X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=udev_sysfs.c;h=7431dd6111692ec0afcd73ff2af56626a6b43747;hp=c4afe0cffba90a95f88ecf4feef4928e3073f765;hb=2658afdcf147afd384e27f0ac9019e27de7ba397;hpb=95776dc6ec174f47fa4dd4d8abf5d457223e5dd4

diff --git a/udev_sysfs.c b/udev_sysfs.c
index c4afe0cff..7431dd611 100644
--- a/udev_sysfs.c
+++ b/udev_sysfs.c
@@ -1,7 +1,5 @@
 /*
- * udev_sysfs.c - sysfs access
- *
- * Copyright (C) 2005 Kay Sievers <kay.sievers@vrfy.org>
+ * Copyright (C) 2005-2006 Kay Sievers <kay.sievers@vrfy.org>
  *
  *	This program is free software; you can redistribute it and/or modify it
  *	under the terms of the GNU General Public License as published by the
@@ -14,7 +12,7 @@
  * 
  *	You should have received a copy of the GNU General Public License along
  *	with this program; if not, write to the Free Software Foundation, Inc.,
- *	675 Mass Ave, Cambridge, MA 02139, USA.
+ *	51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  *
  */
 
@@ -114,6 +112,38 @@ void sysfs_device_set_values(struct sysfs_device *dev, const char *devpath,
 	dbg("kernel_number='%s'", dev->kernel_number);
 }
 
+int sysfs_resolve_link(char *devpath, size_t size)
+{
+	char link_path[PATH_SIZE];
+	char link_target[PATH_SIZE];
+	int len;
+	int i;
+	int back;
+
+	strlcpy(link_path, sysfs_path, sizeof(link_path));
+	strlcat(link_path, devpath, sizeof(link_path));
+	len = readlink(link_path, link_target, sizeof(link_target));
+	if (len <= 0)
+		return -1;
+	link_target[len] = '\0';
+	dbg("path link '%s' points to '%s'", devpath, link_target);
+
+	for (back = 0; strncmp(&link_target[back * 3], "../", 3) == 0; back++)
+		;
+	dbg("base '%s', tail '%s', back %i", devpath, &link_target[back * 3], back);
+	for (i = 0; i <= back; i++) {
+		char *pos = strrchr(devpath, '/');
+
+		if (pos == NULL)
+			return -1;
+		pos[0] = '\0';
+	}
+	dbg("after moving back '%s'", devpath);
+	strlcat(devpath, "/", size);
+	strlcat(devpath, &link_target[back * 3], size);
+	return 0;
+}
+
 struct sysfs_device *sysfs_device_get(const char *devpath)
 {
 	char path[PATH_SIZE];
@@ -146,27 +176,8 @@ struct sysfs_device *sysfs_device_get(const char *devpath)
 		return NULL;
 	}
 	if (S_ISLNK(statbuf.st_mode)) {
-		int i;
-		int back;
-
-		len = readlink(path, link_target, sizeof(link_target));
-		if (len <= 0)
+		if (sysfs_resolve_link(devpath_real, sizeof(devpath_real)) != 0)
 			return NULL;
-		link_target[len] = '\0';
-		dbg("devpath link '%s' points to '%s'", path, link_target);
-
-		for (back = 0; strncmp(&link_target[back * 3], "../", 3) == 0; back++)
-			;
-		dbg("base '%s', tail '%s', back %i", devpath_real, &link_target[back * 3], back);
-		for (i = 0; i <= back; i++) {
-			pos = strrchr(devpath_real, '/');
-			if (pos == NULL)
-				return NULL;
-			pos[0] = '\0';
-		}
-		dbg("after moving back '%s'", devpath_real);
-		strlcat(devpath_real, "/", sizeof(devpath_real));
-		strlcat(devpath_real, &link_target[back * 3], sizeof(devpath_real));
 
 		/* now look for device in cache after path translation */
 		list_for_each_entry(dev_loop, &dev_list, node) {
@@ -186,8 +197,20 @@ struct sysfs_device *sysfs_device_get(const char *devpath)
 
 	sysfs_device_set_values(dev, devpath_real, NULL, NULL);
 
-	/* get subsystem */
-	if (strncmp(dev->devpath, "/class/", 7) == 0) {
+	/* get subsystem name */
+	strlcpy(link_path, sysfs_path, sizeof(link_path));
+	strlcat(link_path, dev->devpath, sizeof(link_path));
+	strlcat(link_path, "/subsystem", sizeof(link_path));
+	len = readlink(link_path, link_target, sizeof(link_target));
+	if (len > 0) {
+		/* get subsystem from "subsystem" link */
+		link_target[len] = '\0';
+		dbg("subsystem link '%s' points to '%s'", link_path, link_target);
+		pos = strrchr(link_target, '/');
+		if (pos != NULL)
+			strlcpy(dev->subsystem, &pos[1], sizeof(dev->subsystem));
+	} else if (strncmp(dev->devpath, "/class/", 7) == 0) {
+		/* get subsystem from class dir */
 		strlcpy(dev->subsystem, &dev->devpath[7], sizeof(dev->subsystem));
 		pos = strchr(dev->subsystem, '/');
 		if (pos != NULL)
@@ -208,38 +231,26 @@ struct sysfs_device *sysfs_device_get(const char *devpath)
 			pos = strrchr(link_target, '/');
 			if (pos != NULL)
 				strlcpy(dev->subsystem, &pos[1], sizeof(dev->subsystem));
-		} else {
-			/* get subsystem from "subsystem" link */
-			strlcpy(link_path, sysfs_path, sizeof(link_path));
-			strlcat(link_path, dev->devpath, sizeof(link_path));
-			strlcat(link_path, "/subsystem", sizeof(link_path));
-			len = readlink(link_path, link_target, sizeof(link_target));
-			if (len > 0) {
-				link_target[len] = '\0';
-				dbg("subsystem link '%s' points to '%s'", link_path, link_target);
-				pos = strrchr(link_target, '/');
-				if (pos != NULL)
-					strlcpy(dev->subsystem, &pos[1], sizeof(dev->subsystem));
-			}
 		}
-		/* get driver name */
-		strlcpy(link_path, sysfs_path, sizeof(link_path));
-		strlcat(link_path, dev->devpath, sizeof(link_path));
-		strlcat(link_path, "/driver", sizeof(link_path));
-		len = readlink(link_path, link_target, sizeof(link_target));
-		if (len > 0) {
-			link_target[len] = '\0';
-			dbg("driver link '%s' points to '%s'", link_path, link_target);
-			pos = strrchr(link_target, '/');
-			if (pos != NULL)
-				strlcpy(dev->driver, &pos[1], sizeof(dev->driver));
-		}
-	} else if (strncmp(dev->devpath, "/bus/", 5) == 0 && strstr(dev->devpath, "/drivers/")) {
+	} else if (strstr(dev->devpath, "/drivers/") != NULL) {
 		strlcpy(dev->subsystem, "drivers", sizeof(dev->subsystem));
 	} else if (strncmp(dev->devpath, "/module/", 8) == 0) {
 		strlcpy(dev->subsystem, "module", sizeof(dev->subsystem));
 	}
 
+	/* get driver name */
+	strlcpy(link_path, sysfs_path, sizeof(link_path));
+	strlcat(link_path, dev->devpath, sizeof(link_path));
+	strlcat(link_path, "/driver", sizeof(link_path));
+	len = readlink(link_path, link_target, sizeof(link_target));
+	if (len > 0) {
+		link_target[len] = '\0';
+		dbg("driver link '%s' points to '%s'", link_path, link_target);
+		pos = strrchr(link_target, '/');
+		if (pos != NULL)
+			strlcpy(dev->driver, &pos[1], sizeof(dev->driver));
+	}
+
 	dbg("add to cache 'devpath=%s', subsystem='%s', driver='%s'", dev->devpath, dev->subsystem, dev->driver);
 	list_add(&dev->node, &dev_list);
 
@@ -249,12 +260,7 @@ struct sysfs_device *sysfs_device_get(const char *devpath)
 struct sysfs_device *sysfs_device_get_parent(struct sysfs_device *dev)
 {
 	char parent_devpath[PATH_SIZE];
-	char device_link[PATH_SIZE];
-	char device_link_target[PATH_SIZE];
 	char *pos;
-	int i;
-	int len;
-	int back;
 
 	dbg("open '%s'", dev->devpath);
 
@@ -264,6 +270,7 @@ struct sysfs_device *sysfs_device_get_parent(struct sysfs_device *dev)
 
 	/* requesting a parent is only valid for devices */
 	if ((strncmp(dev->devpath, "/devices/", 9) != 0) &&
+	    (strncmp(dev->devpath, "/subsystem/", 11) != 0) &&
 	    (strncmp(dev->devpath, "/class/", 7) != 0) &&
 	    (strncmp(dev->devpath, "/block/", 7) != 0))
 		return NULL;
@@ -283,10 +290,13 @@ struct sysfs_device *sysfs_device_get_parent(struct sysfs_device *dev)
 		return NULL;
 	}
 
-	/* at the top level of class/block we want to follow the "device" link */
-	if (strcmp(parent_devpath, "/block") == 0) {
-		dbg("/block top level, look for device link");
-		goto device_link;
+	/* at the subsystems top level we want to follow the old-style "device" link */
+	if (strncmp(parent_devpath, "/subsystem", 10) == 0) {
+		pos = strrchr(parent_devpath, '/');
+		if (pos == &parent_devpath[10] || pos == parent_devpath || strcmp(pos, "/devices") == 0) {
+			dbg("/subsystem top level, look for device link");
+			goto device_link;
+		}
 	}
 	if (strncmp(parent_devpath, "/class", 6) == 0) {
 		pos = strrchr(parent_devpath, '/');
@@ -295,33 +305,20 @@ struct sysfs_device *sysfs_device_get_parent(struct sysfs_device *dev)
 			goto device_link;
 		}
 	}
+	if (strcmp(parent_devpath, "/block") == 0) {
+		dbg("/block top level, look for device link");
+		goto device_link;
+	}
+
 	/* get parent and remember it */
 	dev->parent = sysfs_device_get(parent_devpath);
 	return dev->parent;
 
 device_link:
-	strlcpy(device_link, sysfs_path, sizeof(device_link));
-	strlcat(device_link, dev->devpath, sizeof(device_link));
-	strlcat(device_link, "/device", sizeof(device_link));
-	len = readlink(device_link, device_link_target, sizeof(device_link_target));
-	if (len < 0)
-		return NULL;
-	device_link_target[len] = '\0';
-	dbg("device link '%s' points to '%s'", device_link, device_link_target);
-
-	for (back = 0; strncmp(&device_link_target[back * 3], "../", 3) == 0; back++)
-		;
 	strlcpy(parent_devpath, dev->devpath, sizeof(parent_devpath));
-	dbg("base='%s', tail='%s', back=%i", parent_devpath, &device_link_target[back * 3], back);
-	for (i = 0; i < back; i++) {
-		pos = strrchr(parent_devpath, '/');
-		if (pos == NULL)
-			return NULL;
-		pos[0] = '\0';
-	}
-	dbg("after moving back '%s'", parent_devpath);
-	strlcat(parent_devpath, "/", sizeof(parent_devpath));
-	strlcat(parent_devpath, &device_link_target[back * 3], sizeof(parent_devpath));
+	strlcat(parent_devpath, "/device", sizeof(parent_devpath));
+	if (sysfs_resolve_link(parent_devpath, sizeof(parent_devpath)) != 0)
+		return NULL;
 
 	/* get parent and remember it */
 	dev->parent = sysfs_device_get(parent_devpath);
@@ -348,6 +345,7 @@ char *sysfs_attr_get_value(const char *devpath, const char *attr_name)
 	char value[NAME_SIZE];
 	struct sysfs_attr *attr_loop;
 	struct sysfs_attr *attr;
+	struct stat statbuf;
 	int fd;
 	ssize_t size;
 	size_t sysfs_len;
@@ -377,6 +375,38 @@ char *sysfs_attr_get_value(const char *devpath, const char *attr_name)
 	dbg("add to cache '%s'", path_full);
 	list_add(&attr->node, &attr_list);
 
+	if (lstat(path_full, &statbuf) != 0) {
+		dbg("stat '%s' failed: %s", path_full, strerror(errno));
+		goto out;
+	}
+
+	if (S_ISLNK(statbuf.st_mode)) {
+		/* links return the last element of the target path */
+		char link_target[PATH_SIZE];
+		int len;
+		const char *pos;
+
+		len = readlink(path_full, link_target, sizeof(link_target));
+		if (len > 0) {
+			link_target[len] = '\0';
+			pos = strrchr(link_target, '/');
+			if (pos != NULL) {
+				dbg("cache '%s' with link value '%s'", path_full, value);
+				strlcpy(attr->value_local, &pos[1], sizeof(attr->value_local));
+				attr->value = attr->value_local;
+			}
+		}
+		goto out;
+	}
+
+	/* skip directories */
+	if (S_ISDIR(statbuf.st_mode))
+		goto out;
+
+	/* skip non-readable files */
+	if ((statbuf.st_mode & S_IRUSR) == 0)
+		goto out;
+
 	/* read attribute value */
 	fd = open(path_full, O_RDONLY);
 	if (fd < 0) {
@@ -393,7 +423,7 @@ char *sysfs_attr_get_value(const char *devpath, const char *attr_name)
 	/* got a valid value, store and return it */
 	value[size] = '\0';
 	remove_trailing_chars(value, '\n');
-	dbg("cache '%s' with value '%s'", path_full, value);
+	dbg("cache '%s' with attribute value '%s'", path_full, value);
 	strlcpy(attr->value_local, value, sizeof(attr->value_local));
 	attr->value = attr->value_local;