[PATCH] new version of libsysfs patch

Here's the patch applying the latest libsysfs.
	- adds the latest libsysfs code to udev
		* new code includes dlist implementation, a generic linked list
			implementation. Needed our own because LGPL
		* rearranged structures
		* provided more functions for accessing directory and attributes
	- gets rid of ->directory->path references in namedev.c
	- replaces sysfs_get_value_from_attributes with sysfs_get_classdev_attr

11 files changed, 2569 insertions, 512 deletions

diff --git a/libsysfs/Makefile b/libsysfs/Makefile
index 79cc533959..b82acbdbf2 100644
--- a/libsysfs/Makefile
+++ b/libsysfs/Makefile
@@ -1,15 +1,15 @@
 # Makefile for libsysfs.a
 # Copyright (c) International Business Machines Corp., 2003
 
-H_INCLUDE=../include
+H_INCLUDE=.
 LIB_INCLUDE=.
 OBJS=sysfs_bus.o sysfs_class.o sysfs_device.o sysfs_dir.o sysfs_driver.o \
-	sysfs_utils.o
+	sysfs_utils.o dlist.o
 
 # Install directory
 
 # Options
-CFLAGS=-O2 -Wall -ansi -g
+CFLAGS=-O2 -Wall -g
 
 # sysfs library
 LIBSYSFS=libsysfs.a
@@ -38,5 +38,8 @@ sysfs_driver.o: sysfs_driver.c
 sysfs_utils.o: sysfs_utils.c
 	$(CC) -I$(H_INCLUDE) -I$(LIB_INCLUDE) $(CFLAGS) -c sysfs_utils.c
 
+dlist.o: dlist.c
+	$(CC) -I$(H_INCLUDE) -I$(LIB_INCLUDE) $(CFLAGS) -c dlist.c
+
 clean:
 	$(RM) *.o *~ core $(LIBSYSFS)
diff --git a/libsysfs/dlist.c b/libsysfs/dlist.c
new file mode 100644
index 0000000000..6dfcf726ba
--- /dev/null
+++ b/libsysfs/dlist.c
@@ -0,0 +1,343 @@
+/*
+ * dlist.c
+ *
+ * Copyright (C) 2003 Eric J Bohm
+ *
+ *  This library is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU Lesser General Public
+ *  License as published by the Free Software Foundation; either
+ *  version 2.1 of the License, or (at your option) any later version.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ *  Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public
+ *  License along with this library; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 021110307 USA
+ *
+ */
+
+
+/* Double linked list implementation.
+
+ * You allocate the data and give dlist the pointer.
+ * If your data is complex set the dlist->del_func to a an appropriate
+ * delete function.  Otherwise dlist will just use free.
+
+*/
+#include "dlist.h"
+
+/*
+ * Return pointer to node at marker.
+ * else null if no nodes.
+ */
+
+inline void *dlist_mark(Dlist *list)
+{
+  if(list->marker!=NULL)
+    return(list->marker->data);
+  else
+    return(NULL);
+}
+
+/* 
+ * Set marker to start.
+ */
+
+inline void dlist_start(Dlist *list)
+{
+  list->marker=list->head;
+}
+
+/* 
+ * Set marker to end.
+ */
+
+inline void dlist_end(Dlist *list)
+{
+  list->marker=list->head;
+}
+
+/* internal use function
+ * quickie inline to consolidate the marker movement logic
+ * in one place
+ *
+ * when direction true it moves marker after 
+ * when direction false it moves marker before.
+ * return pointer to data at new marker
+ * if nowhere to move the marker in desired direction return null 
+ */
+inline void *_dlist_mark_move(Dlist *list,int direction)
+{
+  if(direction)
+    {
+      if( list->marker->next!=NULL)
+	list->marker=list->marker->next;
+      else
+	return(NULL);
+    }
+  else
+    {
+      if( list->marker->prev!=NULL)
+	list->marker=list->marker->prev;
+      else
+	return(NULL);
+    }
+  if(list->marker!=list->head)
+    return(list->marker->data);
+  else
+    return(NULL);
+}
+
+/*
+ * Create new linked list to store nodes of datasize.
+ * return null if list cannot be created.
+ */
+Dlist *dlist_new(size_t datasize)
+{
+  Dlist *list=NULL;
+  if((list=malloc(sizeof(Dlist))))
+    {
+      list->marker=NULL;
+      list->count=0L;
+      list->data_size=datasize;
+      list->del_func=free;
+      list->head=&(list->headnode);
+      list->head->prev=NULL;
+      list->head->next=NULL;
+      list->head->data=NULL;
+    }
+  return(list);
+}
+
+/*
+ * Create new linked list to store nodes of datasize set list
+ * data node delete function to the passed in del_func
+ * return null if list cannot be created.
+ */
+Dlist *dlist_new_with_delete(size_t datasize,void (*del_func)(void*))
+{
+  Dlist *list=NULL;
+  list=dlist_new(datasize);
+  if(list!=NULL)
+    list->del_func=del_func;
+  return(list);
+}
+
+
+/*
+ * remove marker node from list
+ * call data_delete function on data if registered.
+ * otherwise call free.
+ * when direction true it moves marker after 
+ * when direction false it moves marker before.
+ * free marker node
+ * return nothing.
+ */
+void dlist_delete(Dlist *list,int direction)
+{
+  if((list->marker != list->head)&&(list->marker!=NULL)) 
+    {
+      DL_node *corpse;
+      corpse=list->marker;
+      _dlist_mark_move(list,direction);
+      if(list->head->next==corpse)
+	list->head->next=corpse->next;
+      if(list->head->prev==corpse)
+	list->head->prev=corpse->prev;
+      if(corpse->prev!=NULL) //should be impossible
+	corpse->prev->next=corpse->next;
+      if(corpse->next!=NULL) //should be impossible
+	corpse->next->prev=corpse->prev;
+      list->del_func(corpse->data);
+      list->count--;
+      free(corpse);
+    }
+}
+
+/*
+ * Insert node containing data at marker.
+ * If direction true it inserts after.
+ * If direction false it inserts before.
+ * move marker to inserted node
+ * return pointer to inserted node
+ */
+void *dlist_insert(Dlist *list,void *data,int direction)
+{
+  DL_node *new_node=NULL;
+  if(list==NULL || data==NULL)
+    return(NULL);
+  if(list->marker==NULL) //in case the marker ends up unset
+    list->marker=list->head;
+  if((new_node=malloc(sizeof(DL_node))))
+    {
+      new_node->data=data;
+      new_node->prev=NULL;
+      new_node->next=NULL;
+      list->count++;
+      if(list->head->next==NULL) //no l
+	{
+	  list->head->next=list->head->prev=new_node;
+	  new_node->prev=list->head;
+	  new_node->next=list->head;
+	}
+      else if(direction)
+	{
+	  new_node->next=list->marker->next;
+	  new_node->prev=list->marker;
+	  list->marker->next->prev=new_node;
+	  list->marker->next=new_node;
+	}
+      else
+	{
+	  new_node->prev=list->marker->prev;
+	  new_node->next=list->marker;
+	  list->marker->prev->next=new_node;
+	  list->marker->prev=new_node;
+	}
+	list->marker=new_node;
+    }
+  else
+    {
+      return(NULL);
+    }
+  return(list->marker->data);
+}
+
+/* 
+ * Remove DL_node from list without deallocating data.
+ * if marker == killme .
+ *  when direction true it moves marker after 
+ *  when direction false it moves marker before.
+ * to previous if there is no next.
+ */
+void *_dlist_remove(Dlist *list,DL_node *killme,int direction)
+{
+  if(killme!=NULL)
+    {
+      void *killer_data=killme->data;
+      // take care of head and marker pointers.
+      if(list->marker==killme)
+	_dlist_mark_move(list,direction);
+      if(killme ==list->head->next)
+	list->head->next=killme->next;
+      if(killme==list->head->prev)  
+	list->head->prev=killme->prev;
+      // remove from list
+      if(killme->prev !=NULL)
+	killme->prev->next=killme->next;
+      if(killme->next !=NULL)
+	killme->next->prev=killme->prev;
+      list->count--;
+      free(killme);
+      return(killer_data);
+    }
+  else
+    return (NULL);
+}
+
+
+/*
+ * Insert node containing data after end.
+ */
+void dlist_push(Dlist *list,void *data)
+{
+  list->marker=list->head->prev;
+  dlist_insert(list,data,1);
+}
+
+/*
+ * Insert node containing data at start.
+ */
+
+void dlist_unshift(Dlist *list,void *data)
+
+{
+  list->marker=list->head->next;
+  dlist_insert(list,data,0);
+}
+
+
+/* 
+ * Remove end node from list.
+ * Return pointer to data in removed node.
+ * Null if no nodes.
+ */
+
+void *dlist_pop(Dlist *list)
+{
+  return(_dlist_remove(list,list->head->prev,0));
+}
+
+/* 
+ * Remove start node from list.
+ * Return pointer to data in removed node.
+ * Null if no nodes.
+ */
+
+void *dlist_shift(Dlist *list)
+{
+  return(_dlist_remove(list,list->head->next,1));
+}
+
+
+/* 
+ * destroy the list freeing all memory
+ */
+
+
+void dlist_destroy(Dlist *list)
+{
+  if(list !=NULL)
+    {
+      dlist_start(list);
+      dlist_next(list);
+      while (dlist_mark(list)) {
+	      dlist_delete(list,1);
+      }
+      free(list);
+    }
+}
+
+/**
+ *  Return void pointer to list_data element matching comp function criteria
+ *  else null
+ *  Does not move the marker.
+ */
+
+void *dlist_find_custom(struct dlist *list, void *target, int (*comp)(void *, void *))
+{
+	/* test the comp function on each node */
+	struct dl_node *nodepointer;
+	dlist_for_each_nomark(list,nodepointer)
+		if(comp(target,nodepointer->data))
+			return(nodepointer->data);
+	return(NULL);
+}
+
+/**
+ * Apply the node_operation function to each data node in the list
+ */
+void dlist_transform(struct dlist *list, void (*node_operation)(void *))
+{
+	struct dl_node *nodepointer;
+	dlist_for_each_nomark(list,nodepointer)
+		node_operation(nodepointer->data);
+}
+
+/**
+ * insert new into list in sorted order
+ * sorter function in form int sorter(new,ith)
+ *       must return 1 for when new should go before ith
+ *       else 0
+ * return pointer to inserted node
+ * NOTE: assumes list is already sorted
+ */
+void *dlist_insert_sorted(struct dlist *list, void *new, int (*sorter)(void *, void *))
+{
+	for(dlist_start(list),dlist_next(list); \
+		list->marker!=list->head && !sorter(new,list->marker->data);dlist_next(list));
+	return(dlist_insert_before(list,new));
+}
diff --git a/libsysfs/dlist.h b/libsysfs/dlist.h
new file mode 100644
index 0000000000..5da79f9ba2
--- /dev/null
+++ b/libsysfs/dlist.h
@@ -0,0 +1,195 @@
+/*
+ * dlist.h
+ *
+ * Copyright (C) 2003 Eric J Bohm
+ *
+ *  This library is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU Lesser General Public
+ *  License as published by the Free Software Foundation; either
+ *  version 2.1 of the License, or (at your option) any later version.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ *  Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public
+ *  License along with this library; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ */
+#ifndef _DLIST_H_
+#define _DLIST_H_
+
+/* Double linked list header.
+   
+* navigate your list with DLIST_PREV and DLIST_NEXT.  These are macros
+* so function call overhead is minimized.
+
+* Supports perl style push, pop, shift, unshift list semantics.
+
+* You allocate the data and give dlist the pointer.  If your data is
+* complex set the dlist->del_func to a an appropriate delete using
+* dlist_new_with_delete.  Your delete function must match 
+(void * )(del(void *)
+*Otherwise dlist will just use free.
+
+* NOTE: The small amount of pain involved in doing that allows us to
+* avoid copy in copy out semantics.
+
+* Dlist uses an internal mark pointer to keep track of where you are
+* in the list.
+
+* insert and delete take a directional parameter. Where direction
+* corresponds to the direction in which you want the list to go.
+* true direction corresponded to progressing forward in the last
+* false to regressing in the list.
+* so a dlist_insert(yourlist,item,1) will insert it after the mark
+* so a dlist_insert(yourlist,item,0) will insert it before the mark
+* any insert will move the mark to the new node regardless of the direction.
+
+* Just use the dlist_(insert|delete)_(before|after) macros if you do not want
+* to think about it.
+
+*/
+#include <malloc.h>
+typedef struct dl_node {
+  struct dl_node *prev;
+  struct dl_node *next;
+  void *data;
+} DL_node;
+
+typedef struct dlist {
+  DL_node *marker;
+  unsigned long count;
+  size_t data_size;
+  void (*del_func)(void *);
+  DL_node headnode;
+  DL_node *head;
+} Dlist;
+
+Dlist *dlist_new(size_t datasize);
+Dlist *dlist_new_with_delete(size_t datasize,void (*del_func)(void*));
+void *_dlist_mark_move(Dlist *list,int direction);
+void *dlist_mark(Dlist *);
+void dlist_start(Dlist *);
+void dlist_end(Dlist *);
+
+void *dlist_insert(Dlist *,void *,int) ;
+
+void *dlist_insert_sorted(struct dlist *list, void *new, int (*sorter)(void *, void *));
+
+void dlist_delete(Dlist *,int);
+
+void dlist_push(Dlist *,void *);
+
+void dlist_unshift(Dlist *,void *);
+
+void *dlist_pop(Dlist *);
+
+void *dlist_shift(Dlist *);
+
+void dlist_destroy(Dlist *);
+
+void *dlist_find_custom(struct dlist *list, void *target, int (*comp)(void *, void *));
+void dlist_transform(struct dlist *list, void (*node_operation)(void *));
+
+
+/* 
+ * _dlist_remove is for internal use only
+ * _dlist_mark_move is for internal use only
+ */
+void *_dlist_remove(struct dlist *,struct dl_node *,int );
+
+#define dlist_prev(A) _dlist_mark_move((A),0)
+#define dlist_next(A) _dlist_mark_move((A),1)
+
+#define dlist_insert_before(A,B) dlist_insert((A),(B),0)
+#define dlist_insert_after(A,B) dlist_insert((A),(B),1)
+
+#define dlist_delete_before(A) dlist_delete((A),0)
+#define dlist_delete_after(A) dlist_delete((A),1)
+
+/**
+ * provide for loop header which iterates the mark from start to end
+ * list: the dlist pointer, use dlist_mark(list) to get iterator
+ */
+#define dlist_for_each(list) \
+	for(dlist_start(list),dlist_next(list); \
+		(list)->marker!=(list)->head;dlist_next(list))
+
+/**
+ * provide for loop header which iterates the mark from end to start
+ * list: the dlist pointer, use dlist_mark(list) to get iterator
+ */
+#define dlist_for_each_rev(list) \
+	for(dlist_end(list),dlist_prev(list); \
+		(list)->marker!=(list)->head;dlist_prev(list))
+
+/**
+ * provide for loop header which iterates through the list without moving mark
+ * list: the dlist_pointer
+ * iterator: dl_node pointer to iterate
+ */
+#define dlist_for_each_nomark(list,iterator) \
+	for((iterator)=(list)->head->next; (iterator)!=(list)->head; \
+		(iterator)=(iterator)->next)
+
+/**
+ * provide for loop header which iterates through the list without moving mark
+ * in reverse
+ * list: the dlist_pointer
+ * iterator: dl_node pointer to iterate
+ */
+#define dlist_for_each_nomark_rev(list,iterator) \
+	for((iterator)=(list)->head->prev; (iterator)!=(list)->head; \
+		(iterator)=(iterator)->prev)
+/**
+ * provide for loop header which iterates through the list providing a
+ * data iterator
+ * list: the dlist pointer
+ * data_iterator: the pointer of type datatype to iterate
+ * datatype:  actual type of the contents in the dl_node->data
+ */
+
+#define dlist_for_each_data(list,data_iterator,datatype) \
+	for(dlist_start(list), (data_iterator)=(datatype *) dlist_next(list); \
+	(list)->marker!=(list)->head;(data_iterator)=(datatype *) dlist_next(list))
+
+/**
+ * provide for loop header which iterates through the list providing a
+ * data iterator in reverse
+ * list: the dlist pointer
+ * data_iterator: the pointer of type datatype to iterate
+ * datatype:  actual type of the contents in the dl_node->data
+ */
+#define dlist_for_each_data_rev(list,data_iterator,datatype) \
+	for(dlist_end(list), (data_iterator)=(datatype *) dlist_prev(list); \
+	(list)->marker!=(list)->head;(data_iterator)=(datatype *) dlist_prev(list))
+
+/**
+ * provide for loop header which iterates through the list providing a
+ * data iterator without moving the mark
+ * list: the dlist pointer
+ * iterator: the dl_node pointer to iterate
+ * data_iterator: the pointer of type datatype to iterate
+ * datatype:  actual type of the contents in the dl_node->data
+ */
+
+#define dlist_for_each_data_nomark(list,iterator,data_iterator,datatype) \
+	for((iterator)=(list)->head->next, (data_iterator)=(datatype *) (iterator)->data; \
+	(iterator)!=(list)->head;(iterator)=(iterator)->next,(data_iterator)=(datatype *) (iterator))
+
+/**
+ * provide for loop header which iterates through the list providing a
+ * data iterator in reverse without moving the mark
+ * list: the dlist pointer
+ * iterator: the dl_node pointer to iterate
+ * data_iterator: the pointer of type datatype to iterate
+ * datatype:  actual type of the contents in the dl_node->data
+ */
+#define dlist_for_each_data_nomark_rev(list,iterator, data_iterator,datatype) \
+	for((iterator)=(list)->head->prev, (data_iterator)=(datatype *) (iterator)->data; \
+	(iterator)!=(list)->head;(iterator)=(iterator)->prev,(data_iterator)=(datatype *) (iterator))
+
+#endif /* _DLIST_H_ */
diff --git a/libsysfs/libsysfs.h b/libsysfs/libsysfs.h
index 01143954e7..ccb9898cb5 100644
--- a/libsysfs/libsysfs.h
+++ b/libsysfs/libsysfs.h
@@ -3,7 +3,7 @@
  *
  * Header Definitions for libsysfs
  *
- * Copyright (C) 2003 International Business Machines, Inc.
+ * Copyright (C) IBM Corp. 2003
  *
  *  This library is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU Lesser General Public
@@ -24,6 +24,7 @@
 #define _LIBSYSFS_H_
 
 #include <sys/types.h>
+#include "dlist.h"
 
 /*
  * Generic #defines go here..
@@ -32,11 +33,17 @@
 #define SYSFS_PROC_MNTS		"/proc/mounts"
 #define SYSFS_BUS_DIR		"/bus"
 #define SYSFS_CLASS_DIR		"/class"
+#define SYSFS_BLOCK_DIR		"/block"
 #define SYSFS_DEVICES_DIR	"/devices"
 #define SYSFS_DEVICES_NAME	"devices"
 #define SYSFS_DRIVERS_DIR	"/drivers"
 #define SYSFS_DRIVERS_NAME	"drivers"
 #define SYSFS_NAME_ATTRIBUTE	"name"
+#define SYSFS_UNKNOWN		"unknown"
+
+/* Some "block" subsystem specific #defines */
+#define SYSFS_QUEUE_NAME	"queue"
+#define SYSFS_IOSCHED_NAME	"iosched"
 
 #define SYSFS_PATH_MAX		255
 #define	SYSFS_NAME_LEN		50
@@ -46,65 +53,84 @@
 #define SYSFS_METHOD_STORE	0x02	/* attr can be changed by user */
 
 struct sysfs_attribute {
-	struct sysfs_attribute *next;
-	char path[SYSFS_PATH_MAX];
-	char *value;
+	unsigned char *value;
 	unsigned short len;		/* value length */
 	unsigned short method;		/* show and store */
+	unsigned char name[SYSFS_NAME_LEN];
+	unsigned char path[SYSFS_PATH_MAX];
 };
 
-struct sysfs_dlink {
-	struct sysfs_dlink *next;
-	char name[SYSFS_NAME_LEN];
-	struct sysfs_directory *target;
+struct sysfs_link {
+	unsigned char name[SYSFS_NAME_LEN];
+	unsigned char path[SYSFS_PATH_MAX];
+	unsigned char target[SYSFS_PATH_MAX];
 };
 
 struct sysfs_directory {
-	struct sysfs_directory *next;
-	char path[SYSFS_PATH_MAX];
-	struct sysfs_directory *subdirs;
-	struct sysfs_dlink *links;
-	struct sysfs_attribute *attributes;
+	struct dlist *subdirs;	
+	struct dlist *links;		
+	struct dlist *attributes;
+	unsigned char name[SYSFS_NAME_LEN];
+	unsigned char path[SYSFS_PATH_MAX];
 };
 
 struct sysfs_driver {
-	struct sysfs_driver *next;
-	char name[SYSFS_NAME_LEN];
-	struct sysfs_directory *directory;
-	struct sysfs_device *device;
+	struct dlist *devices;
+	unsigned char name[SYSFS_NAME_LEN];
+	unsigned char path[SYSFS_PATH_MAX];
+
+	/* for internal use only */
+	struct sysfs_directory *directory;	
 };
 
 struct sysfs_device {
-	struct sysfs_device *next;
-	char name[SYSFS_NAME_LEN];
-	char bus_id[SYSFS_NAME_LEN];
-	struct sysfs_driver *driver;
+	struct sysfs_device *parent;		
+	struct dlist *children;	
+	unsigned char name[SYSFS_NAME_LEN];
+	unsigned char bus_id[SYSFS_NAME_LEN];
+	unsigned char path[SYSFS_PATH_MAX];
+	unsigned char driver_name[SYSFS_NAME_LEN];
+
+	/* for internal use only */
+	struct sysfs_directory *directory;	
+};
+
+struct sysfs_root_device {
+	struct dlist *devices;
+	unsigned char name[SYSFS_NAME_LEN];
+	unsigned char path[SYSFS_PATH_MAX];
+
+	/* for internal use only */
 	struct sysfs_directory *directory;
-	struct sysfs_device *parent;
-	struct sysfs_device *children;
 };
 
 struct sysfs_bus {
-	struct sysfs_bus *next;
-	char name[SYSFS_NAME_LEN];
-	struct sysfs_directory *directory;
-	struct sysfs_driver *drivers;
-	struct sysfs_device *devices;
+	struct dlist *drivers;
+	struct dlist *devices;
+	unsigned char name[SYSFS_NAME_LEN];
+	unsigned char path[SYSFS_PATH_MAX];
+
+	/* internal use only */
+	struct sysfs_directory *directory;	
 };
 
 struct sysfs_class_device {
-	struct sysfs_class_device *next;
-	char name[SYSFS_NAME_LEN];
-	struct sysfs_directory *directory;
 	struct sysfs_device *sysdevice;		/* NULL if virtual */
 	struct sysfs_driver *driver;		/* NULL if not implemented */
+	unsigned char name[SYSFS_NAME_LEN];
+	unsigned char path[SYSFS_PATH_MAX];
+
+	/* for internal use only */
+	struct sysfs_directory *directory;	
 };
 
 struct sysfs_class {
-	struct sysfs_class *next;
-	char name[SYSFS_NAME_LEN];
-	struct sysfs_directory *directory;
-	struct sysfs_class_device *devices;
+	struct dlist *devices;
+	unsigned char name[SYSFS_NAME_LEN];
+	unsigned char path[SYSFS_PATH_MAX];
+
+	/* for internal use only */
+	struct sysfs_directory *directory;	
 };
 
 #ifdef __cplusplus
@@ -114,46 +140,108 @@ extern "C" {
 /*
  * Function Prototypes
  */
-extern int sysfs_get_mnt_path(char *mnt_path, size_t len);
-extern int sysfs_get_name_from_path(const char *path, char *name, size_t len);
-extern int sysfs_get_link(const char *path, char *target, size_t len);
+extern int sysfs_get_mnt_path(unsigned char *mnt_path, size_t len);
+extern int sysfs_get_name_from_path(const unsigned char *path, 
+					unsigned char *name, size_t len);
+extern int sysfs_get_link(const unsigned char *path, unsigned char *target, 
+								size_t len);
+extern struct dlist *sysfs_open_subsystem_list(unsigned char *name);
+extern struct dlist *sysfs_open_bus_devices_list(unsigned char *name);
+extern void sysfs_close_list(struct dlist *list);
 
 /* sysfs directory and file access */
 extern void sysfs_close_attribute(struct sysfs_attribute *sysattr);
-extern struct sysfs_attribute *sysfs_open_attribute(const char *path);
+extern struct sysfs_attribute *sysfs_open_attribute(const unsigned char *path);
 extern int sysfs_read_attribute(struct sysfs_attribute *sysattr);
-extern int sysfs_read_attribute_value(const char *attrpath, char *value, 
-								size_t vsize);
-extern char *sysfs_get_value_from_attributes(struct sysfs_attribute *attr, 
-							const char * name);
+extern int sysfs_read_attribute_value(const unsigned char *attrpath, 
+				unsigned char *value, size_t vsize);
+extern int sysfs_write_attribute(struct sysfs_attribute *sysattr,
+		const unsigned char *new_value, size_t len);
+extern unsigned char *sysfs_get_value_from_attributes(struct dlist *attr, 
+						const unsigned char * name);
 extern void sysfs_close_directory(struct sysfs_directory *sysdir);
-extern struct sysfs_directory *sysfs_open_directory(const char *path);
+extern struct sysfs_directory *sysfs_open_directory(const unsigned char *path);
 extern int sysfs_read_directory(struct sysfs_directory *sysdir);
-extern void sysfs_close_dlink(struct sysfs_dlink *dlink);
-extern struct sysfs_dlink *sysfs_open_dlink(const char *linkpath);
-extern int sysfs_read_dlinks(struct sysfs_dlink *dlink);
+extern int sysfs_read_all_subdirs(struct sysfs_directory *sysdir);
+extern struct sysfs_directory *sysfs_get_subdirectory
+			(struct sysfs_directory *dir, unsigned char *subname);
+extern void sysfs_close_link(struct sysfs_link *ln);
+extern struct sysfs_link *sysfs_open_link(const unsigned char *lnpath);
+extern struct sysfs_link *sysfs_get_directory_link(struct sysfs_directory *dir,
+						unsigned char *linkname);
+extern struct sysfs_link *sysfs_get_subdirectory_link
+			(struct sysfs_directory *dir, unsigned char *linkname);
+extern struct sysfs_attribute *sysfs_get_directory_attribute
+			(struct sysfs_directory *dir, unsigned char *attrname);
 
 /* sysfs driver access */
 extern void sysfs_close_driver(struct sysfs_driver *driver);
-extern struct sysfs_driver *sysfs_open_driver(const char *path);
+extern struct sysfs_driver *sysfs_open_driver(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);
+extern struct dlist *sysfs_get_driver_links(struct sysfs_driver *driver);
+extern void sysfs_close_driver_by_name(struct sysfs_driver *driver);
+extern struct sysfs_driver *sysfs_open_driver_by_name
+	(const unsigned char *drv_name, const unsigned char *bus, size_t bsize);
+extern int sysfs_write_driver_attr(unsigned char *drv, unsigned char *attrib,
+				unsigned char *value, size_t len);
+extern int sysfs_read_driver_attr(unsigned char *drv, unsigned char *attrib,
+				unsigned char *value, size_t len);
 
 /* generic sysfs device access */
+extern void sysfs_close_root_device(struct sysfs_root_device *root);
+extern struct sysfs_root_device *sysfs_open_root_device
+						(const unsigned char *name);
 extern void sysfs_close_device(struct sysfs_device *dev);
-extern void sysfs_close_device_tree(struct sysfs_device *dev);
-extern struct sysfs_device *sysfs_open_device(const char *path);
-extern struct sysfs_device *sysfs_open_device_tree(const char *path);
+extern struct sysfs_device *sysfs_open_device(const unsigned char *path);
 extern struct sysfs_attribute *sysfs_get_device_attr
-				(struct sysfs_device *dev, const char *name);
+			(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, size_t bsize);
+extern int sysfs_write_device_attr(unsigned char *dev, unsigned char *attrib,
+				unsigned char *value, size_t len);
+extern int sysfs_read_device_attr(unsigned char *dev, unsigned char *attrib,
+				unsigned char *value, size_t len);
 
 /* generic sysfs bus access */
 extern void sysfs_close_bus(struct sysfs_bus *bus);
-extern struct sysfs_bus *sysfs_open_bus(const char *name);
+extern struct sysfs_bus *sysfs_open_bus(const unsigned char *name);
+extern struct sysfs_device *sysfs_get_bus_device(struct sysfs_bus *bus,
+						unsigned char *id);
+extern struct sysfs_driver *sysfs_get_bus_driver(struct sysfs_bus *bus,
+						unsigned char *drvname);
+extern struct dlist *sysfs_get_bus_attributes(struct sysfs_bus *bus);
+extern struct sysfs_attribute *sysfs_get_bus_attribute(struct sysfs_bus *bus,
+						unsigned char *attrname);
+extern struct sysfs_device *sysfs_open_bus_device(unsigned char *busname, 
+							unsigned char *dev_id);
+extern int sysfs_find_device_bus(const unsigned char *dev_id, 
+					unsigned char *busname,	size_t bsize);
+extern int sysfs_find_driver_bus(const unsigned char *driver, 
+					unsigned char *busname,	size_t bsize);
 
 /* generic sysfs class access */
 extern void sysfs_close_class_device(struct sysfs_class_device *dev);
-extern struct sysfs_class_device *sysfs_open_class_device(const char *path);
+extern struct sysfs_class_device *sysfs_open_class_device
+					(const unsigned char *path);
 extern void sysfs_close_class(struct sysfs_class *cls);
-extern struct sysfs_class *sysfs_open_class(const char *name);
+extern struct sysfs_class *sysfs_open_class(const unsigned char *name);
+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, unsigned char *name);
+extern struct dlist *sysfs_get_classdev_attributes
+	(struct sysfs_class_device *cdev);
+extern int sysfs_find_device_class(const unsigned char *bus_id, 
+		unsigned char *classname, size_t bsize);
+extern struct sysfs_attribute *sysfs_get_classdev_attr
+	(struct sysfs_class_device *clsdev, const unsigned char *name);
+extern int sysfs_write_classdev_attr(unsigned char *dev, unsigned char *attrib, 
+		unsigned char *value, size_t len);
+extern int sysfs_read_classdev_attr(unsigned char *dev, unsigned char *attrib, 
+		unsigned char *value, size_t len);
 
 #ifdef __cplusplus
 }
diff --git a/libsysfs/sysfs.h b/libsysfs/sysfs.h
index eb2a002958..00599954fd 100644
--- a/libsysfs/sysfs.h
+++ b/libsysfs/sysfs.h
@@ -3,7 +3,7 @@
  *
  * Internal Header Definitions for libsysfs
  *
- * Copyright (C) 2003 International Business Machines, Inc.
+ * Copyright (C) IBM Corp. 2003
  *
  *  This library is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU Lesser General Public
diff --git a/libsysfs/sysfs_bus.c b/libsysfs/sysfs_bus.c
index b2e2b2dd71..19fc275d84 100644
--- a/libsysfs/sysfs_bus.c
+++ b/libsysfs/sysfs_bus.c
@@ -3,7 +3,7 @@
  *
  * Generic bus utility functions for libsysfs
  *
- * Copyright (C) 2003 International Business Machines, Inc.
+ * Copyright (C) IBM Corp. 2003
  *
  *  This library is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU Lesser General Public
@@ -23,28 +23,62 @@
 #include "libsysfs.h"
 #include "sysfs.h"
 
+static void sysfs_close_dev(void *dev)
+{
+	        sysfs_close_device((struct sysfs_device *)dev);
+}
+
+static void sysfs_close_drv(void *drv)
+{
+	        sysfs_close_driver((struct sysfs_driver *)drv);
+}
+
+/*
+ * compares devices' bus ids.
+ * @a: device id looking for
+ * @b: sysfs_device comparing being compared
+ * returns 1 if a==b->bus_id or 0 not equal
+ */
+static int bus_device_id_equal(void *a, void *b)
+{
+	if (a == NULL || b == NULL)
+		return 0;
+
+	if (strcmp(((unsigned char *)a), ((struct sysfs_device *)b)->bus_id) 
+	    == 0)
+		return 1;
+	return 0;
+}
+
+/*
+ * compares drivers' names.
+ * @a: driver name looking for
+ * @b: sysfs_driver comparing being compared
+ * returns 1 if a==b->name or 0 not equal
+ */
+static int bus_driver_name_equal(void *a, void *b)
+{
+	if (a == NULL || b == NULL)
+		return 0;
+
+	if (strcmp(((unsigned char *)a), ((struct sysfs_driver *)b)->name) == 0)
+		return 1;
+	return 0;
+}
+
 /**
  * sysfs_close_bus: close single bus
  * @bus: bus structure
  */
 void sysfs_close_bus(struct sysfs_bus *bus)
 {
-	struct sysfs_device *curdev = NULL, *nextdev = NULL;
-	struct sysfs_driver *curdrv = NULL, *nextdrv = NULL;
-
 	if (bus != NULL) {
 		if (bus->directory != NULL)
 			sysfs_close_directory(bus->directory);
-		for (curdev = bus->devices; curdev != NULL;
-		     curdev = nextdev) {
-			nextdev = curdev->next;
-			sysfs_close_device(curdev);
-		}
-		for (curdrv = bus->drivers; curdrv != NULL;
-		     curdrv = nextdrv) {
-			nextdrv = curdrv->next;
-			sysfs_close_driver(curdrv);
-		}
+		if (bus->devices)
+			dlist_destroy(bus->devices);
+		if (bus->drivers)
+			dlist_destroy(bus->drivers);
 		free(bus);
 	}
 }
@@ -62,10 +96,10 @@ static struct sysfs_bus *alloc_bus(void)
  * open_bus_dir: opens up sysfs bus directory
  * returns sysfs_directory struct with success and NULL with error
  */
-static struct sysfs_directory *open_bus_dir(const char *name)
+static struct sysfs_directory *open_bus_dir(const unsigned char *name)
 {
-	struct sysfs_directory *busdir = NULL, *cur = NULL, *next = NULL;
-	char buspath[SYSFS_PATH_MAX];
+	struct sysfs_directory *busdir = NULL;
+	unsigned char buspath[SYSFS_PATH_MAX];
 
 	if (name == NULL) {
 		errno = EINVAL;
@@ -74,7 +108,7 @@ static struct sysfs_directory *open_bus_dir(const char *name)
 
 	memset(buspath, 0, SYSFS_PATH_MAX);
 	if ((sysfs_get_mnt_path(buspath, SYSFS_PATH_MAX)) != 0) {
-		dprintf(stderr, "Sysfs not supported on this system\n");
+		dprintf("Sysfs not supported on this system\n");
 		return NULL;
 	}
 
@@ -84,54 +118,23 @@ static struct sysfs_directory *open_bus_dir(const char *name)
 	busdir = sysfs_open_directory(buspath);
 	if (busdir == NULL) {
 		errno = EINVAL;
-		dprintf(stderr,"Bus %s not supported on this system\n",
+		dprintf("Bus %s not supported on this system\n",
 			name);
 		return NULL;
 	}
 	if ((sysfs_read_directory(busdir)) != 0) {
-		dprintf(stderr, "Error reading %s bus dir %s\n", name, 
+		dprintf("Error reading %s bus dir %s\n", name, 
 			buspath);
 		sysfs_close_directory(busdir);
 		return NULL;
 	}
 	/* read in devices and drivers subdirs */
-	for (cur = busdir->subdirs; cur != NULL; cur = next) {
-		next = cur->next;
-		if ((sysfs_read_directory(cur)) != 0)
-			continue;
-	}
+	sysfs_read_all_subdirs(busdir);
 
 	return busdir;
 }
 
 /**
- * add_dev_to_bus: adds a bus device to bus device list
- * @bus: bus to add the device
- * @dev: device to add
- */
-static void add_dev_to_bus(struct sysfs_bus *bus, struct sysfs_device *dev)
-{
-	if (bus != NULL && dev != NULL) {
-		dev->next = bus->devices;
-		bus->devices = dev;
-	}
-}
-
-/**
- * add_driver_to_bus: adds a bus driver to bus driver list
- * @bus: bus to add driver to
- * @driver: driver to add
- */
-static void add_driver_to_bus(struct sysfs_bus *bus, 
-				struct sysfs_driver *driver)
-{
-	if (bus != NULL && driver != NULL) {
-		driver->next = bus->drivers;
-		bus->drivers = driver;
-	}
-}
-
-/**
  * get_all_bus_devices: gets all devices for bus
  * @bus: bus to get devices for
  * returns 0 with success and -1 with failure
@@ -140,29 +143,33 @@ static int get_all_bus_devices(struct sysfs_bus *bus)
 {
 	struct sysfs_device *bdev = NULL;
 	struct sysfs_directory *cur = NULL;
-	struct sysfs_dlink *curl = NULL, *nextl = NULL;
-	char dirname[SYSFS_NAME_LEN];
+	struct sysfs_link *curl = NULL;
 
 	if (bus == NULL || bus->directory == NULL) {
 		errno = EINVAL;
 		return -1;
 	}
-	for (cur = bus->directory->subdirs; cur != NULL; cur = cur->next) {
-		memset(dirname, 0, SYSFS_NAME_LEN);
-		if ((sysfs_get_name_from_path(cur->path, dirname,
-		    SYSFS_NAME_LEN)) != 0)
+	if (bus->directory->subdirs == NULL)
+		return 0;
+
+	dlist_for_each_data(bus->directory->subdirs, cur, 
+			struct sysfs_directory) {
+		if (strcmp(cur->name, SYSFS_DEVICES_NAME) != 0)
 			continue;
-		if (strcmp(dirname, SYSFS_DEVICES_NAME) != 0)
+		if (cur->links == NULL)
 			continue;
-		for (curl = cur->links; curl != NULL; curl = nextl) {
-			nextl = curl->next;
-			bdev = sysfs_open_device(curl->target->path);
+		dlist_for_each_data(cur->links, curl, struct sysfs_link) {
+			bdev = sysfs_open_device(curl->target);
 			if (bdev == NULL) {
-				dprintf(stderr, "Error opening device at %s\n",
-					curl->target->path);
+				dprintf("Error opening device at %s\n",
+					curl->target);
 				continue;
 			}
-			add_dev_to_bus(bus, bdev);
+                        if (bus->devices == NULL)
+				bus->devices = dlist_new_with_delete
+					(sizeof(struct sysfs_device),
+						 	sysfs_close_dev);
+			dlist_unshift(bus->devices, bdev);
 		}
 	}
 			
@@ -177,31 +184,35 @@ static int get_all_bus_devices(struct sysfs_bus *bus)
 static int get_all_bus_drivers(struct sysfs_bus *bus)
 {
 	struct sysfs_driver *driver = NULL;
-	struct sysfs_directory *cur = NULL, *next = NULL;
-	struct sysfs_directory *cursub = NULL, *nextsub = NULL;
-	char dirname[SYSFS_NAME_LEN];
+	struct sysfs_directory *cur = NULL;
+	struct sysfs_directory *cursub = NULL;
 
 	if (bus == NULL || bus->directory == NULL) {
 		errno = EINVAL;
 		return -1;
 	}
-	for (cur = bus->directory->subdirs; cur != NULL; cur = next) {
-		next = cur->next;
-		memset(dirname, 0, SYSFS_NAME_LEN);
-		if ((sysfs_get_name_from_path(cur->path, dirname,
-		    SYSFS_NAME_LEN)) != 0)
+	if (bus->directory->subdirs == NULL)
+		return 0;
+
+	dlist_for_each_data(bus->directory->subdirs, cur,
+			struct sysfs_directory) {
+		if (strcmp(cur->name, SYSFS_DRIVERS_NAME) != 0)
 			continue;
-		if (strcmp(dirname, SYSFS_DRIVERS_NAME) != 0)
+		if (cur->subdirs == NULL)
 			continue;
-		for (cursub = cur->subdirs; cursub != NULL; cursub = nextsub) {
-			nextsub = cursub->next;
+		dlist_for_each_data(cur->subdirs, cursub,
+				struct sysfs_directory) {
 			driver = sysfs_open_driver(cursub->path);
 			if (driver == NULL) {
-				dprintf(stderr, "Error opening driver at %s\n",
+				dprintf("Error opening driver at %s\n",
 					cursub->path);
 				continue;
 			}
-			add_driver_to_bus(bus, driver);
+                        if (bus->drivers == NULL)
+				bus->drivers = dlist_new_with_delete
+					(sizeof(struct sysfs_driver),
+					 		sysfs_close_drv);
+			dlist_unshift(bus->drivers, driver);
 		}
 	}
 	
@@ -214,20 +225,22 @@ static int get_all_bus_drivers(struct sysfs_bus *bus)
  * @busid: busid of device to match
  * returns 1 if found and 0 if not found
  */
-static int match_bus_device_to_driver(struct sysfs_driver *driver, char *busid)
+static int match_bus_device_to_driver(struct sysfs_driver *driver, 
+							unsigned char *busid)
 {
-	struct sysfs_dlink *cur = NULL, *next = NULL;
+	struct sysfs_link *cur = NULL;
 	int found = 0;
 
 	if (driver == NULL || driver->directory == NULL || busid == NULL) {
 		errno = EINVAL;
 		return found;
 	}
-	for (cur = driver->directory->links; cur != NULL && found == 0;
-	     cur = next) {
-		next = cur->next;
-		if ((strcmp(cur->name, busid)) == 0)
-			found++;
+	if (driver->directory->links != NULL) {
+		dlist_for_each_data(driver->directory->links, cur,
+				struct sysfs_link) {
+			if ((strcmp(cur->name, busid)) == 0)
+				found++;
+		}
 	}
 	return found;
 }
@@ -238,19 +251,22 @@ static int match_bus_device_to_driver(struct sysfs_driver *driver, char *busid)
  */
 static void link_bus_devices_to_drivers(struct sysfs_bus *bus)
 {
-	struct sysfs_device *dev = NULL, *nextdev = NULL;
-	struct sysfs_driver *drv = NULL, *nextdrv = NULL;
+	struct sysfs_device *dev = NULL;
+	struct sysfs_driver *drv = NULL;
 	
 	if (bus != NULL && bus->devices != NULL && bus->drivers != NULL) {
-		for (dev = bus->devices; dev != NULL; dev = nextdev) {
-			nextdev = dev->next;
-
-			for (drv = bus->drivers; drv != NULL; drv = nextdrv) {
-				nextdrv = drv->next;
+		dlist_for_each_data(bus->devices, dev, struct sysfs_device) {
+			dlist_for_each_data(bus->drivers, drv,
+					struct sysfs_driver) {
 				if ((match_bus_device_to_driver(drv, 
-				    dev->bus_id)) != 0) {
-					dev->driver = drv;
-					drv->device = dev;
+						dev->bus_id)) != 0) {
+					strncpy(dev->driver_name, drv->name,
+							SYSFS_NAME_LEN);
+					if (drv->devices == NULL)
+						drv->devices = dlist_new
+							(sizeof(struct 
+								sysfs_device));
+					dlist_unshift(drv->devices, dev);
 				}
 			}
 		}
@@ -261,7 +277,7 @@ static void link_bus_devices_to_drivers(struct sysfs_bus *bus)
  * sysfs_open_bus: opens specific bus and all its devices on system
  * returns sysfs_bus structure with success or NULL with error.
  */
-struct sysfs_bus *sysfs_open_bus(const char *name)
+struct sysfs_bus *sysfs_open_bus(const unsigned char *name)
 {
 	struct sysfs_bus *bus = NULL;
 	struct sysfs_directory *busdir = NULL;
@@ -273,25 +289,26 @@ struct sysfs_bus *sysfs_open_bus(const char *name)
 
 	bus = alloc_bus();
 	if (bus == NULL) {
-		perror("malloc");
+		dprintf("calloc failed\n");
 		return NULL;
 	}
 	strcpy(bus->name, name);	
 	busdir = open_bus_dir(name);
 	if (busdir == NULL) {
-		dprintf(stderr,"Invalid bus, %s not supported on this system\n",
+		dprintf("Invalid bus, %s not supported on this system\n",
 			name);
 		sysfs_close_bus(bus);
 		return NULL;
 	}
+	strcpy(bus->path, busdir->path);
 	bus->directory = busdir;
 	if ((get_all_bus_devices(bus)) != 0) {
-		dprintf(stderr, "Error reading %s bus devices\n", name);
+		dprintf("Error reading %s bus devices\n", name);
 		sysfs_close_bus(bus);
 		return NULL;
 	}
 	if ((get_all_bus_drivers(bus)) != 0) {
-		dprintf(stderr, "Error reading %s bus drivers\n", name);
+		dprintf("Error reading %s bus drivers\n", name);
 		sysfs_close_bus(bus);
 		return NULL;
 	}
@@ -299,3 +316,198 @@ struct sysfs_bus *sysfs_open_bus(const char *name)
 
 	return bus;
 }
+
+/**
+ * sysfs_get_bus_device: Get specific device on bus using device's id
+ * @bus: bus to find device on
+ * @id: bus_id for device
+ * returns struct sysfs_device reference or NULL if not found.
+ */
+struct sysfs_device *sysfs_get_bus_device(struct sysfs_bus *bus, 
+							unsigned char *id)
+{
+	if (bus == NULL || id == NULL) {
+		errno = EINVAL;
+		return NULL;
+	}
+
+	return (struct sysfs_device *)dlist_find_custom(bus->devices, id,
+		bus_device_id_equal);
+}
+
+/**
+ * sysfs_get_bus_driver: Get specific driver on bus using driver name
+ * @bus: bus to find driver on
+ * @drvname: name of driver
+ * returns struct sysfs_driver reference or NULL if not found.
+ */
+struct sysfs_driver *sysfs_get_bus_driver(struct sysfs_bus *bus, 
+							unsigned char *drvname)
+{
+	if (bus == NULL || drvname == NULL) {
+		errno = EINVAL;
+		return NULL;
+	}
+
+	return (struct sysfs_driver *)dlist_find_custom(bus->drivers, drvname,
+		bus_driver_name_equal);
+}
+
+/**
+ * sysfs_get_bus_attributes: returns bus' dlist of attributes
+ * @bus: bus to get attributes for.
+ * returns dlist of attributes or NULL if there aren't any.
+ */
+struct dlist *sysfs_get_bus_attributes(struct sysfs_bus *bus)
+{
+	if (bus == NULL || bus->directory == NULL)
+		return NULL;
+	return bus->directory->attributes;
+}
+
+/**
+ * sysfs_get_bus_attribute: gets a specific bus attribute, if buses had
+ * 	attributes.
+ * @bus: bus to retrieve attribute from
+ * @attrname: attribute name to retrieve
+ * returns reference to sysfs_attribute if found or NULL if not found
+ */
+struct sysfs_attribute *sysfs_get_bus_attribute(struct sysfs_bus *bus,
+						unsigned char *attrname)
+{
+	if (bus == NULL || bus->directory == NULL || attrname == NULL) {
+		errno = EINVAL;
+		return NULL;
+	}
+	return sysfs_get_directory_attribute(bus->directory, attrname);
+}
+
+/**
+ * sysfs_open_bus_device: locates a device on a bus and returns it. Device
+ * 	must be closed using sysfs_close_device.
+ * @busname: Name of bus to search
+ * @dev_id: Id of device on bus.
+ * returns sysfs_device if found or NULL if not.
+ */
+struct sysfs_device *sysfs_open_bus_device(unsigned char *busname, 
+							unsigned char *dev_id)
+{
+	struct sysfs_device *rdev = NULL;
+	char path[SYSFS_PATH_MAX];
+
+	if (busname == NULL || dev_id == NULL) {
+		errno = EINVAL;
+		return NULL;
+	}
+
+	memset(path, 0, SYSFS_PATH_MAX);
+	if (sysfs_get_mnt_path(path, SYSFS_PATH_MAX) != 0) {
+		dprintf("Error getting sysfs mount point\n");
+		return NULL;
+	}
+
+	strcat(path, SYSFS_BUS_DIR);
+	strcat(path, "/");
+	strcat(path, busname);
+	strcat(path, SYSFS_DEVICES_DIR);
+	strcat(path, "/");
+	strcat(path, dev_id);
+
+	rdev = sysfs_open_device(path);
+	if (rdev == NULL) {
+		dprintf("Error getting device %s on bus %s\n",
+				dev_id, busname);
+		return NULL;
+	}
+	
+	return rdev;
+}
+
+/**
+ * sysfs_find_device_bus: locates the bus a device is on.
+ * @dev_id: device id.
+ * @busname: buffer to copy name to
+ * @bsize: buffer size
+ * returns 0 with success or -1 with error
+ */
+int sysfs_find_device_bus(const unsigned char *dev_id, unsigned char *busname, 
+								size_t bsize)
+{
+	unsigned char subsys[SYSFS_NAME_LEN], *bus = NULL, *curdev = NULL; 
+	struct dlist *buslist = NULL, *device_list = NULL;
+
+	if (dev_id == NULL || busname == NULL) {
+		errno = EINVAL;
+		return -1;
+	}
+	
+	strcpy(subsys, SYSFS_BUS_DIR);	/* subsys = /bus */
+	buslist = sysfs_open_subsystem_list(subsys);
+	if (buslist != NULL) {
+		dlist_for_each_data(buslist, bus, char) {
+			device_list = sysfs_open_bus_devices_list(bus);
+			if (device_list != NULL) {
+				dlist_for_each_data(device_list, 
+						curdev, char) {
+					if (strcmp(dev_id, curdev) == 0) {
+						strncpy(busname, 
+							bus, bsize);
+						sysfs_close_list(device_list);
+						sysfs_close_list(buslist);
+						return 0;
+					}
+				}
+			sysfs_close_list(device_list);
+			}
+		}
+		sysfs_close_list(buslist);
+	}
+	return -1;
+}
+
+/**
+ * sysfs_find_driver_bus: locates the bus the driver is on.
+ * @driver: name of the driver to locate
+ * @busname: buffer to copy name to
+ * @bsize: buffer size
+ * returns 0 with success, -1 with error
+ */
+int sysfs_find_driver_bus(const unsigned char *driver, unsigned char *busname,
+							size_t bsize)
+{
+	unsigned char subsys[SYSFS_PATH_MAX], *bus = NULL, *curdrv = NULL;
+	struct dlist *buslist = NULL, *drivers = NULL;
+
+	if (driver == NULL || busname == NULL) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	memset(subsys, 0, SYSFS_PATH_MAX);
+	strcpy(subsys, SYSFS_BUS_DIR);
+	buslist = sysfs_open_subsystem_list(subsys);
+	if (buslist != NULL) {
+		dlist_for_each_data(buslist, bus, char) {
+			memset(subsys, 0, SYSFS_PATH_MAX);
+			strcpy(subsys, SYSFS_BUS_DIR);
+			strcat(subsys, "/");
+			strcat(subsys, bus);
+			strcat(subsys, SYSFS_DRIVERS_DIR);
+			drivers = sysfs_open_subsystem_list(subsys);
+			if (drivers != NULL) {
+				dlist_for_each_data(drivers, curdrv, char) {
+					if (strcmp(driver, curdrv) == 0) {
+						strncpy(busname, bus, bsize);
+						sysfs_close_list(drivers);
+						sysfs_close_list(buslist);
+						return 0;
+					}
+				}
+				sysfs_close_list(drivers);
+			}
+		}
+		sysfs_close_list(buslist);
+	}
+	return -1;
+}
+					
diff --git a/libsysfs/sysfs_class.c b/libsysfs/sysfs_class.c
index 9d7d8b2227..cb6ca9d00d 100644
--- a/libsysfs/sysfs_class.c
+++ b/libsysfs/sysfs_class.c
@@ -3,7 +3,7 @@
  *
  * Generic class utility functions for libsysfs
  *
- * Copyright (C) 2003 International Business Machines, Inc.
+ * Copyright (C) IBM Corp. 2003
  *
  *  This library is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU Lesser General Public
@@ -23,6 +23,28 @@
 #include "libsysfs.h"
 #include "sysfs.h"
 
+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.
@@ -46,15 +68,11 @@ void sysfs_close_class_device(struct sysfs_class_device *dev)
  */
 void sysfs_close_class(struct sysfs_class *cls)
 {
-	struct sysfs_class_device *cur = NULL, *next = NULL;
-
 	if (cls != NULL) {
 		if (cls->directory != NULL)
 			sysfs_close_directory(cls->directory);
-		for (cur = cls->devices; cur != NULL; cur = next) {
-			next = cur->next;
-			sysfs_close_class_device(cur);
-		}
+		if (cls->devices != NULL) 
+			dlist_destroy(cls->devices);
 		free(cls);
 	}
 }
@@ -82,10 +100,10 @@ static struct sysfs_class *alloc_class(void)
  * open_class_dir: opens up sysfs class directory
  * returns sysfs_directory struct with success and NULL with error
  */
-static struct sysfs_directory *open_class_dir(const char *name)
+static struct sysfs_directory *open_class_dir(const unsigned char *name)
 {
 	struct sysfs_directory *classdir = NULL;
-	char classpath[SYSFS_PATH_MAX];
+	unsigned char classpath[SYSFS_PATH_MAX];
 
 	if (name == NULL) {
 		errno = EINVAL;
@@ -94,7 +112,7 @@ static struct sysfs_directory *open_class_dir(const char *name)
 
 	memset(classpath, 0, SYSFS_PATH_MAX);
 	if ((sysfs_get_mnt_path(classpath, SYSFS_PATH_MAX)) != 0) {
-		dprintf(stderr, "Sysfs not supported on this system\n");
+		dprintf("Sysfs not supported on this system\n");
 		return NULL;
 	}
 
@@ -104,13 +122,11 @@ static struct sysfs_directory *open_class_dir(const char *name)
 	classdir = sysfs_open_directory(classpath);
 	if (classdir == NULL) {
 		errno = EINVAL;
-		dprintf(stderr,"Class %s not supported on this system\n",
-			name);
+		dprintf("Class %s not supported on this system\n", name);
 		return NULL;
 	}
 	if ((sysfs_read_directory(classdir)) != 0) {
-		dprintf(stderr, "Error reading %s class dir %s\n", name, 
-			classpath);
+		dprintf("Error reading %s class dir %s\n", name, classpath);
 		sysfs_close_directory(classdir);
 		return NULL;
 	}
@@ -123,14 +139,13 @@ static struct sysfs_directory *open_class_dir(const char *name)
  * @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 char *path)
+struct sysfs_class_device *sysfs_open_class_device(const unsigned char *path)
 {
 	struct sysfs_class_device *cdev = NULL;
-	struct sysfs_directory *dir = NULL, *cur = NULL;
-	struct sysfs_dlink *curl = NULL;
+	struct sysfs_directory *dir = NULL;
+	struct sysfs_link *curl = NULL;
 	struct sysfs_device *sdev = NULL;
 	struct sysfs_driver *drv = NULL;
-	char temp[SYSFS_NAME_LEN];
 
 	if (path == NULL) {
 		errno = EINVAL;
@@ -138,75 +153,70 @@ struct sysfs_class_device *sysfs_open_class_device(const char *path)
 	}
 	cdev = alloc_class_device();
 	if (cdev == NULL) {
-		perror("malloc");
+		dprintf("calloc failed\n");
 		return NULL;
 	}
-	memset(temp, 0, SYSFS_NAME_LEN);
-	if ((sysfs_get_name_from_path(path, temp, SYSFS_NAME_LEN)) != 0) {
+	if ((sysfs_get_name_from_path(path, cdev->name, SYSFS_NAME_LEN)) != 0) {
 		errno = EINVAL;
-		dprintf(stderr, "Invalid class device path %s\n", path);
+		dprintf("Invalid class device path %s\n", path);
 		sysfs_close_class_device(cdev);
 		return NULL;
 	}
-	strcpy(cdev->name, temp);
 
 	dir = sysfs_open_directory(path);
 	if (dir == NULL) {
-		dprintf(stderr, "Error opening class device at %s\n", path);
+		dprintf("Error opening class device at %s\n", path);
 		sysfs_close_class_device(cdev);
 		return NULL;
 	}
 	if ((sysfs_read_directory(dir)) != 0) {
-		dprintf(stderr, "Error reading class device at %s\n", path);
+		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);
 
-	cur = cdev->directory->subdirs;
-	while(cur != NULL) {
-		sysfs_read_directory(cur);
-		cur = cur->next;
-	}
 	/* get driver and device, if implemented */
-	curl = cdev->directory->links;
-	while (curl != NULL) {
-		if (strncmp(curl->name, SYSFS_DEVICES_NAME, 6) == 0) {
-			sdev = sysfs_open_device(curl->target->path);
-			if (sdev != NULL) {
-				cdev->sysdevice = sdev;
-				if (cdev->driver != NULL) 
-					sdev->driver = cdev->driver;
-			}
-		} else if (strncmp(curl->name, SYSFS_DRIVERS_NAME, 6) == 0) {
-			drv = sysfs_open_driver(curl->target->path);
-			if (drv != NULL) {
-				cdev->driver = drv;
-				if (cdev->sysdevice != NULL) 
-					drv->device = cdev->sysdevice;
+	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);
+					}
+				}
 			}
 		}
-		curl = curl->next;
 	}
 	return cdev;
 }
 
 /**
- * add_dev_to_class: adds a class device to class list
- * @class: class to add the device
- * @dev: device to add
- */
-static void add_dev_to_class(struct sysfs_class *cls, 
-					struct sysfs_class_device *dev)
-{
-	if (cls != NULL && dev != NULL) {
-		dev->next = cls->devices;
-		cls->devices = dev;
-	}
-}
-
-/**
  * get_all_class_devices: gets all devices for class
  * @class: class to get devices for
  * returns 0 with success and -1 with failure
@@ -214,23 +224,27 @@ static void add_dev_to_class(struct sysfs_class *cls,
 static int get_all_class_devices(struct sysfs_class *cls)
 {
 	struct sysfs_class_device *dev = NULL;
-	struct sysfs_directory *cur = NULL, *next = NULL;
+	struct sysfs_directory *cur = NULL;
 
 	if (cls == NULL || cls->directory == NULL) {
 		errno = EINVAL;
 		return -1;
 	}
-	for (cur = cls->directory->subdirs; cur != NULL; cur = next) {
-		next = cur->next;
+	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(stderr, "Error opening device at %s\n",
-				cur->path);
+			dprintf("Error opening device at %s\n",	cur->path);
 			continue;
 		}
-		add_dev_to_class(cls, dev);
+		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 0;
 }
 
@@ -238,7 +252,7 @@ static int get_all_class_devices(struct sysfs_class *cls)
  * 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 char *name)
+struct sysfs_class *sysfs_open_class(const unsigned char *name)
 {
 	struct sysfs_class *cls = NULL;
 	struct sysfs_directory *classdir = NULL;
@@ -250,24 +264,268 @@ struct sysfs_class *sysfs_open_class(const char *name)
 
 	cls = alloc_class();
 	if (cls == NULL) {
-		perror("malloc");
+		dprintf("calloc failed\n");
 		return NULL;
 	}
 	strcpy(cls->name, name);	
 	classdir = open_class_dir(name);
 	if (classdir == NULL) {
-		dprintf(stderr,
-			"Invalid class, %s not supported on this system\n",
+		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(stderr, "Error reading %s class devices\n", name);
+		dprintf("Error reading %s class devices\n", name);
 		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;
+	}
+
+	return (struct sysfs_class_device *)dlist_find_custom(class->devices,
+			name, class_name_equal);
+}
+
+/**
+ * sysfs_open_class_device_by_name: 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
+ */
+struct sysfs_class_device *sysfs_open_class_device_by_name
+		(const unsigned char *classname, unsigned char *name)
+{
+	struct sysfs_class *class = NULL;
+	struct sysfs_class_device *cdev = NULL, *rcdev = NULL;
+
+	if (classname == NULL || name == NULL) {
+		errno = EINVAL;
+		return NULL;
+	}
+	
+	class = sysfs_open_class(classname);
+	if (class == NULL) {
+		dprintf("Error opening class %s\n", classname);
+		return NULL;
+	}
+
+	cdev = sysfs_get_class_device(class, name);
+	if (cdev == NULL) {
+		dprintf("Error getting class device %s from class %s\n",
+				name, classname);
+		sysfs_close_class(class);
+		return NULL;
+	}
+
+	rcdev = sysfs_open_class_device(cdev->directory->path);
+	if (rcdev == NULL) {
+		dprintf("Error getting class device %s from class %s\n",
+				name, classname);
+		sysfs_close_class(class);
+		return NULL;
+	}
+	sysfs_close_class(class);
+	
+	return rcdev;
+}
+
+/**
+ * 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 || cdev->directory == NULL)
+		return NULL;
+
+	return (cdev->directory->attributes);
+}
+
+/**
+ * sysfs_find_device_class: locates the device the device is on
+ * @bus_id: device to look for
+ * @classname: buffer to copy class name to
+ * @bsize: size of buffer
+ * returns 0 with success and -1 with error
+ */
+int sysfs_find_device_class(const unsigned char *bus_id, 
+				unsigned char *classname, size_t bsize)
+{
+	unsigned char class[SYSFS_NAME_LEN], clspath[SYSFS_NAME_LEN];
+	unsigned char *cls = NULL, *clsdev = NULL;
+	struct dlist *clslist = NULL, *clsdev_list = NULL;
+
+	if (bus_id == NULL || classname == NULL) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	strcpy(class, SYSFS_CLASS_DIR);
+	clslist = sysfs_open_subsystem_list(class);
+	if (clslist != NULL) {
+		dlist_for_each_data(clslist, cls, char) {
+			memset(clspath, 0, SYSFS_NAME_LEN);
+			strcpy(clspath, SYSFS_CLASS_DIR);
+			strcat(clspath, "/");
+			strcat(clspath, cls);
+			clsdev_list = sysfs_open_subsystem_list(clspath);
+			if (clsdev_list != NULL) {
+				dlist_for_each_data(clsdev_list, 
+							clsdev, char) {
+					if (strcmp(bus_id, clsdev) == 0) {
+						strncpy(classname, 
+								cls, bsize);
+						sysfs_close_list(clsdev_list);
+						sysfs_close_list(clslist);
+						return 0;
+					}
+				}
+				sysfs_close_list(clsdev_list);
+			}
+		}
+		sysfs_close_list(clslist);
+	}
+	return -1;
+}
+
+/**
+ * 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 sysfs_attribute *sysfs_get_classdev_attr
+		(struct sysfs_class_device *clsdev, const unsigned char *name)
+{
+	struct sysfs_attribute *cur = NULL;
+
+	if (clsdev == NULL || clsdev->directory == NULL ||
+		clsdev->directory->attributes == NULL || name == NULL) {
+		errno = EINVAL;
+		return NULL;
+	}
+
+	cur = sysfs_get_directory_attribute(clsdev->directory,
+						(unsigned char *)name);
+	if (cur != NULL)
+		return cur;
+
+	return NULL;
+}
+
+/**
+ * sysfs_write_classdev_attr: modify writable attribute value for the given
+ * 				class device
+ * @dev: class device name for which the attribute has to be changed
+ * @attrib: attribute to change
+ * @value: value to change to
+ * @len: size of buffer at "value"
+ * Returns 0 on success and -1 on error
+ */
+int sysfs_write_classdev_attr(unsigned char *dev, unsigned char *attrib,
+				unsigned char *value, size_t len)
+{
+	struct sysfs_class_device *clsdev = NULL;
+	struct sysfs_attribute *attribute = NULL;
+	unsigned char class_name[SYSFS_NAME_LEN];
+
+	if (dev == NULL || attrib == NULL || value == NULL) {
+		errno = EINVAL;
+		return -1;
+	}
+	
+	memset(class_name, 0, SYSFS_NAME_LEN);
+	if ((sysfs_find_device_class(dev, 
+					class_name, SYSFS_NAME_LEN)) < 0) {
+		dprintf("Class device %s not found\n", dev);
+		return -1;
+	}
+	clsdev = sysfs_open_class_device_by_name(class_name, dev);
+	if (clsdev == NULL) {
+		dprintf("Error opening %s in class %s\n", dev, class_name);
+		return -1;
+	}
+	attribute = sysfs_get_directory_attribute(clsdev->directory, attrib);
+	if (attribute == NULL) {
+		dprintf("Attribute %s not defined for device %s on class %s\n",
+				attrib, dev, class_name);
+		sysfs_close_class_device(clsdev);
+		return -1;
+	}
+	if ((sysfs_write_attribute(attribute, value, len)) < 0) {
+		dprintf("Error setting %s to %s\n", attrib, value);
+		sysfs_close_class_device(clsdev);
+		return -1;
+	}
+	sysfs_close_class_device(clsdev);
+	return 0;
+}
+
+/**
+ * sysfs_read_classdev_attr: read an attribute for a given class device
+ * @dev: class device name for which the attribute has to be read
+ * @attrib: attribute to read
+ * @value: buffer to return value to user
+ * @len: size of buffer at "value"
+ * Returns 0 on success and -1 on error
+ */
+int sysfs_read_classdev_attr(unsigned char *dev, unsigned char *attrib,
+				unsigned char *value, size_t len)
+{
+	struct sysfs_class_device *clsdev = NULL;
+	struct sysfs_attribute *attribute = NULL;
+	unsigned char class_name[SYSFS_NAME_LEN];
+
+	if (dev == NULL || attrib == NULL || value == NULL) {
+		errno = EINVAL;
+		return -1;
+	}
+	
+	memset(class_name, 0, SYSFS_NAME_LEN);
+	if ((sysfs_find_device_class(dev, 
+					class_name, SYSFS_NAME_LEN)) < 0) {
+		dprintf("Class device %s not found\n", dev);
+		return -1;
+	}
+	clsdev = sysfs_open_class_device_by_name(class_name, dev);
+	if (clsdev == NULL) {
+		dprintf("Error opening %s in class %s\n", dev, class_name);
+		return -1;
+	}
+	attribute = sysfs_get_directory_attribute(clsdev->directory, attrib);
+	if (attribute == NULL) {
+		dprintf("Attribute %s not defined for device %s on class %s\n",
+				attrib, dev, class_name);
+		sysfs_close_class_device(clsdev);
+		return -1;
+	}
+	if (attribute->len > len) {
+		dprintf("Value length %d is greater that suppled buffer %d\n",
+				attribute->len, len);
+		sysfs_close_class_device(clsdev);
+		return -1;
+	}
+	strncpy(value, attribute->value, attribute->len);
+	value[(attribute->len)+1] = 0;
+	sysfs_close_class_device(clsdev);
+	return 0;
+}
diff --git a/libsysfs/sysfs_device.c b/libsysfs/sysfs_device.c
index 185b5cf378..89704dcd80 100644
--- a/libsysfs/sysfs_device.c
+++ b/libsysfs/sysfs_device.c
@@ -3,7 +3,7 @@
  *
  * Generic device utility functions for libsysfs
  *
- * Copyright (C) 2003 International Business Machines, Inc.
+ * Copyright (C) IBM Corp. 2003
  *
  *  This library is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU Lesser General Public
@@ -24,17 +24,52 @@
 #include "sysfs.h"
 
 /**
+ * sysfs_close_device_tree: closes every device in the supplied tree, 
+ * 	closing children only.
+ * @devroot: device root of tree.
+ */
+static void sysfs_close_device_tree(struct sysfs_device *devroot)
+{
+	if (devroot != NULL) {
+		if (devroot->children != NULL) {
+			struct sysfs_device *child = NULL;
+
+			dlist_for_each_data(devroot->children, child,
+					struct sysfs_device) {
+				sysfs_close_device_tree(child);
+			}
+		}
+		sysfs_close_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)
+{
+	sysfs_close_device_tree((struct sysfs_device *)dev);
+}
+
+/**
  * sysfs_close_device: closes and cleans up a device
  * @dev = device to clean up
  */
 void sysfs_close_device(struct sysfs_device *dev)
 {
 	if (dev != NULL) {
-		dev->next = NULL;
-		dev->driver = NULL;
 		if (dev->directory != NULL)
 			sysfs_close_directory(dev->directory);
-		dev->children = NULL;
+		if (dev->children != NULL && dev->children->count == 0)
+			dlist_destroy(dev->children);
 		free(dev);
 	}
 }
@@ -55,24 +90,20 @@ static struct sysfs_device *alloc_device(void)
  * returns sysfs_attribute reference with success or NULL with error.
  */
 struct sysfs_attribute *sysfs_get_device_attr(struct sysfs_device *dev,
-						const char *name)
+						const unsigned char *name)
 {
 	struct sysfs_attribute *cur = NULL;
-	char attrname[SYSFS_NAME_LEN];
 
-	if (dev == NULL || dev->directory == NULL || name == NULL) {
+	if (dev == NULL || dev->directory == NULL 
+	    || dev->directory->attributes == NULL || name == NULL) {
 		errno = EINVAL;
 		return NULL;
 	}
-	for (cur = dev->directory->attributes; cur != NULL; cur = cur->next) {
-		if ((sysfs_get_name_from_path(cur->path, attrname, 
-		    SYSFS_NAME_LEN)) != 0) 
-			continue;
-		if (strcmp(name, attrname) != 0)
-			continue;
-
+	
+	cur = sysfs_get_directory_attribute(dev->directory, 
+			(unsigned char *)name);
+	if (cur != NULL)
 		return cur;
-	}
 
 	return NULL;
 }
@@ -82,11 +113,10 @@ struct sysfs_attribute *sysfs_get_device_attr(struct sysfs_device *dev,
  * @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 char *path)
+struct sysfs_device *sysfs_open_device(const unsigned char *path)
 {
 	struct sysfs_device *dev = NULL;
 	struct sysfs_directory *sdir = NULL;
-	char *p = NULL;
 
 	if (path == NULL) {
 		errno = EINVAL;
@@ -94,106 +124,415 @@ struct sysfs_device *sysfs_open_device(const char *path)
 	}
 	dev = alloc_device();	
 	if (dev == NULL) {
-		dprintf(stderr, "Error allocating device at %s\n", path);
+		dprintf("Error allocating device at %s\n", path);
 		return NULL;
 	}
 	sdir = sysfs_open_directory(path);
 	if (sdir == NULL) {
-		dprintf(stderr, "Invalid device at %s\n", path);
+		dprintf("Invalid device at %s\n", path);
 		errno = EINVAL;
 		sysfs_close_device(dev);
 		return NULL;
 	}
 	if ((sysfs_read_directory(sdir)) != 0) {
-		dprintf(stderr, "Error reading device directory at %s\n", path);
+		dprintf("Error reading device directory at %s\n", path);
 		sysfs_close_directory(sdir);
 		sysfs_close_device(dev);
 		return NULL;
 	}
 	dev->directory = sdir;
-	sysfs_get_name_from_path(sdir->path, dev->bus_id, SYSFS_NAME_LEN);
-	/* get device name */
-	p = sysfs_get_value_from_attributes(sdir->attributes,	
-							SYSFS_NAME_ATTRIBUTE);
-	if (p != NULL) {
-		strncpy(dev->name, p, SYSFS_NAME_LEN);
-		p = dev->name + strlen(dev->name) - 1;
-		if ((strlen(dev->name) > 0) && *p == '\n')
-			*p = '\0';
-	}
+	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);
 
 	return dev;
 }
 
 /**
- * sysfs_close_device_tree: closes every device in the supplied tree, 
- * 	closing children only.
- * @devroot: device root of tree.
+ * 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.
  */
-void sysfs_close_device_tree(struct sysfs_device *devroot)
+static struct sysfs_device *sysfs_open_device_tree(const unsigned char *path)
 {
-	if (devroot != NULL) {
-		if (devroot->children != NULL) {
-			struct sysfs_device *child = NULL, *next = NULL;
-	
-			for (child = devroot->children; child != NULL;
-			     child = next) {
-				next = child->next;
-				sysfs_close_device_tree(child);
+	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);
 		}
-		sysfs_close_device(devroot);
 	}
+
+	return rootdev;
 }
 
 /**
- * add_device_child_to_parent: adds child device to parent
- * @parent: parent device.
- * @child: child device to add.
+ * sysfs_close_root_device: closes root and all devices
+ * @root: root device to close
  */
-static void add_device_child_to_parent(struct sysfs_device *parent,
-					struct sysfs_device *child)
+void sysfs_close_root_device(struct sysfs_root_device *root)
 {
-	if (parent != NULL && child != NULL) {
-		child->next = parent->children;
-		parent->children = child;
-		child->parent = parent;
+	if (root != NULL) {
+		if (root->devices != NULL)
+			dlist_destroy(root->devices);
+		if (root->directory != NULL)
+			sysfs_close_directory(root->directory);
+		free(root);
 	}
 }
 
 /**
- * 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.
+ * 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
  */
-struct sysfs_device *sysfs_open_device_tree(const char *path)
+static struct sysfs_directory *open_root_device_dir(const unsigned char *name)
 {
-	struct sysfs_device *rootdev = NULL, *new = NULL;
+	struct sysfs_directory *rdir = NULL;
+	unsigned char rootpath[SYSFS_PATH_MAX];
+
+	if (name == NULL) {
+		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;
+}
+
+/**
+ * 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
+ */
+static int get_all_root_devices(struct sysfs_root_device *root)
+{
+	struct sysfs_device *dev = NULL;
 	struct sysfs_directory *cur = NULL;
 
-	if (path == NULL) {
+	if (root == NULL || root->directory == NULL) {
+		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 0;
+}
+
+/**
+ * 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
+ */
+struct sysfs_root_device *sysfs_open_root_device(const unsigned char *name)
+{
+	struct sysfs_root_device *root = NULL;
+	struct sysfs_directory *rootdir = NULL;
+
+	if (name == NULL) {
 		errno = EINVAL;
 		return NULL;
 	}
-	rootdev = sysfs_open_device(path);
-	if (rootdev == NULL) {
-		dprintf(stderr, "Error opening root device at %s\n", path);
+
+	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;
+	}
+	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;
+	}
+
+	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);
+}
+
+/**
+ * sysfs_open_device_by_id: 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
+ * @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)
+{
+	char sysfs_path[SYSFS_PATH_MAX], device_path[SYSFS_PATH_MAX];
+	struct sysfs_device *device = NULL;
+
+	if (bus_id == NULL || bus == NULL) {
+		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");
+		return NULL;
+	}
+	
+	device = sysfs_open_device(device_path);
+	if (device == NULL) {
+		dprintf("Error opening device %s\n", bus_id);
 		return NULL;
 	}
-	cur = rootdev->directory->subdirs;
-	while (cur != NULL) {
-		new = sysfs_open_device_tree(cur->path);
-		if (new == NULL) {
-			dprintf(stderr, "Error opening device tree at %s\n",
-				cur->path);
-			sysfs_close_device_tree(rootdev);
-			return NULL;
+
+	return device;
+}
+
+/**
+ * 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
+ */
+static int get_device_absolute_path(const unsigned char *device, 
+					unsigned char *path, size_t psize)
+{
+	unsigned char bus_name[SYSFS_NAME_LEN], bus_path[SYSFS_PATH_MAX];
+
+	if (device == NULL || path == NULL) {
+		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 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 == 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;
+	}
+	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;
 		}
-		add_device_child_to_parent(rootdev, new);	
-		cur = cur->next;
 	}
+	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;
+}
 
-	return rootdev;
+/**
+ * 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;
+	}
+	if (attribute->len > len) {
+		dprintf("Value length %d is larger than supplied buffer %d\n",
+				attribute->len, len);
+		sysfs_close_attribute(attribute);
+		return -1;
+	}
+	strncpy(value, attribute->value, attribute->len);
+	value[(attribute->len)+1] = 0;
+	sysfs_close_attribute(attribute);
+	return 0;
 }
diff --git a/libsysfs/sysfs_dir.c b/libsysfs/sysfs_dir.c
index a83c81f493..ff2edf4615 100644
--- a/libsysfs/sysfs_dir.c
+++ b/libsysfs/sysfs_dir.c
@@ -3,7 +3,7 @@
  *
  * Directory utility functions for libsysfs
  *
- * Copyright (C) 2003 International Business Machines, Inc.
+ * Copyright (C) IBM Corp. 2003
  *
  *  This library is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU Lesser General Public
@@ -24,6 +24,81 @@
 #include "sysfs.h"
 
 /**
+ * sysfs_del_attribute: routine for dlist integration
+ */
+static void sysfs_del_attribute(void *attr)
+{
+        sysfs_close_attribute((struct sysfs_attribute *)attr);
+}
+
+/**
+ * sysfs_del_link: routine for dlist integration
+ */
+static void sysfs_del_link(void *ln)
+{
+        sysfs_close_link((struct sysfs_link *)ln);
+}
+
+/**
+ * sysfs_del_dir: routine for dlist integration
+ */
+static void sysfs_del_directory(void *dir)
+{
+        sysfs_close_directory((struct sysfs_directory *)dir);
+}
+
+/**
+ * dir_attribute_name_equal: compares dir attributes by name
+ * @a: attribute name for comparison
+ * @b: sysfs_attribute to be compared.
+ * returns 1 if a==b->name or 0 if not equal
+ */
+static int dir_attribute_name_equal(void *a, void *b)
+{
+	if (a == NULL || b == NULL)
+		return 0;
+
+	if (strcmp(((unsigned char *)a), ((struct sysfs_attribute *)b)->name) 
+	    == 0)
+		return 1;
+	return 0;
+}
+
+/**
+ * dir_link_name_equal: compares dir links by name
+ * @a: link name for comparison
+ * @b: sysfs_link to be compared.
+ * returns 1 if a==b->name or 0 if not equal
+ */
+static int dir_link_name_equal(void *a, void *b)
+{
+	if (a == NULL || b == NULL)
+		return 0;
+
+	if (strcmp(((unsigned char *)a), ((struct sysfs_link *)b)->name) 
+	    == 0)
+		return 1;
+	return 0;
+}
+
+/**
+ * dir_subdir_name_equal: compares subdirs by name
+ * @a: name of subdirectory to compare
+ * @b: sysfs_directory subdirectory to be compared
+ * returns 1 if a==b->name or 0 if not equal
+ */
+static int dir_subdir_name_equal(void *a, void *b)
+{
+	if (a == NULL || b == NULL)
+		return 0;
+
+	if (strcmp(((unsigned char *)a), ((struct sysfs_directory *)b)->name)
+	    == 0)
+		return 1;
+	return 0;
+}
+
+/**
  * sysfs_close_attribute: closes and cleans up attribute
  * @sysattr: attribute to close.
  */
@@ -51,7 +126,7 @@ static struct sysfs_attribute *alloc_attribute(void)
  * @path: path to attribute.
  * returns sysfs_attribute struct with success and NULL with error.
  */
-struct sysfs_attribute *sysfs_open_attribute(const char *path)
+struct sysfs_attribute *sysfs_open_attribute(const unsigned char *path)
 {
 	struct sysfs_attribute *sysattr = NULL;
 	struct stat fileinfo;
@@ -62,13 +137,22 @@ struct sysfs_attribute *sysfs_open_attribute(const char *path)
 	}
 	sysattr = alloc_attribute();
 	if (sysattr == NULL) {
-		dprintf(stderr, "Error allocating attribute at %s\n", path);
+		dprintf("Error allocating attribute at %s\n", path);
+		return NULL;
+	}
+	if (sysfs_get_name_from_path(path, sysattr->name, SYSFS_NAME_LEN) 
+	    != 0) {
+		dprintf("Error retrieving attribute name from path: %s\n", 
+			path);
+		sysfs_close_attribute(sysattr);
 		return NULL;
 	}
 	strncpy(sysattr->path, path, sizeof(sysattr->path));
 	if ((stat(sysattr->path, &fileinfo)) != 0) {
-		perror("stat");
+		dprintf("Stat failed: No such attribute?\n");
 		sysattr->method = 0;
+		free(sysattr);
+		sysattr = NULL;
 	} else {
 		if (fileinfo.st_mode & S_IRUSR)
 			sysattr->method |= SYSFS_METHOD_SHOW;
@@ -80,14 +164,95 @@ struct sysfs_attribute *sysfs_open_attribute(const char *path)
 }
 
 /**
+ * sysfs_write_attribute: write value to the attribute
+ * @sysattr: attribute to write
+ * @new_value: value to write
+ * @len: length of "new_value"
+ * returns 0 with success and -1 with error.
+ */
+int sysfs_write_attribute(struct sysfs_attribute *sysattr,
+		const unsigned char *new_value, size_t len)
+{
+	int fd;
+	int length;
+	
+	if (sysattr == NULL || new_value == NULL || len == 0) {
+		errno = EINVAL;
+		return -1;
+	}
+	
+	if (!(sysattr->method & SYSFS_METHOD_STORE)) {
+		dprintf ("Store method not supported for attribute %s\n",
+			sysattr->path);
+		return -1;
+	}
+	if (sysattr->method & SYSFS_METHOD_SHOW) {
+		if ((strncmp(sysattr->value, new_value, sysattr->len)) == 0) {
+			dprintf("Attribute %s already has the requested value %s\n",
+					sysattr->name, new_value);
+			return 0;	
+		}
+	}
+	/* 
+	 * open O_WRONLY since some attributes have no "read" but only
+	 * "write" permission 
+	 */ 
+	if ((fd = open(sysattr->path, O_WRONLY)) < 0) {
+		dprintf("Error reading attribute %s\n", sysattr->path);
+		return -1;
+	}
+
+	length = write(fd, new_value, len);
+	if (length < 0) {
+		dprintf("Error writing to the attribute %s - invalid value?\n",
+			sysattr->name);
+		close(fd);
+		return -1;
+	} else if (length != len) {
+		dprintf("Could not write %d bytes to attribute %s\n", 
+					len, sysattr->name);
+		/* 
+		 * since we could not write user supplied number of bytes,
+		 * restore the old value if one available
+		 */
+		if (sysattr->method & SYSFS_METHOD_SHOW) {
+			length = write(fd, sysattr->value, sysattr->len);
+			close(fd);
+			return -1;
+		}
+	}
+	
+	/*
+	 * Validate length that has been copied. Alloc appropriate area
+	 * in sysfs_attribute. Verify first if the attribute supports reading
+	 * (show method). If it does not, do not bother
+	 */ 
+	if (sysattr->method & SYSFS_METHOD_SHOW) {
+		if (length != sysattr->len) {
+			sysattr->value = (char *)realloc(sysattr->value, 
+								length);
+			sysattr->len = length;
+			strncpy(sysattr->value, new_value, length);
+		} else {
+			/*"length" of the new value is same as old one */ 
+			strncpy(sysattr->value, new_value, length);
+		}
+	}
+			
+	close(fd);	
+	return 0;
+}
+
+
+/**
  * sysfs_read_attribute: reads value from attribute
  * @sysattr: attribute to read
  * returns 0 with success and -1 with error.
  */
 int sysfs_read_attribute(struct sysfs_attribute *sysattr)
 {
-	char *fbuf = NULL;
-	char *vbuf = NULL;
+	unsigned char *fbuf = NULL;
+	unsigned char *vbuf = NULL;
 	size_t length = 0;
 	int pgsize = 0;
 	int fd;
@@ -97,34 +262,33 @@ int sysfs_read_attribute(struct sysfs_attribute *sysattr)
 		return -1;
 	}
 	if (!(sysattr->method & SYSFS_METHOD_SHOW)) {
-		dprintf (stderr, "Show method not supported for attribute %s\n",
+		dprintf("Show method not supported for attribute %s\n",
 			sysattr->path);
 		return -1;
 	}
 	pgsize = getpagesize();
-	fbuf = (char *)calloc(1, pgsize+1);
+	fbuf = (unsigned char *)calloc(1, pgsize+1);
 	if (fbuf == NULL) {
-		perror("calloc");
+		dprintf("calloc failed\n");
 		return -1;
 	}
 	if ((fd = open(sysattr->path, O_RDONLY)) < 0) {
-		dprintf (stderr, "Error reading attribute %s\n", sysattr->path);
+		dprintf("Error reading attribute %s\n", sysattr->path);
 		free(fbuf);
 		return -1;
 	}
 	length = read(fd, fbuf, pgsize);
 	if (length < 0) {
-		dprintf (stderr, "Error reading from attribute %s\n",
-			sysattr->path);
+		dprintf("Error reading from attribute %s\n", sysattr->path);
 		close(fd);
 		free(fbuf);
 		return -1;
 	}
 	sysattr->len = length;
 	close(fd);
-	vbuf = (char *)realloc(fbuf, length+1);
+	vbuf = (unsigned char *)realloc(fbuf, length+1);
 	if (vbuf == NULL) {
-		perror("realloc");
+		dprintf("realloc failed\n");
 		free(fbuf);
 		return -1;
 	}
@@ -142,7 +306,8 @@ int sysfs_read_attribute(struct sysfs_attribute *sysattr)
  * @vsize: size of value buffer
  * returns 0 with success and -1 with error.
  */
-int sysfs_read_attribute_value(const char *attrpath, char *value, size_t vsize)
+int sysfs_read_attribute_value(const unsigned char *attrpath, 
+					unsigned char *value, size_t vsize)
 {
 	struct sysfs_attribute *attr = NULL;
 	size_t length = 0;
@@ -154,19 +319,18 @@ int sysfs_read_attribute_value(const char *attrpath, char *value, size_t vsize)
 
 	attr = sysfs_open_attribute(attrpath);
 	if (attr == NULL) {
-		dprintf(stderr, "Invalid attribute path %s\n", attrpath);
+		dprintf("Invalid attribute path %s\n", attrpath);
 		errno = EINVAL;
 		return -1;
 	}
 	if((sysfs_read_attribute(attr)) != 0 || attr->value == NULL) {
-		dprintf(stderr, "Error reading from attribute %s\n", attrpath);
+		dprintf("Error reading from attribute %s\n", attrpath);
 		sysfs_close_attribute(attr);
 		return -1;
 	}
 	length = strlen(attr->value);
 	if (length > vsize) 
-		dprintf(stderr, 
-			"Value length %d is larger than supplied buffer %d\n",
+		dprintf("Value length %d is larger than supplied buffer %d\n",
 			length, vsize);
 	strncpy(value, attr->value, vsize);
 	sysfs_close_attribute(attr);
@@ -179,87 +343,32 @@ int sysfs_read_attribute_value(const char *attrpath, char *value, size_t vsize)
  * 	attribute name, return its value
  * @attr: attribute to search
  * @name: name to look for
- * returns char * value - could be NULL
+ * returns unsigned char * value - could be NULL
  */
-char *sysfs_get_value_from_attributes(struct sysfs_attribute *attr, 
-					const char *name)
+unsigned char *sysfs_get_value_from_attributes(struct dlist *attr, 
+					const unsigned char *name)
 {	
 	struct sysfs_attribute *cur = NULL;
-	char tmpname[SYSFS_NAME_LEN];
 	
 	if (attr == NULL || name == NULL) {
 		errno = EINVAL;
 		return NULL;
-	}	
-	cur = attr;
-	while (cur != NULL) {
-		memset(tmpname, 0, SYSFS_NAME_LEN);	
-		if ((sysfs_get_name_from_path(cur->path, tmpname,
-		    SYSFS_NAME_LEN)) != 0) {
-			cur = cur->next;
-			continue;
-		}
-		if (strcmp(tmpname, name) == 0)
+	}
+	dlist_for_each_data(attr, cur, struct sysfs_attribute) {
+		if (strcmp(cur->name, name) == 0)
 			return cur->value;
-		cur = cur->next;
 	}
 	return NULL;
 }
 
 /**
- * add_subdir_to_dir: adds subdirectory to directory's subdirs
- * @sysdir: directory to add subdir to
- * @subdir: subdirectory to add.
+ * sysfs_close_link: closes and cleans up link.
+ * @ln: link to close.
  */
-static void add_subdir_to_dir(struct sysfs_directory *sysdir, 
-		     struct sysfs_directory *subdir)
+void sysfs_close_link(struct sysfs_link *ln)
 {
-	if (sysdir != NULL && subdir != NULL) {
-		subdir->next = sysdir->subdirs;
-		sysdir->subdirs = subdir;
-	}
-}
-
-/**
- * add_attr_to_dir: adds attribute to directory's attributes
- * @sysdir: directory to add attribute to
- * @sysattr: attribute to add.
- */
-static void add_attr_to_dir(struct sysfs_directory *sysdir, 
-		     			struct sysfs_attribute *sysattr)
-{
-	if (sysdir != NULL && sysattr != NULL) {
-		sysattr->next = sysdir->attributes;
-		sysdir->attributes = sysattr;
-	}
-}
-
-/**
- * sysfs_close_dlink: closes and cleans up directory link.
- * @dlink: directory link to close.
- */
-void sysfs_close_dlink(struct sysfs_dlink *dlink)
-{
-	if (dlink != NULL) {
-		dlink->next = NULL;
-		if (dlink->target != NULL)
-			sysfs_close_directory(dlink->target);
-		free(dlink);
-	}
-}
-
-/**
- * add_dlink_to_dir: adds directory link to directory's links list.
- * @sysdir: directory to add it to.
- * @dlink: link to add.
- */
-static void add_dlink_to_dir(struct sysfs_directory *sysdir, 
-					struct sysfs_dlink *dlink)
-{
-	if (sysdir != NULL && dlink != NULL) {
-		dlink->next = sysdir->links;
-		sysdir->links = dlink;
-	}
+	if (ln != NULL) 
+		free(ln);
 }
 
 /**
@@ -268,35 +377,13 @@ static void add_dlink_to_dir(struct sysfs_directory *sysdir,
  */
 void sysfs_close_directory(struct sysfs_directory *sysdir)
 {
-	struct sysfs_directory *sdir = NULL, *dnext = NULL;
-	struct sysfs_dlink *dlink = NULL, *nextl = NULL;
-	struct sysfs_attribute *attr = NULL, *anext = NULL;
-
 	if (sysdir != NULL) {
-		if (sysdir->subdirs != NULL) {
-			for (sdir = sysdir->subdirs; sdir != NULL;
-			     sdir = dnext) {
-				dnext = sdir->next;
-				sysfs_close_directory(sdir);
-			}
-		}
-		if (sysdir->links != NULL) {
-			for (dlink = sysdir->links; dlink != NULL;
-			    dlink = nextl) {
-				nextl = dlink->next;
-				sysfs_close_dlink(dlink);
-			}
-		}
-		if (sysdir->attributes != NULL) {
-			for (attr = sysdir->attributes; attr != NULL;
-			     attr = anext) {
-				anext = attr->next;
-				/* sysfs_close_attribute(attr); */
-				if (attr->value != NULL)
-					free(attr->value);
-				free(attr);
-			}
-		}
+		if (sysdir->subdirs != NULL) 
+			dlist_destroy(sysdir->subdirs);
+		if (sysdir->links != NULL)
+			dlist_destroy(sysdir->links);
+		if (sysdir->attributes != NULL) 
+			dlist_destroy(sysdir->attributes);
 		free(sysdir);
 	}
 }
@@ -312,12 +399,35 @@ static struct sysfs_directory *alloc_directory(void)
 }
 
 /**
- * alloc_dlink: allocates and initializes directory link structure
- * returns struct sysfs_dlink with success or NULL with error.
+ * alloc_link: allocates and initializes link structure
+ * returns struct sysfs_link with success or NULL with error.
+ */
+static struct sysfs_link *alloc_link(void)
+{
+	return (struct sysfs_link *)calloc(1, sizeof(struct sysfs_link));
+}
+
+/**
+ * sysfs_read_all_subdirs: calls sysfs_read_directory for all subdirs
+ * @sysdir: directory whose subdirs need reading.
+ * returns 0 with success and -1 with error.
  */
-static struct sysfs_dlink *alloc_dlink(void)
+int sysfs_read_all_subdirs(struct sysfs_directory *sysdir)
 {
-	return (struct sysfs_dlink *)calloc(1, sizeof(struct sysfs_dlink));
+	struct sysfs_directory *cursub = NULL;
+
+	if (sysdir == NULL) {
+		errno = EINVAL;
+		return -1;
+	}
+	if (sysdir->subdirs == NULL)
+		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);
+	}
+	return 0;
 }
 
 /**
@@ -326,7 +436,7 @@ static struct sysfs_dlink *alloc_dlink(void)
  * @path: path of directory to open.
  * returns: struct sysfs_directory * with success and NULL on error.
  */
-struct sysfs_directory *sysfs_open_directory(const char *path)
+struct sysfs_directory *sysfs_open_directory(const unsigned char *path)
 {
 	struct sysfs_directory *sdir = NULL;
 
@@ -336,7 +446,12 @@ struct sysfs_directory *sysfs_open_directory(const char *path)
 	}
 	sdir = alloc_directory();
 	if (sdir == NULL) {
-		dprintf(stderr, "Error allocating directory %s\n", path);
+		dprintf("Error allocating directory %s\n", path);
+		return NULL;
+	}
+	if (sysfs_get_name_from_path(path, sdir->name, SYSFS_NAME_LEN) != 0) {
+		dprintf("Error getting directory name from path: %s\n", path);
+		sysfs_close_directory(sdir);
 		return NULL;
 	}
 	strncpy(sdir->path, path, sizeof(sdir->path));
@@ -345,46 +460,33 @@ struct sysfs_directory *sysfs_open_directory(const char *path)
 }
 
 /**
- * sysfs_open_dlink: opens a sysfs directory link, creates struct, and returns
+ * sysfs_open_link: opens a sysfs link, creates struct, and returns
  * @path: path of link to open.
- * returns: struct sysfs_dlink * with success and NULL on error.
+ * returns: struct sysfs_link * with success and NULL on error.
  */
-struct sysfs_dlink *sysfs_open_dlink(const char *linkpath)
+struct sysfs_link *sysfs_open_link(const unsigned char *linkpath)
 {
-	struct sysfs_dlink *dlink = NULL;
-	struct sysfs_directory *tdir = NULL;
-	char name[SYSFS_NAME_LEN];
-	char target[SYSFS_PATH_MAX];
+	struct sysfs_link *ln = NULL;
 
-	if (linkpath == NULL) {
+	if (linkpath == NULL || strlen(linkpath) > SYSFS_PATH_MAX) {
 		errno = EINVAL;
 		return NULL;
 	}
 
-	memset(name, 0, SYSFS_NAME_LEN);
-	memset(target, 0, SYSFS_PATH_MAX);
-	if ((sysfs_get_name_from_path(linkpath, name, SYSFS_NAME_LEN)) != 0
-	    || (sysfs_get_link(linkpath, target, SYSFS_PATH_MAX)) != 0) {
-		errno = EINVAL;
-		dprintf(stderr, "Invalid link path %s\n", linkpath);
+	ln = alloc_link();
+	if (ln == NULL) {
+		dprintf("Error allocating link %s\n", linkpath);
 		return NULL;
 	}
-	dlink = alloc_dlink();
-	if (dlink == NULL) {
-		dprintf(stderr, 
-			"Error allocating directory link %s\n", linkpath);
+	strcpy(ln->path, linkpath);
+	if ((sysfs_get_name_from_path(linkpath, ln->name, SYSFS_NAME_LEN)) != 0
+	    || (sysfs_get_link(linkpath, ln->target, SYSFS_PATH_MAX)) != 0) {
+		errno = EINVAL;
+		dprintf("Invalid link path %s\n", linkpath);
 		return NULL;
 	}
-	strcpy(dlink->name, name);
-	tdir = sysfs_open_directory(target);
-	if (tdir == NULL) {
-		dprintf(stderr, "Invalid directory link target %s\n", target);
-		sysfs_close_dlink(dlink);
-		return NULL;
-	}	
-	dlink->target = tdir;
 
-	return dlink;
+	return ln;
 }
 
 /**
@@ -399,8 +501,8 @@ int sysfs_read_directory(struct sysfs_directory *sysdir)
 	struct stat astats;
 	struct sysfs_attribute *attr = NULL;
 	struct sysfs_directory *subdir = NULL;
-	struct sysfs_dlink *dlink = NULL;
-	char file_path[SYSFS_PATH_MAX];
+	struct sysfs_link *ln = NULL;
+	unsigned char file_path[SYSFS_PATH_MAX];
 	int retval = 0;
 
 	if (sysdir == NULL) {
@@ -409,7 +511,7 @@ int sysfs_read_directory(struct sysfs_directory *sysdir)
 	}
 	dir = opendir(sysdir->path);
 	if (dir == NULL) {
-		perror("opendir");
+		dprintf("Error opening directory %s\n", sysdir->path);
 		return -1;
 	}
 	while(((dirent = readdir(dir)) != NULL) && retval == 0) {
@@ -422,45 +524,57 @@ int sysfs_read_directory(struct sysfs_directory *sysdir)
 		strncat(file_path, "/", sizeof(file_path));
 		strncat(file_path, dirent->d_name, sizeof(file_path));
 		if ((lstat(file_path, &astats)) != 0) {
-			perror("stat");
+			dprintf("stat failed\n");
 			continue;
 		}
 		if (S_ISREG(astats.st_mode)) {	
 			attr = sysfs_open_attribute(file_path);
 			if (attr == NULL) {
-				dprintf (stderr, "Error opening attribute %s\n",
+				dprintf("Error opening attribute %s\n",
 					file_path);
 				retval = -1;
 				break;
 			}
 			if (attr->method & SYSFS_METHOD_SHOW) {
 				if ((sysfs_read_attribute(attr)) != 0) {
-					dprintf (stderr, 
-						"Error reading attribute %s\n",
+					dprintf("Error reading attribute %s\n",
 						file_path);
 					sysfs_close_attribute(attr);
 					continue;
 				}
 			}
-			add_attr_to_dir(sysdir, attr);
+			                        
+			if (sysdir->attributes == NULL) {
+				sysdir->attributes = dlist_new_with_delete
+					(sizeof(struct sysfs_attribute),
+					 		sysfs_del_attribute);
+			}
+			dlist_unshift(sysdir->attributes, attr);
 		} else if (S_ISDIR(astats.st_mode)) {
 			subdir = sysfs_open_directory(file_path);
 			if (subdir == NULL) {
-				dprintf (stderr, "Error opening directory %s\n",
+				dprintf("Error opening directory %s\n",
 					file_path);
 				retval = -1;
 				break;
 			}
-			add_subdir_to_dir(sysdir, subdir);
+			if (sysdir->subdirs == NULL)
+				sysdir->subdirs = dlist_new_with_delete
+					(sizeof(struct sysfs_directory),
+							sysfs_del_directory);
+			dlist_unshift(sysdir->subdirs, subdir);
 		} else if (S_ISLNK(astats.st_mode)) {
-			dlink = sysfs_open_dlink(file_path);
-			if (dlink == NULL) {
-				dprintf(stderr, "Error opening link %s\n",
-					file_path);
+			ln = sysfs_open_link(file_path);
+			if (ln == NULL) {
+				dprintf("Error opening link %s\n", file_path);
 				retval = -1;
 				break;
 			}
-			add_dlink_to_dir(sysdir, dlink);
+			if (sysdir->links == NULL)
+				sysdir->links = dlist_new_with_delete
+						(sizeof(struct sysfs_link),
+						 		sysfs_del_link);
+			dlist_unshift(sysdir->links, ln);
 		}
 	}
 	closedir(dir);
@@ -468,29 +582,123 @@ int sysfs_read_directory(struct sysfs_directory *sysdir)
 }
 
 /**
- * sysfs_read_dlinks: reads a directory link's target directory. Can
- * 	supply a linked list of links.
- * @dlink: directory link to read.
- * returns 0 with success or -1 with error.
+ * sysfs_get_directory_attribute: retrieves attribute attrname
+ * @dir: directory to retrieve attribute from
+ * @attrname: name of attribute to look for
+ * returns sysfs_attribute if found and NULL if not found
  */
-int sysfs_read_dlinks(struct sysfs_dlink *dlink)
+struct sysfs_attribute *sysfs_get_directory_attribute
+			(struct sysfs_directory *dir, unsigned char *attrname)
 {
-	struct sysfs_dlink *cur = NULL;
+	struct sysfs_directory *sdir = NULL;
+	struct sysfs_attribute *attr = NULL;
+	
+	if (dir == NULL || attrname == NULL) {
+		errno = EINVAL;
+		return NULL;
+	}
+	
+	attr = (struct sysfs_attribute *)dlist_find_custom(dir->attributes,
+		attrname, dir_attribute_name_equal);
+	if (attr != NULL)
+		return attr;
+	
+	if (dir->subdirs != NULL) {
+		dlist_for_each_data(dir->subdirs, sdir, 
+					struct sysfs_directory) {
+			if (sdir->attributes == NULL)
+				continue;
+			attr = sysfs_get_directory_attribute(sdir, attrname);
+			if (attr != NULL)
+				return attr;
+		}
+	}
+	return NULL;
+}
 
-	if (dlink == NULL || dlink->target == NULL) {
+/**
+ * sysfs_get_directory_link: retrieves link from one directory list
+ * @dir: directory to retrieve link from
+ * @linkname: name of link to look for
+ * returns reference to sysfs_link if found and NULL if not found
+ */
+struct sysfs_link *sysfs_get_directory_link
+			(struct sysfs_directory *dir, unsigned char *linkname)
+{
+	if (dir == NULL || linkname == NULL) {
 		errno = EINVAL;
-		return -1;
+		return NULL;
 	}
-	cur = dlink;
-	while (cur != NULL) {
-		if ((sysfs_read_directory(cur->target)) != 0) {
-			dprintf(stderr, 
-				"Error reading directory link target %s\n",
-				dlink->name);
-			return -1;
+	return (struct sysfs_link *)dlist_find_custom(dir->links,
+		linkname, dir_link_name_equal);
+}
+
+/**
+ * sysfs_get_subdirectory: retrieves subdirectory by name.
+ * @dir: directory to search for subdirectory.
+ * @subname: subdirectory name to get.
+ * returns reference to subdirectory or NULL if not found
+ */
+struct sysfs_directory *sysfs_get_subdirectory(struct sysfs_directory *dir,
+						unsigned char *subname)
+{
+	struct sysfs_directory *sub = NULL, *cursub = NULL;
+
+	if (dir == NULL || dir->subdirs == NULL || subname == NULL) {
+		errno = EINVAL;
+		return NULL;
+	}
+	sub = (struct sysfs_directory *)dlist_find_custom(dir->subdirs,
+		subname, dir_subdir_name_equal);
+	if (sub != NULL) 
+		return sub;
+
+	if (dir->subdirs != NULL) {
+		dlist_for_each_data(dir->subdirs, cursub, 
+					struct sysfs_directory) {
+			if (cursub->subdirs == NULL)
+				continue;
+			sub = sysfs_get_subdirectory(cursub, subname);
+			if (sub != NULL)
+				return sub;
 		}
-		cur = cur->next;
 	}
-	
-	return 0;
+	return NULL;
+}
+
+/**
+ * sysfs_get_subdirectory_link: looks through all subdirs for specific link.
+ * @dir: directory and subdirectories to search for link.
+ * @linkname: link name to get.
+ * returns reference to link or NULL if not found
+ */
+struct sysfs_link *sysfs_get_subdirectory_link(struct sysfs_directory *dir,
+						unsigned char *linkname)
+{
+	struct sysfs_directory *cursub = NULL;
+	struct sysfs_link *ln = NULL;
+
+	if (dir == NULL || dir->links == NULL || linkname == NULL) {
+		errno = EINVAL;
+		return NULL;
+	}
+
+	ln = sysfs_get_directory_link(dir, linkname);
+	if (ln != NULL)
+		return ln;
+
+	if (dir->subdirs == NULL)
+		return NULL;
+
+	if (dir->subdirs != NULL) {
+		dlist_for_each_data(dir->subdirs, cursub, 
+						struct sysfs_directory) {
+			if (cursub->subdirs == NULL)
+				continue;
+			ln = sysfs_get_subdirectory_link(cursub, linkname);
+			if (ln != NULL)
+				return ln;
+		}
+	}
+	return NULL;
 }
diff --git a/libsysfs/sysfs_driver.c b/libsysfs/sysfs_driver.c
index 6813c85f14..f8e842c65c 100644
--- a/libsysfs/sysfs_driver.c
+++ b/libsysfs/sysfs_driver.c
@@ -3,7 +3,7 @@
  *
  * Driver utility functions for libsysfs
  *
- * Copyright (C) 2003 International Business Machines, Inc.
+ * Copyright (C) IBM Corp. 2003
  *
  *  This library is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU Lesser General Public
@@ -23,19 +23,46 @@
 #include "libsysfs.h"
 #include "sysfs.h"
 
+static void sysfs_close_driver_by_name_dev(void *device)
+{
+	sysfs_close_device((struct sysfs_device *)device);
+}
+
 /**
  * sysfs_close_driver: closes and cleans up driver structure
+ * NOTE: This routine does not deallocate devices list
  * @driver: driver to close
  */
 void sysfs_close_driver(struct sysfs_driver *driver)
 {
 	if (driver != NULL) {
+		if (driver->devices != NULL) {
+			dlist_for_each(driver->devices) 
+				dlist_shift(driver->devices);
+			free(driver->devices);
+			driver->devices = NULL;
+		}
 		if (driver->directory != NULL)
 			sysfs_close_directory(driver->directory);
 		free(driver);
 	}
 }
 
+/** 
+ * sysfs_close_driver_by_name: closes driver and deletes device lists too
+ * @driver: driver to close
+ */ 
+void sysfs_close_driver_by_name(struct sysfs_driver *driver)
+{
+	if (driver != NULL) {
+		if (driver->devices != NULL) 
+			dlist_destroy(driver->devices);
+		if (driver->directory != NULL)
+			sysfs_close_directory(driver->directory);
+		free(driver);
+	}
+}
+		
 /**
  * alloc_driver: allocates and initializes driver
  * returns struct sysfs_driver with success and NULL with error.
@@ -50,11 +77,10 @@ static struct sysfs_driver *alloc_driver(void)
  * @path: path to driver directory
  * returns struct sysfs_driver with success and NULL with error
  */
-struct sysfs_driver *sysfs_open_driver(const char *path)
+struct sysfs_driver *sysfs_open_driver(const unsigned char *path)
 {
 	struct sysfs_driver *driver = NULL;
 	struct sysfs_directory *sdir = NULL;
-	char devname[SYSFS_NAME_LEN];
 
 	if (path == NULL) {
 		errno = EINVAL;
@@ -62,28 +88,280 @@ struct sysfs_driver *sysfs_open_driver(const char *path)
 	}
 	sdir = sysfs_open_directory(path);
 	if (sdir == NULL) {
-		dprintf (stderr, "Error opening directory %s\n", path);
+		dprintf("Error opening directory %s\n", path);
 		return NULL;
 	}
 	if ((sysfs_read_directory(sdir)) != 0) {
-		dprintf (stderr, "Error reading directory %s\n", path);
+		dprintf("Error reading directory %s\n", path);
 		sysfs_close_directory(sdir);
 		return NULL;
 	}
 	driver = alloc_driver();
 	if (driver == NULL) {
-		dprintf(stderr, "Error allocating driver at %s\n", path);
+		dprintf("Error allocating driver at %s\n", path);
 		sysfs_close_directory(sdir);
 		return NULL;
 	}
-	if ((sysfs_get_name_from_path(path, devname, SYSFS_NAME_LEN)) != 0) {
-		dprintf (stderr, "Error reading directory %s\n", path);
-		sysfs_close_directory(sdir);
-		free(driver);
-		return NULL;
-	}
-	strncpy(driver->name, devname, sizeof(driver->name));
+	strcpy(driver->name, sdir->name);
 	driver->directory = sdir;	
+	strcpy(driver->path, sdir->path);
 	
 	return driver;
 }
+
+/**
+ * sysfs_get_driver_attributes: gets list of attributes for the given driver
+ * @driver: sysfs_driver for which attributes are required
+ * returns a dlist of attributes corresponding to the driver if present
+ * 	NULL otherwise
+ */
+struct dlist *sysfs_get_driver_attributes(struct sysfs_driver *driver)
+{
+	if (driver == NULL || driver->directory == NULL)
+		return NULL;
+
+	return(driver->directory->attributes);
+}
+
+/**
+ * sysfs_get_driver_attr: searches driver's attributes by name
+ * @drv: driver to look through
+ * @name: attribute name to get
+ * returns sysfs_attribute reference on success or NULL with error
+ */ 
+struct sysfs_attribute *sysfs_get_driver_attr(struct sysfs_driver *drv,
+					const unsigned char *name)
+{
+	struct sysfs_attribute *cur = NULL;
+
+        if (drv == NULL || drv->directory == NULL
+            || drv->directory->attributes == NULL || name == NULL) {
+                errno = EINVAL;
+                return NULL;
+        }
+
+        cur = sysfs_get_directory_attribute(drv->directory,
+		                        (unsigned char *)name);
+        if (cur != NULL)
+                return cur;
+
+        return NULL;
+}
+
+/**
+ * sysfs_get_driver_links: gets list of links from the given driver
+ * @driver: sysfs_driver for which links list is required
+ * returns a dlist of links corresponding to the driver if present
+ * 	NULL otherwise
+ */
+struct dlist *sysfs_get_driver_links(struct sysfs_driver *driver)
+{
+	if (driver == NULL || driver->directory == NULL)
+		return NULL;
+
+	return(driver->directory->links);
+}
+
+/**
+ * sysfs_open_driver_by_name: open a driver by name and return the bus
+ * the driver is on.
+ * @drv_name: driver to open
+ * @bus: the driver bus
+ * @bsize: size of bus buffer
+ * returns struct sysfs_driver if found, NULL otherwise
+ * NOTE: 
+ * 1. Need to call sysfs_close_driver_by_name to free up memory
+ * 2. Bus the driver is registered with must be supplied.
+ * 	Use sysfs_find_driver_bus() to obtain the bus name
+ */
+struct sysfs_driver *sysfs_open_driver_by_name(const unsigned char *drv_name,
+				const unsigned char *bus, size_t bsize)
+{
+	struct sysfs_driver *driver = NULL;
+	struct sysfs_device *device = NULL;
+	struct sysfs_link *curlink = NULL;
+	unsigned char path[SYSFS_PATH_MAX];
+
+	if (drv_name == NULL || bus == NULL) {
+		errno = EINVAL;
+		return NULL;
+	}
+
+	memset(path, 0, SYSFS_PATH_MAX);
+	if (sysfs_get_mnt_path(path, SYSFS_PATH_MAX) != 0) {
+		dprintf("Error getting sysfs mount path\n");
+		return NULL;
+	}
+	strcat(path, SYSFS_BUS_DIR);
+	strcat(path, "/");
+	strcat(path, bus);
+	strcat(path, SYSFS_DRIVERS_DIR);
+	strcat(path, "/");
+	strcat(path, drv_name);
+	driver = sysfs_open_driver(path);
+	if (driver == NULL) {
+		dprintf("Could not open driver %s\n", drv_name);
+		return NULL;
+	}
+	if (driver->directory->links != NULL) {
+		dlist_for_each_data(driver->directory->links, curlink, 
+							struct sysfs_link) {
+			device = sysfs_open_device(curlink->target);
+			if (device == NULL) {
+				dprintf("Error opening device at %s\n", 
+						curlink->target);
+				sysfs_close_driver_by_name(driver);
+				return NULL;
+			}
+			strcpy(device->driver_name, drv_name);
+			if (driver->devices == NULL) 
+				driver->devices = dlist_new_with_delete
+						(sizeof(struct sysfs_device),
+					 		sysfs_close_driver_by_name_dev);
+			dlist_unshift(driver->devices, device);
+		}
+	}
+	return driver;
+}
+
+/**
+ * get_driver_path: looks up the bus the driver is on and builds path to
+ * 		the driver.
+ * @drv: driver to look for
+ * @path: buffer to return path to driver
+ * @psize: size of "path"
+ * Returns 0 on success and -1 on error
+ */
+static int get_driver_path(const unsigned char *drv, 
+				unsigned char *path, size_t psize)
+{
+	unsigned char bus_name[SYSFS_NAME_LEN];
+
+	if (drv == NULL || path == NULL) {
+		errno = EINVAL;
+		return -1;
+	}
+	memset(bus_name, 0, SYSFS_NAME_LEN);
+	memset(path, 0, SYSFS_PATH_MAX);
+	if ((sysfs_find_driver_bus(drv, bus_name, SYSFS_NAME_LEN)) < 0) {
+		dprintf("Driver %s not found\n", drv);
+		return -1;
+	}
+	if (sysfs_get_mnt_path(path, SYSFS_PATH_MAX) != 0) {
+		dprintf("Error getting sysfs mount path\n");
+		return -1;
+	}
+	strcat(path, SYSFS_BUS_DIR);
+	strcat(path, "/");
+	strcat(path, bus_name);
+	strcat(path, SYSFS_DRIVERS_DIR);
+	strcat(path, "/");
+	strcat(path, drv);
+	fprintf(stdout, "get_driver_path %s\n", path);
+	return 0;
+}
+
+/**
+ * sysfs_write_driver_attr: modify "writable" driver attribute
+ * @drv: driver whose attribute has to be modified
+ * @attrib: Attribute to be modified
+ * @value: Value to change to
+ * Returns 0 on success -1 on failure
+ */ 
+int sysfs_write_driver_attr(unsigned char *drv, unsigned char *attrib,
+					unsigned char *value, size_t len)
+{
+	struct sysfs_attribute *attribute = NULL;
+	unsigned char path[SYSFS_PATH_MAX];
+
+	if (drv == NULL || attrib == NULL || value == NULL) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	memset(path, 0, SYSFS_PATH_MAX);
+	if ((get_driver_path(drv, path, SYSFS_PATH_MAX)) != 0) {
+		dprintf("Error getting to driver %s\n", drv);
+		return -1;
+	}
+	strcat(path, "/");
+	strcat(path, attrib);
+	attribute = sysfs_open_attribute(path);
+        if (attribute == NULL) {
+                dprintf("Attribute %s could not be retrieved for driver %s\n",
+							attrib, drv);
+		return -1;
+	}
+	if (attribute->method & SYSFS_METHOD_SHOW) {
+		if ((sysfs_read_attribute(attribute)) != 0) {
+			dprintf("Error reading attribute %s for driver %s\n",
+					attrib, drv);
+			sysfs_close_attribute(attribute);
+			return -1;
+		}
+	}
+	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;
+}
+
+/**
+ * sysfs_read_driver_attr: read the user supplied driver attribute
+ * @drv: driver whose attribute has to be read
+ * @attrib: Attribute to be read
+ * @value: Buffer to return the read value
+ * @len: Length of the buffer "value"
+ * Returns 0 on success -1 on failure
+ */ 
+int sysfs_read_driver_attr(unsigned char *drv, unsigned char *attrib,
+					unsigned char *value, size_t len)
+{
+	struct sysfs_attribute *attribute = NULL;
+	unsigned char path[SYSFS_PATH_MAX];
+
+	if (drv == NULL || attrib == NULL || value == NULL) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	memset(path, 0, SYSFS_NAME_LEN);
+	if ((get_driver_path(drv, path, SYSFS_PATH_MAX)) != 0) {
+		dprintf("Error getting to driver %s\n", drv);
+		return -1;
+	}
+	strcat(path, "/");
+	strcat(path, attrib);
+	attribute = sysfs_open_attribute(path);
+        if (attribute == NULL) {
+		dprintf("Error opening attribute %s for driver %s\n",
+				attrib, drv);
+		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 driver %s\n", 
+				attrib, drv);
+		sysfs_close_attribute(attribute);
+		return -1;
+	}
+	if (attribute->len > len) {
+		dprintf("Value length %d is larger than supplied buffer %d\n",
+				attribute->len, len);
+		sysfs_close_attribute(attribute);
+		return -1;
+	}
+	strncpy(value, attribute->value, attribute->len);
+	value[(attribute->len)+1] = 0;
+	sysfs_close_attribute(attribute);
+	return 0;
+}
+
diff --git a/libsysfs/sysfs_utils.c b/libsysfs/sysfs_utils.c
index a2410abe69..4475342433 100644
--- a/libsysfs/sysfs_utils.c
+++ b/libsysfs/sysfs_utils.c
@@ -3,7 +3,7 @@
  *
  * System utility functions for libsysfs
  *
- * Copyright (C) 2003 International Business Machines, Inc.
+ * Copyright (C) IBM Corp. 2003
  *
  *  This library is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU Lesser General Public
@@ -30,8 +30,8 @@
  * @len: size of mnt_path
  * returns 0 with success and -1 with error.
  */
-static int sysfs_get_fs_mnt_path(const char *fs_type, char *mnt_path, 
-				 size_t len)
+static int sysfs_get_fs_mnt_path(const unsigned char *fs_type, 
+				unsigned char *mnt_path, size_t len)
 {
 	FILE *mnt;
 	struct mntent *mntent;
@@ -45,7 +45,7 @@ static int sysfs_get_fs_mnt_path(const char *fs_type, char *mnt_path,
 	}
 
 	if ((mnt = setmntent(SYSFS_PROC_MNTS, "r")) == NULL) {
-		dprintf(stderr, "Error getting mount information\n");
+		dprintf("Error getting mount information\n");
 		return -1;
 	}
 	while (ret == 0 && dirlen == 0 && (mntent = getmntent(mnt)) != NULL) {
@@ -54,15 +54,14 @@ static int sysfs_get_fs_mnt_path(const char *fs_type, char *mnt_path,
 			if (dirlen <= (len - 1)) {
 				strcpy(mnt_path, mntent->mnt_dir);
 			} else {
-				dprintf(stderr, 
-					"Error - mount path too long\n");
+				dprintf("Error - mount path too long\n");
 				ret = -1;
 			}
 		}
 	}
 	endmntent(mnt);
 	if (dirlen == 0 && ret == 0) {
-		dprintf(stderr, "Filesystem %s not found!\n", fs_type);
+		dprintf("Filesystem %s not found!\n", fs_type);
 		errno = EINVAL;
 		ret = -1;
 	}
@@ -75,7 +74,7 @@ static int sysfs_get_fs_mnt_path(const char *fs_type, char *mnt_path,
  * @len: size of mnt_path
  * returns 0 with success and -1 with error.
  */
-int sysfs_get_mnt_path(char *mnt_path, size_t len)
+int sysfs_get_mnt_path(unsigned char *mnt_path, size_t len)
 {
 	int ret = -1;
 
@@ -93,9 +92,10 @@ int sysfs_get_mnt_path(char *mnt_path, size_t len)
  * @name: where to put name
  * @len: size of name
  */
-int sysfs_get_name_from_path(const char *path, char *name, size_t len)
+int sysfs_get_name_from_path(const unsigned char *path, unsigned char *name, 
+								size_t len)
 {
-	char *n = NULL;
+	unsigned char *n = NULL;
                                                                                 
 	if (path == NULL || name == NULL) {
 		errno = EINVAL;
@@ -118,11 +118,11 @@ int sysfs_get_name_from_path(const char *path, char *name, size_t len)
  * @target: where to put name
  * @len: size of name
  */
-int sysfs_get_link(const char *path, char *target, size_t len)
+int sysfs_get_link(const unsigned char *path, unsigned char *target, size_t len)
 {
-	char devdir[SYSFS_PATH_MAX];
-	char linkpath[SYSFS_PATH_MAX];
-	char *d = NULL;
+	unsigned char devdir[SYSFS_PATH_MAX];
+	unsigned char linkpath[SYSFS_PATH_MAX];
+	unsigned char *d = NULL;
 
 	if (path == NULL || target == NULL) {
 		errno = EINVAL;
@@ -133,7 +133,7 @@ int sysfs_get_link(const char *path, char *target, size_t len)
 	memset(linkpath, 0, SYSFS_PATH_MAX);
 
 	if ((sysfs_get_mnt_path(devdir, SYSFS_PATH_MAX)) != 0) {
-		dprintf(stderr, "Sysfs not supported on this system\n");
+		dprintf("Sysfs not supported on this system\n");
 		return -1;
 	}
 								        
@@ -154,3 +154,136 @@ int sysfs_get_link(const char *path, char *target, size_t len)
 
 	return 0;
 }
+
+
+/**
+ * sysfs_del_name: free function for sysfs_open_subsystem_list
+ * @name: memory area to be freed
+ */ 
+void sysfs_del_name(void *name)
+{
+	free(name);
+}
+
+
+/**
+ * sysfs_close_list: generic list free routine
+ * @list: dlist to free
+ * Returns nothing
+ */
+void sysfs_close_list(struct dlist *list)
+{
+	if (list != NULL)
+		dlist_destroy(list);
+}
+
+/**
+ * sysfs_open_subsystem_list: gets a list of all supported "name" subsystem
+ * 	details from the system
+ * @name: name of the subsystem, eg., "bus", "class", "devices"
+ * Returns a dlist of supported names or NULL if subsystem not supported
+ */ 
+struct dlist *sysfs_open_subsystem_list(unsigned char *name)
+{
+	unsigned char sysfs_path[SYSFS_PATH_MAX], *subsys_name = NULL;
+	struct sysfs_directory *dir = NULL, *cur = NULL;
+	struct dlist *list = NULL;
+	
+	if (name == NULL)
+		return NULL;
+
+	if (sysfs_get_mnt_path(sysfs_path, SYSFS_PATH_MAX) != 0) {
+		dprintf("Error getting sysfs mount point\n");
+		return NULL;
+	}
+
+	strcat(sysfs_path, name);
+	dir = sysfs_open_directory(sysfs_path);
+	if (dir == NULL) {
+		dprintf("Error opening sysfs_directory at %s\n", sysfs_path);
+		return NULL;
+	}
+
+	if (sysfs_read_directory(dir) != 0) {
+		dprintf("Error reading sysfs_directory at %s\n", sysfs_path);
+		sysfs_close_directory(dir);
+		return NULL;
+	}
+
+	if (dir->subdirs != NULL) {
+		list = dlist_new_with_delete(SYSFS_NAME_LEN,
+				sysfs_del_name);
+		if (list == NULL) {
+			dprintf("Error creating list\n");
+			sysfs_close_directory(dir);
+			return NULL;
+		}
+
+		dlist_for_each_data(dir->subdirs, cur,
+				struct sysfs_directory) {
+			subsys_name = (char *)calloc(1, SYSFS_NAME_LEN);
+			strcpy(subsys_name, cur->name);
+			dlist_unshift(list, subsys_name);
+		}
+	}
+	sysfs_close_directory(dir);
+	return list;
+}
+
+
+/**
+ * sysfs_open_bus_devices_list: gets a list of all devices on "name" bus
+ * @name: name of the subsystem, eg., "pci", "scsi", "usb"
+ * Returns a dlist of supported names or NULL if subsystem not supported
+ */ 
+struct dlist *sysfs_open_bus_devices_list(unsigned char *name)
+{
+	unsigned char sysfs_path[SYSFS_PATH_MAX], *device_name = NULL;
+	struct sysfs_directory *dir = NULL;
+	struct sysfs_link *cur = NULL;
+	struct dlist *list = NULL;
+	
+	if (name == NULL)
+		return NULL;
+
+	if (sysfs_get_mnt_path(sysfs_path, SYSFS_PATH_MAX) != 0) {
+		dprintf("Error getting sysfs mount point\n");
+		return NULL;
+	}
+
+	strcat(sysfs_path, SYSFS_BUS_DIR);
+	strcat(sysfs_path, "/");
+	strcat(sysfs_path, name);
+	strcat(sysfs_path, SYSFS_DEVICES_DIR);
+	dir = sysfs_open_directory(sysfs_path);
+	if (dir == NULL) {
+		dprintf("Error opening sysfs_directory at %s\n", sysfs_path);
+		return NULL;
+	}
+
+	if (sysfs_read_directory(dir) != 0) {
+		dprintf("Error reading sysfs_directory at %s\n", sysfs_path);
+		sysfs_close_directory(dir);
+		return NULL;
+	}
+
+	if (dir->links != NULL) {
+		list = dlist_new_with_delete(SYSFS_NAME_LEN,
+				sysfs_del_name);
+		if (list == NULL) {
+			dprintf("Error creating list\n");
+			sysfs_close_directory(dir);
+			return NULL;
+		}
+
+		dlist_for_each_data(dir->links, cur,
+				struct sysfs_link) {
+			device_name = (char *)calloc(1, SYSFS_NAME_LEN);
+			strcpy(device_name, cur->name);
+			dlist_unshift(list, device_name);
+		}
+	}
+	sysfs_close_directory(dir);
+	return list;
+}
+