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package cluster
// poc_test.go contains proof of concept tests for the byte-range locking logic.
// This goes directly to an underlying filesystem without going through gocryptfs.
import (
"bytes"
"errors"
"io"
"os"
"sync"
"sync/atomic"
"syscall"
"testing"
"golang.org/x/sys/unix"
"github.com/rfjakob/gocryptfs/v2/internal/contentenc"
"github.com/rfjakob/gocryptfs/v2/internal/syscallcompat"
"github.com/rfjakob/gocryptfs/v2/tests/test_helpers"
)
// Check that byte-range locks work on an empty file
func TestPoCFcntlFlock(t *testing.T) {
path := test_helpers.TmpDir + "/" + t.Name()
fd1, err := syscall.Open(path, syscall.O_CREAT|syscall.O_WRONLY|syscall.O_EXCL, 0600)
if err != nil {
t.Fatal(err)
}
defer syscall.Close(fd1)
// F_OFD_SETLK locks on the same fd always succeed, so we have to
// open a 2nd time.
fd2, err := syscall.Open(path, syscall.O_RDWR, 0)
if err != nil {
t.Fatal(err)
}
defer syscall.Close(fd2)
lk := unix.Flock_t{
Type: unix.F_WRLCK,
Whence: unix.SEEK_SET,
Start: 0,
Len: 0,
}
err = unix.FcntlFlock(uintptr(fd1), unix.F_OFD_SETLK, &lk)
if err != nil {
t.Fatal(err)
}
err = unix.FcntlFlock(uintptr(fd2), unix.F_OFD_SETLK, &lk)
if err == nil {
t.Fatal("double-lock succeeded but should have failed")
}
}
// See if we can get garbage data when the file header is read and written concurrently.
// We should get either 0 bytes or 18 correct bytes.
func TestPoCHeaderCreation(t *testing.T) {
path := test_helpers.TmpDir + "/" + t.Name()
var wg sync.WaitGroup
// I ran this with 10000 iteration and no problems to be seen. Let's not waste too
// much testing time.
const loops = 100
var stats struct {
readOk int64
readEmpty int64
writes int64
}
writeBuf := []byte("123456789012345678")
if len(writeBuf) != contentenc.HeaderLen {
t.Fatal("BUG wrong header length")
}
writerThread := func() {
defer wg.Done()
for i := 0; i < loops; i++ {
if t.Failed() {
return
}
f, err := os.OpenFile(path, os.O_CREATE|os.O_RDWR|os.O_EXCL, 0600)
if err != nil {
t.Errorf("BUG: this should not happen: open err=%v", err)
return
}
// Do like gocryptfs does and prealloc the 18 bytes
err = syscallcompat.EnospcPrealloc(int(f.Fd()), 0, contentenc.HeaderLen)
_, err = f.WriteAt(writeBuf, 0)
if err != nil {
t.Errorf("iteration %d: Pwrite: %v", i, err)
}
atomic.AddInt64(&stats.writes, 1)
f.Close()
syscall.Unlink(path)
}
}
readerThread := func() {
defer wg.Done()
for i := 0; i < loops; i++ {
if t.Failed() {
return
}
f, err := os.OpenFile(path, os.O_RDONLY, 0600)
if errors.Is(err, os.ErrNotExist) {
continue
}
if err != nil {
t.Error(err)
return
}
readBuf := make([]byte, contentenc.HeaderLen)
_, err = f.ReadAt(readBuf, 0)
if errors.Is(err, io.EOF) {
atomic.AddInt64(&stats.readEmpty, 1)
goto close
}
if err != nil {
t.Errorf("iteration %d: ReadAt: %v", i, err)
goto close
}
if !bytes.Equal(writeBuf, readBuf) {
t.Errorf("iteration %d: corrupt data received: %x", i, readBuf)
goto close
}
atomic.AddInt64(&stats.readOk, 1)
close:
f.Close()
}
}
wg.Add(2)
go writerThread()
go readerThread()
wg.Wait()
t.Logf("readEmpty=%d readOk=%d writes=%d", stats.readEmpty, stats.readOk, stats.writes)
}
// TestPoCTornWrite simulates what TestConcurrentCreate does.
//
// Fails on ext4, quoting https://stackoverflow.com/a/35256626 :
// > Linux 4.2.6 with ext4: update atomicity = 1 byte
//
// Passes on XFS.
func TestPoCTornWrite(t *testing.T) {
if os.Getenv("ENABLE_CLUSTER_TEST") != "1" {
t.Skipf("This test is disabled by default because it fails unless on XFS.\n" +
"Run it like this: ENABLE_CLUSTER_TEST=1 go test\n" +
"Choose a backing directory by setting TMPDIR.")
}
path := test_helpers.TmpDir + "/" + t.Name()
var wg sync.WaitGroup
const loops = 10000
writerThread := func() {
defer wg.Done()
for i := 0; i < loops; i++ {
if t.Failed() {
return
}
f, err := os.OpenFile(path, os.O_CREATE|os.O_RDWR, 0600)
if err != nil {
t.Errorf("BUG: this should not happen: open err=%v", err)
return
}
// Write
blockData := bytes.Repeat([]byte{byte(i)}, 42)
if _, err = f.WriteAt(blockData, 0); err != nil {
t.Errorf("iteration %d: WriteAt: %v", i, err)
return
}
// Readback and verify
readBuf := make([]byte, 100)
if n, err := f.ReadAt(readBuf, 0); err == io.EOF {
readBuf = readBuf[:n]
} else if err != nil {
t.Error(err)
return
}
if len(readBuf) != len(blockData) {
t.Error("wrong length")
return
}
for _, v := range readBuf {
if v != readBuf[0] {
t.Errorf("iteration %d: inconsistent block: %x", i, readBuf)
return
}
}
f.Close()
}
}
wg.Add(2)
go writerThread()
go writerThread()
wg.Wait()
}
|
