X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=libsysfs%2Fsysfs_class.c;h=edf751b124c515f01c96f37409ba722714e6ba48;hp=54f22eee247abe76c16638ca418e7973349e7a1e;hb=b4f192f054410bf9ddd04b770f0b46f0fd25abce;hpb=edcd336477880368915245a4b7ddd1bca5940b30

diff --git a/libsysfs/sysfs_class.c b/libsysfs/sysfs_class.c
index 54f22eee2..edf751b12 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
@@ -23,151 +23,94 @@
 #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)
+	if (dev) {
+		if (dev->parent)
+			sysfs_close_class_device(dev->parent);
+		if (dev->sysdevice)
 			sysfs_close_device(dev->sysdevice);
-		if (dev->driver != NULL)
-			sysfs_close_driver(dev->driver);
+		if (dev->attrlist)
+			dlist_destroy(dev->attrlist);
 		free(dev);
 	}
 }
 
+static void sysfs_close_cls_dev(void *dev)
+{
+	sysfs_close_class_device((struct sysfs_class_device *)dev);
+}
+
 /**
- * sysfs_close_class: close single class
- * @class: class structure
- */
+ * sysfs_close_class: close the given class
+ * @cls: sysfs_class to close
+ */ 
 void sysfs_close_class(struct sysfs_class *cls)
 {
-	if (cls != NULL) {
-		if (cls->directory != NULL)
-			sysfs_close_directory(cls->directory);
-		if (cls->devices != NULL) 
+	if (cls) {
+		if (cls->devices)
 			dlist_destroy(cls->devices);
+		if (cls->attrlist)
+			dlist_destroy(cls->attrlist);
 		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)
+static int cdev_name_equal(void *a, void *b)
 {
-	return (struct sysfs_class_device *)
-				calloc(1, sizeof(struct sysfs_class_device));
+	if (!a || !b)
+		return 0;
+
+	if (strncmp((char *)a, ((struct sysfs_class_device *)b)->name, 
+				strlen((char *)a)) == 0)
+		return 1;
+
+	return 0;
 }
 
-/**
- * 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));
+	return (struct sysfs_class *) calloc(1, sizeof(struct sysfs_class));
 }
 
 /**
- * open_class_dir: opens up sysfs class directory
- * returns sysfs_directory struct with success and NULL with error
+ * alloc_class_device: mallocs and initializes new class device struct.
+ * returns sysfs_class_device or NULL.
  */
-static struct sysfs_directory *open_class_dir(const unsigned char *name)
+static struct sysfs_class_device *alloc_class_device(void)
 {
-	struct sysfs_directory *classdir = NULL;
-	unsigned char classpath[SYSFS_PATH_MAX];
+	struct sysfs_class_device *dev;
 
-	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;
-	}
-
-	if (sysfs_trailing_slash(classpath) == 0)
-		strcat(classpath, "/");
-	/* 
-	 * 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, SYSFS_BLOCK_NAME);
-	} else {
-		strcat(classpath, SYSFS_CLASS_NAME);
-		strcat(classpath, "/");
-		strcat(classpath, name);
-	}
-	classdir = sysfs_open_directory(classpath);
-	if (classdir == NULL) {
-		errno = EINVAL;
-		dprintf("Class %s not supported on this system\n", name);
-		return NULL;
-	}
-	if ((sysfs_read_directory(classdir)) != 0) {
-		dprintf("Error reading %s class dir %s\n", name, classpath);
-		sysfs_close_directory(classdir);
-		return NULL;
-	}
-
-	return classdir;
+	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_DIR);
-	if (c == NULL) 
-		c = strstr(cdev->path, SYSFS_BLOCK_DIR);
-	else {
-		c++;
-		while (c != NULL && *c != '/') 
-			c++;
+	c = strstr(cdev->path, SYSFS_CLASS_NAME);
+	if (c == NULL) {
+		c = strstr(cdev->path, SYSFS_BLOCK_NAME);
+	} else {
+		c = strstr(c, "/");
 	}
 
-	if (c == NULL) 
-		strcpy(cdev->classname, SYSFS_UNKNOWN);
-
+	if (c == NULL)
+		safestrcpy(cdev->classname, SYSFS_UNKNOWN);
 	else {
-		c++;
+		if (*c == '/')
+			c++;
 		e = c;
 		while (e != NULL && *e != '/' && *e != '\0') {
 			e++;
@@ -178,173 +121,124 @@ 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 char *path)
 {
-	struct sysfs_class_device *cdev = NULL;
-	struct sysfs_directory *dir = NULL;
-	struct sysfs_link *curl = NULL;
-	struct sysfs_device *sdev = NULL;
-	struct sysfs_driver *drv = NULL;
+	struct sysfs_class_device *cdev;
 
-	if (path == NULL) {
+	if (!path) {
 		errno = EINVAL;
 		return NULL;
 	}
+	if (sysfs_path_is_dir(path)) {
+		dprintf("%s is not a valid path to a class device\n", 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("Invalid class device path %s\n", path);
+		dprintf("Error getting class device name\n");
 		sysfs_close_class_device(cdev);
 		return NULL;
 	}
 
-	dir = sysfs_open_directory(path);
-	if (dir == NULL) {
-		dprintf("Error opening class device at %s\n", path);
+	safestrcpy(cdev->path, path);
+	if (sysfs_remove_trailing_slash(cdev->path)) {
+		dprintf("Invalid path to class device %s\n", cdev->path);
 		sysfs_close_class_device(cdev);
 		return NULL;
 	}
-	if ((sysfs_read_directory(dir)) != 0) {
-		dprintf("Error reading class device at %s\n", path);
-		sysfs_close_directory(dir);
-		sysfs_close_class_device(cdev);
-		return NULL;
-	}
-	sysfs_read_all_subdirs(dir);
-	cdev->directory = dir;
-	strcpy(cdev->path, dir->path);
 	set_classdev_classname(cdev);
 
-	/* get driver and device, if implemented */
-	if (cdev->directory->links != NULL) {
-		dlist_for_each_data(cdev->directory->links, curl,
-				struct sysfs_link) {
-			if (strncmp(curl->name, SYSFS_DEVICES_NAME, 6) == 0) {
-				sdev = sysfs_open_device(curl->target);
-				if (sdev != NULL) {
-					cdev->sysdevice = sdev;
-					if (cdev->driver != NULL) 
-						strncpy(sdev->driver_name,
-							cdev->driver->name, 
-							SYSFS_NAME_LEN);
-				}
-			} else if (strncmp(curl->name, 
-						SYSFS_DRIVERS_NAME, 6) == 0) {
-				drv = sysfs_open_driver(curl->target);
-				if (drv != NULL) {
-					cdev->driver = drv;
-					if (cdev->sysdevice != NULL) {
-						strncpy(cdev->sysdevice->name,
-								drv->name, 
-								SYSFS_NAME_LEN);
-						if (drv->devices == NULL)
-							drv->devices = 
-								dlist_new
-								(sizeof(struct 
-								sysfs_device));
-						dlist_unshift(drv->devices, 
-							cdev->sysdevice);
-					}
-				}
-			}
-		}
-	}
 	return cdev;
 }
 
-/**
- * get_all_class_devices: gets all devices for class
- * @class: class to get devices for
- * returns 0 with success and -1 with failure
+/** 
+ * get_blockdev_parent: Get the parent class device for a "block" subsystem 
+ * 		device if present
+ * @clsdev: block subsystem class device whose parent needs to be found
+ * Returns 0 on success and 1 on error
  */
-static int get_all_class_devices(struct sysfs_class *cls)
+static int get_blockdev_parent(struct sysfs_class_device *clsdev)
 {
-	struct sysfs_class_device *dev = NULL;
-	struct sysfs_directory *cur = NULL;
-
-	if (cls == NULL || cls->directory == NULL) {
-		errno = EINVAL;
-		return -1;
+	char parent_path[SYSFS_PATH_MAX];
+	char *c;
+
+	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;
 	}
-	if (cls->directory->subdirs == NULL)
-		return 0;
-	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
-					(sizeof(struct sysfs_class_device),
-					 		sysfs_close_cls_dev);
-		dlist_unshift(cls->devices, dev);
+	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;
 	}
-	return 0;
-}
 
-/**
- * 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;
-	struct sysfs_directory *classdir = NULL;
+	c = strchr(c, '/');
+	if (c == NULL)
+		goto errout;
 
-	if (name == NULL) {
-		errno = EINVAL;
-		return NULL;
-	}
+	*c = '\0';
 
-	cls = alloc_class();
-	if (cls == NULL) {
-		dprintf("calloc failed\n");
-		return NULL;
-	}
-	strcpy(cls->name, name);	
-	classdir = open_class_dir(name);
-	if (classdir == NULL) {
-		dprintf("Invalid class, %s not supported on this system\n",
-			name);
-		sysfs_close_class(cls);
-		return NULL;
-	}
-	cls->directory = classdir;
-	strcpy(cls->path, classdir->path);
-	if ((get_all_class_devices(cls)) != 0) {
-		dprintf("Error reading %s class devices\n", name);
-		sysfs_close_class(cls);
-		return NULL;
+	clsdev->parent = sysfs_open_class_device_path(parent_path);
+	if (!clsdev->parent) {
+		dprintf("Error opening the parent class device at %s\n", 
+								parent_path);
+		return 1;
 	}
+	return 0;
 
-	return cls;
+errout:
+	dprintf("Invalid path %s\n", clsdev->path);
+	return 1;
 }
 
 /**
- * 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
+ * sysfs_get_classdev_parent: Retrieves the parent of a class device. 
+ * 	eg., when working with hda1, this function can be used to retrieve the
+ * 		sysfs_class_device for hda
+ * 		
+ * @clsdev: class device whose parent details are required.
+ * Returns sysfs_class_device of the parent on success, NULL on failure
  */ 
-struct sysfs_class_device *sysfs_get_class_device(struct sysfs_class *class,
-					unsigned char *name)
+struct sysfs_class_device *sysfs_get_classdev_parent
+				(struct sysfs_class_device *clsdev)
 {
-	if (class == NULL || name == NULL) {
+	if (!clsdev) {
 		errno = EINVAL;
 		return NULL;
 	}
+	if (clsdev->parent)
+		return (clsdev->parent);
 
-	return (struct sysfs_class_device *)dlist_find_custom(class->devices,
-			name, class_name_equal);
+	/*
+	 * 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 (!(strncmp(clsdev->classname, SYSFS_BLOCK_NAME, 
+					sizeof(SYSFS_BLOCK_NAME)))) {
+		if ((get_blockdev_parent(clsdev)) == 0) 
+			return (clsdev->parent);
+	}
+	return NULL;
 }
 
 /**
@@ -356,34 +250,34 @@ struct sysfs_class_device *sysfs_get_class_device(struct sysfs_class *class,
  * @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 (sysfs_trailing_slash(path) == 0)
-		strcat(path, "/");
-
-	if (strcmp(classname, SYSFS_BLOCK_NAME) == 0) {
-		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, 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;
 }
 
 /**
- * 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
@@ -391,13 +285,13 @@ 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
-		(const unsigned char *classname, const unsigned char *name)
+struct sysfs_class_device *sysfs_open_class_device
+		(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;
 	}
@@ -409,9 +303,9 @@ struct sysfs_class_device *sysfs_open_class_device_by_name
 							name, classname);
 		return NULL;
 	}
-	
-	cdev = sysfs_open_class_device(devpath);
-	if (cdev == NULL) {
+
+	cdev = sysfs_open_class_device_path(devpath);
+	if (!cdev) {
 		dprintf("Error getting class device %s from class %s\n",
 				name, classname);
 		return NULL;
@@ -420,84 +314,208 @@ struct sysfs_class_device *sysfs_open_class_device_by_name
 }
 
 /**
- * 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
+ * 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_get_classdev_attributes(struct sysfs_class_device *cdev)
+struct sysfs_attribute *sysfs_get_classdev_attr
+		(struct sysfs_class_device *clsdev, const char *name)
 {
-	if (cdev == NULL || cdev->directory == NULL)
+	if (!clsdev || !name) {
+		errno = EINVAL;
 		return NULL;
+	}
+	return get_attribute(clsdev, (char *)name);
+}
 
-	return (cdev->directory->attributes);
+/**
+ * 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 dlist *sysfs_get_classdev_attributes(struct sysfs_class_device *clsdev)
+{
+	if (!clsdev) {
+		errno = EINVAL;
+		return NULL;
+	}
+	return get_attributes_list(clsdev);
 }
 
 /**
- * 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_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_get_classdev_attr
-		(struct sysfs_class_device *clsdev, const unsigned char *name)
+struct sysfs_device *sysfs_get_classdev_device
+		(struct sysfs_class_device *clsdev)
 {
-	struct sysfs_attribute *cur = NULL;
+	char linkpath[SYSFS_PATH_MAX], devpath[SYSFS_PATH_MAX];
 
-	if (clsdev == NULL || clsdev->directory == NULL ||
-		clsdev->directory->attributes == NULL || name == NULL) {
+	if (!clsdev) {
 		errno = EINVAL;
 		return NULL;
 	}
 
-	cur = sysfs_get_directory_attribute(clsdev->directory,
-						(unsigned char *)name);
-	if (cur != NULL)
-		return cur;
+	if (clsdev->sysdevice)
+		return clsdev->sysdevice;
 
-	return NULL;
+	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 clsdev->sysdevice;
 }
 
 /**
- * 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_open_class: opens specific class and all its devices on system
+ * returns sysfs_class structure with success or NULL with error.
  */
-struct sysfs_attribute *sysfs_open_classdev_attr(const unsigned char *classname,
-		const unsigned char *dev, const unsigned char *attrib)
+struct sysfs_class *sysfs_open_class(const char *name)
 {
-	struct sysfs_attribute *attribute = NULL;
-	unsigned char path[SYSFS_PATH_MAX];
+	struct sysfs_class *cls = NULL;
+	char classpath[SYSFS_PATH_MAX];
 
-	if (classname == NULL || dev == NULL || attrib == NULL) {
+	if (!name) {
 		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);
+
+	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) {
+		safestrcat(classpath, "/");
+		safestrcat(classpath, SYSFS_BLOCK_NAME);
+	} else {
+		safestrcat(classpath, "/");
+		safestrcat(classpath, SYSFS_CLASS_NAME);
+		safestrcat(classpath, "/");
+		safestrcat(classpath, name);
+	}
+	if (sysfs_path_is_dir(classpath)) {
+		dprintf("Class %s not found on the system\n", name);
 		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);
+
+	cls = alloc_class();
+	if (cls == NULL) {
+		dprintf("calloc failed\n");
+		return NULL;
+	}
+	safestrcpy(cls->name, name);	
+	safestrcpy(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
+ * @cls: sysfs_class to find the device on
+ * @name: name of the class device to look for
+ * 
+ * Returns sysfs_class_device * on success and NULL on failure
+ */ 
+struct sysfs_class_device *sysfs_get_class_device(struct sysfs_class *cls,
+		const char *name)
+{
+	char path[SYSFS_PATH_MAX];
+	struct sysfs_class_device *cdev = NULL;
+
+	if (!cls || !name) {
+		errno = EINVAL;
 		return NULL;
 	}
-	if ((sysfs_read_attribute(attribute)) != 0) {
-		dprintf("Error reading attribute %s for class device %s\n",
-				attrib, dev);
-		sysfs_close_attribute(attribute);
+
+	if (cls->devices) {
+		cdev = (struct sysfs_class_device *)dlist_find_custom
+			(cls->devices, (void *)name, cdev_name_equal);
+		if (cdev)
+			return cdev;
+	}
+
+	safestrcpy(path, cls->path);
+	safestrcat(path, "/");
+	safestrcat(path, name);
+	if (!sysfs_path_is_dir(path)) {
+		cdev = sysfs_open_class_device_path(path);
+		if (!cdev) {
+			dprintf("Error opening class device at %s\n", path);
+			return NULL;
+		}
+	}
+	if (!cls->devices)
+		cls->devices = dlist_new_with_delete
+			(sizeof(struct sysfs_class_device),
+				 sysfs_close_cls_dev);
+	
+	dlist_unshift_sorted(cls->devices, cdev, sort_list);
+	return cdev;
+}
+
+/**
+ * sysfs_get_class_devices: get all class devices in the given class
+ * @cls: sysfs_class whose devices list is needed
+ *
+ * Returns a dlist of sysfs_class_device * on success and NULL on failure
+ */
+struct dlist *sysfs_get_class_devices(struct sysfs_class *cls)
+{
+	char path[SYSFS_PATH_MAX];
+	char *cdev_name;
+	struct sysfs_class_device *cdev = NULL;
+	struct dlist *dirlist;
+
+	if (!cls) {
+		errno = EINVAL;
 		return NULL;
 	}
-	return attribute;
+
+	safestrcpy(path, cls->path);
+	dirlist = read_dir_subdirs(path);
+	if (dirlist) {
+		dlist_for_each_data(dirlist, cdev_name, char) {
+			if (cls->devices) {
+				cdev = (struct sysfs_class_device *)
+					dlist_find_custom(cls->devices, 
+					(void *)cdev_name, cdev_name_equal);
+				if (cdev)
+					continue;
+			}
+			safestrcpy(path, cls->path);
+			safestrcat(path, "/");
+			safestrcat(path, cdev_name);
+			cdev = sysfs_open_class_device_path(path);
+			if (cdev) {
+				if (!cls->devices)
+					cls->devices = dlist_new_with_delete
+					(sizeof(struct sysfs_class_device),
+					 sysfs_close_cls_dev);
+				dlist_unshift_sorted(cls->devices, cdev,
+						sort_list);
+			}
+		}
+		sysfs_close_list(dirlist);
+	}
+	
+	return cls->devices;
 }
+