syscall, __syscall - indirect system call
syscall(int number, ...);
__syscall(quad_t number, ...);
syscall() performs the system call whose assembly language
the specified number with the specified arguments. Symbolic
for system calls can be found in the header file
__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
in the C library.
The return values are defined by the system call being invoked. In general,
a 0 return value indicates success. A -1 return value
error, and an error code is stored in errno.
The syscall() function call appeared in 4.0BSD.
There is no way to simulate system calls that have multiple
such as pipe(2).
OpenBSD 3.6 June 16, 1993
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