ptem(7) Miscellaneous Information Manual ptem(7)
NAME
ptem - STREAMS pty (pesudo-terminal) Emulation module
SYNOPSIS
DESCRIPTION
is a STREAMS module that emulates a terminal when used in conjunction with (STREAMS line discipline) and (STREAMS slave pty driver). The
module normally sits above and below The user process must push the module onto the slave side of the pty with a call to the STREAMS
ioctl(2) system call before is pushed. is responsible for processing all of the terminal commands that are passed downstream from or from
(STREAMS pty master driver).
and together provide a real terminal behavior for the STREAMS pty slave. However, some of the terminal commands are ignored and cause only
an acknowledgement of the command since there is no real terminal or modem in the pty subsystem. In fact, none of the flags in the field
of the or structures, (which is used by the or respectively), have any effect on the pty except if the baud rate is set to zero. Setting
the baud rate to zero will have the effect of hanging up the pty connection. Similarly, the parity or delay flags in the field will not
have any effect at all on the pty.
As a summary, the module performs the following tasks:
o The following are processed, if appropriate, and acknowledged by sending an message upstream when they are received on write
queue:
and
o Keeps track of the window size needed for the and
o Upon receiving any other on its write queue, acknowledges them negatively by sending an message upstream.
o The following are passed downstream by after they have been processed:
and
o Any message that is received on read queue will be freed in case the module is not pushed on the and the above get to the pty
master STREAMS head, which would then send an message downstream.
o When is opened and all conditions for setting up a controlling terminal are met, it sends an message (with the flag set) upstream
to the STREAMS head to allocate a controlling terminal.
o Upon receiving an message of type on its read queue, sends an message downstream and an message upstream.
o When an message is received on its write queue to set the baud rate to zero (e.g. with CBAUD set to B0), sends an message
upstream and a zero-length message downstream to be read by the pty master process.
o When an message of type is received on its read queue, sends an message downstream and an message upstream with the signal number
set to the same value used in the message.
o When an message of type is received on its read queue, sends an message downstream and an message (with ioc_cmd set to or
upstream to enable or disable the input processing on
o When an message is received on its read or write queue, simply discards the message without any action.
o When an message of type is received on its write queue and if the values in the structure in are not zero, sends an message
upstream with the structure. If the values are zero, sends an message upstream.
o When an message of type is received on its write queue and if the values in the structure in are not zero, sends an message
upstream with the structure. If the values are zero, sends an message upstream.
o When an message of type is received in its write queue, saves the information passed to it in the structure and sends an (with
the signal number set to upstream to the pty slave process if the window size is changed.
o When an message of type is received on its read queue and if the values in the structure in are not zero, sends an message down-
stream with the structure. If the values are zero, sends an message downstream.
o When an message of type is received in its read queue, saves the information passed to it in the structure and sends an (with the
signal number is set to upstream to the pty slave process if the window size is changed.
o All other messages not mentioned above are passed to the next module or driver.
AUTHOR
was developed by HP.
SEE ALSO
ioctl(2), streamio(7), ptm(7), pts(7), ldterm(7).
ptem(7)