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
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);
return RBOOL(FIXNUM_P(num) ? num == e : rb_equal(num, e));
}
Return true if the receiver is a generic SystemCallError, or if the error numbers self and other are the same.
static VALUE
syserr_initialize(int argc, VALUE *argv, VALUE self)
{
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);
}
mesg = errmsg;
rb_call_super(1, &mesg);
rb_ivar_set(self, id_errno, error);
return self;
}
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.
If only numeric object is given, it is treated as an Integer errno, and msg is omitted, otherwise the first argument msg is used as the additional error message.
SystemCallError.new(Errno::EPIPE::Errno) #=> #<Errno::EPIPE: Broken pipe> SystemCallError.new("foo") #=> #<SystemCallError: unknown error - foo> SystemCallError.new("foo", Errno::EPIPE::Errno) #=> #<Errno::EPIPE: Broken pipe - foo>
If func is not nil, it is appended to the message with “ @ ”.
SystemCallError.new("foo", Errno::EPIPE::Errno, "here") #=> #<Errno::EPIPE: Broken pipe @ here - foo>
A subclass of SystemCallError can also be instantiated via the new method of the subclass. See Errno.
static VALUE
syserr_errno(VALUE self)
{
return rb_attr_get(self, id_errno);
}
Return this SystemCallError’s error number.