1 files changed, 69 insertions, 0 deletions
diff --git a/pkg/sentry/fs/lock/lock_set_functions.go b/pkg/sentry/fs/lock/lock_set_functions.go
new file mode 100644
index 000000000..e16f485be
--- /dev/null
+++ b/pkg/sentry/fs/lock/lock_set_functions.go
@@ -0,0 +1,69 @@
+// Copyright 2018 Google Inc.
+//
+// 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
+
+import (
+	"math"
+)
+
+// LockSet maps a set of Locks into a file.  The key is the file offset.
+
+type lockSetFunctions struct{}
+
+func (lockSetFunctions) MinKey() uint64 {
+	return 0
+}
+
+func (lockSetFunctions) MaxKey() uint64 {
+	return math.MaxUint64
+}
+
+func (lockSetFunctions) ClearValue(l *Lock) {
+	*l = Lock{}
+}
+
+func (lockSetFunctions) Merge(r1 LockRange, val1 Lock, r2 LockRange, val2 Lock) (Lock, bool) {
+	// Merge only if the Readers/Writers are identical.
+	if len(val1.Readers) != len(val2.Readers) {
+		return Lock{}, false
+	}
+	for k := range val1.Readers {
+		if !val2.Readers[k] {
+			return Lock{}, false
+		}
+	}
+	if val1.HasWriter != val2.HasWriter {
+		return Lock{}, false
+	}
+	if val1.HasWriter {
+		if val1.Writer != val2.Writer {
+			return Lock{}, false
+		}
+	}
+	return val1, true
+}
+
+func (lockSetFunctions) Split(r LockRange, val Lock, split uint64) (Lock, Lock) {
+	// Copy the segment so that split segments don't contain map references
+	// to other segments.
+	val0 := Lock{Readers: make(map[UniqueID]bool)}
+	for k, v := range val.Readers {
+		val0.Readers[k] = v
+	}
+	val0.HasWriter = val.HasWriter
+	val0.Writer = val.Writer
+
+	return val, val0
+}