/*
 * call-seq:
 *   system_call_error === other  => true or false
 *
 * Return +true+ if the receiver is a generic +SystemCallError+, or
 * if the error numbers _self_ and _other_ are the same.
 */


static VALUE
syserr_eqq(self, exc)
    VALUE self, exc;
{
    VALUE num, e;

    if (!rb_obj_is_kind_of(exc, rb_eSystemCallError)) return Qfalse;
    if (self == rb_eSystemCallError) return Qtrue;

    num = rb_attr_get(exc, rb_intern("errno"));
    if (NIL_P(num)) {
	VALUE klass = CLASS_OF(exc);

	while (TYPE(klass) == T_ICLASS || FL_TEST(klass, FL_SINGLETON)) {
	    klass = (VALUE)RCLASS(klass)->super;
	}
	num = rb_const_get(klass, rb_intern("Errno"));
    }
    e = rb_const_get(self, rb_intern("Errno"));
    if (FIXNUM_P(num) ? num == e : rb_equal(num, e))
	return Qtrue;
    return Qfalse;
}

/*
 * call-seq:
 *   SystemCallError.new(msg, errno)  => system_call_error_subclass
 *
 * If _errno_ corresponds to a known system error code, constructs
 * the appropriate <code>Errno</code> class for that error, otherwise
 * constructs a generic <code>SystemCallError</code> object. The
 * error number is subsequently available via the <code>errno</code>
 * method.
 */

static VALUE
syserr_initialize(argc, argv, self)
    int argc;
    VALUE *argv;
    VALUE self;
{
#if !defined(_WIN32) && !defined(__VMS)
    char *strerror();
#endif
    char *err;
    VALUE mesg, error;
    VALUE klass = rb_obj_class(self);

    if (klass == rb_eSystemCallError) {
	rb_scan_args(argc, argv, "11", &mesg, &error);
	if (argc == 1 && FIXNUM_P(mesg)) {
	    error = mesg; mesg = Qnil;
	}
	if (!NIL_P(error) && st_lookup(syserr_tbl, NUM2LONG(error), &klass)) {
	    /* change class */
	    if (TYPE(self) != T_OBJECT) { /* insurance to avoid type crash */
		rb_raise(rb_eTypeError, "invalid instance type");
	    }
	    RBASIC(self)->klass = klass;
	}
    }
    else {
	rb_scan_args(argc, argv, "01", &mesg);
	error = rb_const_get(klass, rb_intern("Errno"));
    }
    if (!NIL_P(error)) err = strerror(NUM2LONG(error));
    else err = "unknown error";
    if (!NIL_P(mesg)) {
	VALUE str = mesg;
	StringValue(str);
	mesg = rb_str_new(0, strlen(err)+RSTRING(str)->len+3);
	sprintf(RSTRING(mesg)->ptr, "%s - %.*s", err,
		(int)RSTRING(str)->len, RSTRING(str)->ptr);
	rb_str_resize(mesg, strlen(RSTRING(mesg)->ptr));
    }
    else {
	mesg = rb_str_new2(err);
    }
    exc_initialize(1, &mesg, self);
    rb_iv_set(self, "errno", error);
    return self;
}

/*
 * call-seq:
 *   system_call_error.errno   => fixnum
 *
 * Return this SystemCallError's error number.
 */

static VALUE
syserr_errno(self)
    VALUE self;
{
    return rb_attr_get(self, rb_intern("errno"));
}