bsd/man/man2/syscall.2

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  34 .\"     @(#)syscall.2   8.1 (Berkeley) 6/16/93
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  36 .Dd June 16, 1993
  37 .Dt SYSCALL 2
  38 .Os BSD 4
  39 .Sh NAME
  40 .Nm syscall ,
  41 .Nm __syscall
  42 .Nd indirect system call
  43 .Sh SYNOPSIS
  44 .Fd #include <sys/syscall.h>
  45 .Fd #include <unistd.h>
  46 .Ft int
  47 .Fn syscall "int number" "..."
  48 .Ft int
  49 .Fn __syscall "quad_t number" "..."
  50 .Sh DESCRIPTION
  51 .Fn Syscall
  52 performs the system call whose assembly language
  53 interface has the specified
  54 .Fa number
  55 with the specified arguments.
  56 Symbolic constants for system calls can be found in the header file
  57 .Ao Pa sys/syscall.h Ac .
  58 The
  59 .Nm __syscall
  60 form should be used when one or more of the parameters is a
  61 64-bit argument to ensure that argument alignment is correct.
  62 This system call is useful for testing new system calls that
  63 do not have entries in the C library.
  64 .Sh RETURN VALUES
  65 The return values are defined by the system call being invoked.
  66 In general, a 0 return value indicates success.
  67 A -1 return value indicates an error,
  68 and an error code is stored in
  69 .Va errno .
  70 .Sh BUGS
  71 There is no way to simulate system calls that have multiple return values
  72 such as
  73 .Xr pipe 2 .
  74 .Sh HISTORY
  75 The
  76 .Fn syscall
  77 function call appeared in
  78 .Bx 4.0 .