entry(&udev_enumerate->tags_match_list) != NULL)
927 return scan_devices_tags(udev_enumerate);
929 /* walk the subtree of one parent device only */
930 if (udev_enumerate->parent_match != NULL)
931 return scan_devices_children(udev_enumerate);
933 /* scan devices of all subsystems */
934 return scan_devices_all(udev_enumerate);
938 * udev_enumerate_scan_subsystems:
939 * @udev_enumerate: udev enumeration context
941 * Scan /sys for all kernel subsystems, including buses, classes, drivers.
943 * Returns: 0 on success, otherwise a negative error value.
945 _public_ int udev_enumerate_scan_subsystems(struct udev_enumerate *udev_enumerate)
948 const char *subsysdir;
950 if (udev_enumerate == NULL)
953 /* all kernel modules */
954 if (match_subsystem(udev_enumerate, "module"))
955 scan_dir_and_add_devices(udev_enumerate, "module", NULL, NULL);
957 if (stat("/sys/subsystem", &statbuf) == 0)
958 subsysdir = "subsystem";
962 /* all subsystems (only buses support coldplug) */
963 if (match_subsystem(udev_enumerate, "subsystem"))
964 scan_dir_and_add_devices(udev_enumerate, subsysdir, NULL, NULL);
966 /* all subsystem drivers */
967 if (match_subsystem(udev_enumerate, "drivers"))
968 scan_dir(udev_enumerate, subsysdir, "drivers", "drivers");