Move Lock/UnlockPOSIX into LockFD util.

PiperOrigin-RevId: 352904728

3 files changed, 49 insertions, 20 deletions

diff --git a/pkg/sentry/vfs/file_description.go b/pkg/sentry/vfs/file_description.go
index 5321ac80a..dbf8425b4 100644
--- a/pkg/sentry/vfs/file_description.go
+++ b/pkg/sentry/vfs/file_description.go
@@ -454,10 +454,10 @@ type FileDescriptionImpl interface {
 	UnlockBSD(ctx context.Context, uid lock.UniqueID) error
 
 	// LockPOSIX tries to acquire a POSIX-style advisory file lock.
-	LockPOSIX(ctx context.Context, uid lock.UniqueID, t lock.LockType, start, length uint64, whence int16, block lock.Blocker) error
+	LockPOSIX(ctx context.Context, uid lock.UniqueID, t lock.LockType, r lock.LockRange, block lock.Blocker) error
 
 	// UnlockPOSIX releases a POSIX-style advisory file lock.
-	UnlockPOSIX(ctx context.Context, uid lock.UniqueID, start, length uint64, whence int16) error
+	UnlockPOSIX(ctx context.Context, uid lock.UniqueID, ComputeLockRange lock.LockRange) error
 }
 
 // Dirent holds the information contained in struct linux_dirent64.
@@ -802,13 +802,40 @@ func (fd *FileDescription) UnlockBSD(ctx context.Context) error {
 }
 
 // LockPOSIX locks a POSIX-style file range lock.
-func (fd *FileDescription) LockPOSIX(ctx context.Context, uid lock.UniqueID, t lock.LockType, start, end uint64, whence int16, block lock.Blocker) error {
-	return fd.impl.LockPOSIX(ctx, uid, t, start, end, whence, block)
+func (fd *FileDescription) LockPOSIX(ctx context.Context, uid lock.UniqueID, t lock.LockType, r lock.LockRange, block lock.Blocker) error {
+	return fd.impl.LockPOSIX(ctx, uid, t, r, block)
 }
 
 // UnlockPOSIX unlocks a POSIX-style file range lock.
-func (fd *FileDescription) UnlockPOSIX(ctx context.Context, uid lock.UniqueID, start, end uint64, whence int16) error {
-	return fd.impl.UnlockPOSIX(ctx, uid, start, end, whence)
+func (fd *FileDescription) UnlockPOSIX(ctx context.Context, uid lock.UniqueID, r lock.LockRange) error {
+	return fd.impl.UnlockPOSIX(ctx, uid, r)
+}
+
+// ComputeLockRange computes the range of a file lock based on the given values.
+func (fd *FileDescription) ComputeLockRange(ctx context.Context, start uint64, length uint64, whence int16) (lock.LockRange, error) {
+	var off int64
+	switch whence {
+	case linux.SEEK_SET:
+		off = 0
+	case linux.SEEK_CUR:
+		// Note that Linux does not hold any mutexes while retrieving the file
+		// offset, see fs/locks.c:flock_to_posix_lock and fs/locks.c:fcntl_setlk.
+		curOff, err := fd.Seek(ctx, 0, linux.SEEK_CUR)
+		if err != nil {
+			return lock.LockRange{}, err
+		}
+		off = curOff
+	case linux.SEEK_END:
+		stat, err := fd.Stat(ctx, StatOptions{Mask: linux.STATX_SIZE})
+		if err != nil {
+			return lock.LockRange{}, err
+		}
+		off = int64(stat.Size)
+	default:
+		return lock.LockRange{}, syserror.EINVAL
+	}
+
+	return lock.ComputeRange(int64(start), int64(length), off)
 }
 
 // A FileAsync sends signals to its owner when w is ready for IO. This is only
diff --git a/pkg/sentry/vfs/file_description_impl_util.go b/pkg/sentry/vfs/file_description_impl_util.go
index 48ca9de44..9d13e2ccb 100644
--- a/pkg/sentry/vfs/file_description_impl_util.go
+++ b/pkg/sentry/vfs/file_description_impl_util.go
@@ -429,6 +429,16 @@ func (fd *LockFD) UnlockBSD(ctx context.Context, uid fslock.UniqueID) error {
 	return nil
 }
 
+// LockPOSIX implements vfs.FileDescriptionImpl.LockPOSIX.
+func (fd *LockFD) LockPOSIX(ctx context.Context, uid fslock.UniqueID, t fslock.LockType, r fslock.LockRange, block fslock.Blocker) error {
+	return fd.locks.LockPOSIX(ctx, uid, t, r, block)
+}
+
+// UnlockPOSIX implements vfs.FileDescriptionImpl.UnlockPOSIX.
+func (fd *LockFD) UnlockPOSIX(ctx context.Context, uid fslock.UniqueID, r fslock.LockRange) error {
+	return fd.locks.UnlockPOSIX(ctx, uid, r)
+}
+
 // NoLockFD implements Lock*/Unlock* portion of FileDescriptionImpl interface
 // returning ENOLCK.
 //
@@ -446,11 +456,11 @@ func (NoLockFD) UnlockBSD(ctx context.Context, uid fslock.UniqueID) error {
 }
 
 // LockPOSIX implements vfs.FileDescriptionImpl.LockPOSIX.
-func (NoLockFD) LockPOSIX(ctx context.Context, uid fslock.UniqueID, t fslock.LockType, start, length uint64, whence int16, block fslock.Blocker) error {
+func (NoLockFD) LockPOSIX(ctx context.Context, uid fslock.UniqueID, t fslock.LockType, r fslock.LockRange, block fslock.Blocker) error {
 	return syserror.ENOLCK
 }
 
 // UnlockPOSIX implements vfs.FileDescriptionImpl.UnlockPOSIX.
-func (NoLockFD) UnlockPOSIX(ctx context.Context, uid fslock.UniqueID, start, length uint64, whence int16) error {
+func (NoLockFD) UnlockPOSIX(ctx context.Context, uid fslock.UniqueID, r fslock.LockRange) error {
 	return syserror.ENOLCK
 }
diff --git a/pkg/sentry/vfs/lock.go b/pkg/sentry/vfs/lock.go
index 1ff202f2a..bcff35792 100644
--- a/pkg/sentry/vfs/lock.go
+++ b/pkg/sentry/vfs/lock.go
@@ -61,12 +61,8 @@ func (fl *FileLocks) UnlockBSD(uid fslock.UniqueID) {
 }
 
 // LockPOSIX tries to acquire a POSIX-style lock on a file region.
-func (fl *FileLocks) LockPOSIX(ctx context.Context, fd *FileDescription, uid fslock.UniqueID, t fslock.LockType, start, length uint64, whence int16, block fslock.Blocker) error {
-	rng, err := computeRange(ctx, fd, start, length, whence)
-	if err != nil {
-		return err
-	}
-	if fl.posix.LockRegion(uid, t, rng, block) {
+func (fl *FileLocks) LockPOSIX(ctx context.Context, uid fslock.UniqueID, t fslock.LockType, r fslock.LockRange, block fslock.Blocker) error {
+	if fl.posix.LockRegion(uid, t, r, block) {
 		return nil
 	}
 
@@ -82,12 +78,8 @@ func (fl *FileLocks) LockPOSIX(ctx context.Context, fd *FileDescription, uid fsl
 //
 // This operation is always successful, even if there did not exist a lock on
 // the requested region held by uid in the first place.
-func (fl *FileLocks) UnlockPOSIX(ctx context.Context, fd *FileDescription, uid fslock.UniqueID, start, length uint64, whence int16) error {
-	rng, err := computeRange(ctx, fd, start, length, whence)
-	if err != nil {
-		return err
-	}
-	fl.posix.UnlockRegion(uid, rng)
+func (fl *FileLocks) UnlockPOSIX(ctx context.Context, uid fslock.UniqueID, r fslock.LockRange) error {
+	fl.posix.UnlockRegion(uid, r)
 	return nil
 }