a string containing the attribute's name
a string containing the attribute's new value
a GFileQueryInfoFlags
optional GCancellable object, NULL to ignore. [allow-none]
TRUE if the attribute was successfully set to value in the file, FALSE otherwise.
GException on failure.
Sets attribute of type G_FILE_ATTRIBUTE_TYPE_BYTE_STRING to value. If attribute is of a different type, this operation will fail, returning FALSE. If cancellable is not NULL, then the operation can be cancelled by triggering the cancellable object from another thread. If the operation was cancelled, the error G_IO_ERROR_CANCELLED will be returned.