syscallcompat: move quirks logic here & fix darwin

We need to look at f_fstypename acc. to
https://stackoverflow.com/a/52299141/1380267 :

> As filesystem type numbers are now assigned at runtime in
> recent versions of MacOS, you must use f_fstypename to
> determine the type.

https://github.com/rfjakob/gocryptfs/issues/585
This commit is contained in:
Jakob Unterwurzacher 2021-08-11 20:21:32 +02:00
parent 0c16616117
commit 2d386fc92e
8 changed files with 149 additions and 55 deletions

View File

@ -118,7 +118,7 @@ func (f *File) createHeader() (fileID []byte, err error) {
h := contentenc.RandomHeader()
buf := h.Pack()
// Prevent partially written (=corrupt) header by preallocating the space beforehand
if !f.rootNode.args.NoPrealloc && f.rootNode.quirks&quirkBrokenFalloc == 0 {
if !f.rootNode.args.NoPrealloc && f.rootNode.quirks&syscallcompat.QuirkBrokenFalloc == 0 {
err = syscallcompat.EnospcPrealloc(f.intFd(), 0, contentenc.HeaderLen)
if err != nil {
if !syscallcompat.IsENOSPC(err) {

View File

@ -87,7 +87,7 @@ func (n *Node) newChild(ctx context.Context, st *syscall.Stat_t, out *fuse.Entry
out.Attr.FromStat(st)
var gen uint64 = 1
if rn.args.SharedStorage || rn.quirks&quirkDuplicateIno1 != 0 {
if rn.args.SharedStorage || rn.quirks&syscallcompat.QuirkDuplicateIno1 != 0 {
// Make each directory entry a unique node by using a unique generation
// value - see the comment at RootNode.gen for details.
gen = atomic.AddUint64(&rn.gen, 1)

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@ -1,52 +0,0 @@
package fusefrontend
import (
"runtime"
"golang.org/x/sys/unix"
"github.com/rfjakob/gocryptfs/internal/tlog"
)
const (
quirkBrokenFalloc = uint64(1 << iota)
quirkDuplicateIno1
)
func detectQuirks(cipherdir string) (q uint64) {
const (
// From Linux' man statfs
BTRFS_SUPER_MAGIC = 0x9123683e
// From https://github.com/rfjakob/gocryptfs/issues/585#issuecomment-887370065
DARWIN_EXFAT_MAGIC = 35
)
var st unix.Statfs_t
err := unix.Statfs(cipherdir, &st)
if err != nil {
tlog.Warn.Printf("detectQuirks: Statfs on %q failed: %v", cipherdir, err)
return 0
}
logQuirk := func(s string) {
tlog.Info.Printf(tlog.ColorYellow + "detectQuirks: " + s + tlog.ColorReset)
}
// Preallocation on Btrfs is broken ( https://github.com/rfjakob/gocryptfs/issues/395 )
// and slow ( https://github.com/rfjakob/gocryptfs/issues/63 ).
//
// Cast to uint32 avoids compile error on arm: "constant 2435016766 overflows int32"
if uint32(st.Type) == BTRFS_SUPER_MAGIC {
logQuirk("Btrfs detected, forcing -noprealloc. See https://github.com/rfjakob/gocryptfs/issues/395 for why.")
q |= quirkBrokenFalloc
}
// On MacOS ExFAT, all empty files share inode number 1:
// https://github.com/rfjakob/gocryptfs/issues/585
if runtime.GOOS == "darwin" && st.Type == DARWIN_EXFAT_MAGIC {
logQuirk("ExFAT detected, disabling hard links. See https://github.com/rfjakob/gocryptfs/issues/585 for why.")
q |= quirkDuplicateIno1
}
return q
}

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@ -79,7 +79,7 @@ func NewRootNode(args Args, c *contentenc.ContentEnc, n *nametransform.NameTrans
contentEnc: c,
inoMap: inomap.New(),
dirCache: dirCache{ivLen: ivLen},
quirks: detectQuirks(args.Cipherdir),
quirks: syscallcompat.DetectQuirks(args.Cipherdir),
}
return rn
}

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@ -0,0 +1,20 @@
package syscallcompat
import (
"github.com/rfjakob/gocryptfs/internal/tlog"
)
const (
// QuirkBrokenFalloc means the falloc is broken.
// Preallocation on Btrfs is broken ( https://github.com/rfjakob/gocryptfs/issues/395 )
// and slow ( https://github.com/rfjakob/gocryptfs/issues/63 ).
QuirkBrokenFalloc = uint64(1 << iota)
// QuirkDuplicateIno1 means that we have duplicate inode numbers.
// On MacOS ExFAT, all empty files share inode number 1:
// https://github.com/rfjakob/gocryptfs/issues/585
QuirkDuplicateIno1
)
func logQuirk(s string) {
tlog.Info.Printf(tlog.ColorYellow + "DetectQuirks: " + s + tlog.ColorReset)
}

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@ -0,0 +1,41 @@
package syscallcompat
import (
"golang.org/x/sys/unix"
"github.com/rfjakob/gocryptfs/internal/tlog"
)
func DetectQuirks(cipherdir string) (q uint64) {
const (
// From https://github.com/rfjakob/gocryptfs/issues/585#issuecomment-887370065
FstypenameExfat = "exfat"
)
var st unix.Statfs_t
err := unix.Statfs(cipherdir, &st)
if err != nil {
tlog.Warn.Printf("DetectQuirks: Statfs on %q failed: %v", cipherdir, err)
return 0
}
// Convert null-terminated st.Fstypename int8 array to string
var buf []byte
for _, v := range st.Fstypename {
if v == 0 {
break
}
buf = append(buf, byte(v))
}
fstypename := string(buf)
tlog.Debug.Printf("DetectQuirks: Fstypename=%q\n", fstypename)
// On MacOS ExFAT, all empty files share inode number 1:
// https://github.com/rfjakob/gocryptfs/issues/585
if fstypename == FstypenameExfat {
logQuirk("ExFAT detected, disabling hard links. See https://github.com/rfjakob/gocryptfs/issues/585 for why.")
q |= QuirkDuplicateIno1
}
return q
}

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@ -0,0 +1,36 @@
package syscallcompat
import (
"golang.org/x/sys/unix"
"github.com/rfjakob/gocryptfs/internal/tlog"
)
// DetectQuirks decides if there are known quirks on the backing filesystem
// that need to be workarounded.
//
// Tested by tests/root_test.TestBtrfsQuirks
func DetectQuirks(cipherdir string) (q uint64) {
const (
// From Linux' man statfs
BTRFS_SUPER_MAGIC = 0x9123683e
)
var st unix.Statfs_t
err := unix.Statfs(cipherdir, &st)
if err != nil {
tlog.Warn.Printf("DetectQuirks: Statfs on %q failed: %v", cipherdir, err)
return 0
}
// Preallocation on Btrfs is broken ( https://github.com/rfjakob/gocryptfs/issues/395 )
// and slow ( https://github.com/rfjakob/gocryptfs/issues/63 ).
//
// Cast to uint32 avoids compile error on arm: "constant 2435016766 overflows int32"
if uint32(st.Type) == BTRFS_SUPER_MAGIC {
logQuirk("Btrfs detected, forcing -noprealloc. See https://github.com/rfjakob/gocryptfs/issues/395 for why.")
q |= QuirkBrokenFalloc
}
return q
}

View File

@ -12,6 +12,8 @@ import (
"syscall"
"testing"
"github.com/rfjakob/gocryptfs/internal/syscallcompat"
"golang.org/x/sys/unix"
"github.com/rfjakob/gocryptfs/tests/test_helpers"
@ -311,3 +313,50 @@ func TestAcl(t *testing.T) {
dumpAcl()
}
}
// TestBtrfsQuirks needs root permissions because it creates a loop disk
func TestBtrfsQuirks(t *testing.T) {
if os.Getuid() != 0 {
t.Skip("must run as root")
}
img := filepath.Join(test_helpers.TmpDir, t.Name()+".img")
f, err := os.Create(img)
if err != nil {
t.Fatal(err)
}
defer f.Close()
// minimum size for each btrfs device is 114294784
err = f.Truncate(200 * 1024 * 1024)
if err != nil {
t.Fatal(err)
}
// Format as Btrfs
cmd := exec.Command("mkfs.btrfs", img)
out, err := cmd.CombinedOutput()
if err != nil {
t.Log(string(out))
t.Fatal(err)
}
// Mount
mnt := img + ".mnt"
err = os.Mkdir(mnt, 0600)
if err != nil {
t.Fatal(err)
}
cmd = exec.Command("mount", img, mnt)
out, err = cmd.CombinedOutput()
if err != nil {
t.Log(string(out))
t.Fatal(err)
}
defer syscall.Unlink(img)
defer syscall.Unmount(mnt, 0)
quirk := syscallcompat.DetectQuirks(mnt)
if quirk != syscallcompat.QuirkBrokenFalloc {
t.Errorf("wrong quirk: %v", quirk)
}
}