Releasing the former Stadia file transfer tools

The tools allow efficient and fast synchronization of large directory
trees from a Windows workstation to a Linux target machine.

cdc_rsync* support efficient copy of files by using content-defined
chunking (CDC) to identify chunks within files that can be reused.

asset_stream_manager + cdc_fuse_fs support efficient streaming of a
local directory to a remote virtual file system based on FUSE. It also
employs CDC to identify and reuse unchanged data chunks.

common/path_filter.h

@@ -0,0 +1,72 @@
+/*
+ * Copyright 2022 Google LLC
+ *
+ * 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.
+ */
+
+#ifndef COMMON_PATH_FILTER_H_
+#define COMMON_PATH_FILTER_H_
+
+#include <string>
+#include <vector>
+
+namespace cdc_ft {
+namespace internal {
+
+// Returns true iff |path| matches |pattern|. Exposed for testing purposes.
+bool IsMatch(const std::string& pattern, const std::string& path);
+
+}  // namespace internal
+
+// Applies include and exclude filter rules to a path.
+class PathFilter {
+ public:
+  struct Rule {
+    enum class Type {
+      kInclude,
+      kExclude,
+    };
+
+    Type type;
+    std::string pattern;
+    Rule(Type type, std::string pattern);
+  };
+
+  PathFilter();
+  ~PathFilter();
+
+  // Returns true if no rule has been added.
+  bool IsEmpty() const;
+
+  // Adds a rule to the set of filter rules. The |type| determines whether paths
+  // that match |pattern| should be filtered in or out, see IsMatch(). |pattern|
+  // is a Windows style file path pattern and supports * and ? wildcards. Does
+  // not support general glob-style ** or [a-z] patterns.
+  void AddRule(Rule::Type type, std::string pattern);
+
+  // Returns all rules added.
+  const std::vector<Rule>& GetRules() const { return rules_; }
+
+  // Applies filter rules in the order they have been passed to AddRule().
+  // Returns true if the first matching rule is of type |kInclude| or no
+  // matching rule is found. Returns false if the first matching rule is
+  // of type |kExclude|.
+  bool IsMatch(const std::string& path) const;
+
+ private:
+  std::vector<Rule> rules_;
+};
+
+}  // namespace cdc_ft
+
+#endif  // COMMON_PATH_FILTER_H_