github.com/twelsh-aw/go/src@v0.0.0-20230516233729-a56fe86a7c81/runtime/memmove_linux_amd64_test.go (about)

     1  // Copyright 2013 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  	"os"
     9  	"syscall"
    10  	"testing"
    11  	"unsafe"
    12  )
    13  
    14  // TestMemmoveOverflow maps 3GB of memory and calls memmove on
    15  // the corresponding slice.
    16  func TestMemmoveOverflow(t *testing.T) {
    17  	t.Parallel()
    18  	// Create a temporary file.
    19  	tmp, err := os.CreateTemp("", "go-memmovetest")
    20  	if err != nil {
    21  		t.Fatal(err)
    22  	}
    23  	_, err = tmp.Write(make([]byte, 65536))
    24  	if err != nil {
    25  		t.Fatal(err)
    26  	}
    27  	defer os.Remove(tmp.Name())
    28  	defer tmp.Close()
    29  
    30  	// Set up mappings.
    31  	base, _, errno := syscall.Syscall6(syscall.SYS_MMAP,
    32  		0xa0<<32, 3<<30, syscall.PROT_READ|syscall.PROT_WRITE, syscall.MAP_PRIVATE|syscall.MAP_ANONYMOUS, ^uintptr(0), 0)
    33  	if errno != 0 {
    34  		t.Skipf("could not create memory mapping: %s", errno)
    35  	}
    36  	syscall.Syscall(syscall.SYS_MUNMAP, base, 3<<30, 0)
    37  
    38  	for off := uintptr(0); off < 3<<30; off += 65536 {
    39  		_, _, errno := syscall.Syscall6(syscall.SYS_MMAP,
    40  			base+off, 65536, syscall.PROT_READ|syscall.PROT_WRITE, syscall.MAP_SHARED|syscall.MAP_FIXED, tmp.Fd(), 0)
    41  		if errno != 0 {
    42  			t.Skipf("could not map a page at requested 0x%x: %s", base+off, errno)
    43  		}
    44  		defer syscall.Syscall(syscall.SYS_MUNMAP, base+off, 65536, 0)
    45  	}
    46  
    47  	s := unsafe.Slice((*byte)(unsafe.Pointer(base)), 3<<30)
    48  	n := copy(s[1:], s)
    49  	if n != 3<<30-1 {
    50  		t.Fatalf("copied %d bytes, expected %d", n, 3<<30-1)
    51  	}
    52  	n = copy(s, s[1:])
    53  	if n != 3<<30-1 {
    54  		t.Fatalf("copied %d bytes, expected %d", n, 3<<30-1)
    55  	}
    56  }