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Source file src/runtime/runtime_mmap_test.go

Documentation: runtime

  // 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.
  
  // +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris
  
  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 := runtime.Mmap(nil, ^uintptr(0)&^(runtime.GetPhysPageSize()-1), 0, runtime.MAP_ANON|runtime.MAP_PRIVATE, -1, 0)
  
  	// The runtime.mmap function is nosplit, but t.Errorf is not.
  	// Reset the pointer so that we don't get an "invalid stack
  	// pointer" error from t.Errorf if we call it.
  	v := uintptr(p)
  	p = nil
  
  	if v != runtime.ENOMEM {
  		t.Errorf("mmap = %v, want %v", v, 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 := uintptr(runtime.Mmap(nil, 2*ps, 0, runtime.MAP_ANON|runtime.MAP_PRIVATE, -1, 0))
  	if b < 4096 {
  		t.Fatalf("Mmap: %v", b)
  	}
  
  	// Mmap should fail at a half page into the buffer.
  	err := uintptr(runtime.Mmap(unsafe.Pointer(uintptr(b)+ps/2), ps, 0, runtime.MAP_ANON|runtime.MAP_PRIVATE|runtime.MAP_FIXED, -1, 0))
  	if err >= 4096 {
  		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 = uintptr(runtime.Mmap(unsafe.Pointer(uintptr(b)+ps), ps, 0, runtime.MAP_ANON|runtime.MAP_PRIVATE|runtime.MAP_FIXED, -1, 0))
  	if err < 4096 {
  		t.Errorf("Mmap at full-page alignment %d failed: %v", ps, err)
  	}
  }
  

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