libgo/go/runtime/runtime_mmap_test.go

   1 // Copyright 2016 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 package runtime_test
   6
   7 import (
   8         "runtime"
   9         "testing"
  10         "unsafe"
  11 )
  12
  13 // Test that the error value returned by mmap is positive, as that is
  14 // what the code in mem_bsd.go, mem_darwin.go, and mem_linux.go expects.
  15 // See the uses of ENOMEM in sysMap in those files.
  16 func TestMmapErrorSign(t *testing.T) {
  17         p := runtime.Mmap(nil, ^uintptr(0)&^(runtime.GetPhysPageSize()-1), 0, runtime.MAP_ANON|runtime.MAP_PRIVATE, -1, 0)
  18
  19         // The runtime.mmap function is nosplit, but t.Errorf is not.
  20         // Reset the pointer so that we don't get an "invalid stack
  21         // pointer" error from t.Errorf if we call it.
  22         v := uintptr(p)
  23         p = nil
  24
  25         err := runtime.Errno()
  26         if v != ^uintptr(0) || err != runtime.ENOMEM {
  27                 t.Errorf("mmap = %v, %v, want %v", v, err, runtime.ENOMEM)
  28         }
  29 }
  30
  31 func TestPhysPageSize(t *testing.T) {
  32         // Mmap fails if the address is not page aligned, so we can
  33         // use this to test if the page size is the true page size.
  34         ps := runtime.GetPhysPageSize()
  35
  36         // Get a region of memory to play with. This should be page-aligned.
  37         b := uintptr(runtime.Mmap(nil, 2*ps, 0, runtime.MAP_ANON|runtime.MAP_PRIVATE, -1, 0))
  38         if b == ^uintptr(0) {
  39                 t.Fatalf("Mmap: %v %v", b, runtime.Errno())
  40         }
  41
  42         // Mmap should fail at a half page into the buffer.
  43         err := uintptr(runtime.Mmap(unsafe.Pointer(uintptr(b)+ps/2), ps, 0, runtime.MAP_ANON|runtime.MAP_PRIVATE|runtime.MAP_FIXED, -1, 0))
  44         if err != ^uintptr(0) {
  45                 t.Errorf("Mmap should have failed with half-page alignment %d, but succeeded: %v", ps/2, err)
  46         }
  47
  48         // Mmap should succeed at a full page into the buffer.
  49         err = uintptr(runtime.Mmap(unsafe.Pointer(uintptr(b)+ps), ps, 0, runtime.MAP_ANON|runtime.MAP_PRIVATE|runtime.MAP_FIXED, -1, 0))
  50         if err == ^uintptr(0) {
  51                 t.Errorf("Mmap at full-page alignment %d failed: %v %v", ps, err, runtime.Errno())
  52         }
  53 }