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libgocryptfs
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syscallcompat: OSX: add Fallocate and Openat wrappers 

...and convert all calls to syscall.{Fallocate,Openat}
to syscallcompat .

Both syscalls are not available on OSX. We emulate Openat and just
return EOPNOTSUPP for Fallocate.
This commit is contained in:
Jakob Unterwurzacher 2016-07-03 19:14:12 +02:00
parent c9a472c12f
commit 9b725c15cf
5 changed files with 61 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
internal/fusefrontend/file.go
View File

@ -101,7 +101,7 @@ func (f *file) createHeader() error {
buf := h.Pack()
// Prevent partially written (=corrupt) header by preallocating the space beforehand
err := syscallcompat.Prealloc(int(f.fd.Fd()), 0, contentenc.HEADER_LEN)
err := syscallcompat.EnospcPrealloc(int(f.fd.Fd()), 0, contentenc.HEADER_LEN)
if err != nil {
tlog.Warn.Printf("ino%d: createHeader: prealloc failed: %s\n", f.ino, err.Error())
return err
@ -262,7 +262,7 @@ func (f *file) doWrite(data []byte, off int64) (uint32, fuse.Status) {
f.ino, uint64(len(blockData))-f.contentEnc.BlockOverhead(), b.BlockNo)
// Prevent partially written (=corrupt) blocks by preallocating the space beforehand
err := syscallcompat.Prealloc(int(f.fd.Fd()), int64(blockOffset), int64(len(blockData)))
err := syscallcompat.EnospcPrealloc(int(f.fd.Fd()), int64(blockOffset), int64(len(blockData)))
if err != nil {
tlog.Warn.Printf("ino%d fh%d: doWrite: prealloc failed: %s", f.ino, f.intFd(), err.Error())
status = fuse.ToStatus(err)

3
internal/fusefrontend/file_allocate_truncate.go
View File

@ -10,6 +10,7 @@ import (
"github.com/hanwen/go-fuse/fuse"
"github.com/rfjakob/gocryptfs/internal/syscallcompat"
"github.com/rfjakob/gocryptfs/internal/tlog"
)
@ -59,7 +60,7 @@ func (f *file) Allocate(off uint64, sz uint64, mode uint32) fuse.Status {
cipherOff := firstBlock.BlockCipherOff()
cipherSz := lastBlock.BlockCipherOff() - cipherOff +
f.contentEnc.PlainSizeToCipherSize(lastBlock.Skip+lastBlock.Length)
err := syscall.Fallocate(f.intFd(), FALLOC_FL_KEEP_SIZE, int64(cipherOff), int64(cipherSz))
err := syscallcompat.Fallocate(f.intFd(), FALLOC_FL_KEEP_SIZE, int64(cipherOff), int64(cipherSz))
tlog.Debug.Printf("Allocate off=%d sz=%d mode=%x cipherOff=%d cipherSz=%d\n",
off, sz, mode, cipherOff, cipherSz)
if err != nil {

33
internal/syscallcompat/sys_darwin.go
View File

@ -1,5 +1,11 @@
package syscallcompat
import (
"os"
"sync"
"syscall"
)
// prealloc - preallocate space without changing the file size. This prevents
// us from running out of space in the middle of an operation.
func Prealloc(fd int, off int64, len int64) (err error) {
@ -10,3 +16,30 @@ func Prealloc(fd int, off int64, len int64) (err error) {
// See https://github.com/rfjakob/gocryptfs/issues/18 if you want to help.
return nil
}
var openatLock sync.Mutex
// Poor man's Openat:
// 1) fchdir to the dirfd
// 2) open the file
// 3) chdir back.
func Openat(dirfd int, path string, flags int, mode uint32) (fd int, err error) {
openatLock.Lock()
defer openatLock.Unlock()
oldWd, err := os.Getwd()
if err != nil {
return -1, err
}
err = syscall.Fchdir(dirfd)
if err != nil {
return -1, err
}
defer os.Chdir(oldWd)
return syscall.Open(path, flags, mode)
}
func Fallocate(fd int, mode uint32, off int64, len int64) (err error) {
return syscall.EOPNOTSUPP
}

19
internal/syscallcompat/sys_linux.go
View File

@ -11,9 +11,10 @@ const FALLOC_FL_KEEP_SIZE = 0x01
var preallocWarn sync.Once
// prealloc - preallocate space without changing the file size. This prevents
// us from running out of space in the middle of an operation.
func Prealloc(fd int, off int64, len int64) (err error) {
// EnospcPrealloc preallocates ciphertext space without changing the file
// size. This guarantees that we don't run out of space while writing a
// ciphertext block (that would corrupt the block).
func EnospcPrealloc(fd int, off int64, len int64) (err error) {
for {
err = syscall.Fallocate(fd, FALLOC_FL_KEEP_SIZE, off, len)
if err == syscall.EINTR {
@ -23,8 +24,8 @@ func Prealloc(fd int, off int64, len int64) (err error) {
continue
}
if err == syscall.EOPNOTSUPP {
// ZFS does not support fallocate which caused gocryptfs to abort
// every write operation: https://github.com/rfjakob/gocryptfs/issues/22
// ZFS and ext3 do not support fallocate. Warn but continue anyway.
// https://github.com/rfjakob/gocryptfs/issues/22
preallocWarn.Do(func() {
tlog.Warn.Printf("Warning: The underlying filesystem " +
"does not support fallocate(2). gocryptfs will continue working " +
@ -35,3 +36,11 @@ func Prealloc(fd int, off int64, len int64) (err error) {
return err
}
}
func Openat(dirfd int, path string, flags int, mode uint32) (fd int, err error) {
return syscall.Openat(dirfd, path, flags, mode)
}
func Fallocate(fd int, mode uint32, off int64, len int64) (err error) {
return syscall.Fallocate(fd, mode, off, len)
}

15
tests/matrix/matrix_test.go
View File

@ -23,6 +23,7 @@ import (
"syscall"
"testing"
"github.com/rfjakob/gocryptfs/internal/syscallcompat"
"github.com/rfjakob/gocryptfs/tests/test_helpers"
)
@ -176,6 +177,10 @@ const FALLOC_DEFAULT = 0x00
const FALLOC_FL_KEEP_SIZE = 0x01
func TestFallocate(t *testing.T) {
if runtime.GOOS == "darwin" {
t.Skipf("OSX does not support fallocate")
}
fn := test_helpers.DefaultPlainDir + "/fallocate"
file, err := os.Create(fn)
if err != nil {
@ -190,7 +195,7 @@ func TestFallocate(t *testing.T) {
// Allocate 30 bytes, keep size
// gocryptfs || (0 blocks)
// ext4 | d | (1 block)
err = syscall.Fallocate(fd, FALLOC_FL_KEEP_SIZE, 0, 30)
err = syscallcompat.Fallocate(fd, FALLOC_FL_KEEP_SIZE, 0, 30)
if err != nil {
t.Error(err)
}
@ -218,7 +223,7 @@ func TestFallocate(t *testing.T) {
// Allocate the whole file space
// gocryptfs | h | h | d| (1 block)
// ext4 | d | d | d | (3 blocks
err = syscall.Fallocate(fd, FALLOC_DEFAULT, 0, 9000)
err = syscallcompat.Fallocate(fd, FALLOC_DEFAULT, 0, 9000)
if err != nil {
t.Fatal(err)
}
@ -244,7 +249,7 @@ func TestFallocate(t *testing.T) {
// Allocate 10 bytes in the second block
// gocryptfs | h | h | d| (1 block)
// ext4 | d | d | d | (2 blocks)
syscall.Fallocate(fd, FALLOC_DEFAULT, 5000, 10)
syscallcompat.Fallocate(fd, FALLOC_DEFAULT, 5000, 10)
_, nBlocks = test_helpers.Du(t, fd)
if want := 3; nBlocks/8 != int64(want) {
t.Errorf("Expected %d 4k block(s), got %d", want, nBlocks/8)
@ -257,7 +262,7 @@ func TestFallocate(t *testing.T) {
// Grow the file to 4 blocks
// gocryptfs | h | h | d |d| (2 blocks)
// ext4 | d | d | d | d | (3 blocks)
syscall.Fallocate(fd, FALLOC_DEFAULT, 15000, 10)
syscallcompat.Fallocate(fd, FALLOC_DEFAULT, 15000, 10)
_, nBlocks = test_helpers.Du(t, fd)
if want := 4; nBlocks/8 != int64(want) {
t.Errorf("Expected %d 4k block(s), got %d", want, nBlocks/8)
@ -269,7 +274,7 @@ func TestFallocate(t *testing.T) {
// Shrinking a file using fallocate should have no effect
for _, off := range []int64{0, 10, 2000, 5000} {
for _, sz := range []int64{0, 1, 42, 6000} {
syscall.Fallocate(fd, FALLOC_DEFAULT, off, sz)
syscallcompat.Fallocate(fd, FALLOC_DEFAULT, off, sz)
test_helpers.VerifySize(t, fn, 15010)
if md5 := test_helpers.Md5fn(fn); md5 != "c4c44c7a41ab7798a79d093eb44f99fc" {
t.Errorf("Wrong md5 %s", md5)