1 files changed, 53 insertions, 0 deletions
diff --git a/src/runtime/runtime_mmap_test.go b/src/runtime/runtime_mmap_test.go
new file mode 100644
index 0000000..456f913
--- /dev/null
+++ b/src/runtime/runtime_mmap_test.go
@@ -0,0 +1,53 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build unix
+
+package runtime_test
+
+import (
+	"runtime"
+	"testing"
+	"unsafe"
+)
+
+// Test that the error value returned by mmap is positive, as that is
+// what the code in mem_bsd.go, mem_darwin.go, and mem_linux.go expects.
+// See the uses of ENOMEM in sysMap in those files.
+func TestMmapErrorSign(t *testing.T) {
+	p, err := runtime.Mmap(nil, ^uintptr(0)&^(runtime.GetPhysPageSize()-1), 0, runtime.MAP_ANON|runtime.MAP_PRIVATE, -1, 0)
+
+	if p != nil || err != runtime.ENOMEM {
+		t.Errorf("mmap = %v, %v, want nil, %v", p, err, runtime.ENOMEM)
+	}
+}
+
+func TestPhysPageSize(t *testing.T) {
+	// Mmap fails if the address is not page aligned, so we can
+	// use this to test if the page size is the true page size.
+	ps := runtime.GetPhysPageSize()
+
+	// Get a region of memory to play with. This should be page-aligned.
+	b, err := runtime.Mmap(nil, 2*ps, 0, runtime.MAP_ANON|runtime.MAP_PRIVATE, -1, 0)
+	if err != 0 {
+		t.Fatalf("Mmap: %v", err)
+	}
+
+	if runtime.GOOS == "aix" {
+		// AIX does not allow mapping a range that is already mapped.
+		runtime.Munmap(unsafe.Pointer(uintptr(b)), 2*ps)
+	}
+
+	// Mmap should fail at a half page into the buffer.
+	_, err = runtime.Mmap(unsafe.Pointer(uintptr(b)+ps/2), ps, 0, runtime.MAP_ANON|runtime.MAP_PRIVATE|runtime.MAP_FIXED, -1, 0)
+	if err == 0 {
+		t.Errorf("Mmap should have failed with half-page alignment %d, but succeeded: %v", ps/2, err)
+	}
+
+	// Mmap should succeed at a full page into the buffer.
+	_, err = runtime.Mmap(unsafe.Pointer(uintptr(b)+ps), ps, 0, runtime.MAP_ANON|runtime.MAP_PRIVATE|runtime.MAP_FIXED, -1, 0)
+	if err != 0 {
+		t.Errorf("Mmap at full-page alignment %d failed: %v", ps, err)
+	}
+}