ATTACH(5)
NAME
attach, session, nop − messages to initiate activity
SYNOPSIS
Tnop tag[2]
Rnop tag[2]
Tsession tag[2]
Rsession tag[2]
Tattach tag[2] fid[2] uid[28] aname[28] auth[28]
Rattach tag[2] fid[2] qid[8]
DESCRIPTION
The nop request does nothing overt but may be used to synchronize the channel between two service hosts initially.
The session request is used to initialize a connection between a client and a server. All outstanding I/O on the connection is aborted. The set of messages between session requests is called a session. Tags and fids must be unique per session.
The tag should be NOTAG (value 0xFFFF) for a nop or session message.
The attach message serves as a fresh introduction from a user on the client machine to a server. The message identifies the user (uid) and may select the file tree to access (aname). The auth argument contains authorization data derived from the chal field of an auth message; see auth(5) and auth(6).
As a result of the attach transaction, the client will have a connection to the root directory of the desired file tree, represented by fid. An error is returned if fid is already in use. The server’s idea of the root of the file tree is represented by the returned qid.
ENTRY POINTS
An attach transaction will be generated for kernel devices (see intro(3)) when a system call evaluates a file name beginning with #. Pipe(2) generates an attach on the kernel device pipe(3). Mount (see bind(2)) generates auth and attach messages to the remote file server. When the kernel boots, an attach is made to the root device, root(3), and then an auth and an attach are made to the requested file server machine.
SEE ALSO
Plan 9 — January 03, 1993