|SYSCALL(2)||System Calls Manual||SYSCALL(2)|
— indirect system call
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
Since different system calls have different return types, a
__syscall specifying the correct return
type should be declared locally. This is especially important for system
calls returning larger-than-int results.
__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.
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.
syscall() function call appeared in
There is no way to simulate system calls that have multiple return values such as pipe(2).
|May 31, 2007||OpenBSD-5.1|