X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=libsysfs%2Fsysfs_device.c;h=7087730d5f16d7a830c658d3ef22be8b44dd9c77;hp=89704dcd8041092abf6b9f8e6c6362a1bf43ba84;hb=f385ff6512012a75b8381938dd3f55f991b53e9a;hpb=fe3fe3b29ffbc7d0ce7dca6a371da31d8b3ff7f8;ds=sidebyside

diff --git a/libsysfs/sysfs_device.c b/libsysfs/sysfs_device.c
index 89704dcd8..7087730d5 100644
--- a/libsysfs/sysfs_device.c
+++ b/libsysfs/sysfs_device.c
@@ -3,7 +3,7 @@
  *
  * Generic device 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
@@ -24,39 +24,170 @@
 #include "sysfs.h"
 
 /**
- * sysfs_close_device_tree: closes every device in the supplied tree, 
- * 	closing children only.
- * @devroot: device root of tree.
+ * get_dev_driver: fills in the dev->driver_name field 
+ * Returns 0 on SUCCESS and -1 on error
  */
-static void sysfs_close_device_tree(struct sysfs_device *devroot)
+static int get_dev_driver(struct sysfs_device *dev)
 {
-	if (devroot != NULL) {
-		if (devroot->children != NULL) {
-			struct sysfs_device *child = NULL;
+	struct dlist *drvlist;
+	char path[SYSFS_PATH_MAX];
+	char devpath[SYSFS_PATH_MAX];
+	char *drv = NULL, *c;
 
-			dlist_for_each_data(devroot->children, child,
-					struct sysfs_device) {
-				sysfs_close_device_tree(child);
+	if (!dev) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	memset(path, 0, SYSFS_PATH_MAX);
+	memset(devpath, 0, SYSFS_PATH_MAX);
+	safestrcpymax(path, dev->path, SYSFS_PATH_MAX);
+	safestrcatmax(path, "/driver", SYSFS_PATH_MAX);
+	if (!sysfs_path_is_link(path)) {
+		if (!sysfs_get_link(path, devpath, SYSFS_PATH_MAX)) {
+			if (sysfs_get_name_from_path(devpath, 
+					dev->driver_name, SYSFS_NAME_LEN))
+				return -1;
+		}
+		return 0;
+	}
+
+	/*
+	 * Devices on on earlier kernels do not have the "driver" link.
+	 * Look it up in the bus directory.
+	 */
+	if (dev->bus[0] == '\0')
+		return -1;
+	memset(path, 0, SYSFS_PATH_MAX);
+	memset(devpath, 0, SYSFS_PATH_MAX);
+	safestrcpy(path, dev->path);
+	c = strstr(path, SYSFS_DEVICES_NAME);
+	if (c == NULL) {
+		dprintf("Invalid path to device - %s\n", dev->path);
+		return -1;
+	} else
+		*c = '\0';
+	safestrcat(path, SYSFS_BUS_NAME);
+	safestrcat(path, "/");
+	safestrcat(path, dev->bus);
+	safestrcat(path, "/");
+	safestrcat(path, SYSFS_DRIVERS_NAME);
+
+	drvlist = sysfs_open_directory_list(path);
+	if (drvlist) {
+		dlist_for_each_data(drvlist, drv, char) {
+			safestrcpy(devpath, path);
+			safestrcat(devpath, "/");
+			safestrcat(devpath, drv);
+			safestrcat(devpath, "/");
+			safestrcat(devpath, dev->bus_id);
+			if (sysfs_path_is_link(devpath) == 0) {
+				safestrcpy(dev->driver_name, drv);
+				sysfs_close_list(drvlist);
+				return 0;
 			}
 		}
-		sysfs_close_device(devroot);
+		sysfs_close_list(drvlist);
 	}
+	return -1;
 }
 
 /**
- * sysfs_del_device: routine for dlist integration
+ * sysfs_get_device_bus: retrieves the bus name the device is on, checks path 
+ * 	to bus' link to make sure it has correct device.
+ * @dev: device to get busname.
+ * returns 0 with success and -1 with error.
  */
-static void sysfs_del_device(void *dev)
+int sysfs_get_device_bus(struct sysfs_device *dev)
 {
-	sysfs_close_device((struct sysfs_device *)dev);
+	char devpath[SYSFS_PATH_MAX];
+	char subsys[SYSFS_NAME_LEN];
+	char path[SYSFS_PATH_MAX];
+	char target[SYSFS_PATH_MAX];
+	char *bus = NULL, *c;
+	struct dlist *buslist;
+
+	if (!dev) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	memset(path, 0, SYSFS_PATH_MAX);
+	memset(devpath, 0, SYSFS_PATH_MAX);
+	safestrcpymax(path, dev->path, SYSFS_PATH_MAX);
+	safestrcatmax(path, "/bus", SYSFS_PATH_MAX);
+	if (!sysfs_path_is_link(path)) {
+		if (!sysfs_get_link(path, devpath, SYSFS_PATH_MAX)) {
+			if (sysfs_get_name_from_path(devpath, 
+					dev->bus, SYSFS_NAME_LEN))
+				return -1;
+		}
+		return 0;
+	}
+
+	/*
+	 * Devices on on earlier kernels do not have the "bus" link.
+	 * Look it up in the bus directory.
+	 */
+	memset(subsys, 0, SYSFS_NAME_LEN);
+	safestrcpy(subsys, dev->path);
+	c = strstr(subsys, SYSFS_DEVICES_NAME);
+	if (c == NULL) {
+		dprintf("Invalid path to device - %s\n", dev->path);
+		return -1;
+	} else 
+		*c = '\0';
+	safestrcat(subsys, SYSFS_BUS_NAME);
+	buslist = sysfs_open_directory_list(subsys);
+	if (buslist) {
+		dlist_for_each_data(buslist, bus, char) {
+			memset(path, 0, SYSFS_PATH_MAX);
+			safestrcpy(path, subsys);
+			safestrcat(path, "/");
+			safestrcat(path, bus);
+			safestrcat(path, "/");
+			safestrcat(path, SYSFS_DEVICES_NAME);
+			safestrcat(path, "/");
+			safestrcat(path, dev->bus_id);
+			if ((sysfs_path_is_link(path)) == 0) {
+				memset(target, 0, SYSFS_PATH_MAX);
+				if (sysfs_get_link(path, target, 
+						SYSFS_PATH_MAX)) {
+					dprintf("Error getting link target\n");
+					sysfs_close_list(buslist);
+					return -1;
+				}
+				if (!(strncmp(target, dev->path, 
+							SYSFS_PATH_MAX))) {
+					safestrcpy(dev->bus, bus);
+					sysfs_close_list(buslist);
+					return 0;
+				}
+			}
+		}
+		sysfs_close_list(buslist);
+	}
+	return -1;
 }
 
 /**
- * sysfs_close_dev_tree: routine for dlist integration
+ * sysfs_close_device_tree: closes every device in the supplied tree, 
+ * 	closing children only.
+ * @devroot: device root of tree.
  */
-static void sysfs_close_dev_tree(void *dev)
+void sysfs_close_device_tree(struct sysfs_device *devroot)
 {
-	sysfs_close_device_tree((struct sysfs_device *)dev);
+	if (devroot) {
+		if (devroot->children) {
+			struct sysfs_device *child = NULL;
+
+			dlist_for_each_data(devroot->children, child,
+					struct sysfs_device) {
+				sysfs_close_device_tree(child);
+			}
+		}
+		sysfs_close_device(devroot);
+	}
 }
 
 /**
@@ -65,11 +196,13 @@ static void sysfs_close_dev_tree(void *dev)
  */
 void sysfs_close_device(struct sysfs_device *dev)
 {
-	if (dev != NULL) {
-		if (dev->directory != NULL)
-			sysfs_close_directory(dev->directory);
-		if (dev->children != NULL && dev->children->count == 0)
+	if (dev) {
+		if (dev->parent)
+			sysfs_close_device(dev->parent);
+		if (dev->children && dev->children->count)
 			dlist_destroy(dev->children);
+		if (dev->attrlist)
+			dlist_destroy(dev->attrlist);
 		free(dev);
 	}
 }
@@ -80,306 +213,162 @@ void sysfs_close_device(struct sysfs_device *dev)
  */
 static struct sysfs_device *alloc_device(void)
 {
-	return (struct sysfs_device *)calloc(1, sizeof(struct sysfs_device));
-}
-
-/**
- * sysfs_get_device_attr: searches dev's attributes by name
- * @dev: device to look through
- * @name: attribute name to get
- * returns sysfs_attribute reference with success or NULL with error.
- */
-struct sysfs_attribute *sysfs_get_device_attr(struct sysfs_device *dev,
-						const unsigned char *name)
-{
-	struct sysfs_attribute *cur = NULL;
-
-	if (dev == NULL || dev->directory == NULL 
-	    || dev->directory->attributes == NULL || name == NULL) {
-		errno = EINVAL;
-		return NULL;
-	}
-	
-	cur = sysfs_get_directory_attribute(dev->directory, 
-			(unsigned char *)name);
-	if (cur != NULL)
-		return cur;
-
-	return NULL;
+	return (struct sysfs_device *) calloc(1, sizeof(struct sysfs_device));
 }
 
 /**
- * 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 char *path)
 {
-	struct sysfs_device *dev = NULL;
-	struct sysfs_directory *sdir = NULL;
+	struct sysfs_device *dev;
 
-	if (path == NULL) {
+	if (!path) {
 		errno = EINVAL;
 		return NULL;
 	}
-	dev = alloc_device();	
-	if (dev == NULL) {
+	if (sysfs_path_is_dir(path)) {
+		dprintf("Incorrect path to device: %s\n", path);
+		return NULL;
+	}
+	dev = alloc_device();
+	if (!dev) {
 		dprintf("Error allocating device at %s\n", path);
 		return NULL;
 	}
-	sdir = sysfs_open_directory(path);
-	if (sdir == NULL) {
-		dprintf("Invalid device at %s\n", path);
+	if (sysfs_get_name_from_path(path, dev->bus_id, SYSFS_NAME_LEN)) {
 		errno = EINVAL;
+		dprintf("Error getting device bus_id\n");
 		sysfs_close_device(dev);
 		return NULL;
 	}
-	if ((sysfs_read_directory(sdir)) != 0) {
-		dprintf("Error reading device directory at %s\n", path);
-		sysfs_close_directory(sdir);
+	safestrcpy(dev->path, path);
+	if (sysfs_remove_trailing_slash(dev->path)) {
+		dprintf("Invalid path to device %s\n", dev->path);
 		sysfs_close_device(dev);
 		return NULL;
 	}
-	dev->directory = sdir;
-	strcpy(dev->bus_id, sdir->name);
-	strcpy(dev->path, sdir->path);
-
-	/* 
+	/*
 	 * The "name" attribute no longer exists... return the device's
 	 * sysfs representation instead, in the "dev->name" field, which
 	 * implies that the dev->name and dev->bus_id contain same data.
 	 */
-	strncpy(dev->name, sdir->name, SYSFS_NAME_LEN);
+	safestrcpy(dev->name, dev->bus_id);
 
-	return dev;
-}
+	if (sysfs_get_device_bus(dev))
+		dprintf("Could not get device bus\n");
 
-/**
- * sysfs_open_device_tree: opens root device and all of its children,
- *	creating a tree of devices. Only opens children.
- * @path: sysfs path to devices
- * returns struct sysfs_device and its children with success or NULL with
- *	error.
- */
-static struct sysfs_device *sysfs_open_device_tree(const unsigned char *path)
-{
-	struct sysfs_device *rootdev = NULL, *new = NULL;
-	struct sysfs_directory *cur = NULL;
-
-	if (path == NULL) {
-		errno = EINVAL;
-		return NULL;
-	}
-	rootdev = sysfs_open_device(path);
-	if (rootdev == NULL) {
-		dprintf("Error opening root device at %s\n", path);
-		return NULL;
-	}
-	if (rootdev->directory->subdirs != NULL) {
-		dlist_for_each_data(rootdev->directory->subdirs, cur,
-				struct sysfs_directory) {
-			new = sysfs_open_device_tree(cur->path);
-			if (new == NULL) {
-				dprintf("Error opening device tree at %s\n",
-					cur->path);
-				sysfs_close_device_tree(rootdev);
-				return NULL;
-			}
-			if (rootdev->children == NULL)
-				rootdev->children = dlist_new_with_delete
-					(sizeof(struct sysfs_device),
-					sysfs_del_device);
-			dlist_unshift(rootdev->children, new);
-		}
+	if (get_dev_driver(dev)) {
+		dprintf("Could not get device %s's driver\n", dev->bus_id);
+		safestrcpy(dev->driver_name, SYSFS_UNKNOWN);
 	}
 
-	return rootdev;
-}
-
-/**
- * sysfs_close_root_device: closes root and all devices
- * @root: root device to close
- */
-void sysfs_close_root_device(struct sysfs_root_device *root)
-{
-	if (root != NULL) {
-		if (root->devices != NULL)
-			dlist_destroy(root->devices);
-		if (root->directory != NULL)
-			sysfs_close_directory(root->directory);
-		free(root);
-	}
+	return dev;
 }
 
 /**
- * open_root_device_dir: opens up sysfs_directory for specific root dev
- * @name: name of root
- * returns struct sysfs_directory with success and NULL with error
+ * sysfs_get_device_attr: searches dev's attributes by name
+ * @dev: device to look through
+ * @name: attribute name to get
+ * returns sysfs_attribute reference with success or NULL with error.
  */
-static struct sysfs_directory *open_root_device_dir(const unsigned char *name)
+struct sysfs_attribute *sysfs_get_device_attr(struct sysfs_device *dev,
+						const char *name)
 {
-	struct sysfs_directory *rdir = NULL;
-	unsigned char rootpath[SYSFS_PATH_MAX];
-
-	if (name == NULL) {
+	if (!dev || !name) {
 		errno = EINVAL;
 		return NULL;
 	}
-
-	memset(rootpath, 0, SYSFS_PATH_MAX);
-	if (sysfs_get_mnt_path(rootpath, SYSFS_PATH_MAX) != 0) {
-		dprintf ("Sysfs not supported on this system\n");
-		return NULL;
-	}
-
-	strcat(rootpath, SYSFS_DEVICES_DIR);
-	strcat(rootpath, "/");
-	strcat(rootpath, name);
-	rdir = sysfs_open_directory(rootpath);
-	if (rdir == NULL) {
-		errno = EINVAL;
-		dprintf ("Root device %s not supported on this system\n",
-			name);
-		return NULL;
-	}
-	if (sysfs_read_directory(rdir) != 0) {
-		dprintf ("Error reading %s root device at dir %s\n", name,
-			rootpath);
-		sysfs_close_directory(rdir);
-		return NULL;
-	}
-	
-	return rdir;
+	return get_attribute(dev, (char *)name);
 }
 
 /**
- * get_all_root_devices: opens up all the devices under this root device
- * @root: root device to open devices for
- * returns 0 with success and -1 with error
+ * sysfs_get_device_attributes: gets list of device attributes
+ * @dev: device whose attributes list is needed
+ * returns dlist of attributes on success or NULL on error
  */
-static int get_all_root_devices(struct sysfs_root_device *root)
+struct dlist *sysfs_get_device_attributes(struct sysfs_device *dev)
 {
-	struct sysfs_device *dev = NULL;
-	struct sysfs_directory *cur = NULL;
-
-	if (root == NULL || root->directory == NULL) {
+	if (!dev) {
 		errno = EINVAL;
-		return -1;
-	}
-	if (root->directory->subdirs == NULL)
-		return 0;
-
-	dlist_for_each_data(root->directory->subdirs, cur,
-			struct sysfs_directory) {
-		dev = sysfs_open_device_tree(cur->path);
-		if (dev == NULL) {
-			dprintf ("Error opening device at %s\n", cur->path);
-			continue;
-		}
-		if (root->devices == NULL)
-			root->devices = dlist_new_with_delete
-				(sizeof(struct sysfs_device), 
-				sysfs_close_dev_tree);
-		dlist_unshift(root->devices, dev);
+		return NULL;
 	}
-
-	return 0;
+	return get_attributes_list(dev);
 }
 
 /**
- * sysfs_open_root_device: opens sysfs devices root and all of its
- *	devices.
- * @name: name of /sys/devices/root to open
- * returns struct sysfs_root_device if success and NULL with error
+ * get_device_absolute_path: looks up the bus the device is on, gets 
+ * 		absolute path to the device
+ * @device: device for which path is needed
+ * @path: buffer to store absolute path
+ * @psize: size of "path"
+ * Returns 0 on success -1 on failure
  */
-struct sysfs_root_device *sysfs_open_root_device(const unsigned char *name)
+static int get_device_absolute_path(const char *device,	const char *bus, 
+				char *path, size_t psize)
 {
-	struct sysfs_root_device *root = NULL;
-	struct sysfs_directory *rootdir = NULL;
+	char bus_path[SYSFS_PATH_MAX];
 
-	if (name == NULL) {
+	if (!device || !path) {
 		errno = EINVAL;
-		return NULL;
+		return -1;
 	}
 
-	root = (struct sysfs_root_device *)calloc
-					(1, sizeof(struct sysfs_root_device));
-	if (root == NULL) {
-		dprintf("calloc failure\n");
-		return NULL;
-	}
-	rootdir = open_root_device_dir(name);
-	if (rootdir == NULL) {
-		dprintf ("Invalid root device, %s not supported\n", name);
-		sysfs_close_root_device(root);
-		return NULL;
+	memset(bus_path, 0, SYSFS_PATH_MAX);
+	if (sysfs_get_mnt_path(bus_path, SYSFS_PATH_MAX)) {
+		dprintf ("Sysfs not supported on this system\n");
+		return -1;
 	}
-	strcpy(root->path, rootdir->path);
-	root->directory = rootdir;
-	if (get_all_root_devices(root) != 0) {
-		dprintf ("Error retrieving devices for root %s\n", name);
-		sysfs_close_root_device(root);
-		return NULL;
+	safestrcat(bus_path, "/");
+	safestrcat(bus_path, SYSFS_BUS_NAME);
+	safestrcat(bus_path, "/");
+	safestrcat(bus_path, bus);
+	safestrcat(bus_path, "/");
+	safestrcat(bus_path, SYSFS_DEVICES_NAME);
+	safestrcat(bus_path, "/");
+	safestrcat(bus_path, device);
+	/*
+	 * We now are at /sys/bus/"bus_name"/devices/"device" which is a link.
+	 * Now read this link to reach to the device.
+	 */ 
+	if (sysfs_get_link(bus_path, path, psize)) {
+		dprintf("Error getting to device %s\n", device);
+		return -1;
 	}
-
-	return root;
-}
-
-/**
- * sysfs_get_device_attributes: returns a dlist of attributes corresponding to
- * 	the specific device
- * @device: struct sysfs_device * for which attributes are to be returned
- */
-struct dlist *sysfs_get_device_attributes(struct sysfs_device *device)
-{
-	if (device == NULL || device->directory == NULL) 
-		return NULL;
-
-	return (device->directory->attributes);
+	return 0;
 }
 
 /**
- * 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: bus the device belongs to
  * @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
- * @bsize: size of the bus buffer
  * returns struct sysfs_device if found, NULL otherwise
  * NOTE: 
  * 1. Use sysfs_close_device to close the 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, 
-		const unsigned char *bus, size_t bsize)
+struct sysfs_device *sysfs_open_device(const char *bus,	const char *bus_id)
 {
-	char sysfs_path[SYSFS_PATH_MAX], device_path[SYSFS_PATH_MAX];
-	struct sysfs_device *device = NULL;
+	char sysfs_path[SYSFS_PATH_MAX];
+	struct sysfs_device *device;
 
-	if (bus_id == NULL || bus == NULL) {
+	if (!bus_id || !bus) {
 		errno = EINVAL;
 		return NULL;
 	}
 	memset(sysfs_path, 0, SYSFS_PATH_MAX);
-	if ((sysfs_get_mnt_path(sysfs_path, SYSFS_PATH_MAX)) != 0) {
-		dprintf("Error getting sysfs mount path\n");
-		return NULL;
-	}
-	strcat(sysfs_path, SYSFS_BUS_DIR);
-	strcat(sysfs_path, "/");
-	strncat(sysfs_path, bus, bsize);
-	strcat(sysfs_path, SYSFS_DEVICES_DIR);
-	strcat(sysfs_path, "/");
-	strcat(sysfs_path, bus_id);
-
-	/* devices under /sys/bus/xxx/devices are links to devices subsystem */
-	if ((sysfs_get_link(sysfs_path, device_path, SYSFS_PATH_MAX)) < 0) {
-		dprintf("Error getting device path\n");
+	if (get_device_absolute_path(bus_id, bus, sysfs_path, 
+				SYSFS_PATH_MAX)) {
+		dprintf("Error getting to device %s\n", bus_id);
 		return NULL;
 	}
 	
-	device = sysfs_open_device(device_path);
-	if (device == NULL) {
+	device = sysfs_open_device_path(sysfs_path);
+	if (!device) {
 		dprintf("Error opening device %s\n", bus_id);
 		return NULL;
 	}
@@ -388,151 +377,55 @@ struct sysfs_device *sysfs_open_device_by_id(const unsigned char *bus_id,
 }
 
 /**
- * get_device_absolute_path: looks up the bus the device is on, gets 
- * 		absolute path to the device
- * @device: device for which path is needed
- * @path: buffer to store absolute path
- * @psize: size of "path"
- * Returns 0 on success -1 on failure
+ * 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
  */
-static int get_device_absolute_path(const unsigned char *device, 
-					unsigned char *path, size_t psize)
+struct sysfs_device *sysfs_get_device_parent(struct sysfs_device *dev)
 {
-	unsigned char bus_name[SYSFS_NAME_LEN], bus_path[SYSFS_PATH_MAX];
+	char ppath[SYSFS_PATH_MAX], *tmp;
 
-	if (device == NULL || path == NULL) {
+	if (!dev) {
 		errno = EINVAL;
-		return -1;
-	}
-
-	memset(bus_name, 0, SYSFS_NAME_LEN);
-	memset(bus_path, 0, SYSFS_NAME_LEN);
-	if ((sysfs_find_device_bus(device, bus_name, SYSFS_NAME_LEN)) != 0) {
-		dprintf("Device %s not found\n", device);
-		return -1;
-	}
-	if (sysfs_get_mnt_path(bus_path, SYSFS_PATH_MAX) != 0) {
-		dprintf ("Sysfs not supported on this system\n");
-		return -1;
-	}
-	strcat(bus_path, SYSFS_BUS_DIR);
-	strcat(bus_path, "/");
-	strcat(bus_path, bus_name);
-	strcat(bus_path, SYSFS_DEVICES_DIR);
-	strcat(bus_path, "/");
-	strcat(bus_path, device);
-	/*
-	 * We now are at /sys/bus/"bus_name"/devices/"device" which is a link.
-	 * Now read this link to reach to the device.
-	 */ 
-	if ((sysfs_get_link(bus_path, path, SYSFS_PATH_MAX)) != 0) {
-		dprintf("Error getting to device %s\n", device);
-		return -1;
+		return NULL;
 	}
-	return 0;
-}
 
-/**
- * sysfs_write_device_attr: modify a "writable" attribute for the given device
- * @dev: device bus_id for which attribute has to be changed
- * @attrib: attribute to change
- * @value: value to change to
- * @len: "value" length to write
- * Returns 0 on success -1 on error
- */ 
-int sysfs_write_device_attr(unsigned char *dev, unsigned char *attrib,
-					unsigned char *value, size_t len)
-{
-	struct sysfs_attribute *attribute = NULL;
-	unsigned char devpath[SYSFS_PATH_MAX];
+	if (dev->parent)
+		return (dev->parent);
 
-	if (dev == NULL || attrib == NULL || value == NULL) {
-		errno = EINVAL;
-		return -1;
-	}
-	
-	memset(devpath, 0, SYSFS_PATH_MAX);
-	if ((get_device_absolute_path(dev, devpath, SYSFS_PATH_MAX)) != 0) {
-		dprintf("Error finding absolute path to device %s\n", dev);
-		return -1;
-	}
-	strcat(devpath, "/");
-	strcat(devpath, attrib);
-	attribute = sysfs_open_attribute(devpath);
-	if (attribute == NULL) {
-		dprintf("Attribute %s could not be retrieved for device %s\n",
-				attrib, dev);
-		return -1;
+	memset(ppath, 0, SYSFS_PATH_MAX);
+	safestrcpy(ppath, dev->path);
+	tmp = strrchr(ppath, '/');
+	if (!tmp) {
+		dprintf("Invalid path to device %s\n", ppath);
+		return NULL;
 	}
-	if (attribute->method & SYSFS_METHOD_SHOW) {
-		if ((sysfs_read_attribute(attribute)) != 0) {
-			dprintf("Error reading attribute %s for device %s\n",
-					attrib, dev);
-			sysfs_close_attribute(attribute);
-			return -1;
+	if (*(tmp + 1) == '\0') {
+		*tmp = '\0';
+		tmp = strrchr(tmp, '/');
+		if (tmp == NULL) {
+			dprintf("Invalid path to device %s\n", ppath);
+			return NULL;
 		}
 	}
-	if ((sysfs_write_attribute(attribute, value, len)) < 0) {
-		dprintf("Error setting %s to %s\n", attrib, value);
-		sysfs_close_attribute(attribute);
-		return -1;
-	}
-	sysfs_close_attribute(attribute);
-	return 0;
-}
+	*tmp = '\0';
 
-/**
- * sysfs_read_device_attr: read an attribute of the given device
- * @dev: device bus_id for which attribute has to be changed
- * @attrib: attribute to read
- * @value: buffer to return value in
- * @len: size of buffer available
- * Returns 0 on success -1 on error
- */ 
-int sysfs_read_device_attr(unsigned char *dev, unsigned char *attrib,
-					unsigned char *value, size_t len)
-{
-	struct sysfs_attribute *attribute = NULL;
-	unsigned char devpath[SYSFS_PATH_MAX];
-
-	if (dev == NULL || attrib == NULL || value == NULL) {
-		errno = EINVAL;
-		return -1;
-	}
-	
-	memset(devpath, 0, SYSFS_PATH_MAX);
-	if ((get_device_absolute_path(dev, devpath, SYSFS_PATH_MAX)) != 0) {
-		dprintf("Error finding absolute path to device %s\n", dev);
-		return -1;
-	}
-	strcat(devpath, "/");
-	strcat(devpath, attrib);
-	attribute = sysfs_open_attribute(devpath);
-	if (attribute == NULL) {
-		dprintf("Error opening attribute %s for device %s\n",
-				attrib, dev);
-		return -1;
-	}
-	if (!(attribute->method & SYSFS_METHOD_SHOW)) {
-		dprintf("Show method not supported for attribute %s\n",
-				attrib);
-		sysfs_close_attribute(attribute);
-		return -1;
-	}
-	if ((sysfs_read_attribute(attribute)) != 0) {
-		dprintf("Error reading attribute %s for device %s\n",
-				attrib, dev);
-		sysfs_close_attribute(attribute);
-		return -1;
+	/*
+	 * All "devices" have the "detach_state" attribute - validate here
+	 */
+	safestrcat(ppath, "/detach_state");
+	if (sysfs_path_is_file(ppath)) {
+		dprintf("Device at %s does not have a parent\n", dev->path);
+		return NULL;
 	}
-	if (attribute->len > len) {
-		dprintf("Value length %d is larger than supplied buffer %d\n",
-				attribute->len, len);
-		sysfs_close_attribute(attribute);
-		return -1;
+	tmp = strrchr(ppath, '/');
+	*tmp = '\0';
+	dev->parent = sysfs_open_device_path(ppath);
+	if (!dev->parent) {
+		dprintf("Error opening device %s's parent at %s\n", 
+					dev->bus_id, ppath);
+		return NULL;
 	}
-	strncpy(value, attribute->value, attribute->len);
-	value[(attribute->len)+1] = 0;
-	sysfs_close_attribute(attribute);
-	return 0;
+	return (dev->parent);
 }