export - export a name space .EX include "sys.m"; sys := load Sys Sys->PATH; export: fn(fd: ref FD, dir: string, flag: int): int; Export receives and replies to 9P requests from a client on a connection represented by fd , for file operations on the part of the current file name space rooted at dir , which is thus exported. This is the server end of the client's mount call. Names presented by the client are interpreted relative to directory dir , which can be adjusted using sys-pctl (2) and sys-bind (2) before export. The file descriptor fd must be open for reading and writing, and neither mounted elsewhere nor already exported.

Commonly, export 's first argument is a file descriptor open on the data file in the dir of a Connection returned by listen (see dial (2)). Before calling export , the connection on fd can optionally be authenticated and set for encryption or digesting using the functions in security-auth (2).

The export function takes two mutually exclusive flags:

Sys->EXPWAIT Export blocks until all client requests are complete.

Sys->EXPASYNC Client requests are handled by a background (kernel) process. Export returns immediately. The serving process terminates when the client hangs up.

Export a given directory on fd , protecting it from subsequent changes:

.EX exportdir(fd: ref Sys->FD, dir: string, pid: chan of int) { pid <-= sys->pctl(Sys->FORKNS|Sys->FORKENV|Sys->NEWFD, fd.fd :: nil); sys->export(fd, dir, Sys->EXPWAIT); }

The FORKNS given to pctl forks the name space, and prevents the sys->export from seeing the effects of subsequent mounts by the process that calls or spawns exportdir . The exportdir function above might be called using:

.EX pid := chan of int; spawn exportdir(fd, "/", pid); expid := <-pid;

Service will stop automatically when the connection fd returns end-of-file (eg, when it hangs up), but it can also be stopped locally by killing expid .

/emu/port/inferno.c

/emu/port/exportfs.c

/os/port/inferno.c

/os/port/exportfs.c

Export returns a non-negative value on success and -1 on error; the system error string is set.