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.
File.open("does/not/exist")
raises the exception:
Errno::ENOENT: No such file or directory - does/not/exist
Return true if the receiver is a generic SystemCallError, or if the error numbers self and other are the same.
static VALUE
syserr_eqq(VALUE self, VALUE exc)
{
VALUE num, e;
ID en;
CONST_ID(en, "errno");
if (!rb_obj_is_kind_of(exc, rb_eSystemCallError)) {
if (!rb_respond_to(exc, en)) return Qfalse;
}
else if (self == rb_eSystemCallError) return Qtrue;
num = rb_attr_get(exc, rb_intern("errno"));
if (NIL_P(num)) {
num = rb_funcall(exc, en, 0, 0);
}
e = rb_const_get(self, rb_intern("Errno"));
if (FIXNUM_P(num) ? num == e : rb_equal(num, e))
return Qtrue;
return Qfalse;
}
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.
static VALUE
syserr_initialize(int argc, VALUE *argv, VALUE self)
{
#if !defined(_WIN32)
char *strerror();
#endif
const 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(NUM2INT(error));
else err = "unknown error";
if (!NIL_P(mesg)) {
VALUE str = mesg;
StringValue(str);
mesg = rb_sprintf("%s - %.*s", err,
(int)RSTRING_LEN(str), RSTRING_PTR(str));
}
else {
mesg = rb_str_new2(err);
}
rb_enc_associate(mesg, rb_locale_encoding());
rb_call_super(1, &mesg);
rb_iv_set(self, "errno", error);
return self;
}