4.2BSD sigrestartable(2) man page

[dpk%brl-vgr at sri-unix.UUCP]

From:      Doug Kingston <dpk at brl-vgr>

	The following is a manual page for the system call interface
sigrestartable, as developed at BRL and discussed on this list.

sigrestartable.2:

.TH SIGRESTARTABLE 2B "11 January 1984"
.UC 4
.SH NAME
sigrestartable \- change system call restart behavior
.SH SYNOPSIS
.nf
.B sigrestartable(flag);
.B int flag;
.SH DESCRIPTION
.I Sigrestartable
is used to change the system call restart behavior
when a system call is interrupted by a signal.
If the
.I flag
is one (01), then system calls will be restarted if they
are interrupted by a signal and no data has been transferred yet.
This is the default behavior on 4.2 BSD.
.PP
If the
.I flag
is 0, then restarting of system calls is disabled.
If a system call is interrupted and no data has been
transferred, the system call will return -1 with
.I errno
set to EINTR.
Interrupted system calls that have started transfering data
will return the amount of data actually transferred.
This is the signal behavior found on 4.1 BSD
and AT&T System V UNIX systems.
.PP
Note that the new 4.2 BSD signal handling semantics are not altered in
any other way.
Most notably, signal handlers always remain installed
until explicitly changed by a subsequent sigvec(2) call,
and the signal mask operates as documented in sigvec(2).
Programs may switch between restartable and interruptable
system call operation as often as desired in the execution
of a program.
.PP
Issuing an sigrestartable(2) system call during the execution of a signal
handler will cause the new action to take place on the \fInext\fR
signal to be caught.
.SH "RETURN VALUE
None.
.SH "SEE ALSO"
sigvec(2), sigblock(2), sigpause(2), sigsetmask(2).
.SH CAVEAT
This is a BRL-developed system call, and may not have been adopted
on all systems.  Hence, while using this system call may make life
easier locally, it does not enhance the portability of code to other
4.2 BSD systems.

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