Postpone attr reads, remove getpagesize() usage, sysfs_driver.c cleanup

remove sysutils references

14 files changed, 291 insertions, 150 deletions

diff --git a/COPYING b/COPYING
index a8ad126..355916d 100644
--- a/COPYING
+++ b/COPYING
@@ -2,9 +2,9 @@
 The commands are licensed under the GNU General Public License (GPL)
 Version 2, June 1991. The full text of the GPL is located at:
 
-sysutils/cmd/GPL
+sysfsutils/cmd/GPL
 
 The sysfs library is licensed under the GNU Lesser Public License (LGPL)
 Version 2.1, February 1999. The full text of the LGPL is located at:
 
-sysutils/lib/LGPL
+sysfsutils/lib/LGPL
diff --git a/ChangeLog b/ChangeLog
index 3dedc31..47c35c1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,4 +1,11 @@
 
+11/24/2003 - Ananth Mavinakayanahalli <ananth@in.ibm.com>
+		* Removed getpagesize() usage (Dan)
+		* Added patch to postpone reading of attributes until 
+			absolutely necessary
+		* Cleaned up sysfs_driver.c
+		* Changed stale sysutils references to sysfsutils
+
 11/04/2003 - Ananth Mavinakayanahalli <ananth@in.ibm.com>
 		* Added code to consider "block" part of "class"
 		* Fixed systool to show driver details (if available)
diff --git a/README b/README
index a678a4e..6a33772 100644
--- a/README
+++ b/README
@@ -49,13 +49,13 @@ The commands are licensed under the GNU Public License (GPL) Version2,
 June 1991. The full text of the GPL is located in this package's "cmd"
 directory:
 
-sysutils/cmd/GPL
+sysfsutils/cmd/GPL
 
 The library is licensed under the GNU Lesser Public License (LGPL) 
 Version 2.1, February 1999. The full text of the LGPL is located in
 this package's "lib" directory:
 
-sysutils/lib/LGPL
+sysfsutils/lib/LGPL
 
 
 4. Reporting Bugs
diff --git a/cmd/lsbus.c b/cmd/lsbus.c
index 0c2e5ce..7082874 100644
--- a/cmd/lsbus.c
+++ b/cmd/lsbus.c
@@ -200,33 +200,35 @@ void print_device(struct sysfs_device *device)
 {
 	struct dlist *attributes = NULL;
 	unsigned int vendor_id, device_id;
-	unsigned char buf[128], *value = NULL;
+	unsigned char buf[128], path[SYSFS_PATH_MAX], value[256];
 	
 	if (device != NULL) {
-		if (!(strcmp(bus_to_print, "pci")))
+		if (!(strcmp(bus_to_print, "pci"))) {
 			fprintf(stdout, "  %s: ", device->bus_id);
-		else
+			memset(path, 0, SYSFS_PATH_MAX);
+			memset(value, 0, SYSFS_PATH_MAX);
+			strcpy(path, device->path);
+			strcat(path, "/config");
+			if ((sysfs_read_attribute_value(path,
+						value, 256)) == 0) {
+				vendor_id = get_pciconfig_word
+						(PCI_VENDOR_ID, value);
+				device_id = get_pciconfig_word
+						(PCI_DEVICE_ID, value);
+				fprintf(stdout, "%s\n",
+					pci_lookup_name(pacc, buf, 128,
+					PCI_LOOKUP_VENDOR | PCI_LOOKUP_DEVICE,
+					vendor_id, device_id, 0, 0));
+			} else
+				fprintf(stdout, "\n");
+		} else
 			fprintf(stdout, "  %s:\n", device->bus_id);
-		attributes = sysfs_get_device_attributes(device);
-		if (attributes != NULL) {
-			if (!(strcmp(bus_to_print, "pci"))) {
-				value = sysfs_get_value_from_attributes
-							(attributes, "config");
-				if (value != NULL) {
-					vendor_id = get_pciconfig_word
-							(PCI_VENDOR_ID, value);
-					device_id = get_pciconfig_word
-							(PCI_DEVICE_ID, value);
-					fprintf(stdout, "%s\n", 
-						pci_lookup_name(pacc, buf, 128,
-						 PCI_LOOKUP_VENDOR | 
-						 PCI_LOOKUP_DEVICE, 
-						 vendor_id, device_id, 0, 0));
-				}
-			}
-			if (show_options & (SHOW_ATTRIBUTES | 
-				SHOW_ATTRIBUTE_VALUE | SHOW_ALL_ATTRIB_VALUES))
-					print_device_attributes(attributes);
+
+		if (show_options & (SHOW_ATTRIBUTES | SHOW_ATTRIBUTE_VALUE |
+					SHOW_ALL_ATTRIB_VALUES)) {
+			attributes = sysfs_get_device_attributes(device);
+			if (attributes != NULL) 
+				print_device_attributes(attributes);
 		}
 		if (isalnum(device->driver_name[0])) 
 			fprintf (stdout, "\tDriver: %s\n\n", 
diff --git a/cmd/systool.c b/cmd/systool.c
index a2a6bbe..44dba5c 100644
--- a/cmd/systool.c
+++ b/cmd/systool.c
@@ -243,37 +243,36 @@ void show_device(struct sysfs_device *device, int level)
 {
 	struct dlist *attributes = NULL;
         unsigned int vendor_id, device_id;
-        unsigned char buf[128], *value = NULL;
+        unsigned char buf[128], value[256], path[SYSFS_PATH_MAX];
 	
 	if (device != NULL) {
 		indent(level);
-		if (show_bus != NULL && (!(strcmp(show_bus, "pci")))) 
+		if (show_bus != NULL && (!(strcmp(show_bus, "pci")))) {
 			fprintf(stdout, "%s: ", device->bus_id);
-		else
+			memset(path, 0, SYSFS_PATH_MAX);
+			memset(value, 0, SYSFS_PATH_MAX);
+			strcpy(path, device->path);
+			strcat(path, "/config");
+			if ((sysfs_read_attribute_value(path, 
+							value, 256)) == 0) {
+				vendor_id = get_pciconfig_word
+						(PCI_VENDOR_ID, value);
+				device_id = get_pciconfig_word
+						(PCI_DEVICE_ID, value);
+				fprintf(stdout, "%s\n",
+					pci_lookup_name(pacc, buf, 128,
+					PCI_LOOKUP_VENDOR | PCI_LOOKUP_DEVICE,
+						vendor_id, device_id, 0, 0));
+			} else 
+				fprintf(stdout, "\n");
+		} else 
 			fprintf(stdout, "%s\n", device->bus_id);
-		attributes = sysfs_get_device_attributes(device);
-		if (attributes != NULL) {
-			if (show_bus != NULL && (!(strcmp(show_bus, "pci")))) {
-                                value = sysfs_get_value_from_attributes
-							(attributes, "config");
-				if (value != NULL) {
-					vendor_id = get_pciconfig_word
-							(PCI_VENDOR_ID, value);
-					device_id = get_pciconfig_word
-							(PCI_DEVICE_ID, value);
-					fprintf(stdout, "%s\n",
-						pci_lookup_name(pacc, buf, 128,
-							PCI_LOOKUP_VENDOR |
-							PCI_LOOKUP_DEVICE,
-							vendor_id, device_id, 
-							0, 0));
-				}
-			}
-			if (show_options & (SHOW_ATTRIBUTES | 
-					SHOW_ATTRIBUTE_VALUE | 
+
+		if (show_options & (SHOW_ATTRIBUTES | SHOW_ATTRIBUTE_VALUE |
 					SHOW_ALL_ATTRIB_VALUES)) {
+			attributes = sysfs_get_device_attributes(device);
+			if (attributes != NULL) 
 				show_attributes(attributes, (level+4));
-			}
 		}
 		if (device->children != NULL)
 			show_device_children(device->children, (level+4));
@@ -281,7 +280,7 @@ void show_device(struct sysfs_device *device, int level)
 			indent(level+6);
 			fprintf (stdout, "Driver: %s\n", 
 						device->driver_name);
-		}
+		} 
 	}
 }
 
@@ -312,7 +311,7 @@ void show_driver_attributes(struct sysfs_driver *driver, int level)
 {
 	if (driver != NULL) {
 		struct dlist *attributes = NULL;
-		
+	
 		attributes = sysfs_get_driver_attributes(driver);
 		if (attributes != NULL) {
 			struct sysfs_attribute *cur = NULL;
diff --git a/include/libsysfs.h b/include/libsysfs.h
index f7e989e..70cd5e8 100644
--- a/include/libsysfs.h
+++ b/include/libsysfs.h
@@ -163,6 +163,7 @@ 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 unsigned char *path);
+extern int sysfs_read_dir_attributes(struct sysfs_directory *sysdir);
 extern int sysfs_read_directory(struct sysfs_directory *sysdir);
 extern int sysfs_read_all_subdirs(struct sysfs_directory *sysdir);
 extern struct sysfs_directory *sysfs_get_subdirectory
@@ -177,15 +178,16 @@ extern struct sysfs_attribute *sysfs_get_directory_attribute
 			(struct sysfs_directory *dir, unsigned char *attrname);
 
 /* sysfs driver access */
+extern void sysfs_close_bus_driver(struct sysfs_driver *driver);
+extern struct sysfs_driver *sysfs_open_bus_driver(const unsigned char *path);
 extern void sysfs_close_driver(struct sysfs_driver *driver);
 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 struct sysfs_device *sysfs_get_driver_device
+	(struct sysfs_driver *driver, const unsigned char *name);
 extern struct sysfs_attribute *sysfs_open_driver_attr(const unsigned char *bus, 
 		const unsigned char *drv, const unsigned char *attrib);
 
diff --git a/lib/sysfs.h b/lib/sysfs.h
index 0059995..e4c148c 100644
--- a/lib/sysfs.h
+++ b/lib/sysfs.h
@@ -36,7 +36,6 @@
 /* external library functions */
 extern int lstat(const char *file_name, struct stat *buf);
 extern int readlink(const char *path, char *buf, size_t bufsize);
-extern int getpagesize(void);
 extern int isascii(int c);
 
 /* Debugging */
diff --git a/lib/sysfs_bus.c b/lib/sysfs_bus.c
index 3111154..ec5a6f6 100644
--- a/lib/sysfs_bus.c
+++ b/lib/sysfs_bus.c
@@ -30,7 +30,7 @@ static void sysfs_close_dev(void *dev)
 
 static void sysfs_close_drv(void *drv)
 {
-        sysfs_close_driver((struct sysfs_driver *)drv);
+        sysfs_close_bus_driver((struct sysfs_driver *)drv);
 }
 
 /*
@@ -202,7 +202,7 @@ static int get_all_bus_drivers(struct sysfs_bus *bus)
 			continue;
 		dlist_for_each_data(cur->subdirs, cursub,
 				struct sysfs_directory) {
-			driver = sysfs_open_driver(cursub->path);
+			driver = sysfs_open_bus_driver(cursub->path);
 			if (driver == NULL) {
 				dprintf("Error opening driver at %s\n",
 					cursub->path);
@@ -362,6 +362,10 @@ struct dlist *sysfs_get_bus_attributes(struct sysfs_bus *bus)
 {
 	if (bus == NULL || bus->directory == NULL)
 		return NULL;
+	if (bus->directory->attributes == NULL) {
+		if ((sysfs_read_dir_attributes(bus->directory)) != 0) 
+			return NULL;
+	}
 	return bus->directory->attributes;
 }
 
@@ -379,6 +383,10 @@ struct sysfs_attribute *sysfs_get_bus_attribute(struct sysfs_bus *bus,
 		errno = EINVAL;
 		return NULL;
 	}
+	if (bus->directory->attributes == NULL) {
+		if ((sysfs_read_dir_attributes(bus->directory)) != 0) 
+			return NULL;
+	}
 	return sysfs_get_directory_attribute(bus->directory, attrname);
 }
 
diff --git a/lib/sysfs_class.c b/lib/sysfs_class.c
index d7521df..b57d8d7 100644
--- a/lib/sysfs_class.c
+++ b/lib/sysfs_class.c
@@ -236,7 +236,7 @@ struct sysfs_class_device *sysfs_open_class_device(const unsigned char *path)
 				}
 			} else if (strncmp(curl->name, 
 						SYSFS_DRIVERS_NAME, 6) == 0) {
-				drv = sysfs_open_driver(curl->target);
+				drv = sysfs_open_bus_driver(curl->target);
 				if (drv != NULL) {
 					cdev->driver = drv;
 					if (cdev->sysdevice != NULL) {
@@ -425,6 +425,10 @@ struct dlist *sysfs_get_classdev_attributes(struct sysfs_class_device *cdev)
 	if (cdev == NULL || cdev->directory == NULL)
 		return NULL;
 
+	if (cdev->directory->attributes == NULL) {
+		if ((sysfs_read_dir_attributes(cdev->directory)) != 0) 
+			return NULL;
+	}
 	return (cdev->directory->attributes);
 }
 
@@ -439,12 +443,14 @@ struct sysfs_attribute *sysfs_get_classdev_attr
 {
 	struct sysfs_attribute *cur = NULL;
 
-	if (clsdev == NULL || clsdev->directory == NULL ||
-		clsdev->directory->attributes == NULL || name == NULL) {
+	if (clsdev == NULL || clsdev->directory == NULL || name == NULL) {
 		errno = EINVAL;
 		return NULL;
 	}
-
+	if (clsdev->directory->attributes == NULL) {
+		if ((sysfs_read_dir_attributes(clsdev->directory)) != 0) 
+			return NULL;
+	}
 	cur = sysfs_get_directory_attribute(clsdev->directory,
 						(unsigned char *)name);
 	if (cur != NULL)
diff --git a/lib/sysfs_device.c b/lib/sysfs_device.c
index fbd046f..01a7fc1 100644
--- a/lib/sysfs_device.c
+++ b/lib/sysfs_device.c
@@ -165,12 +165,16 @@ struct sysfs_attribute *sysfs_get_device_attr(struct sysfs_device *dev,
 {
 	struct sysfs_attribute *cur = NULL;
 
-	if (dev == NULL || dev->directory == NULL 
-	    || dev->directory->attributes == NULL || name == NULL) {
+	if (dev == NULL || dev->directory == NULL || name == NULL) {
 		errno = EINVAL;
 		return NULL;
 	}
 	
+	if (dev->directory->attributes == NULL) {
+		if ((sysfs_read_dir_attributes(dev->directory)) != 0)
+			return NULL;
+	}
+
 	cur = sysfs_get_directory_attribute(dev->directory, 
 			(unsigned char *)name);
 	if (cur != NULL)
@@ -316,7 +320,7 @@ static struct sysfs_directory *open_root_device_dir(const unsigned char *name)
 			name);
 		return NULL;
 	}
-	if (sysfs_read_directory(rdir) != 0) {
+	if ((sysfs_read_directory(rdir)) != 0) {
 		dprintf ("Error reading %s root device at dir %s\n", name,
 			rootpath);
 		sysfs_close_directory(rdir);
@@ -409,6 +413,10 @@ struct dlist *sysfs_get_device_attributes(struct sysfs_device *device)
 	if (device == NULL || device->directory == NULL) 
 		return NULL;
 
+	if (device->directory->attributes == NULL) {
+		if ((sysfs_read_dir_attributes(device->directory)) != 0)
+			return NULL;
+	}
 	return (device->directory->attributes);
 }
 
diff --git a/lib/sysfs_dir.c b/lib/sysfs_dir.c
index ff2edf4..fabb695 100644
--- a/lib/sysfs_dir.c
+++ b/lib/sysfs_dir.c
@@ -254,7 +254,7 @@ int sysfs_read_attribute(struct sysfs_attribute *sysattr)
 	unsigned char *fbuf = NULL;
 	unsigned char *vbuf = NULL;
 	size_t length = 0;
-	int pgsize = 0;
+	long pgsize = 0;
 	int fd;
 
 	if (sysattr == NULL) {
@@ -266,7 +266,7 @@ int sysfs_read_attribute(struct sysfs_attribute *sysattr)
 			sysattr->path);
 		return -1;
 	}
-	pgsize = getpagesize();
+	pgsize = sysconf(_SC_PAGESIZE);
 	fbuf = (unsigned char *)calloc(1, pgsize+1);
 	if (fbuf == NULL) {
 		dprintf("calloc failed\n");
@@ -423,7 +423,7 @@ int sysfs_read_all_subdirs(struct sysfs_directory *sysdir)
 	if (sysdir->subdirs == NULL)
 		return 0;
 	dlist_for_each_data(sysdir->subdirs, cursub, struct sysfs_directory) {
-		if (sysfs_read_directory(cursub) != 0) 
+		if ((sysfs_read_directory(cursub)) != 0) 
 			dprintf ("Error reading subdirectory %s\n",
 				cursub->name);
 	}
@@ -490,18 +490,16 @@ struct sysfs_link *sysfs_open_link(const unsigned char *linkpath)
 }
 
 /**
- * sysfs_read_directory: grabs attributes, links, and subdirectories
+ * sysfs_read_dir_attributes: grabs attributes for the given directory
  * @sysdir: sysfs directory to open
  * returns 0 with success and -1 with error.
  */
-int sysfs_read_directory(struct sysfs_directory *sysdir)
+int sysfs_read_dir_attributes(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;
 
@@ -550,7 +548,51 @@ int sysfs_read_directory(struct sysfs_directory *sysdir)
 					 		sysfs_del_attribute);
 			}
 			dlist_unshift(sysdir->attributes, attr);
-		} else if (S_ISDIR(astats.st_mode)) {
+		}
+	}
+	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.
+ */
+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;
+
+	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)) {	
 			subdir = sysfs_open_directory(file_path);
 			if (subdir == NULL) {
 				dprintf("Error opening directory %s\n",
@@ -597,17 +639,20 @@ struct sysfs_attribute *sysfs_get_directory_attribute
 		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->attributes == NULL) {
+		if ((sysfs_read_dir_attributes(dir)) != 0) {
+			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;
diff --git a/lib/sysfs_driver.c b/lib/sysfs_driver.c
index 0011177..15eb239 100644
--- a/lib/sysfs_driver.c
+++ b/lib/sysfs_driver.c
@@ -23,17 +23,17 @@
 #include "libsysfs.h"
 #include "sysfs.h"
 
-static void sysfs_close_driver_by_name_dev(void *device)
+static void sysfs_close_driver_device(void *device)
 {
 	sysfs_close_device((struct sysfs_device *)device);
 }
 
 /**
- * sysfs_close_driver: closes and cleans up driver structure
+ * sysfs_close_bus_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)
+void sysfs_close_bus_driver(struct sysfs_driver *driver)
 {
 	if (driver != NULL) {
 		if (driver->devices != NULL) {
@@ -49,10 +49,10 @@ void sysfs_close_driver(struct sysfs_driver *driver)
 }
 
 /** 
- * sysfs_close_driver_by_name: closes driver and deletes device lists too
+ * sysfs_close_driver: closes driver and deletes device lists too
  * @driver: driver to close
  */ 
-void sysfs_close_driver_by_name(struct sysfs_driver *driver)
+void sysfs_close_driver(struct sysfs_driver *driver)
 {
 	if (driver != NULL) {
 		if (driver->devices != NULL) 
@@ -73,11 +73,11 @@ static struct sysfs_driver *alloc_driver(void)
 }
 
 /**
- * sysfs_open_driver: opens and initializes driver structure
+ * sysfs_open_bus_driver: opens and initializes driver structure
  * @path: path to driver directory
  * returns struct sysfs_driver with success and NULL with error
  */
-struct sysfs_driver *sysfs_open_driver(const unsigned char *path)
+struct sysfs_driver *sysfs_open_bus_driver(const unsigned char *path)
 {
 	struct sysfs_driver *driver = NULL;
 	struct sysfs_directory *sdir = NULL;
@@ -120,6 +120,10 @@ struct dlist *sysfs_get_driver_attributes(struct sysfs_driver *driver)
 	if (driver == NULL || driver->directory == NULL)
 		return NULL;
 
+	if (driver->directory->attributes == NULL) {
+		if ((sysfs_read_dir_attributes(driver->directory)) != 0)
+			return NULL;
+	}
 	return(driver->directory->attributes);
 }
 
@@ -134,12 +138,15 @@ struct sysfs_attribute *sysfs_get_driver_attr(struct sysfs_driver *drv,
 {
 	struct sysfs_attribute *cur = NULL;
 
-        if (drv == NULL || drv->directory == NULL
-            || drv->directory->attributes == NULL || name == NULL) {
+        if (drv == NULL || drv->directory == NULL || name == NULL) {
                 errno = EINVAL;
                 return NULL;
         }
 
+	if (drv->directory->attributes == NULL) {
+		if ((sysfs_read_dir_attributes(drv->directory)) != 0)
+			return NULL;
+	}
         cur = sysfs_get_directory_attribute(drv->directory,
 		                        (unsigned char *)name);
         if (cur != NULL)
@@ -162,91 +169,137 @@ struct dlist *sysfs_get_driver_links(struct sysfs_driver *driver)
 	return(driver->directory->links);
 }
 
+
 /**
- * get_driver_path: looks up the bus the driver is on and builds path to
- * 		the driver.
- * @bus: bus on which to search
- * @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 *bus, const unsigned char *drv, 
-				unsigned char *path, size_t psize)
+ * sysfs_open_driver_devices: open up the list of devices this driver supports
+ * @driver: sysfs_driver for which devices are needed
+ * Returns 0 on SUCCESS or -1 with ERROR
+ */ 
+static int sysfs_open_driver_devices(struct sysfs_driver *driver)
 {
-	if (bus == NULL || drv == NULL || path == NULL) {
+	struct sysfs_link *curlink = NULL;
+	struct sysfs_device *device = NULL;
+
+	if (driver == NULL) {
 		errno = EINVAL;
 		return -1;
 	}
-	if (sysfs_get_mnt_path(path, psize) != 0) {
-		dprintf("Error getting sysfs mount path\n");
-		return -1;
+	
+	if (driver->devices != NULL)
+		return 0;
+	
+	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);
+				return -1;
+			}
+			strcpy(device->driver_name, driver->name);
+			if (driver->devices == NULL) 
+				driver->devices = dlist_new_with_delete
+						(sizeof(struct sysfs_device),
+						 sysfs_close_driver_device);
+			dlist_unshift(driver->devices, device);
+		}
 	}
-	strcat(path, SYSFS_BUS_DIR);
-	strcat(path, "/");
-	strcat(path, bus);
-	strcat(path, SYSFS_DRIVERS_DIR);
-	strcat(path, "/");
-	strcat(path, drv);
 	return 0;
 }
-
 /**
- * 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
+ * sysfs_open_driver: open a driver given its path
+ * @path: path to driver to open
  * 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
+ * 1. Need to call sysfs_close_driver to free up memory
  */
-struct sysfs_driver *sysfs_open_driver_by_name(const unsigned char *drv_name,
-				const unsigned char *bus, size_t bsize)
+struct sysfs_driver *sysfs_open_driver(const unsigned char *path)
 {
 	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) {
+	if (path == NULL) {
 		errno = EINVAL;
 		return NULL;
 	}
 
-	memset(path, 0, SYSFS_PATH_MAX);
-	if (get_driver_path(bus, drv_name, path, SYSFS_PATH_MAX) != 0) {
-		dprintf("Error getting to driver %s\n", drv_name);
-		return NULL;
-	}
-	driver = sysfs_open_driver(path);
+	driver = sysfs_open_bus_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);
+		if ((sysfs_open_driver_devices(driver)) != 0) {
+			dprintf("Error reading driver devices\n");
+			sysfs_close_driver(driver);
+			return NULL;
+		}
+	}
+	return driver;
+}
+
+/**
+ * sysfs_get_driver_device: looks up a device from a list of driver's devices
+ * 	and returns its sysfs_device corresponding to it
+ * @driver: sysfs_driver on which to search
+ * @name: name of the device to search
+ * Returns a sysfs_device if found, NULL otherwise
+ */
+struct sysfs_device *sysfs_get_driver_device(struct sysfs_driver *driver,
+				const unsigned char *name)
+{
+	struct sysfs_device *device = NULL;
+
+	if (driver == NULL || name == NULL) {
+		errno = EINVAL;
+		return NULL;
+	}
+
+	if (driver->devices == NULL) {
+		if (driver->directory->links == NULL) {
+			return NULL;
+		} else {
+			if ((sysfs_open_driver_devices(driver)) != 0) {
+				dprintf("Error getting driver devices\n");
 				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;
+	dlist_for_each_data(driver->devices, device, struct sysfs_device) {
+		if (!(strncmp(device->name, name, SYSFS_NAME_LEN)))
+			return device;
+	}
+	return NULL;
 }
 
+/**
+ * get_driver_path: looks up the bus the driver is on and builds path to
+ * 		the driver.
+ * @bus: bus on which to search
+ * @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 *bus, 
+		const unsigned char *drv, unsigned char *path, size_t psize)
+{
+	if (bus == NULL || drv == NULL || path == NULL) {
+		errno = EINVAL;
+		return -1;
+	}
+	if (sysfs_get_mnt_path(path, psize) != 0) {
+		dprintf("Error getting sysfs mount path\n");
+		return -1;
+	}
+	strcat(path, SYSFS_BUS_DIR);
+	strcat(path, "/");
+	strcat(path, bus);
+	strcat(path, SYSFS_DRIVERS_DIR);
+	strcat(path, "/");
+	strcat(path, drv);
+	return 0;
+}
 
 /**
  * sysfs_open_driver_attr: read the user supplied driver attribute
diff --git a/lib/sysfs_utils.c b/lib/sysfs_utils.c
index 7563dff..ede4058 100644
--- a/lib/sysfs_utils.c
+++ b/lib/sysfs_utils.c
@@ -225,7 +225,7 @@ struct dlist *sysfs_open_subsystem_list(unsigned char *name)
 		return NULL;
 	}
 
-	if (sysfs_read_directory(dir) != 0) {
+	if ((sysfs_read_directory(dir)) != 0) {
 		dprintf("Error reading sysfs_directory at %s\n", sysfs_path);
 		sysfs_close_directory(dir);
 		return NULL;
@@ -303,7 +303,7 @@ struct dlist *sysfs_open_bus_devices_list(unsigned char *name)
 		return NULL;
 	}
 
-	if (sysfs_read_directory(dir) != 0) {
+	if ((sysfs_read_directory(dir)) != 0) {
 		dprintf("Error reading sysfs_directory at %s\n", sysfs_path);
 		sysfs_close_directory(dir);
 		return NULL;
diff --git a/test/get_driver.c b/test/get_driver.c
index 8628486..107c9bf 100644
--- a/test/get_driver.c
+++ b/test/get_driver.c
@@ -32,7 +32,7 @@ void print_usage(void)
 
 int main(int argc, char *argv[])
 {
-	char *bus = NULL;
+	char *bus = NULL, path[SYSFS_PATH_MAX];
 	struct sysfs_driver *driver = NULL;
 	struct sysfs_device *device = NULL;
 
@@ -41,6 +41,7 @@ int main(int argc, char *argv[])
 		return 1;
 	}
 
+	memset(path, 0, SYSFS_PATH_MAX);
 	bus = (char *)calloc(1, SYSFS_NAME_LEN);
 	if ((sysfs_find_driver_bus(argv[1], bus, SYSFS_NAME_LEN)) < 0) {
 		fprintf(stdout, "Driver %s not found\n", argv[1]);
@@ -48,7 +49,18 @@ int main(int argc, char *argv[])
 		return 1;
 	}
 	fprintf(stdout, "Driver %s is a member of bus %s\n", argv[1], bus);
-	driver = sysfs_open_driver_by_name(argv[1], bus, SYSFS_NAME_LEN);
+	
+	if ((sysfs_get_mnt_path(path, SYSFS_PATH_MAX)) != 0) {
+		fprintf(stdout, "Sysfs not mounted?\n");
+		return 1;
+	}
+	strcat(path, SYSFS_BUS_DIR);
+	strcat(path, "/");
+	strcat(path, bus);
+	strcat(path, SYSFS_DRIVERS_DIR);
+	strcat(path, "/");
+	strcat(path, argv[1]);
+	driver = sysfs_open_driver(path);
 	if (driver == NULL) {
 		fprintf(stdout, "Device %s not found\n", argv[1]);
 		free(bus);
@@ -61,7 +73,7 @@ int main(int argc, char *argv[])
 	} else 
 		fprintf(stdout, "%s is presently not used by any device\n", argv[1]);
 	
-	sysfs_close_driver_by_name(driver);
+	sysfs_close_driver(driver);
 	free(bus);
 	return 0;
 }