MirOS Manual: syscall(2), __syscall(2)

SYSCALL(2)                 BSD 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, ...);

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>.

     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 gen-
     eral, 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).

MirOS BSD #10-current           June 16, 1993                                1

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