[ruby/io-wait] Don't add IO#wait* methods when RUBY_IO_WAIT_METHODS is defined by Ruby. (https://github.com/ruby/io-wait/pull/19)

* Fix return value compatibility with Ruby 2.x.

* Don't add `IO#wait*` methods in Ruby 3.2+.

https://github.com/ruby/io-wait/commit/54c504d089

ext/io/wait/wait.c

@@ -95,21 +95,24 @@ io_nread(VALUE io)
 
 #ifdef HAVE_RB_IO_WAIT
 static VALUE
-io_wait_event(VALUE io, int event, VALUE timeout)
+io_wait_event(VALUE io, int event, VALUE timeout, int return_io)
 {
     VALUE result = rb_io_wait(io, RB_INT2NUM(event), timeout);
 
     if (!RB_TEST(result)) {
-	return Qnil;
+        return Qnil;
     }
 
     int mask = RB_NUM2INT(result);
 
     if (mask & event) {
-	return io;
+        if (return_io)
+            return io;
+        else
+            return result;
     }
     else {
-	return Qfalse;
+        return Qfalse;
     }
 }
 #endif
@@ -137,15 +140,15 @@ io_ready_p(VALUE io)
     if (rb_io_read_pending(fptr)) return Qtrue;
 
 #ifndef HAVE_RB_IO_WAIT
-    if (wait_for_single_fd(fptr, RB_WAITFD_IN, &tv))
+    return wait_for_single_fd(fptr, RB_WAITFD_IN, &tv) ? Qtrue : Qfalse;
-	return Qtrue;
 #else
-    if (RTEST(io_wait_event(io, RUBY_IO_READABLE, RB_INT2NUM(0))))
+    return io_wait_event(io, RUBY_IO_READABLE, RB_INT2NUM(0), 1);
-	return Qtrue;
 #endif
-    return Qfalse;
 }
 
+// Ruby 3.2+ can define these methods. This macro indicates that case.
+#ifndef RUBY_IO_WAIT_METHODS
+
 /*
  * call-seq:
  *   io.wait_readable          -> truthy or falsy
@@ -184,7 +187,7 @@ io_wait_readable(int argc, VALUE *argv, VALUE io)
     rb_check_arity(argc, 0, 1);
     VALUE timeout = (argc == 1 ? argv[0] : Qnil);
 
-    return io_wait_event(io, RUBY_IO_READABLE, timeout);
+    return io_wait_event(io, RUBY_IO_READABLE, timeout, 1);
 #endif
 }
 
@@ -220,7 +223,7 @@ io_wait_writable(int argc, VALUE *argv, VALUE io)
     rb_check_arity(argc, 0, 1);
     VALUE timeout = (argc == 1 ? argv[0] : Qnil);
 
-    return io_wait_event(io, RUBY_IO_WRITABLE, timeout);
+    return io_wait_event(io, RUBY_IO_WRITABLE, timeout, 1);
 #endif
 }
 
@@ -231,7 +234,8 @@ io_wait_writable(int argc, VALUE *argv, VALUE io)
  *   io.wait_priority(timeout) -> truthy or falsy
  *
  * Waits until IO is priority and returns a truthy value or a falsy
- * value when times out.
+ * value when times out. Priority data is sent and received using
+ * the Socket::MSG_OOB flag and is typically limited to streams.
  *
  * You must require 'io/wait' to use this method.
  */
@@ -248,7 +252,7 @@ io_wait_priority(int argc, VALUE *argv, VALUE io)
     rb_check_arity(argc, 0, 1);
     VALUE timeout = argc == 1 ? argv[0] : Qnil;
 
-    return io_wait_event(io, RUBY_IO_PRIORITY, timeout);
+    return io_wait_event(io, RUBY_IO_PRIORITY, timeout, 1);
 }
 #endif
 
@@ -286,10 +290,22 @@ wait_mode_sym(VALUE mode)
     return 0;
 }
 
+#ifdef HAVE_RB_IO_WAIT
+static inline rb_io_event_t
+io_event_from_value(VALUE value)
+{
+    int events = RB_NUM2INT(value);
+
+    if (events <= 0) rb_raise(rb_eArgError, "Events must be positive integer!");
+
+    return events;
+}
+#endif
+
 /*
  * call-seq:
- *   io.wait(events, timeout) -> truthy or falsy
+ *   io.wait(events, timeout) -> event mask, false or nil
- *   io.wait(timeout = nil, mode = :read) -> truthy or falsy.
+ *   io.wait(timeout = nil, mode = :read) -> self, true, or false
  *
  * Waits until the IO becomes ready for the specified events and returns the
  * subset of events that become ready, or a falsy value when times out.
@@ -335,43 +351,59 @@ io_wait(int argc, VALUE *argv, VALUE io)
 #else
     VALUE timeout = Qundef;
     rb_io_event_t events = 0;
+    int return_io = 0;
 
+    // The documented signature for this method is actually incorrect.
+    // A single timeout is allowed in any position, and multiple symbols can be given.
+    // Whether this is intentional or not, I don't know, and as such I consider this to
+    // be a legacy/slow path.
     if (argc != 2 || (RB_SYMBOL_P(argv[0]) || RB_SYMBOL_P(argv[1]))) {
-	for (int i = 0; i < argc; i += 1) {
+        // We'd prefer to return the actual mask, but this form would return the io itself:
-	    if (RB_SYMBOL_P(argv[i])) {
+        return_io = 1;
-		events |= wait_mode_sym(argv[i]);
-	    }
-	    else if (timeout == Qundef) {
-		rb_time_interval(timeout = argv[i]);
-	    }
-	    else {
-		rb_raise(rb_eArgError, "timeout given more than once");
-	    }
-	}
-	if (timeout == Qundef) timeout = Qnil;
-    }
-    else /* argc == 2 */ {
-	events = RB_NUM2UINT(argv[0]);
-	timeout = argv[1];
-    }
 
-    if (events == 0) {
+        // Slow/messy path:
-	events = RUBY_IO_READABLE;
+        for (int i = 0; i < argc; i += 1) {
+            if (RB_SYMBOL_P(argv[i])) {
+                events |= wait_mode_sym(argv[i]);
+            }
+            else if (timeout == Qundef) {
+                rb_time_interval(timeout = argv[i]);
+            }
+            else {
+                rb_raise(rb_eArgError, "timeout given more than once");
+            }
+        }
+
+        if (timeout == Qundef) timeout = Qnil;
+
+        if (events == 0) {
+            events = RUBY_IO_READABLE;
+        }
+    }
+    else /* argc == 2 and neither are symbols */ {
+        // This is the fast path:
+        events = io_event_from_value(argv[0]);
+        timeout = argv[1];
     }
 
     if (events & RUBY_IO_READABLE) {
-	rb_io_t *fptr = NULL;
+        rb_io_t *fptr = NULL;
-	RB_IO_POINTER(io, fptr);
+        RB_IO_POINTER(io, fptr);
 
-	if (rb_io_read_pending(fptr)) {
+        if (rb_io_read_pending(fptr)) {
-	    return Qtrue;
+            // This was the original behaviour:
-	}
+            if (return_io) return Qtrue;
+            // New behaviour always returns an event mask:
+            else return RB_INT2NUM(RUBY_IO_READABLE);
+        }
     }
 
-    return io_wait_event(io, events, timeout);
+    return io_wait_event(io, events, timeout, return_io);
 #endif
 }
 
+#endif /* RUBY_IO_WAIT_METHODS */
+
 /*
  * IO wait methods
  */
@@ -386,6 +418,7 @@ Init_wait(void)
     rb_define_method(rb_cIO, "nread", io_nread, 0);
     rb_define_method(rb_cIO, "ready?", io_ready_p, 0);
 
+#ifndef RUBY_IO_WAIT_METHODS
     rb_define_method(rb_cIO, "wait", io_wait, -1);
 
     rb_define_method(rb_cIO, "wait_readable", io_wait_readable, -1);
@@ -393,4 +426,5 @@ Init_wait(void)
 #ifdef HAVE_RB_IO_WAIT
     rb_define_method(rb_cIO, "wait_priority", io_wait_priority, -1);
 #endif
+#endif
 }

test/io/wait/test_io_wait.rb

@@ -161,6 +161,34 @@ class TestIOWait < Test::Unit::TestCase
     assert_equal @w, @w.wait(0.01, :read_write)
   end
 
+  def test_wait_mask_writable
+    omit("Missing IO::WRITABLE!") unless IO.const_defined?(:WRITABLE)
+    assert_equal IO::WRITABLE, @w.wait(IO::WRITABLE, 0)
+  end
+  
+  def test_wait_mask_readable
+    omit("Missing IO::READABLE!") unless IO.const_defined?(:READABLE)
+    @w.write("Hello World\n" * 3)
+    assert_equal IO::READABLE, @r.wait(IO::READABLE, 0)
+    
+    @r.gets
+    assert_equal IO::READABLE, @r.wait(IO::READABLE, 0)
+  end
+
+  def test_wait_mask_zero
+    omit("Missing IO::WRITABLE!") unless IO.const_defined?(:WRITABLE)
+    assert_raises(ArgumentError) do
+      @w.wait(0, 0)
+    end
+  end
+
+  def test_wait_mask_negative
+    omit("Missing IO::WRITABLE!") unless IO.const_defined?(:WRITABLE)
+    assert_raises(ArgumentError) do
+      @w.wait(-6, 0)
+    end
+  end
+
 private
 
   def fill_pipe