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60 lines
1.6 KiB
Groff
60 lines
1.6 KiB
Groff
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.\"
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.\" $Id: procsend.2,v 1.1 1997/02/27 07:32:15 gdr Exp $
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.\"
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.\" .TH "MESSAGE IPC" 2 GNO "System Calls" "16 December 1996"
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.TH "MESSAGE IPC" 2 "16 December 1996" GNO "System Calls"
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.SH NAME
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.BR procreceive ,
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.BR procsend ,
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.BR procrecvclr ,
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.BR procrecvtim
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\- GNO message passing IPC system
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.SH SYNOPSIS
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.nf
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#include <gno/gno.h>
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int procsend (pid_t \fIpid\fR, unsigned long \fImsg\fR);
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unsigned long procreceive (void);
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unsigned long procrecvtim (short \fItimeout\fR);
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unsigned long procrecvclr (void);
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.fi
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.SH DESCRIPTION
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These kernel traps comprise GNO's message passing IPC (interprocess
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communication) system. Messages are unsigned 32-bit data values. A
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process sends a message to another by using the
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.BR procsend
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call. You must specify the process ID of the recipient and the message
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to pass.
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.LP
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The
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.BR procreceive
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trap receives a message. If no message has been sent to the process, the
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process sleeps until a message arrives. A
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.BR procreceive
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that is interrupted by a signal will abort and return -1, with
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.BR errno
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set to
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.BR EINTR .
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.LP
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.BR procrecvclr
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is used to clear any pending message a process may have waiting.
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.LP
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.BR procrecvtim
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is similar to
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.BR procreceive ,
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but takes a
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.IR timeout
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argument, specified in 1/10ths of a second. If no message has been
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received in
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.IR timeout
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seconds,
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.BR procrecvtim
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fails and returns -1. The message buffer for a process is only one message
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deep; any attempt to
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.BR procsend
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a message to a process that already has one queued will result in an error.
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.LP
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For an IPC system with a deeper queue, see the Ports IPC man page,
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.BR ports (2).
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.SH "SEE ALSO"
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.BR ports (2).
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