Install headers, add read_attr routines, fix bugs in sysfs_dir.c

8 files changed, 394 insertions, 73 deletions

diff --git a/ChangeLog b/ChangeLog
index b737a14..a034368 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,6 +1,14 @@
 
+10/20/2003 - Ananth Mavinakayanahalli <ananth@in.ibm.com>
+		* Added code to install header files (from include dir)
+			to /usr/local/include/ directory
+		* Added "read_attr" functions for device, driver and
+			class; simplified "write_attr" handling
+		* Made sysfs_get_directory_attribute() recurse subdirs
+		* Fixed potential bugs in sysfs_dir.c
+
 10/17/2003 - Daniel Stekloff <dsteklof@us.ibm.com>
-		* Add "path" to device in sysfs_device structure
+		* Added "path" to device in sysfs_device structure
 
 10/15/2003 - Ananth Mavinakayanahalli <ananth@in.ibm.com>
 		* Fixed bug in sysfs_block.c (initrd)
diff --git a/Makefile.am b/Makefile.am
index ead8a23..b48ca6d 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -1,5 +1,6 @@
 EXTRA_DIST = docs include
 SUBDIRS = lib cmd test
+include_HEADERS = include/libsysfs.h include/dlist.h
 
 dist-hook:
 	rm -rf `find $(distdir)/docs -name CVS`
diff --git a/Makefile.in b/Makefile.in
index 5382b28..0510d3e 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -85,21 +85,24 @@ am__quote = @am__quote@
 install_sh = @install_sh@
 EXTRA_DIST = docs include
 SUBDIRS = lib cmd test
+include_HEADERS = include/libsysfs.h include/dlist.h
 subdir = .
 ACLOCAL_M4 = $(top_srcdir)/aclocal.m4
 mkinstalldirs = $(SHELL) $(top_srcdir)/mkinstalldirs
 CONFIG_HEADER = config.h
 CONFIG_CLEAN_FILES =
 DIST_SOURCES =
+HEADERS = $(include_HEADERS)
+
 
 RECURSIVE_TARGETS = info-recursive dvi-recursive install-info-recursive \
 	uninstall-info-recursive all-recursive install-data-recursive \
 	install-exec-recursive installdirs-recursive install-recursive \
 	uninstall-recursive check-recursive installcheck-recursive
-DIST_COMMON = README AUTHORS COPYING ChangeLog INSTALL Makefile.am \
-	Makefile.in NEWS TODO aclocal.m4 config.guess config.h.in \
-	config.sub configure configure.ac depcomp install-sh ltmain.sh \
-	missing mkinstalldirs
+DIST_COMMON = README $(include_HEADERS) AUTHORS COPYING ChangeLog \
+	INSTALL Makefile.am Makefile.in NEWS TODO aclocal.m4 \
+	config.guess config.h.in config.sub configure configure.ac \
+	depcomp install-sh ltmain.sh missing mkinstalldirs
 DIST_SUBDIRS = $(SUBDIRS)
 all: config.h
 	$(MAKE) $(AM_MAKEFLAGS) all-recursive
@@ -148,6 +151,24 @@ clean-libtool:
 distclean-libtool:
 	-rm -f libtool
 uninstall-info-am:
+includeHEADERS_INSTALL = $(INSTALL_HEADER)
+install-includeHEADERS: $(include_HEADERS)
+	@$(NORMAL_INSTALL)
+	$(mkinstalldirs) $(DESTDIR)$(includedir)
+	@list='$(include_HEADERS)'; for p in $$list; do \
+	  if test -f "$$p"; then d=; else d="$(srcdir)/"; fi; \
+	  f="`echo $$p | sed -e 's|^.*/||'`"; \
+	  echo " $(includeHEADERS_INSTALL) $$d$$p $(DESTDIR)$(includedir)/$$f"; \
+	  $(includeHEADERS_INSTALL) $$d$$p $(DESTDIR)$(includedir)/$$f; \
+	done
+
+uninstall-includeHEADERS:
+	@$(NORMAL_UNINSTALL)
+	@list='$(include_HEADERS)'; for p in $$list; do \
+	  f="`echo $$p | sed -e 's|^.*/||'`"; \
+	  echo " rm -f $(DESTDIR)$(includedir)/$$f"; \
+	  rm -f $(DESTDIR)$(includedir)/$$f; \
+	done
 
 # This directory's subdirectories are mostly independent; you can cd
 # into them and run `make' without going through this Makefile.
@@ -260,6 +281,7 @@ distcleancheck_listfiles = find . -type f -print
 distdir: $(DISTFILES)
 	$(am__remove_distdir)
 	mkdir $(distdir)
+	$(mkinstalldirs) $(distdir)/include
 	@list='$(DISTFILES)'; for file in $$list; do \
 	  if test -f $$file || test -d $$file; then d=.; else d=$(srcdir); fi; \
 	  dir=`echo "$$file" | sed -e 's,/[^/]*$$,,'`; \
@@ -350,9 +372,10 @@ distcleancheck: distclean
 	       exit 1; } >&2
 check-am: all-am
 check: check-recursive
-all-am: Makefile config.h
+all-am: Makefile $(HEADERS) config.h
 installdirs: installdirs-recursive
 installdirs-am:
+	$(mkinstalldirs) $(DESTDIR)$(includedir)
 
 install: install-recursive
 install-exec: install-exec-recursive
@@ -395,7 +418,7 @@ info: info-recursive
 
 info-am:
 
-install-data-am:
+install-data-am: install-includeHEADERS
 
 install-exec-am:
 
@@ -414,7 +437,7 @@ mostlyclean: mostlyclean-recursive
 
 mostlyclean-am: mostlyclean-generic mostlyclean-libtool
 
-uninstall-am: uninstall-info-am
+uninstall-am: uninstall-includeHEADERS uninstall-info-am
 
 uninstall-info: uninstall-info-recursive
 
@@ -425,14 +448,15 @@ uninstall-info: uninstall-info-recursive
 	distcleancheck distdir dvi dvi-am dvi-recursive info info-am \
 	info-recursive install install-am install-data install-data-am \
 	install-data-recursive install-exec install-exec-am \
-	install-exec-recursive install-info install-info-am \
-	install-info-recursive install-man install-recursive \
-	install-strip installcheck installcheck-am installdirs \
-	installdirs-am installdirs-recursive maintainer-clean \
-	maintainer-clean-generic maintainer-clean-recursive mostlyclean \
-	mostlyclean-generic mostlyclean-libtool mostlyclean-recursive \
-	tags tags-recursive uninstall uninstall-am uninstall-info-am \
-	uninstall-info-recursive uninstall-recursive
+	install-exec-recursive install-includeHEADERS install-info \
+	install-info-am install-info-recursive install-man \
+	install-recursive install-strip installcheck installcheck-am \
+	installdirs installdirs-am installdirs-recursive \
+	maintainer-clean maintainer-clean-generic \
+	maintainer-clean-recursive mostlyclean mostlyclean-generic \
+	mostlyclean-libtool mostlyclean-recursive tags tags-recursive \
+	uninstall uninstall-am uninstall-includeHEADERS \
+	uninstall-info-am uninstall-info-recursive uninstall-recursive
 
 
 dist-hook:
diff --git a/include/libsysfs.h b/include/libsysfs.h
index 819959e..980d91b 100644
--- a/include/libsysfs.h
+++ b/include/libsysfs.h
@@ -203,6 +203,8 @@ 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);
@@ -217,6 +219,8 @@ 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);
@@ -253,6 +257,8 @@ 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);
 
 /* generic sysfs block access */
 extern void sysfs_close_block_device(struct sysfs_block_device *block);
diff --git a/lib/sysfs_class.c b/lib/sysfs_class.c
index 37c5243..cb6ca9d 100644
--- a/lib/sysfs_class.c
+++ b/lib/sysfs_class.c
@@ -413,7 +413,7 @@ int sysfs_find_device_class(const unsigned char *bus_id,
  * @name: attribute name to get
  * returns sysfs_attribute reference with success or NULL with error
  */
-struct sysfs_attribute *sysfs_get_classdev_attribute
+struct sysfs_attribute *sysfs_get_classdev_attr
 		(struct sysfs_class_device *clsdev, const unsigned char *name)
 {
 	struct sysfs_attribute *cur = NULL;
@@ -438,6 +438,7 @@ struct sysfs_attribute *sysfs_get_classdev_attribute
  * @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,
@@ -478,3 +479,53 @@ int sysfs_write_classdev_attr(unsigned char *dev, unsigned char *attrib,
 	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/lib/sysfs_device.c b/lib/sysfs_device.c
index 635ba64..89704dc 100644
--- a/lib/sysfs_device.c
+++ b/lib/sysfs_device.c
@@ -388,6 +388,51 @@ struct sysfs_device *sysfs_open_device_by_id(const unsigned char *bus_id,
 }
 
 /**
+ * get_device_absolute_path: looks up the bus the device is on, gets 
+ * 		absolute path to the device
+ * @device: device for which path is needed
+ * @path: buffer to store absolute path
+ * @psize: size of "path"
+ * Returns 0 on success -1 on failure
+ */
+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
@@ -398,38 +443,96 @@ struct sysfs_device *sysfs_open_device_by_id(const unsigned char *bus_id,
 int sysfs_write_device_attr(unsigned char *dev, unsigned char *attrib,
 					unsigned char *value, size_t len)
 {
-	struct sysfs_device *device = NULL;
 	struct sysfs_attribute *attribute = NULL;
-	unsigned char bus_name[SYSFS_NAME_LEN];
+	unsigned char devpath[SYSFS_PATH_MAX];
 
 	if (dev == NULL || attrib == NULL || value == NULL) {
 		errno = EINVAL;
 		return -1;
 	}
 	
-	memset(bus_name, 0, SYSFS_NAME_LEN);
-	if ((sysfs_find_device_bus(dev, bus_name, SYSFS_NAME_LEN)) != 0) {
-		dprintf("Device %s not found\n", dev);
+	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;
 	}
-	device = sysfs_open_device_by_id(dev, bus_name, SYSFS_NAME_LEN);
-	if (device == NULL) {
-		dprintf("Error opening device %s\n", dev);
-		return -1;
-	}
-	attribute = sysfs_get_directory_attribute(device->directory, attrib);
+	strcat(devpath, "/");
+	strcat(devpath, attrib);
+	attribute = sysfs_open_attribute(devpath);
 	if (attribute == NULL) {
-		dprintf("Attribute %s not defined for device %s\n",
+		dprintf("Attribute %s could not be retrieved for device %s\n",
 				attrib, dev);
-		sysfs_close_device(device);
 		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;
+		}
+	}
 	if ((sysfs_write_attribute(attribute, value, len)) < 0) {
 		dprintf("Error setting %s to %s\n", attrib, value);
-		sysfs_close_device(device);
+		sysfs_close_attribute(attribute);
 		return -1;
 	}
-	sysfs_close_device(device);
+	sysfs_close_attribute(attribute);
 	return 0;
 }
+
+/**
+ * sysfs_read_device_attr: read an attribute of the given device
+ * @dev: device bus_id for which attribute has to be changed
+ * @attrib: attribute to read
+ * @value: buffer to return value in
+ * @len: size of buffer available
+ * Returns 0 on success -1 on error
+ */ 
+int sysfs_read_device_attr(unsigned char *dev, unsigned char *attrib,
+					unsigned char *value, size_t len)
+{
+	struct sysfs_attribute *attribute = NULL;
+	unsigned char devpath[SYSFS_PATH_MAX];
+
+	if (dev == NULL || attrib == NULL || value == NULL) {
+		errno = EINVAL;
+		return -1;
+	}
 	
+	memset(devpath, 0, SYSFS_PATH_MAX);
+	if ((get_device_absolute_path(dev, devpath, SYSFS_PATH_MAX)) != 0) {
+		dprintf("Error finding absolute path to device %s\n", dev);
+		return -1;
+	}
+	strcat(devpath, "/");
+	strcat(devpath, attrib);
+	attribute = sysfs_open_attribute(devpath);
+	if (attribute == NULL) {
+		dprintf("Error opening attribute %s for device %s\n",
+				attrib, dev);
+		return -1;
+	}
+	if (!(attribute->method & SYSFS_METHOD_SHOW)) {
+		dprintf("Show method not supported for attribute %s\n",
+				attrib);
+		sysfs_close_attribute(attribute);
+		return -1;
+	}
+	if ((sysfs_read_attribute(attribute)) != 0) {
+		dprintf("Error reading attribute %s for device %s\n",
+				attrib, dev);
+		sysfs_close_attribute(attribute);
+		return -1;
+	}
+	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/lib/sysfs_dir.c b/lib/sysfs_dir.c
index 77375f0..ff2edf4 100644
--- a/lib/sysfs_dir.c
+++ b/lib/sysfs_dir.c
@@ -149,8 +149,10 @@ struct sysfs_attribute *sysfs_open_attribute(const unsigned char *path)
 	}
 	strncpy(sysattr->path, path, sizeof(sysattr->path));
 	if ((stat(sysattr->path, &fileinfo)) != 0) {
-		dprintf("stat failed\n");
+		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;
@@ -211,24 +213,30 @@ int sysfs_write_attribute(struct sysfs_attribute *sysattr,
 					len, sysattr->name);
 		/* 
 		 * since we could not write user supplied number of bytes,
-		 * restore the old value
+		 * restore the old value if one available
 		 */
-		length = write(fd, sysattr->value, sysattr->len);
-		close(fd);
-		return -1;
+		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
+	 * in sysfs_attribute. Verify first if the attribute supports reading
+	 * (show method). If it does not, do not bother
 	 */ 
-	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);
+	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);	
@@ -582,12 +590,30 @@ 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) {
 		errno = EINVAL;
 		return NULL;
 	}
-	return (struct sysfs_attribute *)dlist_find_custom(dir->attributes,
+	
+	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;
 }
 
 /**
@@ -627,12 +653,15 @@ struct sysfs_directory *sysfs_get_subdirectory(struct sysfs_directory *dir,
 	if (sub != NULL) 
 		return sub;
 
-	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;
+	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;
+		}
 	}
 	return NULL;
 }
@@ -661,12 +690,15 @@ struct sysfs_link *sysfs_get_subdirectory_link(struct sysfs_directory *dir,
 	if (dir->subdirs == NULL)
 		return 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;
+	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/lib/sysfs_driver.c b/lib/sysfs_driver.c
index 51a9107..9d331cc 100644
--- a/lib/sysfs_driver.c
+++ b/lib/sysfs_driver.c
@@ -225,6 +225,43 @@ struct sysfs_driver *sysfs_open_driver_by_name(const unsigned char *drv_name,
 }
 
 /**
+ * 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
@@ -234,38 +271,97 @@ struct sysfs_driver *sysfs_open_driver_by_name(const unsigned char *drv_name,
 int sysfs_write_driver_attr(unsigned char *drv, unsigned char *attrib,
 					unsigned char *value, size_t len)
 {
-	struct sysfs_driver *driver = NULL;
 	struct sysfs_attribute *attribute = NULL;
-	unsigned char busname[SYSFS_NAME_LEN];
+	unsigned char path[SYSFS_PATH_MAX];
 
 	if (drv == NULL || attrib == NULL || value == NULL) {
 		errno = EINVAL;
 		return -1;
 	}
 
-	memset(busname, 0, SYSFS_NAME_LEN);
-	if ((sysfs_find_driver_bus(drv, busname, SYSFS_NAME_LEN)) < 0) {
-		dprintf("Driver %s not found\n", drv);
-		return -1;
-	}
-	driver = sysfs_open_driver_by_name(drv, busname, SYSFS_NAME_LEN);
-	if (driver == NULL) {
-		dprintf("Could not open driverr %s\n", drv);
+	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;
 	}
-	attribute = sysfs_get_directory_attribute(driver->directory, attrib);
+	strcat(path, "/");
+	strcat(path, attrib);
+	attribute = sysfs_open_attribute(path);
         if (attribute == NULL) {
-                dprintf("Attribute %s not defined for driver %s\n", 
+                dprintf("Attribute %s could not be retrieved for driver %s\n",
 							attrib, drv);
-		sysfs_close_driver_by_name(driver);
 		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_driver_by_name(driver);
+		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 busname[SYSFS_NAME_LEN], 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;
 	}
-	sysfs_close_driver_by_name(driver);
+	strncpy(value, attribute->value, attribute->len);
+	value[(attribute->len)+1] = 0;
+	sysfs_close_attribute(attribute);
 	return 0;
 }