github.com/panjjo/go@v0.0.0-20161104043856-d62b31386338/src/runtime/runtime_mmap_test.go (about)

     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  // +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris
     6  
     7  package runtime_test
     8  
     9  import (
    10  	"runtime"
    11  	"testing"
    12  	"unsafe"
    13  )
    14  
    15  // Test that the error value returned by mmap is positive, as that is
    16  // what the code in mem_bsd.go, mem_darwin.go, and mem_linux.go expects.
    17  // See the uses of ENOMEM in sysMap in those files.
    18  func TestMmapErrorSign(t *testing.T) {
    19  	p := runtime.Mmap(nil, ^uintptr(0)&^(runtime.GetPhysPageSize()-1), 0, runtime.MAP_ANON|runtime.MAP_PRIVATE, -1, 0)
    20  
    21  	// The runtime.mmap function is nosplit, but t.Errorf is not.
    22  	// Reset the pointer so that we don't get an "invalid stack
    23  	// pointer" error from t.Errorf if we call it.
    24  	v := uintptr(p)
    25  	p = nil
    26  
    27  	if v != runtime.ENOMEM {
    28  		t.Errorf("mmap = %v, want %v", v, runtime.ENOMEM)
    29  	}
    30  }
    31  
    32  func TestPhysPageSize(t *testing.T) {
    33  	// Mmap fails if the address is not page aligned, so we can
    34  	// use this to test if the page size is the true page size.
    35  	ps := runtime.GetPhysPageSize()
    36  
    37  	// Get a region of memory to play with. This should be page-aligned.
    38  	b := uintptr(runtime.Mmap(nil, 2*ps, 0, runtime.MAP_ANON|runtime.MAP_PRIVATE, -1, 0))
    39  	if b < 4096 {
    40  		t.Fatalf("Mmap: %v", b)
    41  	}
    42  
    43  	// Mmap should fail at a half page into the buffer.
    44  	err := uintptr(runtime.Mmap(unsafe.Pointer(uintptr(b)+ps/2), ps, 0, runtime.MAP_ANON|runtime.MAP_PRIVATE|runtime.MAP_FIXED, -1, 0))
    45  	if err >= 4096 {
    46  		t.Errorf("Mmap should have failed with half-page alignment %d, but succeeded: %v", ps/2, err)
    47  	}
    48  
    49  	// Mmap should succeed at a full page into the buffer.
    50  	err = uintptr(runtime.Mmap(unsafe.Pointer(uintptr(b)+ps), ps, 0, runtime.MAP_ANON|runtime.MAP_PRIVATE|runtime.MAP_FIXED, -1, 0))
    51  	if err < 4096 {
    52  		t.Errorf("Mmap at full-page alignment %d failed: %v", ps, err)
    53  	}
    54  }