chiark / gitweb /
libudev: enumerate - scan /sys/module
[elogind.git] / libudev / libudev-enumerate.c
index 96cf0609073dd283695338c76219d3aff61b3f4a..0b028bab8477614c2ffb5b2531a5613bf7ff69fa 100644 (file)
@@ -1,7 +1,7 @@
 /*
  * libudev - interface to udev device information
  *
- * Copyright (C) 2008 Kay Sievers <kay.sievers@vrfy.org>
+ * Copyright (C) 2008-2010 Kay Sievers <kay.sievers@vrfy.org>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -51,11 +51,13 @@ struct udev_enumerate {
        struct udev_list_node subsystem_nomatch_list;
        struct udev_list_node sysname_match_list;
        struct udev_list_node properties_match_list;
+       struct udev_list_node tags_match_list;
        struct udev_list_node devices_list;
        struct syspath *devices;
        unsigned int devices_cur;
        unsigned int devices_max;
        bool devices_uptodate:1;
+       bool match_is_initialized;
 };
 
 /**
@@ -64,7 +66,7 @@ struct udev_enumerate {
  *
  * Returns: an enumeration context
  **/
-struct udev_enumerate *udev_enumerate_new(struct udev *udev)
+UDEV_EXPORT struct udev_enumerate *udev_enumerate_new(struct udev *udev)
 {
        struct udev_enumerate *udev_enumerate;
 
@@ -79,6 +81,7 @@ struct udev_enumerate *udev_enumerate_new(struct udev *udev)
        udev_list_init(&udev_enumerate->subsystem_nomatch_list);
        udev_list_init(&udev_enumerate->sysname_match_list);
        udev_list_init(&udev_enumerate->properties_match_list);
+       udev_list_init(&udev_enumerate->tags_match_list);
        udev_list_init(&udev_enumerate->devices_list);
        return udev_enumerate;
 }
@@ -91,7 +94,7 @@ struct udev_enumerate *udev_enumerate_new(struct udev *udev)
  *
  * Returns: the passed enumeration context
  **/
-struct udev_enumerate *udev_enumerate_ref(struct udev_enumerate *udev_enumerate)
+UDEV_EXPORT struct udev_enumerate *udev_enumerate_ref(struct udev_enumerate *udev_enumerate)
 {
        if (udev_enumerate == NULL)
                return NULL;
@@ -106,7 +109,7 @@ struct udev_enumerate *udev_enumerate_ref(struct udev_enumerate *udev_enumerate)
  * Drop a reference of an enumeration context. If the refcount reaches zero,
  * all resources of the enumeration context will be released.
  **/
-void udev_enumerate_unref(struct udev_enumerate *udev_enumerate)
+UDEV_EXPORT void udev_enumerate_unref(struct udev_enumerate *udev_enumerate)
 {
        unsigned int i;
 
@@ -121,6 +124,7 @@ void udev_enumerate_unref(struct udev_enumerate *udev_enumerate)
        udev_list_cleanup_entries(udev_enumerate->udev, &udev_enumerate->subsystem_nomatch_list);
        udev_list_cleanup_entries(udev_enumerate->udev, &udev_enumerate->sysname_match_list);
        udev_list_cleanup_entries(udev_enumerate->udev, &udev_enumerate->properties_match_list);
+       udev_list_cleanup_entries(udev_enumerate->udev, &udev_enumerate->tags_match_list);
        udev_list_cleanup_entries(udev_enumerate->udev, &udev_enumerate->devices_list);
        for (i = 0; i < udev_enumerate->devices_cur; i++)
                free(udev_enumerate->devices[i].syspath);
@@ -134,7 +138,7 @@ void udev_enumerate_unref(struct udev_enumerate *udev_enumerate)
  *
  * Returns: the udev library context.
  */
-struct udev *udev_enumerate_get_udev(struct udev_enumerate *udev_enumerate)
+UDEV_EXPORT struct udev *udev_enumerate_get_udev(struct udev_enumerate *udev_enumerate)
 {
        if (udev_enumerate == NULL)
                return NULL;
@@ -190,7 +194,8 @@ static int syspath_cmp(const void *p1, const void *p2)
        return ret;
 }
 
-static int devices_delay(struct udev *udev, const char *syspath)
+/* For devices that should be moved to the absolute end of the list */
+static bool devices_delay_end(struct udev *udev, const char *syspath)
 {
        static const char *delay_device_list[] = {
                "/block/md",
@@ -204,9 +209,35 @@ static int devices_delay(struct udev *udev, const char *syspath)
        for (i = 0; delay_device_list[i] != NULL; i++) {
                if (strstr(&syspath[len], delay_device_list[i]) != NULL) {
                        dbg(udev, "delaying: %s\n", syspath);
-                       return 1;
+                       return true;
                }
        }
+       return false;
+}
+
+/* For devices that should just be moved a little bit later, just
+ * before the point where some common path prefix changes. Returns the
+ * number of characters that make up that common prefix */
+static size_t devices_delay_later(struct udev *udev, const char *syspath)
+{
+       const char *c;
+
+       /* For sound cards the control device must be enumerated last
+        * to make sure it's the final device node that gets ACLs
+        * applied. Applications rely on this fact and use ACL changes
+        * on the control node as an indicator that the ACL change of
+        * the entire sound card completed. The kernel makes this
+        * guarantee when creating those devices, and hence we should
+        * too when enumerating them. */
+
+       if ((c = strstr(syspath, "/sound/card"))) {
+               c += 11;
+               c += strcspn(c, "/");
+
+               if (strncmp(c, "/controlC", 9) == 0)
+                       return c - syspath + 1;
+       }
+
        return 0;
 }
 
@@ -216,14 +247,15 @@ static int devices_delay(struct udev *udev, const char *syspath)
  *
  * Returns: the first entry of the sorted list of device paths.
  */
-struct udev_list_entry *udev_enumerate_get_list_entry(struct udev_enumerate *udev_enumerate)
+UDEV_EXPORT struct udev_list_entry *udev_enumerate_get_list_entry(struct udev_enumerate *udev_enumerate)
 {
        if (udev_enumerate == NULL)
                return NULL;
        if (!udev_enumerate->devices_uptodate) {
                unsigned int i;
                unsigned int max;
-               struct syspath *prev = NULL;
+               struct syspath *prev = NULL, *move_later = NULL;
+               size_t move_later_prefix = 0;
 
                udev_list_cleanup_entries(udev_enumerate->udev, &udev_enumerate->devices_list);
                qsort(udev_enumerate->devices, udev_enumerate->devices_cur, sizeof(struct syspath), syspath_cmp);
@@ -240,20 +272,47 @@ struct udev_list_entry *udev_enumerate_get_list_entry(struct udev_enumerate *ude
                        prev = entry;
 
                        /* skip to be delayed devices, and add them to the end of the list */
-                       if (devices_delay(udev_enumerate->udev, entry->syspath)) {
+                       if (devices_delay_end(udev_enumerate->udev, entry->syspath)) {
                                syspath_add(udev_enumerate, entry->syspath);
+                               /* need to update prev here for the case realloc() gives a different address */
+                               prev = &udev_enumerate->devices[i];
                                continue;
                        }
 
+                       /* skip to be delayed devices, and move the to
+                        * the point where the prefix changes. We can
+                        * only move one item at a time. */
+                       if (!move_later) {
+                               move_later_prefix = devices_delay_later(udev_enumerate->udev, entry->syspath);
+
+                               if (move_later_prefix > 0) {
+                                       move_later = entry;
+                                       continue;
+                               }
+                       }
+
+                       if (move_later &&
+                           strncmp(entry->syspath, move_later->syspath, move_later_prefix) != 0) {
+
+                               udev_list_entry_add(udev_enumerate->udev, &udev_enumerate->devices_list,
+                                           move_later->syspath, NULL, 0);
+                               move_later = NULL;
+                       }
+
                        udev_list_entry_add(udev_enumerate->udev, &udev_enumerate->devices_list,
-                                           entry->syspath, NULL, 0, 0);
+                                           entry->syspath, NULL, 0);
                }
+
+               if (move_later)
+                       udev_list_entry_add(udev_enumerate->udev, &udev_enumerate->devices_list,
+                                           move_later->syspath, NULL, 0);
+
                /* add and cleanup delayed devices from end of list */
                for (i = max; i < udev_enumerate->devices_cur; i++) {
                        struct syspath *entry = &udev_enumerate->devices[i];
 
                        udev_list_entry_add(udev_enumerate->udev, &udev_enumerate->devices_list,
-                                           entry->syspath, NULL, 0, 0);
+                                           entry->syspath, NULL, 0);
                        free(entry->syspath);
                }
                udev_enumerate->devices_cur = max;
@@ -270,14 +329,14 @@ struct udev_list_entry *udev_enumerate_get_list_entry(struct udev_enumerate *ude
  *
  * Returns: 0 on success, otherwise a negative error value.
  */
-int udev_enumerate_add_match_subsystem(struct udev_enumerate *udev_enumerate, const char *subsystem)
+UDEV_EXPORT int udev_enumerate_add_match_subsystem(struct udev_enumerate *udev_enumerate, const char *subsystem)
 {
        if (udev_enumerate == NULL)
                return -EINVAL;
        if (subsystem == NULL)
                return 0;
        if (udev_list_entry_add(udev_enumerate_get_udev(udev_enumerate),
-                               &udev_enumerate->subsystem_match_list, subsystem, NULL, 1, 0) == NULL)
+                               &udev_enumerate->subsystem_match_list, subsystem, NULL, UDEV_LIST_UNIQUE) == NULL)
                return -ENOMEM;
        return 0;
 }
@@ -289,14 +348,14 @@ int udev_enumerate_add_match_subsystem(struct udev_enumerate *udev_enumerate, co
  *
  * Returns: 0 on success, otherwise a negative error value.
  */
-int udev_enumerate_add_nomatch_subsystem(struct udev_enumerate *udev_enumerate, const char *subsystem)
+UDEV_EXPORT int udev_enumerate_add_nomatch_subsystem(struct udev_enumerate *udev_enumerate, const char *subsystem)
 {
        if (udev_enumerate == NULL)
                return -EINVAL;
        if (subsystem == NULL)
                return 0;
        if (udev_list_entry_add(udev_enumerate_get_udev(udev_enumerate),
-                               &udev_enumerate->subsystem_nomatch_list, subsystem, NULL, 1, 0) == NULL)
+                               &udev_enumerate->subsystem_nomatch_list, subsystem, NULL, UDEV_LIST_UNIQUE) == NULL)
                return -ENOMEM;
        return 0;
 }
@@ -309,14 +368,14 @@ int udev_enumerate_add_nomatch_subsystem(struct udev_enumerate *udev_enumerate,
  *
  * Returns: 0 on success, otherwise a negative error value.
  */
-int udev_enumerate_add_match_sysattr(struct udev_enumerate *udev_enumerate, const char *sysattr, const char *value)
+UDEV_EXPORT int udev_enumerate_add_match_sysattr(struct udev_enumerate *udev_enumerate, const char *sysattr, const char *value)
 {
        if (udev_enumerate == NULL)
                return -EINVAL;
        if (sysattr == NULL)
                return 0;
        if (udev_list_entry_add(udev_enumerate_get_udev(udev_enumerate),
-                          &udev_enumerate->sysattr_match_list, sysattr, value, 0, 0) == NULL)
+                               &udev_enumerate->sysattr_match_list, sysattr, value, 0) == NULL)
                return -ENOMEM;
        return 0;
 }
@@ -329,28 +388,24 @@ int udev_enumerate_add_match_sysattr(struct udev_enumerate *udev_enumerate, cons
  *
  * Returns: 0 on success, otherwise a negative error value.
  */
-int udev_enumerate_add_nomatch_sysattr(struct udev_enumerate *udev_enumerate, const char *sysattr, const char *value)
+UDEV_EXPORT int udev_enumerate_add_nomatch_sysattr(struct udev_enumerate *udev_enumerate, const char *sysattr, const char *value)
 {
        if (udev_enumerate == NULL)
                return -EINVAL;
        if (sysattr == NULL)
                return 0;
        if (udev_list_entry_add(udev_enumerate_get_udev(udev_enumerate),
-                          &udev_enumerate->sysattr_nomatch_list, sysattr, value, 0, 0) == NULL)
+                          &udev_enumerate->sysattr_nomatch_list, sysattr, value, 0) == NULL)
                return -ENOMEM;
        return 0;
 }
 
-static int match_sysattr_value(struct udev *udev, const char *syspath, const char *sysattr, const char *match_val)
+static int match_sysattr_value(struct udev_device *dev, const char *sysattr, const char *match_val)
 {
-       struct udev_device *device;
        const char *val = NULL;
        bool match = false;
 
-       device = udev_device_new_from_syspath(udev, syspath);
-       if (device == NULL)
-               return -EINVAL;
-       val = udev_device_get_sysattr_value(device, sysattr);
+       val = udev_device_get_sysattr_value(dev, sysattr);
        if (val == NULL)
                goto exit;
        if (match_val == NULL) {
@@ -362,7 +417,6 @@ static int match_sysattr_value(struct udev *udev, const char *syspath, const cha
                goto exit;
        }
 exit:
-       udev_device_unref(device);
        return match;
 }
 
@@ -374,18 +428,63 @@ exit:
  *
  * Returns: 0 on success, otherwise a negative error value.
  */
-int udev_enumerate_add_match_property(struct udev_enumerate *udev_enumerate, const char *property, const char *value)
+UDEV_EXPORT int udev_enumerate_add_match_property(struct udev_enumerate *udev_enumerate, const char *property, const char *value)
 {
        if (udev_enumerate == NULL)
                return -EINVAL;
        if (property == NULL)
                return 0;
        if (udev_list_entry_add(udev_enumerate_get_udev(udev_enumerate),
-                               &udev_enumerate->properties_match_list, property, value, 0, 0) == NULL)
+                               &udev_enumerate->properties_match_list, property, value, 0) == NULL)
+               return -ENOMEM;
+       return 0;
+}
+
+/**
+ * udev_enumerate_add_match_tag:
+ * @udev_enumerate: context
+ * @tag: filter for a tag of the device to include in the list
+ *
+ * Returns: 0 on success, otherwise a negative error value.
+ */
+UDEV_EXPORT int udev_enumerate_add_match_tag(struct udev_enumerate *udev_enumerate, const char *tag)
+{
+       if (udev_enumerate == NULL)
+               return -EINVAL;
+       if (tag == NULL)
+               return 0;
+       if (udev_list_entry_add(udev_enumerate_get_udev(udev_enumerate),
+                               &udev_enumerate->tags_match_list, tag, NULL, UDEV_LIST_UNIQUE) == NULL)
                return -ENOMEM;
        return 0;
 }
 
+/**
+ * udev_enumerate_add_match_is_initialized:
+ * @udev_enumerate: context
+ *
+ * Match only devices which udev has set up already. This makes
+ * sure, that the device node permissions and context are properly set
+ * and that network devices are fully renamed.
+ *
+ * Usually, devices which are found in the kernel but not already
+ * handled by udev, have still pending events. Services should subscribe
+ * to monitor events and wait for these devices to become ready, instead
+ * of using uninitialized devices.
+ *
+ * For now, this will not affect devices which do not have a device node
+ * and are not network interfaces.
+ *
+ * Returns: 0 on success, otherwise a negative error value.
+ */
+UDEV_EXPORT int udev_enumerate_add_match_is_initialized(struct udev_enumerate *udev_enumerate)
+{
+       if (udev_enumerate == NULL)
+               return -EINVAL;
+       udev_enumerate->match_is_initialized = true;
+       return 0;
+}
+
 /**
  * udev_enumerate_add_match_sysname:
  * @udev_enumerate: context
@@ -393,58 +492,49 @@ int udev_enumerate_add_match_property(struct udev_enumerate *udev_enumerate, con
  *
  * Returns: 0 on success, otherwise a negative error value.
  */
-int udev_enumerate_add_match_sysname(struct udev_enumerate *udev_enumerate, const char *sysname)
+UDEV_EXPORT int udev_enumerate_add_match_sysname(struct udev_enumerate *udev_enumerate, const char *sysname)
 {
        if (udev_enumerate == NULL)
                return -EINVAL;
        if (sysname == NULL)
                return 0;
        if (udev_list_entry_add(udev_enumerate_get_udev(udev_enumerate),
-                               &udev_enumerate->sysname_match_list, sysname, NULL, 1, 0) == NULL)
+                               &udev_enumerate->sysname_match_list, sysname, NULL, UDEV_LIST_UNIQUE) == NULL)
                return -ENOMEM;
        return 0;
 }
 
-static int match_sysattr(struct udev_enumerate *udev_enumerate, const char *syspath)
+static bool match_sysattr(struct udev_enumerate *udev_enumerate, struct udev_device *dev)
 {
-       struct udev *udev = udev_enumerate_get_udev(udev_enumerate);
        struct udev_list_entry *list_entry;
 
        /* skip list */
        udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_enumerate->sysattr_nomatch_list)) {
-               if (match_sysattr_value(udev, syspath,
-                                    udev_list_entry_get_name(list_entry),
-                                    udev_list_entry_get_value(list_entry)))
-                       return 0;
+               if (match_sysattr_value(dev, udev_list_entry_get_name(list_entry),
+                                       udev_list_entry_get_value(list_entry)))
+                       return false;
        }
        /* include list */
        if (udev_list_get_entry(&udev_enumerate->sysattr_match_list) != NULL) {
                udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_enumerate->sysattr_match_list)) {
                        /* anything that does not match, will make it FALSE */
-                       if (!match_sysattr_value(udev, syspath,
-                                             udev_list_entry_get_name(list_entry),
-                                             udev_list_entry_get_value(list_entry)))
-                               return 0;
+                       if (!match_sysattr_value(dev, udev_list_entry_get_name(list_entry),
+                                                udev_list_entry_get_value(list_entry)))
+                               return false;
                }
-               return 1;
+               return true;
        }
-       return 1;
+       return true;
 }
 
-static int match_property(struct udev_enumerate *udev_enumerate, const char *syspath)
+static bool match_property(struct udev_enumerate *udev_enumerate, struct udev_device *dev)
 {
-       struct udev_device *dev;
        struct udev_list_entry *list_entry;
-       int match = false;
+       bool match = false;
 
        /* no match always matches */
        if (udev_list_get_entry(&udev_enumerate->properties_match_list) == NULL)
-               return 1;
-
-       /* no device does not match */
-       dev = udev_device_new_from_syspath(udev_enumerate->udev, syspath);
-       if (dev == NULL)
-               return 0;
+               return true;
 
        /* loop over matches */
        udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_enumerate->properties_match_list)) {
@@ -472,23 +562,38 @@ static int match_property(struct udev_enumerate *udev_enumerate, const char *sys
                }
        }
 out:
-       udev_device_unref(dev);
        return match;
 }
 
-static int match_sysname(struct udev_enumerate *udev_enumerate, const char *sysname)
+static bool match_tag(struct udev_enumerate *udev_enumerate, struct udev_device *dev)
+{
+       struct udev_list_entry *list_entry;
+
+       /* no match always matches */
+       if (udev_list_get_entry(&udev_enumerate->tags_match_list) == NULL)
+               return true;
+
+       /* loop over matches */
+       udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_enumerate->tags_match_list))
+               if (!udev_device_has_tag(dev, udev_list_entry_get_name(list_entry)))
+                       return false;
+
+       return true;
+}
+
+static bool match_sysname(struct udev_enumerate *udev_enumerate, const char *sysname)
 {
        struct udev_list_entry *list_entry;
 
        if (udev_list_get_entry(&udev_enumerate->sysname_match_list) == NULL)
-               return 1;
+               return true;
 
        udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_enumerate->sysname_match_list)) {
                if (fnmatch(udev_list_entry_get_name(list_entry), sysname, 0) != 0)
                        continue;
-               return 1;
+               return true;
        }
-       return 0;
+       return false;
 }
 
 static int scan_dir_and_add_devices(struct udev_enumerate *udev_enumerate,
@@ -506,57 +611,71 @@ static int scan_dir_and_add_devices(struct udev_enumerate *udev_enumerate,
        if (subdir1 != NULL)
                l = util_strpcpyl(&s, l, "/", subdir1, NULL);
        if (subdir2 != NULL)
-               l = util_strpcpyl(&s, l, "/", subdir2, NULL);
+               util_strpcpyl(&s, l, "/", subdir2, NULL);
        dir = opendir(path);
        if (dir == NULL)
-               return -1;
+               return -ENOENT;
        for (dent = readdir(dir); dent != NULL; dent = readdir(dir)) {
                char syspath[UTIL_PATH_SIZE];
-               char filename[UTIL_PATH_SIZE];
-               struct stat statbuf;
+               struct udev_device *dev;
 
                if (dent->d_name[0] == '.')
                        continue;
+
                if (!match_sysname(udev_enumerate, dent->d_name))
                        continue;
 
                util_strscpyl(syspath, sizeof(syspath), path, "/", dent->d_name, NULL);
-               if (lstat(syspath, &statbuf) != 0)
-                       continue;
-               if (S_ISREG(statbuf.st_mode))
+               dev = udev_device_new_from_syspath(udev_enumerate->udev, syspath);
+               if (dev == NULL)
                        continue;
-               if (S_ISLNK(statbuf.st_mode))
-                       util_resolve_sys_link(udev, syspath, sizeof(syspath));
 
-               util_strscpyl(filename, sizeof(filename), syspath, "/uevent", NULL);
-               if (stat(filename, &statbuf) != 0)
-                       continue;
-               if (!match_sysattr(udev_enumerate, syspath))
-                       continue;
-               if (!match_property(udev_enumerate, syspath))
-                       continue;
-               syspath_add(udev_enumerate, syspath);
+               if (udev_enumerate->match_is_initialized) {
+                       /*
+                        * All devices with a device node or network interfaces
+                        * possibly need udev to adjust the device node permission
+                        * or context, or rename the interface before it can be
+                        * reliably used from other processes.
+                        *
+                        * For now, we can only check these types of devices, we
+                        * might not store a database, and have no way to find out
+                        * for all other types of devices.
+                        */
+                       if (!udev_device_get_is_initialized(dev) &&
+                           (major(udev_device_get_devnum(dev)) > 0 || udev_device_get_ifindex(dev) > 0))
+                               goto nomatch;
+               }
+               if (!match_tag(udev_enumerate, dev))
+                       goto nomatch;
+               if (!match_property(udev_enumerate, dev))
+                       goto nomatch;
+               if (!match_sysattr(udev_enumerate, dev))
+                       goto nomatch;
+
+               syspath_add(udev_enumerate, udev_device_get_syspath(dev));
+nomatch:
+               udev_device_unref(dev);
        }
        closedir(dir);
        return 0;
 }
 
-static int match_subsystem(struct udev_enumerate *udev_enumerate, const char *subsystem)
+static bool match_subsystem(struct udev_enumerate *udev_enumerate, const char *subsystem)
 {
        struct udev_list_entry *list_entry;
 
        udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_enumerate->subsystem_nomatch_list)) {
                if (fnmatch(udev_list_entry_get_name(list_entry), subsystem, 0) == 0)
-                       return 0;
+                       return false;
        }
        if (udev_list_get_entry(&udev_enumerate->subsystem_match_list) != NULL) {
                udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_enumerate->subsystem_match_list)) {
                        if (fnmatch(udev_list_entry_get_name(list_entry), subsystem, 0) == 0)
-                               return 1;
+                               return true;
                }
-               return 0;
+               return false;
        }
-       return 1;
+       return true;
 }
 
 static int scan_dir(struct udev_enumerate *udev_enumerate, const char *basedir, const char *subdir, const char *subsystem)
@@ -591,7 +710,7 @@ static int scan_dir(struct udev_enumerate *udev_enumerate, const char *basedir,
  *
  * Returns: 0 on success, otherwise a negative error value.
  */
-int udev_enumerate_add_syspath(struct udev_enumerate *udev_enumerate, const char *syspath)
+UDEV_EXPORT int udev_enumerate_add_syspath(struct udev_enumerate *udev_enumerate, const char *syspath)
 {
        struct udev_device *udev_device;
 
@@ -614,7 +733,7 @@ int udev_enumerate_add_syspath(struct udev_enumerate *udev_enumerate, const char
  *
  * Returns: 0 on success, otherwise a negative error value.
  **/
-int udev_enumerate_scan_devices(struct udev_enumerate *udev_enumerate)
+UDEV_EXPORT int udev_enumerate_scan_devices(struct udev_enumerate *udev_enumerate)
 {
        struct udev *udev = udev_enumerate_get_udev(udev_enumerate);
        char base[UTIL_PATH_SIZE];
@@ -622,29 +741,60 @@ int udev_enumerate_scan_devices(struct udev_enumerate *udev_enumerate)
 
        if (udev_enumerate == NULL)
                return -EINVAL;
-       util_strscpyl(base, sizeof(base), udev_get_sys_path(udev), "/subsystem", NULL);
-       if (stat(base, &statbuf) == 0) {
-               /* we have /subsystem/, forget all the old stuff */
-               dbg(udev, "searching '/subsystem/*/devices/*' dir\n");
-               scan_dir(udev_enumerate, "subsystem", "devices", NULL);
+
+       if (udev_list_get_entry(&udev_enumerate->tags_match_list) != NULL) {
+               struct udev_list_entry *list_entry;
+
+               /* scan only tagged devices, use tags reverse-index, instead of searching all devices in /sys */
+               udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_enumerate->tags_match_list)) {
+                       DIR *dir;
+                       struct dirent *dent;
+                       char path[UTIL_PATH_SIZE];
+
+                       util_strscpyl(path, sizeof(path), udev_get_run_path(udev), "/tags/",
+                                     udev_list_entry_get_name(list_entry), NULL);
+                       dir = opendir(path);
+                       if (dir == NULL)
+                               continue;
+                       for (dent = readdir(dir); dent != NULL; dent = readdir(dir)) {
+                               struct udev_device *dev;
+
+                               if (dent->d_name[0] == '.')
+                                       continue;
+
+                               dev = udev_device_new_from_id_filename(udev_enumerate->udev, dent->d_name);
+                               if (dev == NULL)
+                                       continue;
+
+                               if (!match_subsystem(udev_enumerate, udev_device_get_subsystem(dev)))
+                                       goto nomatch;
+                               if (!match_sysname(udev_enumerate, udev_device_get_sysname(dev)))
+                                       goto nomatch;
+                               if (!match_property(udev_enumerate, dev))
+                                       goto nomatch;
+                               if (!match_sysattr(udev_enumerate, dev))
+                                       goto nomatch;
+
+                               syspath_add(udev_enumerate, udev_device_get_syspath(dev));
+nomatch:
+                               udev_device_unref(dev);
+                       }
+                       closedir(dir);
+               }
        } else {
+               util_strscpyl(base, sizeof(base), udev_get_sys_path(udev), "/subsystem", NULL);
+               if (stat(base, &statbuf) == 0) {
+                       /* we have /subsystem/, forget all the old stuff */
+                       dbg(udev, "searching '/subsystem/*/devices/*' dir\n");
+                       scan_dir(udev_enumerate, "subsystem", "devices", NULL);
+               } else {
                dbg(udev, "searching '/bus/*/devices/*' dir\n");
-               scan_dir(udev_enumerate, "bus", "devices", NULL);
-               dbg(udev, "searching '/class/*' dir\n");
-               scan_dir(udev_enumerate, "class", NULL, NULL);
-               /* if block isn't a class, scan /block/ */
-               util_strscpyl(base, sizeof(base), udev_get_sys_path(udev), "/class/block", NULL);
-               if (stat(base, &statbuf) != 0) {
-                       if (match_subsystem(udev_enumerate, "block")) {
-                               dbg(udev, "searching '/block/*' dir\n");
-                               /* scan disks */
-                               scan_dir_and_add_devices(udev_enumerate, "block", NULL, NULL);
-                               /* scan partitions */
-                               dbg(udev, "searching '/block/*/*' dir\n");
-                               scan_dir(udev_enumerate, "block", NULL, "block");
-                       }
+                       scan_dir(udev_enumerate, "bus", "devices", NULL);
+                       dbg(udev, "searching '/class/*' dir\n");
+                       scan_dir(udev_enumerate, "class", NULL, NULL);
                }
        }
+
        return 0;
 }
 
@@ -654,7 +804,7 @@ int udev_enumerate_scan_devices(struct udev_enumerate *udev_enumerate)
  *
  * Returns: 0 on success, otherwise a negative error value.
  **/
-int udev_enumerate_scan_subsystems(struct udev_enumerate *udev_enumerate)
+UDEV_EXPORT int udev_enumerate_scan_subsystems(struct udev_enumerate *udev_enumerate)
 {
        struct udev *udev = udev_enumerate_get_udev(udev_enumerate);
        char base[UTIL_PATH_SIZE];
@@ -663,15 +813,26 @@ int udev_enumerate_scan_subsystems(struct udev_enumerate *udev_enumerate)
 
        if (udev_enumerate == NULL)
                return -EINVAL;
+
+       /* all kernel modules */
+       if (match_subsystem(udev_enumerate, "module")) {
+               dbg(udev, "searching '%s/modules/*' dir\n", subsysdir);
+               scan_dir_and_add_devices(udev_enumerate, "module", NULL, NULL);
+       }
+
        util_strscpyl(base, sizeof(base), udev_get_sys_path(udev), "/subsystem", NULL);
        if (stat(base, &statbuf) == 0)
                subsysdir = "subsystem";
        else
                subsysdir = "bus";
+
+       /* all subsystems (only buses support coldplug) */
        if (match_subsystem(udev_enumerate, "subsystem")) {
                dbg(udev, "searching '%s/*' dir\n", subsysdir);
                scan_dir_and_add_devices(udev_enumerate, subsysdir, NULL, NULL);
        }
+
+       /* all subsystem drivers */
        if (match_subsystem(udev_enumerate, "drivers")) {
                dbg(udev, "searching '%s/*/drivers/*' dir\n", subsysdir);
                scan_dir(udev_enumerate, subsysdir, "drivers", "drivers");