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 remainder 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