optional GCancellable object, NULL to ignore. [allow-none]
a NUL terminated byte array with the line that was read in (without the newlines). Set length to a gsize to get the length of the read line. On an error, it will return NULL and error will be set. If there's no content to read, it will still return NULL, but error won't be set. [transfer full][array zero-terminated=1][element-type guint8]
GException on failure.
Reads a line from the data input stream. Note that no encoding checks or conversion is performed; the input is not guaranteed to be UTF-8, and may in fact have embedded NUL characters. 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.