Merge pull request #175 from simleb/master

Fix #174 ptr() panic on uintptr

2 files changed, 43 insertions, 1 deletions

diff --git a/gl.go b/gl.go
index 1763b05..82f237c 100644
--- a/gl.go
+++ b/gl.go
@@ -54,7 +54,7 @@ func freeString(ptr *C.GLchar) { C.free(unsafe.Pointer(ptr)) }
 
 func ptr(v interface{}) unsafe.Pointer {
 
-	if v == nil || reflect.ValueOf(v).IsNil() {
+	if v == nil {
 		return unsafe.Pointer(nil)
 	}
 
@@ -65,8 +65,14 @@ func ptr(v interface{}) unsafe.Pointer {
 		offset, _ := v.(uintptr)
 		return unsafe.Pointer(offset)
 	case reflect.Ptr:
+		if rv.IsNil() {
+			return unsafe.Pointer(nil)
+		}
 		et = rv.Elem()
 	case reflect.Slice:
+		if rv.IsNil() || rv.Len() == 0 {
+			return unsafe.Pointer(nil)
+		}
 		et = rv.Index(0)
 	default:
 		panic("type must be a pointer, a slice, uintptr or nil")
diff --git a/gl_test.go b/gl_test.go
new file mode 100644
index 0000000..8aba62c
--- /dev/null
+++ b/gl_test.go
@@ -0,0 +1,36 @@
+// Copyright 2012 The go-gl Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package gl
+
+import (
+	"testing"
+	"unsafe"
+)
+
+func TestPtr(t *testing.T) {
+	// test nil
+	if p, q := unsafe.Pointer(nil), ptr(nil); p != q {
+		t.Fatalf("expected %#v, got %#v\n", p, q)
+	}
+
+	// test nil interface
+	var r interface{}
+	if p, q := unsafe.Pointer(nil), ptr(r); p != q {
+		t.Fatalf("expected %#v, got %#v\n", p, q)
+	}
+
+	// test nil pointer
+	var s *int
+	if p, q := unsafe.Pointer(nil), ptr(s); p != q {
+		t.Fatalf("expected %#v, got %#v\n", p, q)
+	}
+
+	// test uinptr
+	for _, n := range []uintptr{0, 1, 2, 42} {
+		if p, q := unsafe.Pointer(n), ptr(n); p != q {
+			t.Fatalf("expected %#v, got %#v\n", p, q)
+		}
+	}
+}