Corrected "write attribute" functions

5 files changed, 118 insertions, 54 deletions

diff --git a/ChangeLog b/ChangeLog
index 6393174..09ba5c3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,4 +1,11 @@
 
+09/23/2003 - Ananth Mavinakayanahalli <ananth@in.ibm.com>
+		* Fixed "write" attribute functions.
+		* Removed sysfs_write_attribute_value()
+		* Added sysfs_change_attribute_value() - a wrapper for
+			sysfs_write_attribute()
+		* Simplified sysfs_get_device_attr()
+		
 09/16/2003 - Ananth Mavinakayanahalli <ananth@in.ibm.com>
 		* Patch sysfs_close_driver() so as not to segfault when
 			during dlist shifting.
@@ -22,7 +29,7 @@
 		* Simplify sysfs_find_device_bus_name()
 
 09/04/2003 - Ananth Mavinakayanahalli <ananth@in.ibm.com>
-		* Simplify sysfs_open_bus_device
+		* Simplified sysfs_open_bus_device
 
 08/29/2003 - Ananth Mavinakayanahalli <ananth@in.ibm.com>
 		* Removed "bus_name" from struct sysfs_device
diff --git a/include/libsysfs.h b/include/libsysfs.h
index 827e305..d7fc69b 100644
--- a/include/libsysfs.h
+++ b/include/libsysfs.h
@@ -142,6 +142,8 @@ extern int sysfs_get_link(const unsigned char *path, unsigned char *target,
 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);
+extern int sysfs_change_attribute_value(unsigned char *device,
+		unsigned char *attribute, unsigned char *value);
 
 /* sysfs directory and file access */
 extern void sysfs_close_attribute(struct sysfs_attribute *sysattr);
@@ -149,9 +151,8 @@ 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 unsigned char *attrpath, 
 				unsigned char *value, size_t vsize);
-extern int sysfs_write_attribute(struct sysfs_attribute *sysattr);
-extern int sysfs_write_attribute_value(const unsigned char *attrpath,
-				unsigned char *value);
+extern int sysfs_write_attribute(struct sysfs_attribute *sysattr,
+		const unsigned char *new_value);
 extern unsigned char *sysfs_get_value_from_attributes(struct dlist *attr, 
 						const unsigned char * name);
 extern void sysfs_close_directory(struct sysfs_directory *sysdir);
@@ -188,7 +189,7 @@ extern struct sysfs_device *sysfs_open_device_tree(const unsigned char *path);
 extern struct sysfs_attribute *sysfs_get_device_attr
 			(struct sysfs_device *dev, const unsigned char *name);
 extern struct dlist *sysfs_get_device_attributes(struct sysfs_device *device);
-extern struct sysfs_driver *sysfs_open_driver_by_name
+extern struct sysfs_device *sysfs_open_device_by_name
 		(unsigned char *dev_name, unsigned char *bus, size_t bsize);
 
 /* generic sysfs bus access */
diff --git a/lib/sysfs_device.c b/lib/sysfs_device.c
index e37789c..6f28a24 100644
--- a/lib/sysfs_device.c
+++ b/lib/sysfs_device.c
@@ -73,20 +73,17 @@ struct sysfs_attribute *sysfs_get_device_attr(struct sysfs_device *dev,
 						const unsigned char *name)
 {
 	struct sysfs_attribute *cur = NULL;
-	unsigned char attrname[SYSFS_NAME_LEN];
 
 	if (dev == NULL || dev->directory == NULL 
 	    || dev->directory->attributes == NULL || name == NULL) {
 		errno = EINVAL;
 		return NULL;
 	}
-	dlist_for_each_data(dev->directory->attributes, cur,
-			struct sysfs_attribute) {
-		if (strcmp(cur->name, attrname) != 0)
-			continue;
-
+	
+	cur = sysfs_get_directory_attribute(dev->directory, 
+			(unsigned char *)name);
+	if (cur != NULL)
 		return cur;
-	}
 
 	return NULL;
 }
@@ -350,8 +347,8 @@ struct dlist *sysfs_get_device_attributes(struct sysfs_device *device)
  * returns struct sysfs_device if found, NULL otherwise
  * NOTE: Use sysfs_close_device to close the device
  */
-struct sysfs_device *sysfs_open_device_by_name(char *dev_name, char *bus,
-							size_t bsize)
+struct sysfs_device *sysfs_open_device_by_name(unsigned char *dev_name, 
+		unsigned char *bus, size_t bsize)
 {
 	char sysfs_path[SYSFS_PATH_MAX], device_path[SYSFS_PATH_MAX];
 	struct sysfs_device *device = NULL;
diff --git a/lib/sysfs_dir.c b/lib/sysfs_dir.c
index 4c271cc..af48032 100644
--- a/lib/sysfs_dir.c
+++ b/lib/sysfs_dir.c
@@ -160,12 +160,14 @@ struct sysfs_attribute *sysfs_open_attribute(const unsigned char *path)
 
 	return sysattr;
 }
+
 /**
  * sysfs_write_attribute: write value to the attribute
  * @sysattr: attribute to write
  * returns 0 with success and -1 with error.
  */
-int sysfs_write_attribute(struct sysfs_attribute *sysattr)
+int sysfs_write_attribute(struct sysfs_attribute *sysattr,
+		const unsigned char *new_value)
 {
 	int fd;
 	int length;
@@ -180,19 +182,43 @@ int sysfs_write_attribute(struct sysfs_attribute *sysattr)
 			sysattr->path);
 		return -1;
 	}
-		
-	if ((fd = open(sysattr->path, O_RDWR)) < 0) {
+	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) {
+		perror("sysfs_write_attribute: open");
 		dprintf ("Error reading attribute %s\n", sysattr->path);
 		return -1;
 	}
 
-	length = write(fd, sysattr->value, sizeof(sysattr->value));
+	length = write(fd, new_value, strlen(new_value));
 	if (length < 0) {
+		perror("sysfs_write_attribute: write");
 		dprintf("Error write to the attribute %s\n",
 			sysattr->path);
 		close(fd);
 		return -1;
 	}
+	
+	/*
+	 * Validate length that has been copied. Alloc appropriate area
+	 * in sysfs_attribute
+	 */ 
+	if (length != sysattr->len) {
+		free(sysattr->value);	/* can we use realloc here? */
+		sysattr->value = (char *)calloc(1, 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;
 }
@@ -252,42 +278,6 @@ int sysfs_read_attribute(struct sysfs_attribute *sysattr)
 }
 
 /**
- * sysfs_write_attribute_value: given path to attribute, 
- * value will be saved to the attribute.
- * @attrpath: sysfs path to attribute
- * @value: value to give to attribute
- * returns 0 with success and -1 with error.
- */
-int sysfs_write_attribute_value(const unsigned char *attrpath, 
-						unsigned char *value)
-{
-	struct sysfs_attribute *attr = NULL;
-	
-	if (attrpath == NULL || value == NULL) {
-		errno = EINVAL;
-		return -1;
-	}
-
-	attr = sysfs_open_attribute(attrpath);
-	if (attr == NULL) {
-		dprintf("Invalid attribute path %s\n", attrpath);
-		errno = EINVAL;
-		return -1;
-	}
-	strncpy(attr->value,value,sizeof(value));
-	if ((sysfs_write_attribute(attr) != 0 )) {
-		dprintf("Error write to attribute %s\n", attrpath);
-		sysfs_close_attribute(attr);
-		return -1;
-	}
-
-	sysfs_close_attribute(attr);
-
-	return 0;
-}
-
-
-/**
  * sysfs_read_attribute_value: given path to attribute, return its value.
  *	values can be up to a pagesize, if buffer is smaller the value will 
  *	be truncated. 
diff --git a/lib/sysfs_utils.c b/lib/sysfs_utils.c
index 2dcf22a..617311e 100644
--- a/lib/sysfs_utils.c
+++ b/lib/sysfs_utils.c
@@ -285,3 +285,72 @@ struct dlist *sysfs_open_bus_devices_list(unsigned char *name)
 	sysfs_close_directory(dir);
 	return list;
 }
+
+
+/**
+ * sysfs_change_attribute_value: "write" attribute support
+ * @device: bus/class device for which attribute has to be changed
+ * @attribute: attribute thats needs modification
+ * @value: value to change to
+ * returns 0 on success and -1 on error
+ */
+int sysfs_change_attribute_value(unsigned char *device, 
+		unsigned char *attribute, unsigned char *value)
+{
+	struct sysfs_device *dev = NULL;
+	struct sysfs_class_device *clsdev = NULL;
+	struct sysfs_attribute *attrib = NULL;
+	struct dlist *attributes = NULL;
+	char subsys_name[SYSFS_NAME_LEN];
+
+	if (device == NULL || attribute == NULL || value == NULL) {
+		dprintf("Incorrect parameters supplied\n");
+		return -1;
+	}
+
+	dev = sysfs_open_device_by_name(device, subsys_name, SYSFS_NAME_LEN);
+	if (dev != NULL) {
+		attrib = sysfs_get_directory_attribute(dev->directory,
+								attribute);
+		if (attrib == NULL) {
+			dprintf("Attribute %s not defined for device %s\n",
+					attribute, device);
+			sysfs_close_device(dev);
+			return -1;
+		}
+		if ((sysfs_write_attribute(attrib, value)) < 0) {
+			dprintf("Error writing value %s to attribute %s\n",
+					value, attribute);
+			sysfs_close_device(dev);
+			return -1;
+		}
+		return 0;
+	}
+	
+	/* not found in bus subsys - look in class */
+	if ((sysfs_find_device_class_name(device, subsys_name, 
+					SYSFS_NAME_LEN)) < 0) {
+		dprintf("Device %s not found\n", device);
+		return -1;
+	}
+	clsdev = sysfs_open_class_device_by_name(subsys_name, device);
+	if (clsdev != NULL) {
+		attrib = sysfs_get_directory_attribute(clsdev->directory,
+								attribute);
+		if (attrib != NULL) {
+			if ((sysfs_write_attribute(attrib, value)) == 0) {
+				sysfs_close_class_device(clsdev);
+				return 0;
+			}
+			dprintf("Error writing attribute value\n");
+			sysfs_close_class_device(clsdev);
+			return -1;
+		}
+		dprintf("Attribute %s not defined for device %s\n", 
+							attribute, device);
+		return -1;
+	}
+	dprintf("Device %s not found\n", device);
+	return -1;
+}
+