-/**
- * sysfs_write_attribute: write value to the attribute
- * @sysattr: attribute to write
- * @new_value: value to write
- * @len: length of "new_value"
- * returns 0 with success and -1 with error.
- */
-int sysfs_write_attribute(struct sysfs_attribute *sysattr,
- const unsigned char *new_value, size_t len)
-{
- int fd;
- int length;
-
- if (sysattr == NULL || new_value == NULL || len == 0) {
- errno = EINVAL;
- return -1;
- }
-
- if (!(sysattr->method & SYSFS_METHOD_STORE)) {
- dprintf ("Store method not supported for attribute %s\n",
- sysattr->path);
- return -1;
- }
- if (sysattr->method & SYSFS_METHOD_SHOW) {
- /*
- * read attribute again to see if we can get an updated value
- */
- if ((sysfs_read_attribute(sysattr)) != 0) {
- dprintf("Error reading attribute\n");
- return -1;
- }
- 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) {
- dprintf("Error reading attribute %s\n", sysattr->path);
- return -1;
- }
-
- length = write(fd, new_value, len);
- if (length < 0) {
- dprintf("Error writing to the attribute %s - invalid value?\n",
- sysattr->name);
- close(fd);
- return -1;
- } else if (length != len) {
- dprintf("Could not write %d bytes to attribute %s\n",
- len, sysattr->name);
- /*
- * since we could not write user supplied number of bytes,
- * restore the old value if one available
- */
- 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. Verify first if the attribute supports reading
- * (show method). If it does not, do not bother
- */
- 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);
- return 0;
-}
-
-