SYSCALL(2) OpenBSD Programmer's Manual SYSCALL(2)NAME
syscall, __syscall - indirect system call
SYNOPSIS
#include <sys/syscall.h>
#include <unistd.h>
int
syscall(int number, ...);
__syscall(quad_t number, ...);
DESCRIPTIONsyscall() 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>.
Since different system calls have different return types, a prototype of
__syscall specifying the correct return type should be declared locally.
This is especially important for system calls returning larger-than-int
results.
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
The return values are defined by the system call being invoked. In
general, for system calls returning int, a 0 return value indicates
success. A -1 return value indicates an error, and an error code is
stored in errno.
HISTORY
The syscall() function call appeared in 4.0BSD.
BUGS
There is no way to simulate system calls that have multiple return values
such as pipe(2).
OpenBSD 4.9 May 31, 2007 OpenBSD 4.9
