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

2 files changed, 0 insertions, 85 deletions

diff --git a/pkg/sentry/vfs/lock/BUILD b/pkg/sentry/vfs/lock/BUILD
deleted file mode 100644
index d9ab063b7..000000000
--- a/pkg/sentry/vfs/lock/BUILD
+++ /dev/null
@@ -1,13 +0,0 @@
-load("//tools:defs.bzl", "go_library")
-
-package(licenses = ["notice"])
-
-go_library(
-    name = "lock",
-    srcs = ["lock.go"],
-    visibility = ["//pkg/sentry:internal"],
-    deps = [
-        "//pkg/sentry/fs/lock",
-        "//pkg/syserror",
-    ],
-)
diff --git a/pkg/sentry/vfs/lock/lock.go b/pkg/sentry/vfs/lock/lock.go
deleted file mode 100644
index 724dfe743..000000000
--- a/pkg/sentry/vfs/lock/lock.go
+++ /dev/null
@@ -1,72 +0,0 @@
-// Copyright 2020 The gVisor Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-// Package lock provides POSIX and BSD style file locking for VFS2 file
-// implementations.
-//
-// The actual implementations can be found in the lock package under
-// sentry/fs/lock.
-package lock
-
-import (
-	fslock "gvisor.dev/gvisor/pkg/sentry/fs/lock"
-	"gvisor.dev/gvisor/pkg/syserror"
-)
-
-// FileLocks supports POSIX and BSD style locks, which correspond to fcntl(2)
-// and flock(2) respectively in Linux. It can be embedded into various file
-// implementations for VFS2 that support locking.
-//
-// Note that in Linux these two types of locks are _not_ cooperative, because
-// race and deadlock conditions make merging them prohibitive. We do the same
-// and keep them oblivious to each other.
-type FileLocks struct {
-	// bsd is a set of BSD-style advisory file wide locks, see flock(2).
-	bsd fslock.Locks
-
-	// posix is a set of POSIX-style regional advisory locks, see fcntl(2).
-	posix fslock.Locks
-}
-
-// LockBSD tries to acquire a BSD-style lock on the entire file.
-func (fl *FileLocks) LockBSD(uid fslock.UniqueID, t fslock.LockType, block fslock.Blocker) error {
-	if fl.bsd.LockRegion(uid, t, fslock.LockRange{0, fslock.LockEOF}, block) {
-		return nil
-	}
-	return syserror.ErrWouldBlock
-}
-
-// UnlockBSD releases a BSD-style lock on the entire file.
-//
-// 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) UnlockBSD(uid fslock.UniqueID) {
-	fl.bsd.UnlockRegion(uid, fslock.LockRange{0, fslock.LockEOF})
-}
-
-// LockPOSIX tries to acquire a POSIX-style lock on a file region.
-func (fl *FileLocks) LockPOSIX(uid fslock.UniqueID, t fslock.LockType, rng fslock.LockRange, block fslock.Blocker) error {
-	if fl.posix.LockRegion(uid, t, rng, block) {
-		return nil
-	}
-	return syserror.ErrWouldBlock
-}
-
-// UnlockPOSIX releases a POSIX-style lock on a file region.
-//
-// 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(uid fslock.UniqueID, rng fslock.LockRange) {
-	fl.posix.UnlockRegion(uid, rng)
-}