hardcoresushi/libgocryptfs
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syscallcompat: add GetdentsSpecial()

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GetdentsSpecial calls then Getdents syscall,
with normal entries and "." / ".." split into two slices.
This commit is contained in:
Jakob Unterwurzacher 2021-05-23 12:00:09 +02:00
parent 7d72baca69
commit 1b3c3b1347
5 changed files with 74 additions and 30 deletions
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23
internal/syscallcompat/getdents_linux.go
View File

@ -27,7 +27,7 @@ const sizeofDirent = int(unsafe.Sizeof(unix.Dirent{}))
const maxReclen = 280
// getdents wraps unix.Getdents and converts the result to []fuse.DirEntry.
func getdents(fd int) ([]fuse.DirEntry, error) {
func getdents(fd int) (entries []fuse.DirEntry, entriesSpecial []fuse.DirEntry, err error) {
// Collect syscall result in smartBuf.
// "bytes.Buffer" is smart about expanding the capacity and avoids the
// exponential runtime of simple append().
@ -44,9 +44,9 @@ func getdents(fd int) ([]fuse.DirEntry, error) {
} else if err != nil {
if smartBuf.Len() > 0 {
tlog.Warn.Printf("warning: unix.Getdents returned errno %d in the middle of data ( https://github.com/rfjakob/gocryptfs/issues/483 )", err.(syscall.Errno))
return nil, syscall.EIO
return nil, nil, syscall.EIO
}
return nil, err
return nil, nil, err
}
if n == 0 {
break
@ -66,12 +66,12 @@ func getdents(fd int) ([]fuse.DirEntry, error) {
tlog.Warn.Printf("Getdents: corrupt entry #%d: Reclen=0 at offset=%d. Returning EBADR",
numEntries, offset)
// EBADR = Invalid request descriptor
return nil, syscall.EBADR
return nil, nil, syscall.EBADR
}
if int(s.Reclen) > maxReclen {
tlog.Warn.Printf("Getdents: corrupt entry #%d: Reclen=%d > %d. Returning EBADR",
numEntries, s.Reclen, maxReclen)
return nil, syscall.EBADR
return nil, nil, syscall.EBADR
}
offset += int(s.Reclen)
numEntries++
@ -80,17 +80,22 @@ func getdents(fd int) ([]fuse.DirEntry, error) {
// Note: syscall.ParseDirent() only returns the names,
// we want all the data, so we have to implement
// it on our own.
entries := make([]fuse.DirEntry, 0, numEntries)
entries = make([]fuse.DirEntry, 0, numEntries)
offset = 0
for offset < len(buf) {
s := *(*unix.Dirent)(unsafe.Pointer(&buf[offset]))
name, err := getdentsName(s)
if err != nil {
return nil, err
return nil, nil, err
}
offset += int(s.Reclen)
if name == "." || name == ".." {
// os.File.Readdir() drops "." and "..". Let's be compatible.
// These are always directories, no need to call convertDType.
entriesSpecial = append(entriesSpecial, fuse.DirEntry{
Ino: s.Ino,
Mode: syscall.S_IFDIR,
Name: name,
})
continue
}
mode, err := convertDType(fd, name, s.Type)
@ -105,7 +110,7 @@ func getdents(fd int) ([]fuse.DirEntry, error) {
Name: name,
})
}
return entries, nil
return entries, entriesSpecial, nil
}
// getdentsName extracts the filename from a Dirent struct and returns it as

50
internal/syscallcompat/getdents_other.go
View File

@ -9,27 +9,11 @@ import (
"github.com/hanwen/go-fuse/v2/fuse"
)
// emulateGetdents reads all directory entries from the open directory "fd"
// and returns them in a fuse.DirEntry slice.
func emulateGetdents(fd int) (out []fuse.DirEntry, err error) {
// os.File closes the fd in its finalizer. Duplicate the fd to not affect
// the original fd.
newFd, err := syscall.Dup(fd)
if err != nil {
return nil, err
}
f := os.NewFile(uintptr(newFd), "")
defer f.Close()
// Get all file names in the directory
names, err := f.Readdirnames(0)
if err != nil {
return nil, err
}
// Stat all of them and convert to fuse.DirEntry
out = make([]fuse.DirEntry, 0, len(names))
func fillDirEntries(fd int, names []string) ([]fuse.DirEntry, error) {
out := make([]fuse.DirEntry, 0, len(names))
for _, name := range names {
var st unix.Stat_t
err = Fstatat(fd, name, &st, unix.AT_SYMLINK_NOFOLLOW)
err := Fstatat(fd, name, &st, unix.AT_SYMLINK_NOFOLLOW)
if err == syscall.ENOENT {
// File disappeared between readdir and stat. Pretend we did not
// see it.
@ -47,3 +31,31 @@ func emulateGetdents(fd int) (out []fuse.DirEntry, err error) {
}
return out, nil
}
// emulateGetdents reads all directory entries from the open directory "fd"
// and returns normal entries and "." / ".." split into two slices.
func emulateGetdents(fd int) (out []fuse.DirEntry, outSpecial []fuse.DirEntry, err error) {
// os.File closes the fd in its finalizer. Duplicate the fd to not affect
// the original fd.
newFd, err := syscall.Dup(fd)
if err != nil {
return nil, nil, err
}
f := os.NewFile(uintptr(newFd), "")
defer f.Close()
// Get all file names in the directory
names, err := f.Readdirnames(0)
if err != nil {
return nil, nil, err
}
// Stat all the names and convert to fuse.DirEntry
out, err = fillDirEntries(fd, names)
if err != nil {
return nil, nil, err
}
outSpecial, err = fillDirEntries(fd, []string{".", ".."})
if err != nil {
return nil, nil, err
}
return out, outSpecial, nil
}

17
internal/syscallcompat/getdents_test.go
View File

@ -83,7 +83,7 @@ func testGetdents(t *testing.T) {
if err != nil {
t.Fatal(err)
}
getdentsEntries, err := getdentsUnderTest(int(fd.Fd()))
getdentsEntries, special, err := getdentsUnderTest(int(fd.Fd()))
if err != nil {
t.Log(err)
skipOnGccGo(t)
@ -114,5 +114,20 @@ func testGetdents(t *testing.T) {
}
}
}
if len(special) != 2 {
t.Error(special)
}
if !(special[0].Name == "." && special[1].Name == ".." ||
special[1].Name == "." && special[0].Name == "..") {
t.Error(special)
}
for _, v := range special {
if v.Ino == 0 {
t.Error(v)
}
if v.Mode != syscall.S_IFDIR {
t.Error(v)
}
}
}
}

5
internal/syscallcompat/sys_darwin.go
View File

@ -216,6 +216,11 @@ func UtimesNanoAtNofollow(dirfd int, path string, a *time.Time, m *time.Time) (e
}
func Getdents(fd int) ([]fuse.DirEntry, error) {
entries, _, err := emulateGetdents(fd)
return entries, err
}
func GetdentsSpecial(fd int) (entries []fuse.DirEntry, entriesSpecial []fuse.DirEntry, err error) {
return emulateGetdents(fd)
}

9
internal/syscallcompat/sys_linux.go
View File

@ -244,8 +244,15 @@ func UtimesNanoAtNofollow(dirfd int, path string, a *time.Time, m *time.Time) (e
return err
}
// Getdents syscall.
// Getdents syscall with "." and ".." filtered out.
func Getdents(fd int) ([]fuse.DirEntry, error) {
entries, _, err := getdents(fd)
return entries, err
}
// GetdentsSpecial calls the Getdents syscall,
// with normal entries and "." / ".." split into two slices.
func GetdentsSpecial(fd int) (entries []fuse.DirEntry, entriesSpecial []fuse.DirEntry, err error) {
return getdents(fd)
}