date and time created 92/06/23 17:55:33 by mckusick

[unix-history] / usr / src / lib / libc / sys / syscall.2

.\" Copyright (c) 1980, 1991 Regents of the University of California.
.\" All rights reserved.
.\"
.\" %sccs.include.redist.man%
.\"
.\"     @(#)syscall.2	6.3 (Berkeley) %G%
.\"
.Dd 
.Dt SYSCALL 2
.Os BSD 4
.Sh NAME
.Nm syscall
.Nd indirect system call
.Sh SYNOPSIS
.Fd #include <unistd.h>
.Fd #include <sys/syscall.h>
.Ft int
.Fn syscall "int number" "..."
.Sh DESCRIPTION
.Fn Syscall
performs the system call whose assembly language
interface has the specified
.Fa number
with the specified arguments.
Symbolic constants for system calls can be found in the header file
.Ao Pa syscall.h Ac .
.Pp
.Sh RETURN VALUES
The r0 value of the system call is returned.
When the C-bit is set,
.Fn syscall
returns -1 and sets the
external variable 
.Va errno
(see
.Xr intro 2 ) .
.Sh BUGS
There is no way to simulate system calls
such as
.Xr pipe 2 .
.Sh HISTORY
The
.Nm
function call appeared in
.Bx 4.0 .