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  //go:build unix
     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, err := runtime.Mmap(nil, ^uintptr(0)&^(runtime.GetPhysPageSize()-1), 0, runtime.MAP_ANON|runtime.MAP_PRIVATE, -1, 0)
    20  
    21  	if p != nil || err != runtime.ENOMEM {
    22  		t.Errorf("mmap = %v, %v, want nil, %v", p, err, runtime.ENOMEM)
    23  	}
    24  }
    25  
    26  func TestPhysPageSize(t *testing.T) {
    27  	// Mmap fails if the address is not page aligned, so we can
    28  	// use this to test if the page size is the true page size.
    29  	ps := runtime.GetPhysPageSize()
    30  
    31  	// Get a region of memory to play with. This should be page-aligned.
    32  	b, err := runtime.Mmap(nil, 2*ps, 0, runtime.MAP_ANON|runtime.MAP_PRIVATE, -1, 0)
    33  	if err != 0 {
    34  		t.Fatalf("Mmap: %v", err)
    35  	}
    36  
    37  	if runtime.GOOS == "aix" {
    38  		// AIX does not allow mapping a range that is already mapped.
    39  		runtime.Munmap(unsafe.Pointer(uintptr(b)), 2*ps)
    40  	}
    41  
    42  	// Mmap should fail at a half page into the buffer.
    43  	_, err = runtime.Mmap(unsafe.Pointer(uintptr(b)+ps/2), ps, 0, runtime.MAP_ANON|runtime.MAP_PRIVATE|runtime.MAP_FIXED, -1, 0)
    44  	if err == 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 = runtime.Mmap(unsafe.Pointer(uintptr(b)+ps), ps, 0, runtime.MAP_ANON|runtime.MAP_PRIVATE|runtime.MAP_FIXED, -1, 0)
    50  	if err != 0 {
    51  		t.Errorf("Mmap at full-page alignment %d failed: %v", ps, err)
    52  	}
    53  }
    54
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