diff options
Diffstat (limited to 'lib/sysfs_class.c')
| -rw-r--r-- | lib/sysfs_class.c | 53 |
1 files changed, 52 insertions, 1 deletions
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; +} |