Changes for directory/attribute read optimization

6 files changed, 363 insertions, 219 deletions

diff --git a/ChangeLog b/ChangeLog
index 7c27d69..7969c4f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,4 +1,7 @@
 
+12/08/2003 - Daniel Stekloff <dsteklof@us.ibm.com>
+		* Patched code for directory/attribute read optimization
+
 12/05/2003 - Daniel Stekloff <dsteklof@us.ibm.com>
 		* Remove unused argument from sysfs_get_device_by_id()
 
diff --git a/lib/sysfs_bus.c b/lib/sysfs_bus.c
index 5ed3904..615407e 100644
--- a/lib/sysfs_bus.c
+++ b/lib/sysfs_bus.c
@@ -93,35 +93,6 @@ 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 unsigned char *buspath)
-{
-	struct sysfs_directory *busdir = NULL;
-
-	if (buspath == NULL) {
-		errno = EINVAL;
-		return NULL;
-	}
-
-	busdir = sysfs_open_directory(buspath);
-	if (busdir == NULL) {
-		dprintf("Error opening directory at path %s\n", buspath);
-		return NULL;
-	}
-	if ((sysfs_read_directory(busdir)) != 0) {
-		dprintf("Error reading bus dir %s\n", buspath);
-		sysfs_close_directory(busdir);
-		return NULL;
-	}
-	/* read in devices and drivers subdirs */
-	sysfs_read_all_subdirs(busdir);
-
-	return busdir;
-}
-
-/**
  * sysfs_get_bus_devices: gets all devices for bus
  * @bus: bus to get devices for
  * returns dlist of devices with success and NULL with failure
@@ -129,42 +100,40 @@ static struct sysfs_directory *open_bus_dir(const unsigned char *buspath)
 struct dlist *sysfs_get_bus_devices(struct sysfs_bus *bus)
 {
 	struct sysfs_device *bdev = NULL;
-	struct sysfs_directory *cur = NULL;
+	struct sysfs_directory *devdir = NULL;
 	struct sysfs_link *curl = NULL;
+	unsigned char path[SYSFS_PATH_MAX];
 
 	if (bus == NULL) {
 		errno = EINVAL;
 		return NULL;
 	}
-	if (bus->directory == NULL) {
-		bus->directory = open_bus_dir(bus->path);
-		if (bus->directory == NULL)
-			return NULL;
-	}
-	if (bus->directory->subdirs == NULL)
+	memset(path, 0, SYSFS_PATH_MAX);
+	strcpy(path, bus->path);
+	strcat(path, "/");
+	strcat(path, SYSFS_DEVICES_NAME);
+	devdir = sysfs_open_directory(path);
+	if (devdir == NULL) 
 		return NULL;
 
-	dlist_for_each_data(bus->directory->subdirs, cur, 
-			struct sysfs_directory) {
-		if (strcmp(cur->name, SYSFS_DEVICES_NAME) != 0)
-			continue;
-		if (cur->links == NULL)
+	if (sysfs_read_dir_links(devdir) != 0) {
+		sysfs_close_directory(devdir);
+		return NULL;
+	}
+
+	dlist_for_each_data(devdir->links, curl, struct sysfs_link) {
+		bdev = sysfs_open_device(curl->target);
+		if (bdev == NULL) {
+			dprintf("Error opening device at %s\n",	curl->target);
 			continue;
-		dlist_for_each_data(cur->links, curl, struct sysfs_link) {
-			bdev = sysfs_open_device(curl->target);
-			if (bdev == NULL) {
-				dprintf("Error opening device at %s\n",
-					curl->target);
-				continue;
-			}
-                        if (bus->devices == NULL)
-				bus->devices = dlist_new_with_delete
-					(sizeof(struct sysfs_device),
-						 	sysfs_close_dev);
-			dlist_unshift(bus->devices, bdev);
 		}
+		if (bus->devices == NULL)
+			bus->devices = dlist_new_with_delete
+				(sizeof(struct sysfs_device), sysfs_close_dev);
+		dlist_unshift(bus->devices, bdev);
 	}
-			
+	sysfs_close_directory(devdir);
+
 	return (bus->devices);
 }
 
@@ -176,42 +145,38 @@ struct dlist *sysfs_get_bus_devices(struct sysfs_bus *bus)
 struct dlist *sysfs_get_bus_drivers(struct sysfs_bus *bus)
 {
 	struct sysfs_driver *driver = NULL;
-	struct sysfs_directory *cur = NULL;
+	struct sysfs_directory *drvdir = NULL;
 	struct sysfs_directory *cursub = NULL;
+	unsigned char path[SYSFS_PATH_MAX];
 
 	if (bus == NULL) {
 		errno = EINVAL;
 		return NULL;
 	}
-	if (bus->directory == NULL) {
-		bus->directory = open_bus_dir(bus->path);
-		if (bus->directory == NULL) 
-			return NULL;
-	}
-	if (bus->directory->subdirs == NULL)
+	memset(path, 0, SYSFS_PATH_MAX);
+	strcpy(path, bus->path);
+	strcat(path, "/");
+	strcat(path, SYSFS_DRIVERS_NAME);
+	drvdir = sysfs_open_directory(path);
+	if (drvdir == NULL) 
 		return NULL;
 
-	dlist_for_each_data(bus->directory->subdirs, cur,
-			struct sysfs_directory) {
-		if (strcmp(cur->name, SYSFS_DRIVERS_NAME) != 0)
-			continue;
-		if (cur->subdirs == NULL)
+	if (sysfs_read_dir_subdirs(drvdir) != 0) {
+		sysfs_close_directory(drvdir);
+		return NULL;
+	}
+	dlist_for_each_data(drvdir->subdirs, cursub, struct sysfs_directory) {
+		driver = sysfs_open_driver(cursub->path);
+		if (driver == NULL) {
+			dprintf("Error opening driver at %s\n",	cursub->path);
 			continue;
-		dlist_for_each_data(cur->subdirs, cursub,
-				struct sysfs_directory) {
-			driver = sysfs_open_driver(cursub->path);
-			if (driver == NULL) {
-				dprintf("Error opening driver at %s\n",
-					cursub->path);
-				continue;
-			}
-                        if (bus->drivers == NULL)
-				bus->drivers = dlist_new_with_delete
-					(sizeof(struct sysfs_driver),
-					 		sysfs_close_drv);
-			dlist_unshift(bus->drivers, driver);
 		}
+		if (bus->drivers == NULL)
+			bus->drivers = dlist_new_with_delete
+				(sizeof(struct sysfs_driver), sysfs_close_drv);
+		dlist_unshift(bus->drivers, driver);
 	}
+	sysfs_close_directory(drvdir);
 	return (bus->drivers);
 }
 
@@ -378,6 +343,12 @@ struct dlist *sysfs_get_bus_attributes(struct sysfs_bus *bus)
 	if (bus->directory->attributes == NULL) {
 		if ((sysfs_read_dir_attributes(bus->directory)) != 0) 
 			return NULL;
+	} else {
+		if ((sysfs_refresh_attributes
+					(bus->directory->attributes)) != 0) {
+			dprintf("Error refreshing bus attributes\n");
+			return NULL;
+		}
 	}
 	return bus->directory->attributes;
 }
@@ -496,4 +467,3 @@ int sysfs_find_driver_bus(const unsigned char *driver, unsigned char *busname,
 	}
 	return -1;
 }
-					
diff --git a/lib/sysfs_class.c b/lib/sysfs_class.c
index 6501ac5..5d4da33 100644
--- a/lib/sysfs_class.c
+++ b/lib/sysfs_class.c
@@ -98,33 +98,6 @@ static struct sysfs_class *alloc_class(void)
 	return (struct sysfs_class *)calloc(1, sizeof(struct sysfs_class));
 }
 
-/**
- * open_class_dir: opens up sysfs class directory
- * returns sysfs_directory struct with success and NULL with error
- */
-static struct sysfs_directory *open_class_dir(const unsigned char *path)
-{
-	struct sysfs_directory *classdir = NULL;
-
-	if (path == NULL) {
-		errno = EINVAL;
-		return NULL;
-	}
-
-	classdir = sysfs_open_directory(path);
-	if (classdir == NULL) {
-		errno = EINVAL;
-		return NULL;
-	}
-	if ((sysfs_read_directory(classdir)) != 0) {
-		dprintf("Error reading class dir %s\n", path);
-		sysfs_close_directory(classdir);
-		return NULL;
-	}
-
-	return classdir;
-}
-
 /** 
  * set_classdev_classname: Grabs classname from path
  * @cdev: class device to set
@@ -206,13 +179,15 @@ struct dlist *sysfs_get_class_devices(struct sysfs_class *cls)
 		return NULL;
 	}
 	if (cls->directory == NULL) {
-		cls->directory = open_class_dir(cls->path);
+		cls->directory = sysfs_open_directory(cls->path);
 		if (cls->directory == NULL) 
 			return NULL;
 	}
-		
-	if (cls->directory->subdirs == NULL)
+
+	if ((sysfs_read_dir_subdirs(cls->directory) != 0) 
+	    || cls->directory->subdirs == NULL)
 		return NULL;
+
 	dlist_for_each_data(cls->directory->subdirs, cur, 
 			struct sysfs_directory) {
 		dev = sysfs_open_class_device(cur->path);
@@ -323,22 +298,20 @@ struct sysfs_device *sysfs_get_classdev_device
 		return (clsdev->sysdevice);
 	
 	if (clsdev->directory == NULL) {
-		clsdev->directory = open_class_dir(clsdev->path);
+		clsdev->directory = sysfs_open_directory(clsdev->path);
 		if (clsdev->directory == NULL)
 			return NULL;
 	}
-	if (clsdev->directory->links != NULL) {
-		devlink = sysfs_get_directory_link(clsdev->directory, "device");
-		if (devlink != NULL) {
-			clsdev->sysdevice = sysfs_open_device
-						(devlink->target);
-			if (clsdev->sysdevice == NULL)
-				return NULL;
-			if (clsdev->driver != NULL) 
-				strcpy(clsdev->sysdevice->driver_name,
-							clsdev->driver->name);
-		}
-	}
+	devlink = sysfs_get_directory_link(clsdev->directory, "device");
+	if (devlink == NULL) 
+		return NULL;
+
+	clsdev->sysdevice = sysfs_open_device(devlink->target);
+	if (clsdev->sysdevice == NULL)
+		return NULL;
+	if (clsdev->driver != NULL) 
+		strcpy(clsdev->sysdevice->driver_name, clsdev->driver->name);
+
 	return (clsdev->sysdevice);
 }
 				
@@ -363,19 +336,16 @@ struct sysfs_driver *sysfs_get_classdev_driver
 		return (clsdev->driver);
 	
 	if (clsdev->directory == NULL) {
-		clsdev->directory = open_class_dir(clsdev->path);
+		clsdev->directory = sysfs_open_directory(clsdev->path);
 		if (clsdev->directory == NULL)
 			return NULL;
 	}
-	if (clsdev->directory->links != NULL) {
-		drvlink = sysfs_get_directory_link(clsdev->directory, "driver");
-		if (drvlink != NULL) {
-			clsdev->driver = sysfs_open_driver
-						(drvlink->target);
-			if (clsdev->driver == NULL)
-				return NULL;
+	drvlink = sysfs_get_directory_link(clsdev->directory, "driver");
+	if (drvlink != NULL) {
+		clsdev->driver = sysfs_open_driver(drvlink->target);
+		if (clsdev->driver == NULL)
+			return NULL;
 			
-		}
 	}
 	return (clsdev->driver);
 }
@@ -557,11 +527,7 @@ struct dlist *sysfs_get_classdev_attributes(struct sysfs_class_device *cdev)
 		return NULL;
 
 	if (cdev->directory == NULL) {
-		/*
-		 * class devices have attributes in subdirs too.. so read
-		 * the directory before reading the attributes
-		 */ 
-		cdev->directory = open_class_dir(cdev->path);
+		cdev->directory = sysfs_open_directory(cdev->path);
 		if (cdev->directory == NULL) 
 			return NULL;
 	}
@@ -571,6 +537,12 @@ struct dlist *sysfs_get_classdev_attributes(struct sysfs_class_device *cdev)
 							cdev->directory->path);
 			return NULL;
 		}
+	} else {
+		if ((sysfs_refresh_attributes
+					(cdev->directory->attributes)) != 0) {
+			dprintf("Error refreshing classdev attributes\n");
+			return NULL;
+		}
 	}
 	return (cdev->directory->attributes);
 }
@@ -585,6 +557,7 @@ struct sysfs_attribute *sysfs_get_classdev_attr
 		(struct sysfs_class_device *clsdev, const unsigned char *name)
 {
 	struct sysfs_attribute *cur = NULL;
+	struct sysfs_directory *sdir = NULL;
 	struct dlist *attrlist = NULL;
 	
 	if (clsdev == NULL || name == NULL) {
@@ -593,19 +566,32 @@ struct sysfs_attribute *sysfs_get_classdev_attr
 	}
 	
 	if (clsdev->directory == NULL) {
-		/* 
-		 * Class devices can have attributes in their subdirs
-		 * and hence we read_directory here
-		 */ 
-		clsdev->directory = open_class_dir(clsdev->path);
+		clsdev->directory = sysfs_open_directory(clsdev->path);
 		if (clsdev->directory == NULL) 
 			return NULL;
 	}
+	/* 
+	 * First, see if it's in the current directory. Then look at 
+	 * subdirs since class devices can have subdirs of attributes.
+	 */ 
 	cur = sysfs_get_directory_attribute(clsdev->directory,
 						(unsigned char *)name);
 	if (cur != NULL)
 		return cur;
 
+	if (clsdev->directory->subdirs == NULL) 
+		if ((sysfs_read_dir_subdirs(clsdev->directory)) != 0 ||
+		    clsdev->directory->subdirs == NULL) 
+			return NULL;
+
+	dlist_for_each_data(clsdev->directory->subdirs, sdir,
+				struct sysfs_directory) {
+		cur = sysfs_get_directory_attribute(sdir, 
+						(unsigned char *)name);
+		if (cur != NULL)
+			return cur;
+	}
+		
 	return NULL;
 }
 
diff --git a/lib/sysfs_device.c b/lib/sysfs_device.c
index 91ce150..e5540dd 100644
--- a/lib/sysfs_device.c
+++ b/lib/sysfs_device.c
@@ -377,6 +377,12 @@ struct dlist *sysfs_get_device_attributes(struct sysfs_device *device)
 	if (device->directory->attributes == NULL) {
 		if ((sysfs_read_dir_attributes(device->directory)) != 0)
 			return NULL;
+	} else {
+		if ((sysfs_refresh_attributes
+				(device->directory->attributes)) != 0) {
+			dprintf("Error refreshing device attributes\n");
+			return NULL;
+		}
 	}
 	return (device->directory->attributes);
 }
diff --git a/lib/sysfs_dir.c b/lib/sysfs_dir.c
index f3c683d..7046d20 100644
--- a/lib/sysfs_dir.c
+++ b/lib/sysfs_dir.c
@@ -187,6 +187,13 @@ int sysfs_write_attribute(struct sysfs_attribute *sysattr,
 		return -1;
 	}
 	if (sysattr->method & SYSFS_METHOD_SHOW) {
+		/*
+		 * read attribute again to see if we can get an updated value 
+		 */
+		if ((sysfs_read_attribute(sysattr)) != 0) {
+			dprintf("Error reading attribute\n");
+			return -1;
+		}
 		if ((strncmp(sysattr->value, new_value, sysattr->len)) == 0) {
 			dprintf("Attribute %s already has the requested value %s\n",
 					sysattr->name, new_value);
@@ -284,6 +291,14 @@ int sysfs_read_attribute(struct sysfs_attribute *sysattr)
 		free(fbuf);
 		return -1;
 	}
+	if (sysattr->len > 0) {
+		if ((sysattr->len == length) && 
+				(!(strncmp(sysattr->value, fbuf, length)))) {
+			close(fd);
+			return 0;
+		}
+		free(sysattr->value);
+	}
 	sysattr->len = length;
 	close(fd);
 	vbuf = (unsigned char *)realloc(fbuf, length+1);
@@ -421,8 +436,10 @@ int sysfs_read_all_subdirs(struct sysfs_directory *sysdir)
 		errno = EINVAL;
 		return -1;
 	}
-	if (sysdir->subdirs == NULL)
-		return 0;
+	if (sysdir->subdirs == NULL) 
+		if ((sysfs_read_dir_subdirs(sysdir) != 0) 
+		    || 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",
@@ -491,6 +508,108 @@ struct sysfs_link *sysfs_open_link(const unsigned char *linkpath)
 }
 
 /**
+ * sysfs_refresh_attributes: Refresh attributes list
+ * @attrlist: list of attributes to refresh
+ * Returns 0 on success, 1 on failure
+ */
+int sysfs_refresh_attributes(struct dlist *attrlist)
+{
+	struct sysfs_attribute *attr = NULL;
+
+	if (attrlist == NULL) {
+		errno = EINVAL;
+		return 1;
+	}
+	dlist_for_each_data(attrlist, attr, struct sysfs_attribute) {
+		if (attr->method & SYSFS_METHOD_SHOW) {
+			if ((sysfs_read_attribute(attr)) != 0) {
+				dprintf("Error reading attribute %s\n", path);
+				return 1;
+			}
+		}
+	}
+	return 0;
+}
+
+/**
+ * add_attribute: open and add attribute at path to given directory
+ * @sysdir: directory to add attribute to
+ * @path: path to attribute
+ * returns 0 with success and -1 with error.
+ */
+static int add_attribute(struct sysfs_directory *sysdir, 
+					const unsigned char *path)
+{
+	struct sysfs_attribute *attr = NULL;
+
+	attr = sysfs_open_attribute(path);
+	if (attr == NULL) {
+		dprintf("Error opening attribute %s\n",	path);
+		return -1;
+	}
+	if (attr->method & SYSFS_METHOD_SHOW) {
+		if ((sysfs_read_attribute(attr)) != 0) {
+			dprintf("Error reading attribute %s\n",	path);
+			sysfs_close_attribute(attr);
+			return 0;
+		}
+	}
+			                        
+	if (sysdir->attributes == NULL) {
+		sysdir->attributes = dlist_new_with_delete
+			(sizeof(struct sysfs_attribute), sysfs_del_attribute);
+	}
+	dlist_unshift(sysdir->attributes, attr);
+
+	return 0;
+}
+
+/**
+ * add_subdirectory: open and add subdirectory at path to given directory
+ * @sysdir: directory to add subdir to
+ * @path: path to subdirectory
+ * returns 0 with success and -1 with error.
+ */
+static int add_subdirectory(struct sysfs_directory *sysdir, 
+					const unsigned char *path)
+{
+	struct sysfs_directory *subdir = NULL;
+
+	subdir = sysfs_open_directory(path);
+	if (subdir == NULL) {
+		dprintf("Error opening directory %s\n", path);
+		return -1;
+	}
+	if (sysdir->subdirs == NULL)
+		sysdir->subdirs = dlist_new_with_delete
+			(sizeof(struct sysfs_directory), sysfs_del_directory);
+	dlist_unshift(sysdir->subdirs, subdir);
+	return 0;
+}
+
+/**
+ * add_link: open and add link at path to given directory
+ * @sysdir: directory to add link to
+ * @path: path to link
+ * returns 0 with success and -1 with error.
+ */
+static int add_link(struct sysfs_directory *sysdir, const unsigned char *path)
+{
+	struct sysfs_link *ln = NULL;
+
+	ln = sysfs_open_link(path);
+	if (ln == NULL) {
+		dprintf("Error opening link %s\n", path);
+		return -1;
+	}
+	if (sysdir->links == NULL)
+		sysdir->links = dlist_new_with_delete
+				(sizeof(struct sysfs_link), sysfs_del_link);
+	dlist_unshift(sysdir->links, ln);
+	return 0;
+}
+
+/**
  * sysfs_read_dir_attributes: grabs attributes for the given directory
  * @sysdir: sysfs directory to open
  * returns 0 with success and -1 with error.
@@ -500,7 +619,6 @@ int sysfs_read_dir_attributes(struct sysfs_directory *sysdir)
 	DIR *dir = NULL;
 	struct dirent *dirent = NULL;
 	struct stat astats;
-	struct sysfs_attribute *attr = NULL;
 	unsigned char file_path[SYSFS_PATH_MAX];
 	int retval = 0;
 
@@ -526,29 +644,52 @@ int sysfs_read_dir_attributes(struct sysfs_directory *sysdir)
 			dprintf("stat failed\n");
 			continue;
 		}
-		if (S_ISREG(astats.st_mode)) {	
-			attr = sysfs_open_attribute(file_path);
-			if (attr == NULL) {
-				dprintf("Error opening attribute %s\n",
-					file_path);
-				retval = -1;
+		if (S_ISREG(astats.st_mode)) 
+			retval = add_attribute(sysdir, file_path);
+	}
+	closedir(dir);
+	return(retval);
+}
+
+/**
+ * sysfs_read_dir_links: grabs links in a specific directory
+ * @sysdir: sysfs directory to read links
+ * returns 0 with success and -1 with error.
+ */
+int sysfs_read_dir_links(struct sysfs_directory *sysdir)
+{
+	DIR *dir = NULL;
+	struct dirent *dirent = NULL;
+	struct stat astats;
+	unsigned char file_path[SYSFS_PATH_MAX];
+	int retval = 0;
+
+	if (sysdir == NULL) {
+		errno = EINVAL;
+		return -1;
+	}
+	dir = opendir(sysdir->path);
+	if (dir == NULL) {
+		dprintf("Error opening directory %s\n", sysdir->path);
+		return -1;
+	}
+	while(((dirent = readdir(dir)) != NULL) && retval == 0) {
+		if (0 == strcmp(dirent->d_name, "."))
+			 continue;
+		if (0 == strcmp(dirent->d_name, ".."))
+			continue;
+		memset(file_path, 0, SYSFS_PATH_MAX);
+		strncpy(file_path, sysdir->path, sizeof(file_path));
+		strncat(file_path, "/", sizeof(file_path));
+		strncat(file_path, dirent->d_name, sizeof(file_path));
+		if ((lstat(file_path, &astats)) != 0) {
+			dprintf("stat failed\n");
+			continue;
+		}
+		if (S_ISLNK(astats.st_mode)) {
+			retval = add_link(sysdir, file_path);
+			if (retval != 0)
 				break;
-			}
-			if (attr->method & SYSFS_METHOD_SHOW) {
-				if ((sysfs_read_attribute(attr)) != 0) {
-					dprintf("Error reading attribute %s\n",
-						file_path);
-					sysfs_close_attribute(attr);
-					continue;
-				}
-			}
-			                        
-			if (sysdir->attributes == NULL) {
-				sysdir->attributes = dlist_new_with_delete
-					(sizeof(struct sysfs_attribute),
-					 		sysfs_del_attribute);
-			}
-			dlist_unshift(sysdir->attributes, attr);
 		}
 	}
 	closedir(dir);
@@ -556,6 +697,48 @@ int sysfs_read_dir_attributes(struct sysfs_directory *sysdir)
 }
 
 /**
+ * sysfs_read_dir_subdirs: grabs subdirs in a specific directory
+ * @sysdir: sysfs directory to read links
+ * returns 0 with success and -1 with error.
+ */
+int sysfs_read_dir_subdirs(struct sysfs_directory *sysdir)
+{
+	DIR *dir = NULL;
+	struct dirent *dirent = NULL;
+	struct stat astats;
+	unsigned char file_path[SYSFS_PATH_MAX];
+	int retval = 0;
+
+	if (sysdir == NULL) {
+		errno = EINVAL;
+		return -1;
+	}
+	dir = opendir(sysdir->path);
+	if (dir == NULL) {
+		dprintf("Error opening directory %s\n", sysdir->path);
+		return -1;
+	}
+	while(((dirent = readdir(dir)) != NULL) && retval == 0) {
+		if (0 == strcmp(dirent->d_name, "."))
+			 continue;
+		if (0 == strcmp(dirent->d_name, ".."))
+			continue;
+		memset(file_path, 0, SYSFS_PATH_MAX);
+		strncpy(file_path, sysdir->path, sizeof(file_path));
+		strncat(file_path, "/", sizeof(file_path));
+		strncat(file_path, dirent->d_name, sizeof(file_path));
+		if ((lstat(file_path, &astats)) != 0) {
+			dprintf("stat failed\n");
+			continue;
+		}
+		if (S_ISDIR(astats.st_mode))
+			retval = add_subdirectory(sysdir, file_path);
+	}
+	closedir(dir);
+	return(retval);
+}
+
+/**
  * sysfs_read_directory: grabs attributes, links, and subdirectories
  * @sysdir: sysfs directory to open
  * returns 0 with success and -1 with error.
@@ -565,8 +748,6 @@ int sysfs_read_directory(struct sysfs_directory *sysdir)
 	DIR *dir = NULL;
 	struct dirent *dirent = NULL;
 	struct stat astats;
-	struct sysfs_attribute *attr = NULL;
-	struct sysfs_directory *subdir = NULL;
 	struct sysfs_link *ln = NULL;
 	unsigned char file_path[SYSFS_PATH_MAX];
 	int retval = 0;
@@ -593,39 +774,22 @@ int sysfs_read_directory(struct sysfs_directory *sysdir)
 			dprintf("stat failed\n");
 			continue;
 		}
-		if (S_ISDIR(astats.st_mode)) {	
-			subdir = sysfs_open_directory(file_path);
-			if (subdir == NULL) {
-				dprintf("Error opening directory %s\n",
-					file_path);
-				retval = -1;
-				break;
-			}
-			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)) {
-			ln = sysfs_open_link(file_path);
-			if (ln == NULL) {
-				dprintf("Error opening link %s\n", file_path);
-				retval = -1;
-				break;
-			}
-			if (sysdir->links == NULL)
-				sysdir->links = dlist_new_with_delete
-						(sizeof(struct sysfs_link),
-						 		sysfs_del_link);
-			dlist_unshift(sysdir->links, ln);
-		}
+		if (S_ISDIR(astats.st_mode)) 
+			retval = add_subdirectory(sysdir, file_path);
+
+		else if (S_ISLNK(astats.st_mode))
+			retval = add_link(sysdir, file_path);
+
+		else if (S_ISREG(astats.st_mode))
+			retval = add_attribute(sysdir, file_path);
 	}
 	closedir(dir);
 	return(retval);
 }
 
 /**
- * sysfs_get_directory_attribute: retrieves attribute attrname
+ * sysfs_get_directory_attribute: retrieves attribute attrname from current
+ *	directory only
  * @dir: directory to retrieve attribute from
  * @attrname: name of attribute to look for
  * returns sysfs_attribute if found and NULL if not found
@@ -633,7 +797,6 @@ int sysfs_read_directory(struct sysfs_directory *sysdir)
 struct sysfs_attribute *sysfs_get_directory_attribute
 			(struct sysfs_directory *dir, unsigned char *attrname)
 {
-	struct sysfs_directory *sdir = NULL;
 	struct sysfs_attribute *attr = NULL;
 	
 	if (dir == NULL || attrname == NULL) {
@@ -641,24 +804,22 @@ struct sysfs_attribute *sysfs_get_directory_attribute
 		return NULL;
 	}
 
-	if (dir->attributes == NULL) {
-		if ((sysfs_read_dir_attributes(dir)) != 0) 
+	if (dir->attributes == NULL) 
+		if ((sysfs_read_dir_attributes(dir) != 0) 
+		    || (dir->attributes == NULL))
 			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) {
-			attr = sysfs_get_directory_attribute(sdir, attrname);
-			if (attr != NULL)
-				return attr;
-		}
+			(dir->attributes, attrname, dir_attribute_name_equal);
+	if (attr != NULL) {
+		if ((sysfs_read_attribute(attr)) != 0) {
+			dprintf("Attribute at %s no longer exists?\n", 
+							attr->path);
+			return NULL;
+		} else
+			return attr;
 	}
+
 	return NULL;
 }
 
@@ -675,6 +836,10 @@ struct sysfs_link *sysfs_get_directory_link
 		errno = EINVAL;
 		return NULL;
 	}
+	if (dir->links == NULL)
+		if ((sysfs_read_dir_links(dir) != 0) || (dir->links == NULL))
+			return NULL;
+
 	return (struct sysfs_link *)dlist_find_custom(dir->links,
 		linkname, dir_link_name_equal);
 }
@@ -690,10 +855,15 @@ struct sysfs_directory *sysfs_get_subdirectory(struct sysfs_directory *dir,
 {
 	struct sysfs_directory *sub = NULL, *cursub = NULL;
 
-	if (dir == NULL || dir->subdirs == NULL || subname == NULL) {
+	if (dir == NULL || subname == NULL) {
 		errno = EINVAL;
 		return NULL;
 	}
+
+	if (dir->subdirs == NULL)
+		if (sysfs_read_dir_subdirs(dir) != 0)
+			return NULL;
+
 	sub = (struct sysfs_directory *)dlist_find_custom(dir->subdirs,
 		subname, dir_subdir_name_equal);
 	if (sub != NULL) 
@@ -702,8 +872,12 @@ struct sysfs_directory *sysfs_get_subdirectory(struct sysfs_directory *dir,
 	if (dir->subdirs != NULL) {
 		dlist_for_each_data(dir->subdirs, cursub, 
 					struct sysfs_directory) {
-			if (cursub->subdirs == NULL)
-				continue;
+			if (cursub->subdirs == NULL) {
+				if (sysfs_read_dir_subdirs(cursub) != 0)
+					continue;
+				if (cursub->subdirs == NULL)
+					continue;
+			}
 			sub = sysfs_get_subdirectory(cursub, subname);
 			if (sub != NULL)
 				return sub;
@@ -724,7 +898,7 @@ struct sysfs_link *sysfs_get_subdirectory_link(struct sysfs_directory *dir,
 	struct sysfs_directory *cursub = NULL;
 	struct sysfs_link *ln = NULL;
 
-	if (dir == NULL || dir->links == NULL || linkname == NULL) {
+	if (dir == NULL || linkname == NULL) {
 		errno = EINVAL;
 		return NULL;
 	}
@@ -733,14 +907,13 @@ struct sysfs_link *sysfs_get_subdirectory_link(struct sysfs_directory *dir,
 	if (ln != NULL)
 		return ln;
 
-	if (dir->subdirs == NULL)
-		return NULL;
+	if (dir->subdirs == NULL) 
+		if (sysfs_read_dir_subdirs(dir) != 0)
+			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;
diff --git a/lib/sysfs_driver.c b/lib/sysfs_driver.c
index 6857b6f..b243fc7 100644
--- a/lib/sysfs_driver.c
+++ b/lib/sysfs_driver.c
@@ -153,6 +153,12 @@ struct dlist *sysfs_get_driver_attributes(struct sysfs_driver *driver)
 			dprintf("Error reading driver attributes\n");
 			return NULL;
 		}
+	} else {
+		if ((sysfs_refresh_attributes
+				(driver->directory->attributes)) != 0) {
+			dprintf("Error refreshing driver attributes\n");
+			return NULL;
+		}
 	}
 	return(driver->directory->attributes);
 }