SRV(3)SRV(3)
NAME
srv – server registry
SYNOPSIS
bind #s /srv
#s/service1
#s/service2
...
DESCRIPTION
The
srv
device provides a one-level directory holding
already-open channels to services.
In effect,
srv
is a bulletin board on which processes may post open file descriptors
to make them available to other processes.
To install a channel, create
a new file such as
/srv/myserv
and then write a text string (suitable for
strtoul;
see
atof(2))
giving the file descriptor number of an open file.
Any process may then open
/srv/myserv
to acquire another reference to the open file that was registered.
An entry in
srv
holds a reference to the associated file even if no process has the
file open. Removing the file from
/srv
releases that reference.
It is an error to write more than one number into a server file,
or to create a file with a name that is already being used.
EXAMPLE
To drop one end of a pipe into
/srv,
that is, to create a named pipe:
int fd, p[2];
char buf[32];
pipe(p);
fd = create("/srv/namedpipe", OWRITE, 0666);
fprint(fd, "%d", p[0]);
close(fd);
close(p[0]);
fprint(p[1], "hello");
At this point, any process may open and read
/srv/namedpipe
to receive the
hello
string. Data written to
/srv/namedpipe
can be received by executing
read(p[1], buf, sizeof buf);
in the above process.
SOURCE
/sys/src/9/port/devsrv.c