NAME
syscall, __syscall
— indirect system
call
LIBRARY
library “libc”
SYNOPSIS
#include
<sys/syscall.h>
#include <unistd.h>
int
syscall(int
number, ...);
off_t
__syscall(quad_t
number, ...);
DESCRIPTION
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
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
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).