NAME    [Toc]    [Back]

     syscall, __syscall - indirect system call

SYNOPSIS    [Toc]    [Back]

     #include <sys/syscall.h>
     #include <unistd.h>

     int
     syscall(int number, ...);

     int
     __syscall(quad_t number, ...);

DESCRIPTION    [Toc]    [Back]

     syscall() performs the system call whose  assembly  language
interface has
     the specified number with the specified arguments.  Symbolic
constants
     for  system  calls  can  be  found  in   the   header   file
<sys/syscall.h>.  The
     __syscall form should be used when one or more of the parameters is a
     64-bit argument to ensure that argument  alignment  is  correct.  This system
  call is useful for testing new system calls that do not
have entries
     in the C library.

RETURN VALUES    [Toc]    [Back]

     The return values are defined by the system call  being  invoked.  In general,
 a 0 return value indicates success.  A -1 return value
indicates an
     error, and an error code is stored in errno.

HISTORY    [Toc]    [Back]

     The syscall() function call appeared in 4.0BSD.

BUGS    [Toc]    [Back]

     There is no way to simulate system calls that have  multiple
return values
     such as pipe(2).

OpenBSD      3.6                           June      16,     1993