Implement POSIX locks

- Change FileDescriptionImpl Lock/UnlockPOSIX signature to
  take {start,length,whence}, so the correct offset can be
  calculated in the implementations.
- Create PosixLocker interface to make it possible to share
  the same locking code from different implementations.

Closes #1480

PiperOrigin-RevId: 316910286

1 files changed, 12 insertions, 6 deletions

diff --git a/pkg/sentry/vfs/file_description.go b/pkg/sentry/vfs/file_description.go
index 13c48824e..e0538ea53 100644
--- a/pkg/sentry/vfs/file_description.go
+++ b/pkg/sentry/vfs/file_description.go
@@ -438,14 +438,10 @@ type FileDescriptionImpl interface {
 	UnlockBSD(ctx context.Context, uid lock.UniqueID) error
 
 	// LockPOSIX tries to acquire a POSIX-style advisory file lock.
-	//
-	// TODO(gvisor.dev/issue/1480): POSIX-style file locking
-	LockPOSIX(ctx context.Context, uid lock.UniqueID, t lock.LockType, rng lock.LockRange, block lock.Blocker) error
+	LockPOSIX(ctx context.Context, uid lock.UniqueID, t lock.LockType, start, length uint64, whence int16, block lock.Blocker) error
 
 	// UnlockPOSIX releases a POSIX-style advisory file lock.
-	//
-	// TODO(gvisor.dev/issue/1480): POSIX-style file locking
-	UnlockPOSIX(ctx context.Context, uid lock.UniqueID, rng lock.LockRange) error
+	UnlockPOSIX(ctx context.Context, uid lock.UniqueID, start, length uint64, whence int16) error
 }
 
 // Dirent holds the information contained in struct linux_dirent64.
@@ -764,3 +760,13 @@ func (fd *FileDescription) LockBSD(ctx context.Context, lockType lock.LockType,
 func (fd *FileDescription) UnlockBSD(ctx context.Context) error {
 	return fd.impl.UnlockBSD(ctx, fd)
 }
+
+// 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)
+}
+
+// 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)
+}