udevd: use dev_t or netif ifindex as database key

We need to preserve the database of network interfaces while we
rename them. Use the kernel's numbers wherever possible, instead
of the device names.

Fix wrong database filenames which contain a '/', translated
from '!' in the kernel name.

Fix segfault for kobject pathes where the subsystem can not be
determined from sysfs.

1 files changed, 49 insertions, 2 deletions

diff --git a/libudev/libudev-device.c b/libudev/libudev-device.c
index 9b5d79ff4b..d87b0c6c8a 100644
--- a/libudev/libudev-device.c
+++ b/libudev/libudev-device.c
@@ -54,6 +54,7 @@ struct udev_device {
 	char *devpath_old;
 	char *sysname_old;
 	char *knodename;
+	char *id_filename;
 	char **envp;
 	char *monitor_buf;
 	size_t monitor_buf_len;
@@ -230,6 +231,7 @@ const char *udev_device_get_property_value(struct udev_device *udev_device, cons
 
 int udev_device_read_db(struct udev_device *udev_device)
 {
+	const char *id;
 	struct stat stats;
 	char filename[UTIL_PATH_SIZE];
 	char line[UTIL_LINE_SIZE];
@@ -238,8 +240,10 @@ int udev_device_read_db(struct udev_device *udev_device)
 	if (udev_device->db_loaded)
 		return 0;
 
-	util_strscpyl(filename, sizeof(filename), udev_get_dev_path(udev_device->udev), "/.udev/db/",
-		      udev_device_get_subsystem(udev_device), ":", udev_device_get_sysname(udev_device), NULL);
+	id = udev_device_get_id_filename(udev_device);
+	if (id == NULL)
+		return -1;
+	util_strscpyl(filename, sizeof(filename), udev_get_dev_path(udev_device->udev), "/.udev/db/", id, NULL);
 
 	if (lstat(filename, &stats) != 0) {
 		dbg(udev_device->udev, "no db file to read %s: %m\n", filename);
@@ -799,6 +803,7 @@ void udev_device_unref(struct udev_device *udev_device)
 	free(udev_device->devpath_old);
 	free(udev_device->sysname_old);
 	free(udev_device->knodename);
+	free(udev_device->id_filename);
 	free(udev_device->envp);
 	free(udev_device->monitor_buf);
 	dbg(udev_device->udev, "udev_device: %p released\n", udev_device);
@@ -1287,6 +1292,40 @@ int udev_device_add_devlink(struct udev_device *udev_device, const char *devlink
 	return 0;
 }
 
+const char *udev_device_get_id_filename(struct udev_device *udev_device)
+{
+	if (udev_device->id_filename == NULL) {
+		if (udev_device_get_subsystem(udev_device) == NULL)
+			return NULL;
+
+		if (major(udev_device_get_devnum(udev_device)) > 0) {
+			/* use dev_t -- b259:131072, c254:0 */
+			if (asprintf(&udev_device->id_filename, "%c%u:%u",
+				     strcmp(udev_device_get_subsystem(udev_device), "block") == 0 ? 'b' : 'c',
+				     major(udev_device_get_devnum(udev_device)),
+				     minor(udev_device_get_devnum(udev_device))) < 0)
+				udev_device->id_filename = NULL;
+		} else if (strcmp(udev_device_get_subsystem(udev_device), "net") == 0) {
+			/* use netdev ifindex -- n3 */
+			if (asprintf(&udev_device->id_filename, "n%u", udev_device_get_ifindex(udev_device)) < 0)
+				udev_device->id_filename = NULL;
+		} else {
+			/*
+			 * use $subsys:$syname -- pci:0000:00:1f.2
+			 * sysname() has '!' translated, get it from devpath
+			 */
+			const char *sysname;
+			sysname = strrchr(udev_device->devpath, '/');
+			if (sysname == NULL)
+				return NULL;
+			sysname = &sysname[1];
+			if (asprintf(&udev_device->id_filename, "+%s:%s", udev_device_get_subsystem(udev_device), sysname) < 0)
+				udev_device->id_filename = NULL;
+		}
+	}
+	return udev_device->id_filename;
+}
+
 int udev_device_add_tag(struct udev_device *udev_device, const char *tag)
 {
 	if (strchr(tag, ':') != NULL || strchr(tag, ' ') != NULL)
@@ -1500,7 +1539,11 @@ int udev_device_get_event_timeout(struct udev_device *udev_device)
 
 int udev_device_set_event_timeout(struct udev_device *udev_device, int event_timeout)
 {
+	char num[32];
+
 	udev_device->event_timeout = event_timeout;
+	snprintf(num, sizeof(num), "%u", event_timeout);
+	udev_device_add_property(udev_device, "TIMEOUT", num);
 	return 0;
 }
 
@@ -1560,6 +1603,10 @@ int udev_device_get_ifindex(struct udev_device *udev_device)
 
 int udev_device_set_ifindex(struct udev_device *udev_device, int ifindex)
 {
+	char num[32];
+
 	udev_device->ifindex = ifindex;
+	snprintf(num, sizeof(num), "%u", ifindex);
+	udev_device_add_property(udev_device, "IFINDEX", num);
 	return 0;
 }