runtime_mmap_test.go

Documentation: runtime

     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  //go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris
     6  // +build aix darwin dragonfly freebsd linux netbsd openbsd solaris
     7  
     8  package runtime_test
     9  
    10  import (
    11  	"runtime"
    12  	"testing"
    13  	"unsafe"
    14  )
    15  
    16  // Test that the error value returned by mmap is positive, as that is
    17  // what the code in mem_bsd.go, mem_darwin.go, and mem_linux.go expects.
    18  // See the uses of ENOMEM in sysMap in those files.
    19  func TestMmapErrorSign(t *testing.T) {
    20  	p, err := runtime.Mmap(nil, ^uintptr(0)&^(runtime.GetPhysPageSize()-1), 0, runtime.MAP_ANON|runtime.MAP_PRIVATE, -1, 0)
    21  
    22  	if p != nil || err != runtime.ENOMEM {
    23  		t.Errorf("mmap = %v, %v, want nil, %v", p, err, runtime.ENOMEM)
    24  	}
    25  }
    26  
    27  func TestPhysPageSize(t *testing.T) {
    28  	// Mmap fails if the address is not page aligned, so we can
    29  	// use this to test if the page size is the true page size.
    30  	ps := runtime.GetPhysPageSize()
    31  
    32  	// Get a region of memory to play with. This should be page-aligned.
    33  	b, err := runtime.Mmap(nil, 2*ps, 0, runtime.MAP_ANON|runtime.MAP_PRIVATE, -1, 0)
    34  	if err != 0 {
    35  		t.Fatalf("Mmap: %v", err)
    36  	}
    37  
    38  	if runtime.GOOS == "aix" {
    39  		// AIX does not allow mapping a range that is already mapped.
    40  		runtime.Munmap(unsafe.Pointer(uintptr(b)), 2*ps)
    41  	}
    42  
    43  	// Mmap should fail at a half page into the buffer.
    44  	_, err = runtime.Mmap(unsafe.Pointer(uintptr(b)+ps/2), ps, 0, runtime.MAP_ANON|runtime.MAP_PRIVATE|runtime.MAP_FIXED, -1, 0)
    45  	if err == 0 {
    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 = runtime.Mmap(unsafe.Pointer(uintptr(b)+ps), ps, 0, runtime.MAP_ANON|runtime.MAP_PRIVATE|runtime.MAP_FIXED, -1, 0)
    51  	if err != 0 {
    52  		t.Errorf("Mmap at full-page alignment %d failed: %v", ps, err)
    53  	}
    54  }
    55
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