SystemCallError.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.

Source Code

/*
* 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;
       size_t len;

       StringValue(str);
       len = strlen(err)+RSTRING(str)->len+3;
       mesg = rb_str_new(0, len);
       snprintf(RSTRING(mesg)->ptr, len+1, "%s - %.*s", err,
               (int)RSTRING(str)->len, RSTRING(str)->ptr);
       rb_str_resize(mesg, strlen(RSTRING(mesg)->ptr));
   }
   else {
       mesg = rb_str_new2(err);
   }
   rb_call_super(1, &mesg);
   rb_iv_set(self, "errno", error);
   return self;
}