- TYPE (enum mnsh_msg_type, always sent) - the message type.
- INT1 and
- INT2 (int, always sent, though not always used) - two
- values whose meaning is message-type-dependent.
+ values whose meaning is message-type-dependent.
See enum mnsh_msg_type documentation below.
- FD (int, optional, sent using SCM_RIGHTS) - an open file
- descriptor.
+ descriptor.
- BUF (unstructured data, optional) - some data with message-
- type-dependent meaning.
+ type-dependent meaning.
Note that the helper process is the child of a call to fork,
so all code in the helper must be async-signal-safe. */