fcall(3) [plan9 man page]

FCALL(3)						     Library Functions Manual							  FCALL(3)

NAME

       fcall - recreate packet delimiters

SYNOPSIS

       Fctlfd = open(".../ctl", ORDWR);
       Fwrite(ctlfd, "push fcall", 10);

DESCRIPTION

       Fcall  is a stream module (see stream(3)) that can be pushed onto a connection to a 9P file server. The function of the module is to recre-
       ate packet delimiters lost in transmission.  The 9P protocol demands that network connections preserve delimiters between messages  written
       to  the file server.  Stream based protocols, like TCP, are unable to preserve delimiters. The delimiters must be recreated by the receiver
       before a packet is read by a file system.

       Fcall examines a data stream and identifies 9P messages from their type. The length of the message is computed from the	header.   Data	is
       collected  and  buffered  by  the  stream module until an entire 9P message has been assembled. A single message is then delimited and sent
       upstream to be read by a file server.

SEE ALSO

       stream(3), ip(3), exportfs(4), srv(4)

SOURCE

       /sys/src/9/port/stfcall.c

																	  FCALL(3)

STREAM(3)						     Library Functions Manual							 STREAM(3)

NAME

       stream - a structure for communications

SYNOPSIS

       bind streamdevice dir

       dir/data
       dir/ctl

DESCRIPTION

       A  stream  is  not a device per se.  However, many devices use the streams package in the kernel to implement communications channels.  The
       properties described here are common to all such channels.

       All streams are represented by two standard files, ctl and data, plus any others the particular device wants to add.  Reading  and  writing
       the  data  file	receives  and sends data on the channel.  If the channel is message oriented, each write will represent a message and each
       read will return at most one message.  If the buffer given in a read is smaller than the message, subsequent reads will return the  remain-
       der of the message.

       Writing	textual command strings to the ctl file performs control operations on the stream.  The strings need not be null-terminated.  Each
       device may add to the control operations.  The common control operations are:

       hangup	     Hang up this stream.  Any subsequent writes will return an error.	The first subsequent read will return  0.   All  following
		     ones will return an error.

       push name     Push the module name onto the top of the stream.

       pop	     Pop the top module off the stream

       Reading	the  ctl  file returns a textual identifier for the stream.  This is used by multiplexed devices and its use is described with the
       particular device.

SEE ALSO

       pipe(3), dk(3), cons(3), async(3), fcall(3), ip(3), reboot(3)

SOURCE

       /sys/src/9/port/st*.c

																	 STREAM(3)