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