syscall

/*
 *  call-seq:
 *     syscall(fixnum [, args...])   => integer
 *  
 *  Calls the operating system function identified by _fixnum_,
 *  passing in the arguments, which must be either +String+
 *  objects, or +Integer+ objects that ultimately fit within
 *  a native +long+. Up to nine parameters may be passed (14
 *  on the Atari-ST). The function identified by _fixnum_ is system
 *  dependent. On some Unix systems, the numbers may be obtained from a
 *  header file called <code>syscall.h</code>.
 *     
 *     syscall 4, 1, "hello\n", 6   # '4' is write(2) on our box
 *     
 *  <em>produces:</em>
 *     
 *     hello
 */

static VALUE
rb_f_syscall(argc, argv)
    int argc;
    VALUE *argv;
{
#if defined(HAVE_SYSCALL) && !defined(__CHECKER__)
#ifdef atarist
    unsigned long arg[14]; /* yes, we really need that many ! */
#else
    unsigned long arg[8];
#endif
    int retval = -1;
    int i = 1;
    int items = argc - 1;

    /* This probably won't work on machines where sizeof(long) != sizeof(int)
     * or where sizeof(long) != sizeof(char*).  But such machines will
     * not likely have syscall implemented either, so who cares?
     */

    rb_secure(2);
    if (argc == 0)
        rb_raise(rb_eArgError, "too few arguments for syscall");
    if (argc > sizeof(arg) / sizeof(arg[0]))
        rb_raise(rb_eArgError, "too many arguments for syscall");
    arg[0] = NUM2LONG(argv[0]); argv++;
    while (items--) {
        VALUE v = rb_check_string_type(*argv);

        if (!NIL_P(v)) {
            StringValue(v);
            rb_str_modify(v);
            arg[i] = (unsigned long)StringValueCStr(v);
        }
        else {
            arg[i] = (unsigned long)NUM2LONG(*argv);
        }
        argv++;
        i++;
    }
    TRAP_BEG;
    switch (argc) {
      case 1:
        retval = syscall(arg[0]);
        break;
      case 2:
        retval = syscall(arg[0],arg[1]);
        break;
      case 3:
        retval = syscall(arg[0],arg[1],arg[2]);
        break;
      case 4:
        retval = syscall(arg[0],arg[1],arg[2],arg[3]);
        break;
      case 5:
        retval = syscall(arg[0],arg[1],arg[2],arg[3],arg[4]);
        break;
      case 6:
        retval = syscall(arg[0],arg[1],arg[2],arg[3],arg[4],arg[5]);
        break;
      case 7:
        retval = syscall(arg[0],arg[1],arg[2],arg[3],arg[4],arg[5],arg[6]);
        break;
      case 8:
        retval = syscall(arg[0],arg[1],arg[2],arg[3],arg[4],arg[5],arg[6],
          arg[7]);
        break;
#ifdef atarist
      case 9:
        retval = syscall(arg[0],arg[1],arg[2],arg[3],arg[4],arg[5],arg[6],
          arg[7], arg[8]);
        break;
      case 10:
        retval = syscall(arg[0],arg[1],arg[2],arg[3],arg[4],arg[5],arg[6],
          arg[7], arg[8], arg[9]);
        break;
      case 11:
        retval = syscall(arg[0],arg[1],arg[2],arg[3],arg[4],arg[5],arg[6],
          arg[7], arg[8], arg[9], arg[10]);
        break;
      case 12:
        retval = syscall(arg[0],arg[1],arg[2],arg[3],arg[4],arg[5],arg[6],
          arg[7], arg[8], arg[9], arg[10], arg[11]);
        break;
      case 13:
        retval = syscall(arg[0],arg[1],arg[2],arg[3],arg[4],arg[5],arg[6],
          arg[7], arg[8], arg[9], arg[10], arg[11], arg[12]);
        break;
      case 14:
        retval = syscall(arg[0],arg[1],arg[2],arg[3],arg[4],arg[5],arg[6],
          arg[7], arg[8], arg[9], arg[10], arg[11], arg[12], arg[13]);
        break;
#endif /* atarist */
    }
    TRAP_END;
    if (retval < 0) rb_sys_fail(0);
    return INT2NUM(retval);
#else
    rb_notimplement();
    return Qnil;                /* not reached */
#endif
}