X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=libsysfs%2Fsysfs_class.c;h=a93de573d43b4b083db00f40537ba0c73b96a36a;hp=05305056dd9ce195bae5347850af2d604f2127b7;hb=f385ff6512012a75b8381938dd3f55f991b53e9a;hpb=0bad3406c1e8eba6d5af2cbfd44d8a61231fa2bb

diff --git a/libsysfs/sysfs_class.c b/libsysfs/sysfs_class.c
index 05305056d..a93de573d 100644
--- a/libsysfs/sysfs_class.c
+++ b/libsysfs/sysfs_class.c
@@ -3,7 +3,7 @@
  *
  * Generic class utility functions for libsysfs
  *
- * Copyright (C) IBM Corp. 2003
+ * Copyright (C) IBM Corp. 2003-2005
  *
  *  This library is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU Lesser General Public
@@ -20,92 +20,46 @@
  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  *
  */
-#include "sysfs/libsysfs.h"
+#include "libsysfs.h"
 #include "sysfs.h"
 
-static void sysfs_close_cls_dev(void *dev)
-{
-	sysfs_close_class_device((struct sysfs_class_device *)dev);
-}
-
-/**
- * class_name_equal: compares class_devices' name
- * @a: class_name looking for
- * @b: sysfs_class_device being compared
- */
-static int class_name_equal(void *a, void *b)
-{
-	if (a == NULL || b == NULL)
-		return 0;
-
-	if (strcmp(((unsigned char *)a), ((struct sysfs_class_device *)b)->name)
-		== 0)
-		return 1;
-
-	return 0;
-}
-
 /**
  * sysfs_close_class_device: closes a single class device.
  * @dev: class device to close.
  */
 void sysfs_close_class_device(struct sysfs_class_device *dev)
 {
-	if (dev != NULL) {
-		if (dev->directory != NULL)
-			sysfs_close_directory(dev->directory);
-		if (dev->sysdevice != NULL)
-			sysfs_close_device(dev->sysdevice);
-		if (dev->driver != NULL)
-			sysfs_close_driver(dev->driver);
-		if (dev->parent != NULL)
+	if (dev) {
+		if (dev->parent)
 			sysfs_close_class_device(dev->parent);
+		if (dev->sysdevice)
+			sysfs_close_device(dev->sysdevice);
+		if (dev->attrlist)
+			dlist_destroy(dev->attrlist);
 		free(dev);
 	}
 }
 
-/**
- * sysfs_close_class: close single class
- * @class: class structure
- */
-void sysfs_close_class(struct sysfs_class *cls)
-{
-	if (cls != NULL) {
-		if (cls->directory != NULL)
-			sysfs_close_directory(cls->directory);
-		if (cls->devices != NULL) 
-			dlist_destroy(cls->devices);
-		free(cls);
-	}
-}
-
 /**
  * alloc_class_device: mallocs and initializes new class device struct.
  * returns sysfs_class_device or NULL.
  */
 static struct sysfs_class_device *alloc_class_device(void)
 {
-	return (struct sysfs_class_device *)
-				calloc(1, sizeof(struct sysfs_class_device));
-}
+	struct sysfs_class_device *dev;
 
-/**
- * alloc_class: mallocs new class structure
- * returns sysfs_class struct or NULL
- */
-static struct sysfs_class *alloc_class(void)
-{
-	return (struct sysfs_class *)calloc(1, sizeof(struct sysfs_class));
+	dev = calloc(1, sizeof(struct sysfs_class_device));
+	return dev;
 }
 
-/** 
+/**
  * set_classdev_classname: Grabs classname from path
  * @cdev: class device to set
  * Returns nothing
  */
 static void set_classdev_classname(struct sysfs_class_device *cdev)
 {
-	unsigned char *c = NULL, *e = NULL;
+	char *c, *e;
 	int count = 0;
 
 	c = strstr(cdev->path, SYSFS_CLASS_NAME);
@@ -116,7 +70,7 @@ static void set_classdev_classname(struct sysfs_class_device *cdev)
 	}
 
 	if (c == NULL)
-		strcpy(cdev->classname, SYSFS_UNKNOWN);
+		safestrcpy(cdev->classname, SYSFS_UNKNOWN);
 	else {
 		if (*c == '/')
 			c++;
@@ -134,12 +88,11 @@ static void set_classdev_classname(struct sysfs_class_device *cdev)
  * @path: path to class device.
  * returns struct sysfs_class_device with success and NULL with error.
  */
-struct sysfs_class_device *sysfs_open_class_device_path
-					(const unsigned char *path)
+struct sysfs_class_device *sysfs_open_class_device_path(const char *path)
 {
-	struct sysfs_class_device *cdev = NULL;
+	struct sysfs_class_device *cdev;
 
-	if (path == NULL) {
+	if (!path) {
 		errno = EINVAL;
 		return NULL;
 	}
@@ -148,18 +101,18 @@ struct sysfs_class_device *sysfs_open_class_device_path
 		return NULL;
 	}
 	cdev = alloc_class_device();
-	if (cdev == NULL) {
+	if (!cdev) {
 		dprintf("calloc failed\n");
 		return NULL;
 	}
-	if ((sysfs_get_name_from_path(path, cdev->name, SYSFS_NAME_LEN)) != 0) {
+	if (sysfs_get_name_from_path(path, cdev->name, SYSFS_NAME_LEN)) {
 		errno = EINVAL;
 		dprintf("Error getting class device name\n");
 		sysfs_close_class_device(cdev);
 		return NULL;
 	}
 
-	strcpy(cdev->path, path);
+	safestrcpy(cdev->path, path);
 	if ((sysfs_remove_trailing_slash(cdev->path)) != 0) {
 		dprintf("Invalid path to class device %s\n", cdev->path);
 		sysfs_close_class_device(cdev);
@@ -170,249 +123,6 @@ struct sysfs_class_device *sysfs_open_class_device_path
 	return cdev;
 }
 
-/**
- * sysfs_get_class_devices: gets all devices for class
- * @class: class to get devices for
- * returns dlist of class_devices with success and NULL with error
- */
-struct dlist *sysfs_get_class_devices(struct sysfs_class *cls)
-{
-	struct sysfs_class_device *dev = NULL;
-	struct sysfs_directory *cur = NULL;
-
-	if (cls == NULL) {
-		errno = EINVAL;
-		return NULL;
-	}
-
-	if (cls->devices != NULL) 
-		return cls->devices;
-
-	if (cls->directory == NULL) {
-		cls->directory = sysfs_open_directory(cls->path);
-		if (cls->directory == NULL) 
-			return NULL;
-	}
-
-	if ((sysfs_read_dir_subdirs(cls->directory)) != 0) 
-		return NULL;
-
-	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);
-		}
-	}
-	return cls->devices;
-}
-
-/**
- * sysfs_open_class: opens specific class and all its devices on system
- * returns sysfs_class structure with success or NULL with error.
- */
-struct sysfs_class *sysfs_open_class(const unsigned char *name)
-{
-	struct sysfs_class *cls = NULL;
-	unsigned char classpath[SYSFS_PATH_MAX];
-
-	if (name == NULL) {
-		errno = EINVAL;
-		return NULL;
-	}
-
-	memset(classpath, 0, SYSFS_PATH_MAX);
-        if ((sysfs_get_mnt_path(classpath, SYSFS_PATH_MAX)) != 0) {
-                dprintf("Sysfs not supported on this system\n");
-                return NULL;
-        }
-
-	/* 
-	 * We shall now treat "block" also as a class. Hence, check here
-	 * if "name" is "block" and proceed accordingly
-	 */
-	if (strcmp(name, SYSFS_BLOCK_NAME) == 0) {
-		strcat(classpath, "/");
-		strcat(classpath, SYSFS_BLOCK_NAME);
-	} else {
-		strcat(classpath, "/");
-		strcat(classpath, SYSFS_CLASS_NAME);
-		strcat(classpath, "/");
-		strcat(classpath, name);
-	}
-	if ((sysfs_path_is_dir(classpath)) != 0) {
-		dprintf("Class %s not found on the system\n", name);
-		return NULL;
-	}
-
-	cls = alloc_class();
-	if (cls == NULL) {
-		dprintf("calloc failed\n");
-		return NULL;
-	}
-	strcpy(cls->name, name);	
-	strcpy(cls->path, classpath);
-	if ((sysfs_remove_trailing_slash(cls->path)) != 0) {
-		dprintf("Invalid path to class device %s\n", cls->path);
-		sysfs_close_class(cls);
-		return NULL;
-	}
-	
-	return cls;
-}
-
-/**
- * sysfs_get_class_device: Get specific class device using the device's id
- * @class: class to find device on
- * @name: class name of the device
- */ 
-struct sysfs_class_device *sysfs_get_class_device(struct sysfs_class *class,
-					unsigned char *name)
-{
-	if (class == NULL || name == NULL) {
-		errno = EINVAL;
-		return NULL;
-	}
-
-	if (class->devices == NULL) {
-		class->devices = sysfs_get_class_devices(class);
-		if (class->devices == NULL) 
-			return NULL;
-	}
-	return (struct sysfs_class_device *)dlist_find_custom(class->devices,
-			name, class_name_equal);
-}
-
-/**
- * sysfs_get_classdev_device: returns the sysfs_device corresponding to
- * 		sysfs_class_device, if present
- * @clsdev: class device whose sysfs_device is required
- * Returns sysfs_device on success, NULL on error or if device is not
- * implemented
- */ 
-struct sysfs_device *sysfs_get_classdev_device
-			(struct sysfs_class_device *clsdev)
-{
-	struct sysfs_link *devlink = NULL;
-	unsigned char devpath[SYSFS_PATH_MAX];
-	
-	if (clsdev == NULL) {
-		errno = EINVAL;
-		return NULL;
-	}
-	strcpy(devpath, clsdev->path);
-	strcat(devpath, "/device");
-	if ((sysfs_path_is_link(devpath)) != 0) {
-		if (clsdev->sysdevice != NULL) {
-			sysfs_close_device(clsdev->sysdevice);
-			clsdev->sysdevice = NULL;
-		}
-		return NULL;
-	}
-	
-	if (clsdev->directory == NULL) {
-		clsdev->directory = sysfs_open_directory(clsdev->path);
-		if (clsdev->directory == NULL)
-			return NULL;
-	}
-	devlink = sysfs_get_directory_link(clsdev->directory, "device");
-	if (devlink == NULL) {
-		if (clsdev->sysdevice != NULL) {
-			dprintf("Device link no longer exists\n");
-			sysfs_close_device(clsdev->sysdevice);
-			clsdev->sysdevice = NULL;
-		}
-		return NULL;
-	}
-
-	if (clsdev->sysdevice != NULL) {
-		if (!strncmp(devlink->target, clsdev->sysdevice->path,
-						SYSFS_PATH_MAX)) 
-			/* sysdevice hasn't changed */
-			return (clsdev->sysdevice);
-		else 
-			/* come here only if the device link for has changed */
-			sysfs_close_device(clsdev->sysdevice);
-	}
-
-	clsdev->sysdevice = sysfs_open_device_path(devlink->target);
-	if (clsdev->sysdevice == NULL)
-		return NULL;
-	if (clsdev->driver != NULL) 
-		strcpy(clsdev->sysdevice->driver_name, clsdev->driver->name);
-
-	return (clsdev->sysdevice);
-}
-				
-/**
- * sysfs_get_classdev_driver: returns the sysfs_driver corresponding to
- * 		sysfs_class_device, if present
- * @clsdev: class device whose sysfs_device is required
- * Returns sysfs_driver on success, NULL on error or if driver is not
- * implemented
- */ 
-struct sysfs_driver *sysfs_get_classdev_driver
-			(struct sysfs_class_device *clsdev)
-{
-	struct sysfs_link *drvlink = NULL;
-	unsigned char drvpath[SYSFS_PATH_MAX];
-	
-	if (clsdev == NULL) {
-		errno = EINVAL;
-		return NULL;
-	}
- 	strcpy(drvpath, clsdev->path);
-        strcat(drvpath, "/driver");
-	if ((sysfs_path_is_link(drvpath)) != 0) {
-		if (clsdev->driver != NULL) {
-			sysfs_close_driver(clsdev->driver);
-			clsdev->driver = NULL;
-		}
-		return NULL;
-	}
-	 
-	if (clsdev->directory == NULL) {
-		clsdev->directory = sysfs_open_directory(clsdev->path);
-		if (clsdev->directory == NULL)
-			return NULL;
-	}
-	drvlink = sysfs_get_directory_link(clsdev->directory, "driver");
-	if (drvlink == NULL) {
-		if (clsdev->driver != NULL) {
-			dprintf("Driver link no longer exists\n");
-			sysfs_close_driver(clsdev->driver);
-			clsdev->driver = NULL;
-		}
-		return NULL;
-	}
-	if (clsdev->driver != NULL) {
-		if (!strncmp(drvlink->target, clsdev->driver->path,
-	      						SYSFS_PATH_MAX))
-			/* driver hasn't changed */
-	 		return (clsdev->driver);
- 		else
-			/* come here only if the device link for has changed */
-			sysfs_close_driver(clsdev->driver);
-	}
-		
-	clsdev->driver = sysfs_open_driver_path(drvlink->target);
-	if (clsdev->driver == NULL)
-		return NULL;
-	if (clsdev->sysdevice != NULL)
-		strcpy(clsdev->sysdevice->driver_name, clsdev->driver->name);
-
-	return (clsdev->driver);
-}
-
 /** 
  * get_blockdev_parent: Get the parent class device for a "block" subsystem 
  * 		device if present
@@ -421,36 +131,36 @@ struct sysfs_driver *sysfs_get_classdev_driver
  */
 static int get_blockdev_parent(struct sysfs_class_device *clsdev)
 {
-	unsigned char parent_path[SYSFS_PATH_MAX], *c = NULL;
+	char parent_path[SYSFS_PATH_MAX];
+	char *c;
 
-	strcpy(parent_path, clsdev->path);
+	safestrcpy(parent_path, clsdev->path);
 	c = strstr(parent_path, SYSFS_BLOCK_NAME);
 	if (c == NULL) {
 		dprintf("Class device %s does not belong to BLOCK subsystem\n",
 				clsdev->name);
 		return 1;
 	}
-
 	c += strlen(SYSFS_BLOCK_NAME);
 	if (*c == '/')
 		c++;
 	else
 		goto errout;
 
-       /* validate whether the given class device is a partition or not */
-        if ((strncmp(c, clsdev->name, strlen(clsdev->name))) == 0) {
-                dprintf("%s not a partition\n", clsdev->name);
-                return 1;
-        }
-		      
-      	c = strchr(c, '/');
+	/* validate whether the given class device is a partition or not */
+	if ((strncmp(c, clsdev->name, strlen(clsdev->name))) == 0) {
+		dprintf("%s not a partition\n", clsdev->name);
+		return 1;
+	}
+
+	c = strchr(c, '/');
 	if (c == NULL)
 		goto errout;
 
 	*c = '\0';
-					
+
 	clsdev->parent = sysfs_open_class_device_path(parent_path);
-	if (clsdev->parent == NULL) {
+	if (!clsdev->parent) {
 		dprintf("Error opening the parent class device at %s\n", 
 								parent_path);
 		return 1;
@@ -473,20 +183,21 @@ errout:
 struct sysfs_class_device *sysfs_get_classdev_parent
 				(struct sysfs_class_device *clsdev)
 {
-	if (clsdev == NULL) {
+	if (!clsdev) {
 		errno = EINVAL;
 		return NULL;
 	}
-	if (clsdev->parent != NULL)
+	if (clsdev->parent)
 		return (clsdev->parent);
-	
-	/* 
+
+	/*
 	 * As of now, only block devices have a parent child heirarchy in sysfs
 	 * We do not know, if, in the future, more classes will have a similar
 	 * structure. Hence, we now call a specialized function for block and
 	 * later we can add support functions for other subsystems as required.
-	 */ 
-	if (!(strcmp(clsdev->classname, SYSFS_BLOCK_NAME))) {
+	 */
+	if (!(strncmp(clsdev->classname, SYSFS_BLOCK_NAME, 
+					sizeof(SYSFS_BLOCK_NAME)))) {
 		if ((get_blockdev_parent(clsdev)) == 0) 
 			return (clsdev->parent);
 	}
@@ -502,28 +213,29 @@ struct sysfs_class_device *sysfs_get_classdev_parent
  * @psize: size of "path"
  * Returns 0 on SUCCESS or -1 on error
  */
-static int get_classdev_path(const unsigned char *classname, 
-		const unsigned char *clsdev, unsigned char *path, size_t len)
+static int get_classdev_path(const char *classname, const char *clsdev, 
+		char *path, size_t len)
 {
-	if (classname == NULL || clsdev == NULL || path == NULL) {
+	if (!classname || !clsdev || !path) {
 		errno = EINVAL;
 		return -1;
 	}
-        if (sysfs_get_mnt_path(path, len) != 0) {
-                dprintf("Error getting sysfs mount path\n");
-                return -1;
+	if (sysfs_get_mnt_path(path, len) != 0) {
+		dprintf("Error getting sysfs mount path\n");
+		return -1;
 	}
-	if (strcmp(classname, SYSFS_BLOCK_NAME) == 0) {
-		strcat(path, "/");
-		strcat(path, SYSFS_BLOCK_NAME);
+	if (strncmp(classname, SYSFS_BLOCK_NAME,
+				sizeof(SYSFS_BLOCK_NAME)) == 0) {
+		safestrcatmax(path, "/", len);
+		safestrcatmax(path, SYSFS_BLOCK_NAME, len);
 	} else {
-		strcat(path, "/");
-		strcat(path, SYSFS_CLASS_NAME);
-		strcat(path, "/");
-		strcat(path, classname);
+		safestrcatmax(path, "/", len);
+		safestrcatmax(path, SYSFS_CLASS_NAME, len);
+		safestrcatmax(path, "/", len);
+		safestrcatmax(path, classname, len);
 	}
-	strcat(path, "/");
-	strcat(path, clsdev);
+	safestrcatmax(path, "/", len);
+	safestrcatmax(path, clsdev, len);
 	return 0;
 }
 
@@ -537,12 +249,12 @@ static int get_classdev_path(const unsigned char *classname,
  * 	Call sysfs_close_class_device() to close the class device
  */
 struct sysfs_class_device *sysfs_open_class_device
-		(const unsigned char *classname, const unsigned char *name)
+		(const char *classname, const char *name)
 {
-	unsigned char devpath[SYSFS_PATH_MAX];
-	struct sysfs_class_device *cdev = NULL;
+	char devpath[SYSFS_PATH_MAX];
+	struct sysfs_class_device *cdev;
 
-	if (classname == NULL || name == NULL) {
+	if (!classname || !name) {
 		errno = EINVAL;
 		return NULL;
 	}
@@ -554,9 +266,9 @@ struct sysfs_class_device *sysfs_open_class_device
 							name, classname);
 		return NULL;
 	}
-	
+
 	cdev = sysfs_open_class_device_path(devpath);
-	if (cdev == NULL) {
+	if (!cdev) {
 		dprintf("Error getting class device %s from class %s\n",
 				name, classname);
 		return NULL;
@@ -565,146 +277,61 @@ struct sysfs_class_device *sysfs_open_class_device
 }
 
 /**
- * sysfs_get_classdev_attributes: returns a dlist of attributes for
- * 	the requested class_device
- * @cdev: sysfs_class_dev for which attributes are needed
- * returns a dlist of attributes if exists, NULL otherwise
- */
-struct dlist *sysfs_get_classdev_attributes(struct sysfs_class_device *cdev)
-{
-	if (cdev == NULL)
-		return NULL;
-
-	if (cdev->directory == NULL) {
-		cdev->directory = sysfs_open_directory(cdev->path);
-		if (cdev->directory == NULL) 
-			return NULL;
-	}
-	if (cdev->directory->attributes == NULL) {
-		if ((sysfs_read_dir_attributes(cdev->directory)) != 0) 
-			return NULL;
-	}
-	return (cdev->directory->attributes);
-}
-
-/**
- * sysfs_refresh_clsassdev_attributes: refreshes the driver's list of attributes
- * @clsdev: sysfs_class_device whose attributes to refresh
- *
- * NOTE: Upon return, prior references to sysfs_attributes for this classdev
- *              _may_ not be valid
- *
- * Returns list of attributes on success and NULL on failure
+ * sysfs_get_classdev_attr: searches class device's attributes by name
+ * @clsdev: class device to look through
+ * @name: attribute name to get
+ * returns sysfs_attribute reference with success or NULL with error
  */
-struct dlist *sysfs_refresh_classdev_attributes
-			(struct sysfs_class_device *clsdev)
+struct sysfs_attribute *sysfs_get_classdev_attr
+		(struct sysfs_class_device *clsdev, const char *name)
 {
-	if (clsdev == NULL) {
+	if (!clsdev || !name) {
 		errno = EINVAL;
 		return NULL;
 	}
-
-	if (clsdev->directory == NULL)
-		return (sysfs_get_classdev_attributes(clsdev));
-
-	if ((sysfs_refresh_dir_attributes(clsdev->directory)) != 0) {
-		dprintf("Error refreshing class_device attributes\n");
-		return NULL;
-	}
-
-	return (clsdev->directory->attributes);
+	return get_attribute(clsdev, (char *)name);
 }
 
 /**
- * sysfs_get_classdev_attr: searches class device's attributes by name
- * @clsdev: class device to look through
- * @name: attribute name to get
- * returns sysfs_attribute reference with success or NULL with error
+ * sysfs_get_classdev_attributes: gets list of classdev attributes
+ * @clsdev: class device whose attributes list is needed
+ * returns dlist of attributes on success or NULL on error
  */
-struct sysfs_attribute *sysfs_get_classdev_attr
-		(struct sysfs_class_device *clsdev, const unsigned char *name)
+struct dlist *sysfs_get_classdev_attributes(struct sysfs_class_device *clsdev)
 {
-	struct sysfs_attribute *cur = NULL;
-	struct sysfs_directory *sdir = NULL;
-	struct dlist *attrlist = NULL;
-	
-	if (clsdev == NULL || name == NULL) {
+	if (!clsdev) {
 		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) {
-		cur = sysfs_get_directory_attribute(clsdev->directory,
-						(unsigned char *)name);
-		if (cur != NULL)
-			return cur;
-	}
-
-	if (clsdev->directory->subdirs == NULL) 
-		if ((sysfs_read_dir_subdirs(clsdev->directory)) != 0 ||
-		    clsdev->directory->subdirs == NULL) 
-			return NULL;
-
-	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;
-			cur = sysfs_get_directory_attribute(sdir,
-							(unsigned char *)name);
-			if (cur == NULL)
-				continue;
-		}
-	}
-	return cur;
+	return get_attributes_list(clsdev);
 }
 
 /**
- * sysfs_open_classdev_attr: read an attribute for a given class device
- * @classname: name of the class on which to look
- * @dev: class device name for which the attribute has to be read
- * @attrib: attribute to read
- * Returns sysfs_attribute * on SUCCESS and NULL on error
- * 
- * NOTE:
- * 	A call to sysfs_close_attribute() is required to close the
- * 	attribute returned and to free memory
+ * sysfs_get_classdev_device: gets the sysfs_device associated with the
+ * 	given sysfs_class_device
+ * @clsdev: class device whose associated sysfs_device is needed
+ * returns struct sysfs_device * on success or NULL on error
  */
-struct sysfs_attribute *sysfs_open_classdev_attr(const unsigned char *classname,
-		const unsigned char *dev, const unsigned char *attrib)
+struct sysfs_device *sysfs_get_classdev_device
+		(struct sysfs_class_device *clsdev)
 {
-	struct sysfs_attribute *attribute = NULL;
-	unsigned char path[SYSFS_PATH_MAX];
+	char linkpath[SYSFS_PATH_MAX], devpath[SYSFS_PATH_MAX];
 
-	if (classname == NULL || dev == NULL || attrib == NULL) {
+	if (!clsdev) {
 		errno = EINVAL;
 		return NULL;
 	}
-	memset(path, 0, SYSFS_PATH_MAX);
-	if ((get_classdev_path(classname, dev, path, SYSFS_PATH_MAX)) != 0) {
-		dprintf("Error getting to device %s on class %s\n",
-						dev, classname);
-		return NULL;
-	}
-	strcat(path, "/");
-	strcat(path, attrib);
-	attribute = sysfs_open_attribute(path);
-	if (attribute == NULL) {
-		dprintf("Error opening attribute %s on class device %s\n",
-				attrib, dev);
-		return NULL;
-	}
-	if ((sysfs_read_attribute(attribute)) != 0) {
-		dprintf("Error reading attribute %s for class device %s\n",
-				attrib, dev);
-		sysfs_close_attribute(attribute);
-		return NULL;
+
+	if (clsdev->sysdevice)
+		return clsdev->sysdevice;
+
+	memset(linkpath, 0, SYSFS_PATH_MAX);
+	safestrcpy(linkpath, clsdev->path);
+	safestrcat(linkpath, "/device");
+	if (!sysfs_path_is_link(linkpath)) {
+		memset(devpath, 0, SYSFS_PATH_MAX);
+		if (!sysfs_get_link(linkpath, devpath, SYSFS_PATH_MAX))
+			clsdev->sysdevice = sysfs_open_device_path(devpath);
 	}
-	return attribute;
+	return clsdev->sysdevice;
 }
-