[PATCH] libsysfs 0.4.0 patch

Ananth released sysfsutils 0.4.0 last night, I'm sure you saw the email.
Here's a patch with the latest changes from the pre-patch I already
gave you. It includes sysfs_get_device_parent(), which you said you
needed. I've run your test scripts and I've built scsi_id. Please
play around with this and check it out.

There are quite a few changes. Please do not access
structure pointers, like sysfs_device's parent, directly like
dev->parent. Please use the "get" function to retrieve. The functions
load things on demand and refresh views under the covers.

9 files changed, 236 insertions, 176 deletions

diff --git a/extras/scsi_id/scsi_id.c b/extras/scsi_id/scsi_id.c
index 3a34643c81..6bb41132de 100644
--- a/extras/scsi_id/scsi_id.c
+++ b/extras/scsi_id/scsi_id.c
@@ -158,7 +158,7 @@ static int get_major_minor(const char *devpath, int *major, int *minor)
 	char *dev;
 
 	dprintf("%s\n", devpath);
-	class_dev = sysfs_open_class_device(devpath);
+	class_dev = sysfs_open_class_device_path(devpath);
 	if (!class_dev) {
 		log_message(LOG_WARNING, "open class %s failed: %s\n", devpath,
 			    strerror(errno));
@@ -708,7 +708,7 @@ static int scsi_id(const char *target_path, char *maj_min_dev)
 		return 1;
 	}
 
-	scsi_dev = sysfs_open_class_device(full_dev_path);
+	scsi_dev = sysfs_open_class_device_path(full_dev_path);
 	if (!scsi_dev) {
 		log_message(LOG_WARNING, "open class %s failed: %s\n",
 			    full_dev_path, strerror(errno));
diff --git a/libsysfs/libsysfs.h b/libsysfs/libsysfs.h
index aca25772b5..2ffe1005cc 100644
--- a/libsysfs/libsysfs.h
+++ b/libsysfs/libsysfs.h
@@ -182,7 +182,9 @@ extern struct sysfs_attribute *sysfs_get_directory_attribute
 
 /* sysfs driver access */
 extern void sysfs_close_driver(struct sysfs_driver *driver);
-extern struct sysfs_driver *sysfs_open_driver(const unsigned char *path);
+extern struct sysfs_driver *sysfs_open_driver
+	(const unsigned char *drv_name, const unsigned char *bus_name);
+extern struct sysfs_driver *sysfs_open_driver_path(const unsigned char *path);
 extern struct sysfs_attribute *sysfs_get_driver_attr
 		(struct sysfs_driver *drv, const unsigned char *name);
 extern struct dlist *sysfs_get_driver_attributes(struct sysfs_driver *driver);
@@ -199,12 +201,13 @@ extern struct sysfs_root_device *sysfs_open_root_device
 						(const unsigned char *name);
 extern struct dlist *sysfs_get_root_devices(struct sysfs_root_device *root);
 extern void sysfs_close_device(struct sysfs_device *dev);
-extern struct sysfs_device *sysfs_open_device(const unsigned char *path);
+extern struct sysfs_device *sysfs_open_device
+		(const unsigned char *bus_id, const unsigned char *bus);
+extern struct sysfs_device *sysfs_get_device_parent(struct sysfs_device *dev);
+extern struct sysfs_device *sysfs_open_device_path(const unsigned char *path);
 extern struct sysfs_attribute *sysfs_get_device_attr
 			(struct sysfs_device *dev, const unsigned char *name);
 extern struct dlist *sysfs_get_device_attributes(struct sysfs_device *device);
-extern struct sysfs_device *sysfs_open_device_by_id
-		(const unsigned char *bus_id, const unsigned char *bus);
 extern struct sysfs_attribute *sysfs_open_device_attr(const unsigned char *bus, 
 		const unsigned char *bus_id, const unsigned char *attrib);
 
@@ -227,8 +230,10 @@ extern int sysfs_find_driver_bus(const unsigned char *driver,
 
 /* generic sysfs class access */
 extern void sysfs_close_class_device(struct sysfs_class_device *dev);
-extern struct sysfs_class_device *sysfs_open_class_device
+extern struct sysfs_class_device *sysfs_open_class_device_path
 					(const unsigned char *path);
+extern struct sysfs_class_device *sysfs_open_class_device
+	(const unsigned char *class, const unsigned char *name);
 extern struct sysfs_device *sysfs_get_classdev_device
 				(struct sysfs_class_device *clsdev);
 extern struct sysfs_driver *sysfs_get_classdev_driver
@@ -240,8 +245,6 @@ extern struct sysfs_class *sysfs_open_class(const unsigned char *name);
 extern struct dlist *sysfs_get_class_devices(struct sysfs_class *cls);
 extern struct sysfs_class_device *sysfs_get_class_device
 	(struct sysfs_class *class, unsigned char *name);
-extern struct sysfs_class_device *sysfs_open_class_device_by_name
-	(const unsigned char *class, const unsigned char *name);
 extern struct dlist *sysfs_get_classdev_attributes
 	(struct sysfs_class_device *cdev);
 extern struct sysfs_attribute *sysfs_get_classdev_attr
diff --git a/libsysfs/sysfs_bus.c b/libsysfs/sysfs_bus.c
index 3e6c22bbb1..d9da0f84cf 100644
--- a/libsysfs/sysfs_bus.c
+++ b/libsysfs/sysfs_bus.c
@@ -121,16 +121,20 @@ struct dlist *sysfs_get_bus_devices(struct sysfs_bus *bus)
 		return NULL;
 	}
 
-	dlist_for_each_data(devdir->links, curl, struct sysfs_link) {
-		bdev = sysfs_open_device(curl->target);
-		if (bdev == NULL) {
-			dprintf("Error opening device at %s\n",	curl->target);
-			continue;
+	if (devdir->links != 0) {
+		dlist_for_each_data(devdir->links, curl, struct sysfs_link) {
+			bdev = sysfs_open_device_path(curl->target);
+			if (bdev == NULL) {
+				dprintf("Error opening device at %s\n",	
+								curl->target);
+				continue;
+			}
+			if (bus->devices == NULL)
+				bus->devices = dlist_new_with_delete
+					(sizeof(struct sysfs_device), 
+					 		sysfs_close_dev);
+			dlist_unshift(bus->devices, bdev);
 		}
-		if (bus->devices == NULL)
-			bus->devices = dlist_new_with_delete
-				(sizeof(struct sysfs_device), sysfs_close_dev);
-		dlist_unshift(bus->devices, bdev);
 	}
 	sysfs_close_directory(devdir);
 
@@ -165,16 +169,21 @@ struct dlist *sysfs_get_bus_drivers(struct sysfs_bus *bus)
 		sysfs_close_directory(drvdir);
 		return NULL;
 	}
-	dlist_for_each_data(drvdir->subdirs, cursub, struct sysfs_directory) {
-		driver = sysfs_open_driver(cursub->path);
-		if (driver == NULL) {
-			dprintf("Error opening driver at %s\n",	cursub->path);
-			continue;
+	if (drvdir->subdirs != NULL) {
+		dlist_for_each_data(drvdir->subdirs, cursub, 
+						struct sysfs_directory) {
+			driver = sysfs_open_driver_path(cursub->path);
+			if (driver == NULL) {
+				dprintf("Error opening driver at %s\n",	
+								cursub->path);
+				continue;
+			}
+			if (bus->drivers == NULL)
+				bus->drivers = dlist_new_with_delete
+					(sizeof(struct sysfs_driver), 
+					 		sysfs_close_drv);
+			dlist_unshift(bus->drivers, driver);
 		}
-		if (bus->drivers == NULL)
-			bus->drivers = dlist_new_with_delete
-				(sizeof(struct sysfs_driver), sysfs_close_drv);
-		dlist_unshift(bus->drivers, driver);
 	}
 	sysfs_close_directory(drvdir);
 	return (bus->drivers);
@@ -347,10 +356,9 @@ struct sysfs_device *sysfs_open_bus_device(unsigned char *busname,
 		dprintf("Error getting sysfs mount point\n");
 		return NULL;
 	}
-	
+
 	if (sysfs_trailing_slash(path) == 0)
 		strcat(path, "/");
-
 	strcat(path, SYSFS_BUS_NAME);
 	strcat(path, "/");
 	strcat(path, busname);
@@ -359,7 +367,7 @@ struct sysfs_device *sysfs_open_bus_device(unsigned char *busname,
 	strcat(path, "/");
 	strcat(path, dev_id);
 
-	rdev = sysfs_open_device(path);
+	rdev = sysfs_open_device_path(path);
 	if (rdev == NULL) {
 		dprintf("Error getting device %s on bus %s\n",
 				dev_id, busname);
diff --git a/libsysfs/sysfs_class.c b/libsysfs/sysfs_class.c
index 169600d5fd..16eaf6e514 100644
--- a/libsysfs/sysfs_class.c
+++ b/libsysfs/sysfs_class.c
@@ -130,11 +130,12 @@ static void set_classdev_classname(struct sysfs_class_device *cdev)
 }
 
 /**
- * sysfs_open_class_device: Opens and populates class device
+ * sysfs_open_class_device_path: Opens and populates class device
  * @path: path to class device.
  * returns struct sysfs_class_device with success and NULL with error.
  */
-struct sysfs_class_device *sysfs_open_class_device(const unsigned char *path)
+struct sysfs_class_device *sysfs_open_class_device_path
+					(const unsigned char *path)
 {
 	struct sysfs_class_device *cdev = NULL;
 
@@ -184,22 +185,24 @@ struct dlist *sysfs_get_class_devices(struct sysfs_class *cls)
 			return NULL;
 	}
 
-	if ((sysfs_read_dir_subdirs(cls->directory) != 0) 
-	    || cls->directory->subdirs == NULL)
+	if ((sysfs_read_dir_subdirs(cls->directory)) != 0) 
 		return NULL;
 
-	dlist_for_each_data(cls->directory->subdirs, cur, 
-			struct sysfs_directory) {
-		dev = sysfs_open_class_device(cur->path);
-		if (dev == NULL) {
-			dprintf("Error opening device at %s\n",	cur->path);
-			continue;
-		}
-		if (cls->devices == NULL)
-			cls->devices = dlist_new_with_delete
+	if (cls->directory->subdirs != NULL) {
+		dlist_for_each_data(cls->directory->subdirs, cur, 
+						struct sysfs_directory) {
+			dev = sysfs_open_class_device_path(cur->path);
+			if (dev == NULL) {
+				dprintf("Error opening device at %s\n",	
+								cur->path);
+				continue;
+			}
+			if (cls->devices == NULL)
+				cls->devices = dlist_new_with_delete
 					(sizeof(struct sysfs_class_device),
 					 		sysfs_close_cls_dev);
-		dlist_unshift(cls->devices, dev);
+			dlist_unshift(cls->devices, dev);
+		}
 	}
 	return cls->devices;
 }
@@ -223,7 +226,6 @@ struct sysfs_class *sysfs_open_class(const unsigned char *name)
                 dprintf("Sysfs not supported on this system\n");
                 return NULL;
         }
-
 	if (sysfs_trailing_slash(classpath) == 0)
 		strcat(classpath, "/");
 
@@ -307,7 +309,7 @@ struct sysfs_device *sysfs_get_classdev_device
 	if (devlink == NULL) 
 		return NULL;
 
-	clsdev->sysdevice = sysfs_open_device(devlink->target);
+	clsdev->sysdevice = sysfs_open_device_path(devlink->target);
 	if (clsdev->sysdevice == NULL)
 		return NULL;
 	if (clsdev->driver != NULL) 
@@ -343,7 +345,7 @@ struct sysfs_driver *sysfs_get_classdev_driver
 	}
 	drvlink = sysfs_get_directory_link(clsdev->directory, "driver");
 	if (drvlink != NULL) {
-		clsdev->driver = sysfs_open_driver(drvlink->target);
+		clsdev->driver = sysfs_open_driver_path(drvlink->target);
 		if (clsdev->driver == NULL)
 			return NULL;
 			
@@ -401,7 +403,7 @@ static int get_blockdev_parent(struct sysfs_class_device *clsdev)
 		goto errout;
 
 	*c = '\0';
-	clsdev->parent = sysfs_open_class_device(parent_path);
+	clsdev->parent = sysfs_open_class_device_path(parent_path);
 	if (clsdev->parent == NULL) {
 		dprintf("Error opening the parent class device at %s\n", 
 								parent_path);
@@ -482,7 +484,7 @@ static int get_classdev_path(const unsigned char *classname,
 }
 
 /**
- * sysfs_open_class_device_by_name: Locates a specific class_device and returns it.
+ * sysfs_open_class_device: Locates a specific class_device and returns it.
  * Class_device must be closed using sysfs_close_class_device
  * @classname: Class to search
  * @name: name of the class_device
@@ -490,7 +492,7 @@ static int get_classdev_path(const unsigned char *classname,
  * NOTE:
  * 	Call sysfs_close_class_device() to close the class device
  */
-struct sysfs_class_device *sysfs_open_class_device_by_name
+struct sysfs_class_device *sysfs_open_class_device
 		(const unsigned char *classname, const unsigned char *name)
 {
 	unsigned char devpath[SYSFS_PATH_MAX];
@@ -509,7 +511,7 @@ struct sysfs_class_device *sysfs_open_class_device_by_name
 		return NULL;
 	}
 	
-	cdev = sysfs_open_class_device(devpath);
+	cdev = sysfs_open_class_device_path(devpath);
 	if (cdev == NULL) {
 		dprintf("Error getting class device %s from class %s\n",
 				name, classname);
@@ -572,32 +574,41 @@ struct sysfs_attribute *sysfs_get_classdev_attr
 		errno = EINVAL;
 		return NULL;
 	}
+	
 	/* 
 	 * First, see if it's in the current directory. Then look at 
 	 * subdirs since class devices can have subdirs of attributes.
 	 */ 
 	attrlist = sysfs_get_classdev_attributes(clsdev);
-	if (attrlist == NULL)
-		return NULL;
-	cur = sysfs_get_directory_attribute(clsdev->directory,
+	if (attrlist != NULL) {
+		cur = sysfs_get_directory_attribute(clsdev->directory,
 						(unsigned char *)name);
-	if (cur != NULL)
-		return cur;
+		if (cur != NULL)
+			return cur;
+	}
 
 	if (clsdev->directory->subdirs == NULL) 
 		if ((sysfs_read_dir_subdirs(clsdev->directory)) != 0 ||
 		    clsdev->directory->subdirs == NULL) 
 			return NULL;
 
-	dlist_for_each_data(clsdev->directory->subdirs, sdir,
-				struct sysfs_directory) {
-		cur = sysfs_get_directory_attribute(sdir, 
-						(unsigned char *)name);
-		if (cur != NULL)
-			return cur;
+	if (clsdev->directory->subdirs != NULL) {
+		dlist_for_each_data(clsdev->directory->subdirs, sdir,
+						struct sysfs_directory) {
+			if ((sysfs_path_is_dir(sdir->path)) != 0) 
+				continue;
+			if (sdir->attributes == NULL) {
+				cur = sysfs_get_directory_attribute(sdir,
+							(unsigned char *)name);
+			} else {
+				if ((sysfs_refresh_attributes
+						(sdir->attributes)) == 0)
+				cur = sysfs_get_directory_attribute(sdir, 
+							(unsigned char *)name);
+			}
+		}
 	}
-		
-	return NULL;
+	return cur;
 }
 
 /**
@@ -643,3 +654,4 @@ struct sysfs_attribute *sysfs_open_classdev_attr(const unsigned char *classname,
 	}
 	return attribute;
 }
+
diff --git a/libsysfs/sysfs_device.c b/libsysfs/sysfs_device.c
index 82b54719ff..66d5f9aef7 100644
--- a/libsysfs/sysfs_device.c
+++ b/libsysfs/sysfs_device.c
@@ -105,14 +105,6 @@ static void sysfs_close_device_tree(struct sysfs_device *devroot)
 }
 
 /**
- * sysfs_del_device: routine for dlist integration
- */
-static void sysfs_del_device(void *dev)
-{
-	sysfs_close_device((struct sysfs_device *)dev);
-}
-
-/**
  * sysfs_close_dev_tree: routine for dlist integration
  */
 static void sysfs_close_dev_tree(void *dev)
@@ -127,6 +119,8 @@ static void sysfs_close_dev_tree(void *dev)
 void sysfs_close_device(struct sysfs_device *dev)
 {
 	if (dev != NULL) {
+		if (dev->parent != NULL)
+			sysfs_close_device(dev->parent);
 		if (dev->directory != NULL)
 			sysfs_close_directory(dev->directory);
 		if (dev->children != NULL && dev->children->count == 0)
@@ -164,7 +158,7 @@ static struct sysfs_directory *open_device_dir(const unsigned char *path)
 		dprintf ("Device %s not supported on this system\n", path);
 		return NULL;
 	}
-	if ((sysfs_read_directory(rdir)) != 0) {
+	if ((sysfs_read_dir_subdirs(rdir)) != 0) {
 		dprintf ("Error reading device at dir %s\n", path);
 		sysfs_close_directory(rdir);
 		return NULL;
@@ -174,11 +168,11 @@ static struct sysfs_directory *open_device_dir(const unsigned char *path)
 }
 
 /**
- * sysfs_open_device: opens and populates device structure
+ * sysfs_open_device_path: opens and populates device structure
  * @path: path to device, this is the /sys/devices/ path
  * returns sysfs_device structure with success or NULL with error
  */
-struct sysfs_device *sysfs_open_device(const unsigned char *path)
+struct sysfs_device *sysfs_open_device_path(const unsigned char *path)
 {
 	struct sysfs_device *dev = NULL;
 
@@ -232,7 +226,7 @@ static struct sysfs_device *sysfs_open_device_tree(const unsigned char *path)
 		errno = EINVAL;
 		return NULL;
 	}
-	rootdev = sysfs_open_device(path);
+	rootdev = sysfs_open_device_path(path);
 	if (rootdev == NULL) {
 		dprintf("Error opening root device at %s\n", path);
 		return NULL;
@@ -255,7 +249,7 @@ static struct sysfs_device *sysfs_open_device_tree(const unsigned char *path)
 			if (rootdev->children == NULL)
 				rootdev->children = dlist_new_with_delete
 					(sizeof(struct sysfs_device),
-					sysfs_del_device);
+					sysfs_close_dev_tree);
 			dlist_unshift(rootdev->children, new);
 		}
 	}
@@ -342,7 +336,6 @@ struct sysfs_root_device *sysfs_open_root_device(const unsigned char *name)
 
 	if (sysfs_trailing_slash(rootpath) == 0)
 		strcat(rootpath, "/");
-
 	strcat(rootpath, SYSFS_DEVICES_NAME);
 	strcat(rootpath, "/");
 	strcat(rootpath, name);
@@ -357,6 +350,7 @@ struct sysfs_root_device *sysfs_open_root_device(const unsigned char *name)
 		dprintf("calloc failure\n");
 		return NULL;
 	}
+	strcpy(root->name, name);
 	strcpy(root->path, rootpath);
 	return root;
 }
@@ -416,10 +410,8 @@ struct sysfs_attribute *sysfs_get_device_attr(struct sysfs_device *dev,
 
 	cur = sysfs_get_directory_attribute(dev->directory, 
 			(unsigned char *)name);
-	if (cur != NULL)
-		return cur;
 
-	return NULL;
+	return cur;
 }
 
 /**
@@ -445,10 +437,8 @@ static int get_device_absolute_path(const unsigned char *device,
 		dprintf ("Sysfs not supported on this system\n");
 		return -1;
 	}
-
 	if (sysfs_trailing_slash(bus_path) == 0)
 		strcat(bus_path, "/");
-
 	strcat(bus_path, SYSFS_BUS_NAME);
 	strcat(bus_path, "/");
 	strcat(bus_path, bus);
@@ -468,7 +458,7 @@ static int get_device_absolute_path(const unsigned char *device,
 }
 
 /**
- * sysfs_open_device_by_id: open a device by id (use the "bus" subsystem)
+ * sysfs_open_device: open a device by id (use the "bus" subsystem)
  * @bus_id: bus_id of the device to open - has to be the "bus_id" in 
  * 		/sys/bus/xxx/devices
  * @bus: bus the device belongs to
@@ -478,7 +468,7 @@ static int get_device_absolute_path(const unsigned char *device,
  * 2. Bus the device is on must be supplied
  * 	Use sysfs_find_device_bus to get the bus name
  */
-struct sysfs_device *sysfs_open_device_by_id(const unsigned char *bus_id, 
+struct sysfs_device *sysfs_open_device(const unsigned char *bus_id, 
 						const unsigned char *bus)
 {
 	char sysfs_path[SYSFS_PATH_MAX];
@@ -495,7 +485,7 @@ struct sysfs_device *sysfs_open_device_by_id(const unsigned char *bus_id,
 		return NULL;
 	}
 	
-	device = sysfs_open_device(sysfs_path);
+	device = sysfs_open_device_path(sysfs_path);
 	if (device == NULL) {
 		dprintf("Error opening device %s\n", bus_id);
 		return NULL;
@@ -504,6 +494,60 @@ struct sysfs_device *sysfs_open_device_by_id(const unsigned char *bus_id,
 	return device;
 }
 
+/**
+ * sysfs_get_device_parent: opens up given device's parent and returns a 
+ * 	reference to its sysfs_device
+ * @dev: sysfs_device whose parent is requested
+ * Returns sysfs_device of the parent on success and NULL on failure
+ */
+struct sysfs_device *sysfs_get_device_parent(struct sysfs_device *dev)
+{
+	unsigned char ppath[SYSFS_PATH_MAX], *tmp = NULL;
+
+	if (dev == NULL) {
+		errno = EINVAL;
+		return NULL;
+	}
+
+	if (dev->parent != NULL)
+		return (dev->parent);
+
+	memset(ppath, 0, SYSFS_PATH_MAX);
+	strcpy(ppath, dev->path);
+	tmp = strrchr(ppath, '/');
+	if (tmp == NULL) {
+		dprintf("Invalid path to device %s\n", ppath);
+		return NULL;
+	}
+	if (*(tmp +1) == '\0') {
+		*tmp = '\0';
+		tmp = strrchr(tmp, '/');
+		if (tmp == NULL) {
+			dprintf("Invalid path to device %s\n", ppath);
+			return NULL;
+		}
+	}
+	*tmp = '\0';
+	
+	/*
+	 * All "devices" have the "detach_state" attribute - validate here
+	 */
+	strcat(ppath, "/detach_state");
+	if ((sysfs_path_is_file(ppath)) != 0) {
+		dprintf("Device at %s does not have a parent\n", dev->path);
+		return NULL;
+	}
+	tmp = strrchr(ppath, '/');
+	*tmp = '\0';
+	dev->parent = sysfs_open_device_path(ppath);
+	if (dev->parent == NULL) {
+		dprintf("Error opening device %s's parent at %s\n", 
+					dev->bus_id, ppath);
+		return NULL;
+	}
+	return (dev->parent);
+}
+
 /*
  * sysfs_open_device_attr: open the given device's attribute
  * @bus: Bus on which to look
diff --git a/libsysfs/sysfs_dir.c b/libsysfs/sysfs_dir.c
index ac2ecfcbe1..7dbee8aba8 100644
--- a/libsysfs/sysfs_dir.c
+++ b/libsysfs/sysfs_dir.c
@@ -1,5 +1,5 @@
 /*
- * syfs_dir.c
+ * sysfs_dir.c
  *
  * Directory utility functions for libsysfs
  *
@@ -147,7 +147,7 @@ struct sysfs_attribute *sysfs_open_attribute(const unsigned char *path)
 		sysfs_close_attribute(sysattr);
 		return NULL;
 	}
-	strncpy(sysattr->path, path, sizeof(sysattr->path));
+	strncpy(sysattr->path, path, SYSFS_PATH_MAX);
 	if ((stat(sysattr->path, &fileinfo)) != 0) {
 		dprintf("Stat failed: No such attribute?\n");
 		sysattr->method = 0;
@@ -260,7 +260,7 @@ int sysfs_read_attribute(struct sysfs_attribute *sysattr)
 {
 	unsigned char *fbuf = NULL;
 	unsigned char *vbuf = NULL;
-	size_t length = 0;
+	ssize_t length = 0;
 	long pgsize = 0;
 	int fd;
 
@@ -441,13 +441,15 @@ int sysfs_read_all_subdirs(struct sysfs_directory *sysdir)
 		return -1;
 	}
 	if (sysdir->subdirs == NULL) 
-		if ((sysfs_read_dir_subdirs(sysdir) != 0) 
-		    || sysdir->subdirs == NULL)
+		if ((sysfs_read_dir_subdirs(sysdir)) != 0) 
 			return 0;
-	dlist_for_each_data(sysdir->subdirs, cursub, struct sysfs_directory) {
-		if ((sysfs_read_directory(cursub)) != 0) 
-			dprintf ("Error reading subdirectory %s\n",
-				cursub->name);
+	if (sysdir->subdirs != NULL) {
+		dlist_for_each_data(sysdir->subdirs, cursub, 
+						struct sysfs_directory) {
+			if ((sysfs_read_dir_subdirs(cursub)) != 0) 
+				dprintf ("Error reading subdirectory %s\n",
+						cursub->name);
+		}
 	}
 	return 0;
 }
@@ -476,7 +478,7 @@ struct sysfs_directory *sysfs_open_directory(const unsigned char *path)
 		sysfs_close_directory(sdir);
 		return NULL;
 	}
-	strncpy(sdir->path, path, sizeof(sdir->path));
+	strncpy(sdir->path, path, SYSFS_PATH_MAX);
 
 	return sdir;
 }
@@ -527,7 +529,8 @@ int sysfs_refresh_attributes(struct dlist *attrlist)
 	dlist_for_each_data(attrlist, attr, struct sysfs_attribute) {
 		if (attr->method & SYSFS_METHOD_SHOW) {
 			if ((sysfs_read_attribute(attr)) != 0) {
-				dprintf("Error reading attribute %s\n", attr->path);
+				dprintf("Error reading attribute %s\n", 
+								attr->path);
 				if ((sysfs_path_is_file(attr->path)) != 0) {
 					dprintf("Attr %s no longer exists\n", 
 								attr->name);
@@ -540,12 +543,6 @@ int sysfs_refresh_attributes(struct dlist *attrlist)
 			}
 		}
 	}
-	if (attrlist->count == 0) {
-		dprintf("No attributes in the list, destroying list now\n");
-		dlist_destroy(attrlist);
-		attrlist = NULL;
-		return 1;
-	}
 	return 0;
 }
 
@@ -655,9 +652,9 @@ int sysfs_read_dir_attributes(struct sysfs_directory *sysdir)
 		if (0 == strcmp(dirent->d_name, ".."))
 			continue;
 		memset(file_path, 0, SYSFS_PATH_MAX);
-		strncpy(file_path, sysdir->path, sizeof(file_path));
-		strncat(file_path, "/", sizeof(file_path));
-		strncat(file_path, dirent->d_name, sizeof(file_path));
+		strncpy(file_path, sysdir->path, SYSFS_PATH_MAX);
+		strcat(file_path, "/");
+		strcat(file_path, dirent->d_name);
 		if ((lstat(file_path, &astats)) != 0) {
 			dprintf("stat failed\n");
 			continue;
@@ -697,9 +694,9 @@ int sysfs_read_dir_links(struct sysfs_directory *sysdir)
 		if (0 == strcmp(dirent->d_name, ".."))
 			continue;
 		memset(file_path, 0, SYSFS_PATH_MAX);
-		strncpy(file_path, sysdir->path, sizeof(file_path));
-		strncat(file_path, "/", sizeof(file_path));
-		strncat(file_path, dirent->d_name, sizeof(file_path));
+		strncpy(file_path, sysdir->path, SYSFS_PATH_MAX);
+		strcat(file_path, "/");
+		strcat(file_path, dirent->d_name);
 		if ((lstat(file_path, &astats)) != 0) {
 			dprintf("stat failed\n");
 			continue;
@@ -742,9 +739,9 @@ int sysfs_read_dir_subdirs(struct sysfs_directory *sysdir)
 		if (0 == strcmp(dirent->d_name, ".."))
 			continue;
 		memset(file_path, 0, SYSFS_PATH_MAX);
-		strncpy(file_path, sysdir->path, sizeof(file_path));
-		strncat(file_path, "/", sizeof(file_path));
-		strncat(file_path, dirent->d_name, sizeof(file_path));
+		strncpy(file_path, sysdir->path, SYSFS_PATH_MAX);
+		strcat(file_path, "/");
+		strcat(file_path, dirent->d_name);
 		if ((lstat(file_path, &astats)) != 0) {
 			dprintf("stat failed\n");
 			continue;
@@ -784,9 +781,9 @@ int sysfs_read_directory(struct sysfs_directory *sysdir)
 		if (0 == strcmp(dirent->d_name, ".."))
 			continue;
 		memset(file_path, 0, SYSFS_PATH_MAX);
-		strncpy(file_path, sysdir->path, sizeof(file_path));
-		strncat(file_path, "/", sizeof(file_path));
-		strncat(file_path, dirent->d_name, sizeof(file_path));
+		strncpy(file_path, sysdir->path, SYSFS_PATH_MAX);
+		strcat(file_path, "/");
+		strcat(file_path, dirent->d_name);
 		if ((lstat(file_path, &astats)) != 0) {
 			dprintf("stat failed\n");
 			continue;
@@ -829,26 +826,20 @@ struct sysfs_attribute *sysfs_get_directory_attribute
 
 	attr = (struct sysfs_attribute *)dlist_find_custom
 			(dir->attributes, attrname, dir_attribute_name_equal);
-	if (attr != NULL) {
-		/*
-		 * don't read here since we would have read the attribute in 
-		 * in the routine that called this routine
-		 */ 
-		return attr;
-	} else {
+	if (attr == NULL) {
 		memset(new_path, 0, SYSFS_PATH_MAX);
 		strcpy(new_path, dir->path);
 		strcat(new_path, "/");
 		strcat(new_path, attrname);
 		if ((sysfs_path_is_file(new_path)) == 0) {
 		 	if ((add_attribute(dir, new_path)) == 0) {
-				attr = (struct sysfs_attribute *)dlist_find_custom
-					(dir->attributes, attrname, dir_attribute_name_equal);
+				attr = (struct sysfs_attribute *)
+					dlist_find_custom(dir->attributes, 
+					attrname, dir_attribute_name_equal);
 			}
-			return attr;
 		}
 	}
-	return NULL;
+	return attr;
 }
 
 /**
diff --git a/libsysfs/sysfs_driver.c b/libsysfs/sysfs_driver.c
index 4372b19f10..695ca794f1 100644
--- a/libsysfs/sysfs_driver.c
+++ b/libsysfs/sysfs_driver.c
@@ -66,29 +66,6 @@ static int open_driver_dir(struct sysfs_driver *driver)
 }
 
 /**
- * read_driver_dir: Read driver directory's subdirs and links
- * @driver: Driver to read
- * Returns 0 on success and 1 on failure
- */
-static int read_driver_dir(struct sysfs_driver *driver)
-{
-	if (driver == NULL) {
-		errno = EINVAL;
-		return 1;
-	}
-	if (driver->directory == NULL) {
-		if ((open_driver_dir(driver)) == 1)
-			return 1;
-	}
-	if ((sysfs_read_directory(driver->directory)) != 0) {
-		dprintf("Error reading driver directory at %s\n", 
-				driver->path);
-		return 1;
-	}
-	return 0;
-}
-
-/**
  * alloc_driver: allocates and initializes driver
  * returns struct sysfs_driver with success and NULL with error.
  */
@@ -98,11 +75,11 @@ static struct sysfs_driver *alloc_driver(void)
 }
 
 /**
- * sysfs_open_driver: opens and initializes driver structure
+ * sysfs_open_driver_path: opens and initializes driver structure
  * @path: path to driver directory
  * returns struct sysfs_driver with success and NULL with error
  */
-struct sysfs_driver *sysfs_open_driver(const unsigned char *path)
+struct sysfs_driver *sysfs_open_driver_path(const unsigned char *path)
 {
 	struct sysfs_driver *driver = NULL;
 
@@ -185,13 +162,10 @@ struct sysfs_attribute *sysfs_get_driver_attr(struct sysfs_driver *drv,
         }
 	
 	attrlist = sysfs_get_driver_attributes(drv);
-	if (attrlist != NULL) {
+	if (attrlist != NULL) 
 		cur = sysfs_get_directory_attribute(drv->directory,
 						(unsigned char *)name);
-	        if (cur != NULL)
-        	        return cur;
-	}
-        return NULL;
+        return cur;
 }
 
 /**
@@ -209,7 +183,7 @@ struct dlist *sysfs_get_driver_links(struct sysfs_driver *driver)
 	if (driver->directory == NULL) {
 		if ((open_driver_dir(driver)) == 1)
 			return NULL;
-		if ((read_driver_dir(driver)) != 0) 
+		if ((sysfs_read_dir_links(driver->directory)) != 0) 
 			return NULL;
 	}
 	return(driver->directory->links);
@@ -236,13 +210,13 @@ struct dlist *sysfs_get_driver_devices(struct sysfs_driver *driver)
 	if (driver->directory == NULL) {
 		if ((open_driver_dir(driver)) == 1) 
 			return NULL;
-		if ((read_driver_dir(driver)) != 0) 
+		if ((sysfs_read_dir_links(driver->directory)) != 0) 
 			return NULL;
 	}
 	if (driver->directory->links != NULL) {
 		dlist_for_each_data(driver->directory->links, curlink, 
 						struct sysfs_link) {
-			device = sysfs_open_device(curlink->target);
+			device = sysfs_open_device_path(curlink->target);
 			if (device == NULL) {
 				dprintf("Error opening device at %s\n", 
 						curlink->target);
@@ -345,7 +319,7 @@ struct sysfs_attribute *sysfs_open_driver_attr(const unsigned char *bus,
 		return NULL;
 	}
 
-	memset(path, 0, SYSFS_NAME_LEN);
+	memset(path, 0, SYSFS_PATH_MAX);
 	if ((get_driver_path(bus, drv, path, SYSFS_PATH_MAX)) != 0) {
 		dprintf("Error getting to driver %s\n", drv);
 		return NULL;
@@ -367,3 +341,33 @@ struct sysfs_attribute *sysfs_open_driver_attr(const unsigned char *bus,
 	return attribute;
 }
 
+/**
+ * sysfs_open_driver: open driver by name, given its bus
+ * @drv_name: Name of the driver
+ * @bus_name: Name of the bus
+ * Returns the sysfs_driver reference on success and NULL on failure
+ */
+struct sysfs_driver *sysfs_open_driver(const unsigned char *drv_name,
+				const unsigned char *bus_name)
+{
+	unsigned char path[SYSFS_PATH_MAX];
+	struct sysfs_driver *driver = NULL;
+
+	if (drv_name == NULL || bus_name == NULL) {
+		errno = EINVAL;
+		return NULL;
+	}
+
+	memset(path, 0, SYSFS_PATH_MAX);
+	if ((get_driver_path(bus_name, drv_name, path, SYSFS_PATH_MAX)) != 0) {
+		dprintf("Error getting to driver %s\n", drv_name);
+		return NULL;
+	}
+	driver = sysfs_open_driver_path(path);
+	if (driver == NULL) {
+		dprintf("Error opening driver at %s\n", path);
+		return NULL;
+	}
+	return driver;
+}
+
diff --git a/libsysfs/sysfs_utils.c b/libsysfs/sysfs_utils.c
index c2ce13433d..009ae94efa 100644
--- a/libsysfs/sysfs_utils.c
+++ b/libsysfs/sysfs_utils.c
@@ -1,5 +1,5 @@
 /*
- * syfs_utils.c
+ * sysfs_utils.c
  *
  * System utility functions for libsysfs
  *
@@ -135,17 +135,21 @@ int sysfs_get_name_from_path(const unsigned char *path, unsigned char *name,
 	}
 	memset(tmp, 0, SYSFS_PATH_MAX);
 	strcpy(tmp, path);
-	n = &tmp[strlen(tmp)-1];
-	if (strncmp(n, "/", 1) == 0)
-		*n = '\0';	
 	n = strrchr(tmp, '/');
 	if (n == NULL) {
 		errno = EINVAL;
 		return -1;
 	}
+	if (*(n+1) == '\0') {
+		*n = '\0';
+		n = strrchr(tmp, '/');
+		if (n == NULL) {
+			errno = EINVAL;
+			return -1;
+		}
+	}
 	n++;
 	strncpy(name, n, len);
-
 	return 0;
 }
 
@@ -233,7 +237,6 @@ struct dlist *sysfs_open_subsystem_list(unsigned char *name)
 	unsigned char *c = NULL;
 	struct sysfs_directory *dir = NULL, *cur = NULL;
 	struct dlist *list = NULL;
-	struct stat astats;
 	
 	if (name == NULL)
 		return NULL;
@@ -242,7 +245,6 @@ struct dlist *sysfs_open_subsystem_list(unsigned char *name)
 		dprintf("Error getting sysfs mount point\n");
 		return NULL;
 	}
-
 	if (sysfs_trailing_slash(sysfs_path) == 0)
 		strcat(sysfs_path, "/");
 	strcat(sysfs_path, name);
@@ -252,7 +254,7 @@ struct dlist *sysfs_open_subsystem_list(unsigned char *name)
 		return NULL;
 	}
 
-	if (sysfs_read_directory(dir) != 0) {
+	if ((sysfs_read_dir_subdirs(dir)) != 0) {
 		dprintf("Error reading sysfs_directory at %s\n", sysfs_path);
 		sysfs_close_directory(dir);
 		return NULL;
@@ -285,11 +287,7 @@ struct dlist *sysfs_open_subsystem_list(unsigned char *name)
 		if (c == NULL)
 			goto out;
 		strcpy(c, SYSFS_BLOCK_NAME);
-		if ((lstat(sysfs_path, &astats)) != 0) {
-			dprintf("stat() failed\n");
-			goto out;
-		}
-		if (S_ISDIR(astats.st_mode)) {
+		if ((sysfs_path_is_dir(sysfs_path)) == 0) {
 			subsys_name = (char *)calloc(1, SYSFS_NAME_LEN);
 			strcpy(subsys_name, SYSFS_BLOCK_NAME);
 			dlist_unshift(list, subsys_name);
@@ -333,7 +331,7 @@ struct dlist *sysfs_open_bus_devices_list(unsigned char *name)
 		return NULL;
 	}
 
-	if (sysfs_read_directory(dir) != 0) {
+	if ((sysfs_read_dir_links(dir)) != 0) {
 		dprintf("Error reading sysfs_directory at %s\n", sysfs_path);
 		sysfs_close_directory(dir);
 		return NULL;
diff --git a/udev-add.c b/udev-add.c
index 33ee633fd8..ba5c864165 100644
--- a/udev-add.c
+++ b/udev-add.c
@@ -242,9 +242,9 @@ static struct sysfs_class_device *get_class_dev(char *device_name)
 	dbg("looking at '%s'", dev_path);
 
 	/* open up the sysfs class device for this thing... */
-	class_dev = sysfs_open_class_device(dev_path);
+	class_dev = sysfs_open_class_device_path(dev_path);
 	if (class_dev == NULL) {
-		dbg ("sysfs_open_class_device failed");
+		dbg ("sysfs_open_class_device_path failed");
 		goto exit;
 	}
 	dbg("class_dev->name='%s'", class_dev->name);