*
* 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
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
-#include "libsysfs.h"
+#include "sysfs/libsysfs.h"
#include "sysfs.h"
+static 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.
sysfs_close_device(dev->sysdevice);
if (dev->driver != NULL)
sysfs_close_driver(dev->driver);
+ if (dev->parent != NULL)
+ sysfs_close_class_device(dev->parent);
free(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);
}
}
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
+/**
+ * set_classdev_classname: Grabs classname from path
+ * @cdev: class device to set
+ * Returns nothing
*/
-static struct sysfs_directory *open_class_dir(const char *name)
+static void set_classdev_classname(struct sysfs_class_device *cdev)
{
- struct sysfs_directory *classdir = NULL;
- char classpath[SYSFS_PATH_MAX];
-
- if (name == NULL) {
- errno = EINVAL;
- return NULL;
- }
+ unsigned char *c = NULL, *e = NULL;
+ int count = 0;
- 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");
- return NULL;
+ c = strstr(cdev->path, SYSFS_CLASS_NAME);
+ if (c == NULL) {
+ c = strstr(cdev->path, SYSFS_BLOCK_NAME);
+ } else {
+ c = strstr(c, "/");
}
- strcat(classpath, SYSFS_CLASS_DIR);
- strcat(classpath, "/");
- strcat(classpath, name);
- classdir = sysfs_open_directory(classpath);
- if (classdir == NULL) {
- errno = EINVAL;
- dprintf(stderr,"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);
- sysfs_close_directory(classdir);
- return NULL;
+ if (c == NULL)
+ strcpy(cdev->classname, SYSFS_UNKNOWN);
+ else {
+ if (*c == '/')
+ c++;
+ e = c;
+ while (e != NULL && *e != '/' && *e != '\0') {
+ e++;
+ count++;
+ }
+ strncpy(cdev->classname, c, count);
}
-
- return classdir;
}
/**
- * sysfs_open_class_device: Opens and populates class device
+ * sysfs_open_class_device_path: Opens and populates class device
* @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_path
+ (const unsigned char *path)
{
struct sysfs_class_device *cdev = NULL;
- struct sysfs_directory *dir = NULL, *cur = NULL;
- struct sysfs_dlink *curl = NULL;
- struct sysfs_device *sdev = NULL;
- struct sysfs_driver *drv = NULL;
- char temp[SYSFS_NAME_LEN];
if (path == NULL) {
errno = EINVAL;
return NULL;
}
+ if ((sysfs_path_is_dir(path)) != 0) {
+ dprintf("%s is not a valid path to a class device\n", path);
+ return NULL;
+ }
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("Error getting class device name\n");
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);
+ strcpy(cdev->path, path);
+ if ((sysfs_remove_trailing_slash(cdev->path)) != 0) {
+ dprintf("Invalid path to class device %s\n", cdev->path);
sysfs_close_class_device(cdev);
return NULL;
}
- if ((sysfs_read_directory(dir)) != 0) {
- dprintf(stderr, "Error reading class device at %s\n", path);
- sysfs_close_directory(dir);
- sysfs_close_class_device(cdev);
+ set_classdev_classname(cdev);
+
+ return cdev;
+}
+
+/**
+ * sysfs_get_class_devices: gets all devices for class
+ * @class: class to get devices for
+ * returns dlist of class_devices with success and NULL with error
+ */
+struct dlist *sysfs_get_class_devices(struct sysfs_class *cls)
+{
+ struct sysfs_class_device *dev = NULL;
+ struct sysfs_directory *cur = NULL;
+
+ if (cls == NULL) {
+ errno = EINVAL;
return NULL;
}
- cdev->directory = dir;
- cur = cdev->directory->subdirs;
- while(cur != NULL) {
- sysfs_read_directory(cur);
- cur = cur->next;
+ if (cls->devices != NULL)
+ return cls->devices;
+
+ if (cls->directory == NULL) {
+ cls->directory = sysfs_open_directory(cls->path);
+ if (cls->directory == NULL)
+ return NULL;
}
- /* 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 ((sysfs_read_dir_subdirs(cls->directory)) != 0)
+ return NULL;
+
+ if (cls->directory->subdirs != NULL) {
+ dlist_for_each_data(cls->directory->subdirs, cur,
+ struct sysfs_directory) {
+ dev = sysfs_open_class_device_path(cur->path);
+ if (dev == NULL) {
+ dprintf("Error opening device at %s\n",
+ cur->path);
+ continue;
}
+ if (cls->devices == NULL)
+ cls->devices = dlist_new_with_delete
+ (sizeof(struct sysfs_class_device),
+ sysfs_close_cls_dev);
+ dlist_unshift(cls->devices, dev);
}
- curl = curl->next;
}
- return cdev;
+ return cls->devices;
}
/**
- * add_dev_to_class: adds a class device to class list
- * @class: class to add the device
- * @dev: device to add
+ * sysfs_open_class: opens specific class and all its devices on system
+ * returns sysfs_class structure with success or NULL with error.
*/
-static void add_dev_to_class(struct sysfs_class *cls,
- struct sysfs_class_device *dev)
+struct sysfs_class *sysfs_open_class(const unsigned char *name)
{
- if (cls != NULL && dev != NULL) {
- dev->next = cls->devices;
- cls->devices = dev;
+ struct sysfs_class *cls = NULL;
+ unsigned char classpath[SYSFS_PATH_MAX];
+
+ if (name == NULL) {
+ errno = EINVAL;
+ return NULL;
}
+
+ memset(classpath, 0, SYSFS_PATH_MAX);
+ if ((sysfs_get_mnt_path(classpath, SYSFS_PATH_MAX)) != 0) {
+ dprintf("Sysfs not supported on this system\n");
+ return NULL;
+ }
+
+ /*
+ * We shall now treat "block" also as a class. Hence, check here
+ * if "name" is "block" and proceed accordingly
+ */
+ if (strcmp(name, SYSFS_BLOCK_NAME) == 0) {
+ strcat(classpath, "/");
+ strcat(classpath, SYSFS_BLOCK_NAME);
+ } else {
+ strcat(classpath, "/");
+ strcat(classpath, SYSFS_CLASS_NAME);
+ strcat(classpath, "/");
+ strcat(classpath, name);
+ }
+ if ((sysfs_path_is_dir(classpath)) != 0) {
+ dprintf("Class %s not found on the system\n", name);
+ return NULL;
+ }
+
+ cls = alloc_class();
+ if (cls == NULL) {
+ dprintf("calloc failed\n");
+ return NULL;
+ }
+ strcpy(cls->name, name);
+ strcpy(cls->path, classpath);
+ if ((sysfs_remove_trailing_slash(cls->path)) != 0) {
+ dprintf("Invalid path to class device %s\n", cls->path);
+ sysfs_close_class(cls);
+ return NULL;
+ }
+
+ return cls;
}
/**
- * get_all_class_devices: gets all devices for class
- * @class: class to get devices for
- * returns 0 with success and -1 with failure
+ * 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;
+ }
+
+ if (class->devices == NULL) {
+ class->devices = sysfs_get_class_devices(class);
+ if (class->devices == NULL)
+ return NULL;
+ }
+ return (struct sysfs_class_device *)dlist_find_custom(class->devices,
+ name, class_name_equal);
+}
+
+/**
+ * sysfs_get_classdev_device: returns the sysfs_device corresponding to
+ * sysfs_class_device, if present
+ * @clsdev: class device whose sysfs_device is required
+ * Returns sysfs_device on success, NULL on error or if device is not
+ * implemented
+ */
+struct sysfs_device *sysfs_get_classdev_device
+ (struct sysfs_class_device *clsdev)
+{
+ struct sysfs_link *devlink = NULL;
+ unsigned char devpath[SYSFS_PATH_MAX];
+
+ if (clsdev == NULL) {
+ errno = EINVAL;
+ return NULL;
+ }
+ strcpy(devpath, clsdev->path);
+ strcat(devpath, "/device");
+ if ((sysfs_path_is_link(devpath)) != 0) {
+ if (clsdev->sysdevice != NULL) {
+ sysfs_close_device(clsdev->sysdevice);
+ clsdev->sysdevice = NULL;
+ }
+ return NULL;
+ }
+
+ if (clsdev->directory == NULL) {
+ clsdev->directory = sysfs_open_directory(clsdev->path);
+ if (clsdev->directory == NULL)
+ return NULL;
+ }
+ devlink = sysfs_get_directory_link(clsdev->directory, "device");
+ if (devlink == NULL) {
+ if (clsdev->sysdevice != NULL) {
+ dprintf("Device link no longer exists\n");
+ sysfs_close_device(clsdev->sysdevice);
+ clsdev->sysdevice = NULL;
+ }
+ return NULL;
+ }
+
+ if (clsdev->sysdevice != NULL) {
+ if (!strncmp(devlink->target, clsdev->sysdevice->path,
+ SYSFS_PATH_MAX))
+ /* sysdevice hasn't changed */
+ return (clsdev->sysdevice);
+ else
+ /* come here only if the device link for has changed */
+ sysfs_close_device(clsdev->sysdevice);
+ }
+
+ clsdev->sysdevice = sysfs_open_device_path(devlink->target);
+ if (clsdev->sysdevice == NULL)
+ return NULL;
+ if (clsdev->driver != NULL)
+ strcpy(clsdev->sysdevice->driver_name, clsdev->driver->name);
+
+ return (clsdev->sysdevice);
+}
+
+/**
+ * sysfs_get_classdev_driver: returns the sysfs_driver corresponding to
+ * sysfs_class_device, if present
+ * @clsdev: class device whose sysfs_device is required
+ * Returns sysfs_driver on success, NULL on error or if driver is not
+ * implemented
+ */
+struct sysfs_driver *sysfs_get_classdev_driver
+ (struct sysfs_class_device *clsdev)
+{
+ struct sysfs_link *drvlink = NULL;
+ unsigned char drvpath[SYSFS_PATH_MAX];
+
+ if (clsdev == NULL) {
+ errno = EINVAL;
+ return NULL;
+ }
+ strcpy(drvpath, clsdev->path);
+ strcat(drvpath, "/driver");
+ if ((sysfs_path_is_link(drvpath)) != 0) {
+ if (clsdev->driver != NULL) {
+ sysfs_close_driver(clsdev->driver);
+ clsdev->driver = NULL;
+ }
+ return NULL;
+ }
+
+ if (clsdev->directory == NULL) {
+ clsdev->directory = sysfs_open_directory(clsdev->path);
+ if (clsdev->directory == NULL)
+ return NULL;
+ }
+ drvlink = sysfs_get_directory_link(clsdev->directory, "driver");
+ if (drvlink == NULL) {
+ if (clsdev->driver != NULL) {
+ dprintf("Driver link no longer exists\n");
+ sysfs_close_driver(clsdev->driver);
+ clsdev->driver = NULL;
+ }
+ return NULL;
+ }
+ if (clsdev->driver != NULL) {
+ if (!strncmp(drvlink->target, clsdev->driver->path,
+ SYSFS_PATH_MAX))
+ /* driver hasn't changed */
+ return (clsdev->driver);
+ else
+ /* come here only if the device link for has changed */
+ sysfs_close_driver(clsdev->driver);
+ }
+
+ clsdev->driver = sysfs_open_driver_path(drvlink->target);
+ if (clsdev->driver == NULL)
+ return NULL;
+ if (clsdev->sysdevice != NULL)
+ strcpy(clsdev->sysdevice->driver_name, clsdev->driver->name);
+
+ return (clsdev->driver);
+}
+
+/**
+ * get_blockdev_parent: Get the parent class device for a "block" subsystem
+ * device if present
+ * @clsdev: block subsystem class device whose parent needs to be found
+ * Returns 0 on success and 1 on error
*/
-static int get_all_class_devices(struct sysfs_class *cls)
+static int get_blockdev_parent(struct sysfs_class_device *clsdev)
{
- struct sysfs_class_device *dev = NULL;
- struct sysfs_directory *cur = NULL, *next = NULL;
+ unsigned char parent_path[SYSFS_PATH_MAX], *c = NULL;
+
+ strcpy(parent_path, clsdev->path);
+ c = strstr(parent_path, SYSFS_BLOCK_NAME);
+ if (c == NULL) {
+ dprintf("Class device %s does not belong to BLOCK subsystem\n",
+ clsdev->name);
+ return 1;
+ }
+
+ c += strlen(SYSFS_BLOCK_NAME);
+ if (*c == '/')
+ c++;
+ else
+ goto errout;
+
+ /* validate whether the given class device is a partition or not */
+ if ((strncmp(c, clsdev->name, strlen(clsdev->name))) == 0) {
+ dprintf("%s not a partition\n", clsdev->name);
+ return 1;
+ }
+
+ c = strchr(c, '/');
+ if (c == NULL)
+ goto errout;
+
+ *c = '\0';
+
+ clsdev->parent = sysfs_open_class_device_path(parent_path);
+ if (clsdev->parent == NULL) {
+ dprintf("Error opening the parent class device at %s\n",
+ parent_path);
+ return 1;
+ }
+ return 0;
+
+errout:
+ dprintf("Invalid path %s\n", clsdev->path);
+ return 1;
+}
- if (cls == NULL || cls->directory == NULL) {
+/**
+ * sysfs_get_classdev_parent: Retrieves the parent of a class device.
+ * eg., when working with hda1, this function can be used to retrieve the
+ * sysfs_class_device for hda
+ *
+ * @clsdev: class device whose parent details are required.
+ * Returns sysfs_class_device of the parent on success, NULL on failure
+ */
+struct sysfs_class_device *sysfs_get_classdev_parent
+ (struct sysfs_class_device *clsdev)
+{
+ if (clsdev == NULL) {
+ errno = EINVAL;
+ return NULL;
+ }
+ if (clsdev->parent != NULL)
+ return (clsdev->parent);
+
+ /*
+ * As of now, only block devices have a parent child heirarchy in sysfs
+ * We do not know, if, in the future, more classes will have a similar
+ * structure. Hence, we now call a specialized function for block and
+ * later we can add support functions for other subsystems as required.
+ */
+ if (!(strcmp(clsdev->classname, SYSFS_BLOCK_NAME))) {
+ if ((get_blockdev_parent(clsdev)) == 0)
+ return (clsdev->parent);
+ }
+ return NULL;
+}
+
+/**
+ * get_classdev_path: given the class and a device in the class, return the
+ * absolute path to the device
+ * @classname: name of the class
+ * @clsdev: the class device
+ * @path: buffer to return path
+ * @psize: size of "path"
+ * Returns 0 on SUCCESS or -1 on error
+ */
+static int get_classdev_path(const unsigned char *classname,
+ const unsigned char *clsdev, unsigned char *path, size_t len)
+{
+ if (classname == NULL || clsdev == NULL || path == NULL) {
errno = EINVAL;
return -1;
}
- for (cur = cls->directory->subdirs; cur != NULL; cur = next) {
- next = cur->next;
- dev = sysfs_open_class_device(cur->path);
- if (dev == NULL) {
- dprintf(stderr, "Error opening device at %s\n",
- cur->path);
- continue;
- }
- add_dev_to_class(cls, dev);
+ if (sysfs_get_mnt_path(path, len) != 0) {
+ dprintf("Error getting sysfs mount path\n");
+ return -1;
+ }
+ if (strcmp(classname, SYSFS_BLOCK_NAME) == 0) {
+ strcat(path, "/");
+ strcat(path, SYSFS_BLOCK_NAME);
+ } else {
+ strcat(path, "/");
+ strcat(path, SYSFS_CLASS_NAME);
+ strcat(path, "/");
+ strcat(path, classname);
}
-
+ strcat(path, "/");
+ strcat(path, clsdev);
return 0;
}
/**
- * sysfs_open_class: opens specific class and all its devices on system
- * returns sysfs_class structure with success or NULL with error.
+ * sysfs_open_class_device: 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
+ *
+ * NOTE:
+ * Call sysfs_close_class_device() to close the class device
*/
-struct sysfs_class *sysfs_open_class(const char *name)
+struct sysfs_class_device *sysfs_open_class_device
+ (const unsigned char *classname, const unsigned char *name)
{
- struct sysfs_class *cls = NULL;
- struct sysfs_directory *classdir = NULL;
+ unsigned char devpath[SYSFS_PATH_MAX];
+ struct sysfs_class_device *cdev = NULL;
- if (name == NULL) {
+ if (classname == NULL || name == NULL) {
errno = EINVAL;
return NULL;
}
+
+ memset(devpath, 0, SYSFS_PATH_MAX);
+ if ((get_classdev_path(classname, name, devpath,
+ SYSFS_PATH_MAX)) != 0) {
+ dprintf("Error getting to device %s on class %s\n",
+ name, classname);
+ return NULL;
+ }
+
+ cdev = sysfs_open_class_device_path(devpath);
+ if (cdev == NULL) {
+ dprintf("Error getting class device %s from class %s\n",
+ name, classname);
+ return NULL;
+ }
+ return cdev;
+}
+
+/**
+ * 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)
+ return NULL;
+
+ if (cdev->directory == NULL) {
+ cdev->directory = sysfs_open_directory(cdev->path);
+ if (cdev->directory == NULL)
+ return NULL;
+ }
+ if (cdev->directory->attributes == NULL) {
+ if ((sysfs_read_dir_attributes(cdev->directory)) != 0)
+ return NULL;
+ }
+ return (cdev->directory->attributes);
+}
- cls = alloc_class();
- if (cls == NULL) {
- perror("malloc");
+/**
+ * sysfs_refresh_clsassdev_attributes: refreshes the driver's list of attributes
+ * @clsdev: sysfs_class_device whose attributes to refresh
+ *
+ * NOTE: Upon return, prior references to sysfs_attributes for this classdev
+ * _may_ not be valid
+ *
+ * Returns list of attributes on success and NULL on failure
+ */
+struct dlist *sysfs_refresh_classdev_attributes
+ (struct sysfs_class_device *clsdev)
+{
+ if (clsdev == NULL) {
+ errno = EINVAL;
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",
- name);
- sysfs_close_class(cls);
+
+ if (clsdev->directory == NULL)
+ return (sysfs_get_classdev_attributes(clsdev));
+
+ if ((sysfs_refresh_dir_attributes(clsdev->directory)) != 0) {
+ dprintf("Error refreshing class_device attributes\n");
return NULL;
}
- cls->directory = classdir;
- if ((get_all_class_devices(cls)) != 0) {
- dprintf(stderr, "Error reading %s class devices\n", name);
- sysfs_close_class(cls);
+
+ return (clsdev->directory->attributes);
+}
+
+/**
+ * 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;
+ struct sysfs_directory *sdir = NULL;
+ struct dlist *attrlist = NULL;
+
+ if (clsdev == NULL || name == NULL) {
+ errno = EINVAL;
return NULL;
}
+
+ /*
+ * First, see if it's in the current directory. Then look at
+ * subdirs since class devices can have subdirs of attributes.
+ */
+ attrlist = sysfs_get_classdev_attributes(clsdev);
+ if (attrlist != NULL) {
+ cur = sysfs_get_directory_attribute(clsdev->directory,
+ (unsigned char *)name);
+ if (cur != NULL)
+ return cur;
+ }
- return cls;
+ if (clsdev->directory->subdirs == NULL)
+ if ((sysfs_read_dir_subdirs(clsdev->directory)) != 0 ||
+ clsdev->directory->subdirs == NULL)
+ return NULL;
+
+ if (clsdev->directory->subdirs != NULL) {
+ dlist_for_each_data(clsdev->directory->subdirs, sdir,
+ struct sysfs_directory) {
+ if ((sysfs_path_is_dir(sdir->path)) != 0)
+ continue;
+ cur = sysfs_get_directory_attribute(sdir,
+ (unsigned char *)name);
+ if (cur == NULL)
+ continue;
+ }
+ }
+ return cur;
}
+
+/**
+ * sysfs_open_classdev_attr: read an attribute for a given class device
+ * @classname: name of the class on which to look
+ * @dev: class device name for which the attribute has to be read
+ * @attrib: attribute to read
+ * Returns sysfs_attribute * on SUCCESS and NULL on error
+ *
+ * NOTE:
+ * A call to sysfs_close_attribute() is required to close the
+ * attribute returned and to free memory
+ */
+struct sysfs_attribute *sysfs_open_classdev_attr(const unsigned char *classname,
+ const unsigned char *dev, const unsigned char *attrib)
+{
+ struct sysfs_attribute *attribute = NULL;
+ unsigned char path[SYSFS_PATH_MAX];
+
+ if (classname == NULL || dev == NULL || attrib == NULL) {
+ errno = EINVAL;
+ return NULL;
+ }
+ memset(path, 0, SYSFS_PATH_MAX);
+ if ((get_classdev_path(classname, dev, path, SYSFS_PATH_MAX)) != 0) {
+ dprintf("Error getting to device %s on class %s\n",
+ dev, classname);
+ return NULL;
+ }
+ strcat(path, "/");
+ strcat(path, attrib);
+ attribute = sysfs_open_attribute(path);
+ if (attribute == NULL) {
+ dprintf("Error opening attribute %s on class device %s\n",
+ attrib, dev);
+ return NULL;
+ }
+ if ((sysfs_read_attribute(attribute)) != 0) {
+ dprintf("Error reading attribute %s for class device %s\n",
+ attrib, dev);
+ sysfs_close_attribute(attribute);
+ return NULL;
+ }
+ return attribute;
+}
+
~ianmdlvl / elogind.git / blobdiff