Exception: SystemCallError

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
Instance Chain:
Inherits: StandardError
Defined in: error.c,


SystemCallError is the base class for all low-level platform-dependent errors.

The errors available on the current platform are subclasses of SystemCallError and are defined in the ::Errno module.


raises the exception:

Errno::ENOENT: No such file or directory - does/not/exist

Class Attribute Summary

::Exception - Inherited


Returns true if exception messages will be sent to a tty.

Class Method Summary

::Exception - Inherited


With no argument, or if the argument is the same as the receiver, return the receiver.


Construct a new ::Exception object, optionally passing in a message.

Instance Method Summary

::Exception - Inherited


Equality—If obj is not an ::Exception, returns false.


Returns any backtrace associated with the exception.


Returns any backtrace associated with the exception.


Returns the previous exception ($!) at the time this exception was raised.


With no argument, or if the argument is the same as the receiver, return the receiver.


Returns formatted string of exception.


Return this exception's class name and message.


Returns the result of invoking exception.to_s.


Sets the backtrace information associated with exc.


Returns exception's message (or the name of the exception if no message is set).

Constructor Details

.new(msg, errno) ⇒ system_call_error_subclass

If errno corresponds to a known system error code, constructs the appropriate ::Errno class for that error, otherwise constructs a generic SystemCallError object. The error number is subsequently available via the #errno method.

[ GitHub ]

# File 'error.c', line 1943

static VALUE
syserr_initialize(int argc, VALUE *argv, VALUE self)
#if !defined(_WIN32)
    char *strerror();
    const char *err;
    VALUE mesg, error, func, errmsg;
    VALUE klass = rb_obj_class(self);

    if (klass == rb_eSystemCallError) {
	st_data_t data = (st_data_t)klass;
	rb_scan_args(argc, argv, "12", &mesg, &error, &func);
	if (argc == 1 && FIXNUM_P(mesg)) {
	    error = mesg; mesg = Qnil;
	if (!NIL_P(error) && st_lookup(syserr_tbl, NUM2LONG(error), &data)) {
	    klass = (VALUE)data;
	    /* change class */
	    if (!RB_TYPE_P(self, T_OBJECT)) { /* insurance to avoid type crash */
		rb_raise(rb_eTypeError, "invalid instance type");
	    RBASIC_SET_CLASS(self, klass);
    else {
	rb_scan_args(argc, argv, "02", &mesg, &func);
	error = rb_const_get(klass, id_Errno);
    if (!NIL_P(error)) err = strerror(NUM2INT(error));
    else err = "unknown error";

    errmsg = rb_enc_str_new_cstr(err, rb_locale_encoding());
    if (!NIL_P(mesg)) {
	VALUE str = StringValue(mesg);

	if (!NIL_P(func)) rb_str_catf(errmsg, " @ %"PRIsVALUE, func);
	rb_str_catf(errmsg, " - %"PRIsVALUE, str);
	OBJ_INFECT(errmsg, mesg);
    mesg = errmsg;

    rb_call_super(1, &mesg);
    rb_ivar_set(self, id_errno, error);
    return self;

Class Method Details

.===(other) ⇒ Boolean

Return true if the receiver is a generic SystemCallError, or if the error numbers self and other are the same.

[ GitHub ]

# File 'error.c', line 2011

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

    if (!rb_obj_is_kind_of(exc, rb_eSystemCallError)) {
	if (!rb_respond_to(exc, id_errno)) return Qfalse;
    else if (self == rb_eSystemCallError) return Qtrue;

    num = rb_attr_get(exc, id_errno);
    if (NIL_P(num)) {
	num = rb_funcallv(exc, id_errno, 0, 0);
    e = rb_const_get(self, id_Errno);
    if (FIXNUM_P(num) ? num == e : rb_equal(num, e))
	return Qtrue;
    return Qfalse;

Instance Method Details


Return this SystemCallError's error number.

[ GitHub ]

# File 'error.c', line 1997

static VALUE
syserr_errno(VALUE self)
    return rb_attr_get(self, id_errno);