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.

absl_helper/BUILD

@@ -0,0 +1,12 @@
+package(default_visibility = ["//visibility:public"])
+
+cc_library(
+    name = "jedec_size_flag",
+    srcs = ["jedec_size_flag.cc"],
+    hdrs = ["jedec_size_flag.h"],
+    deps = [
+        "@com_google_absl//absl/flags:flag",
+        "@com_google_absl//absl/flags:marshalling",
+        "@com_google_absl//absl/strings",
+    ],
+)

absl_helper/jedec_size_flag.cc

@@ -0,0 +1,93 @@
+// 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.
+
+#include "absl_helper/jedec_size_flag.h"
+
+namespace cdc_ft {
+
+namespace {
+
+JedecUnit ToJedecUnit(char c) {
+  switch (c) {
+    case 'b':
+    case 'B':
+      return JedecUnit::Byte;
+    case 'k':
+    case 'K':
+      return JedecUnit::Kilo;
+    case 'm':
+    case 'M':
+      return JedecUnit::Mega;
+    case 'g':
+    case 'G':
+      return JedecUnit::Giga;
+    case 't':
+    case 'T':
+      return JedecUnit::Tera;
+    case 'p':
+    case 'P':
+      return JedecUnit::Peta;
+    default:
+      return JedecUnit::Unkown;
+  }
+}
+
+int LeftShiftAmount(JedecUnit unit) {
+  switch (unit) {
+    case JedecUnit::Kilo:
+      return 10;
+    case JedecUnit::Mega:
+      return 20;
+    case JedecUnit::Giga:
+      return 30;
+    case JedecUnit::Tera:
+      return 40;
+    case JedecUnit::Peta:
+      return 50;
+    default:
+      return 0;
+  }
+}
+
+}  // namespace
+
+bool AbslParseFlag(absl::string_view text, JedecSize* flag, std::string* err) {
+  if (text.empty()) return false;
+  JedecUnit unit = ToJedecUnit(text.back());
+  if (unit != JedecUnit::Unkown) {
+    text.remove_suffix(1);
+  } else {
+    // Are we dealing with a digit character?
+    if (text.back() >= '0' && text.back() <= '9') {
+      unit = JedecUnit::Byte;
+    } else {
+      *err =
+          "Supported size units are (B)yte, (K)ilo, (M)ega, (G)iga, (T)era, "
+          "(P)eta.";
+      return false;
+    }
+  }
+  // Try to parse a plain uint64_t value.
+  uint64_t size;
+  if (!absl::ParseFlag(text, &size, err)) {
+    return false;
+  }
+  flag->SetSize(size << LeftShiftAmount(unit));
+  return true;
+}
+
+std::string AbslUnparseFlag(const JedecSize& size) {
+  return absl::UnparseFlag(size.Size());
+}
+};  // namespace cdc_ft

absl_helper/jedec_size_flag.h

@@ -0,0 +1,61 @@
+/*
+ * 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 ABSL_HELPER_JEDEC_SIZE_FLAG_H_
+#define ABSL_HELPER_JEDEC_SIZE_FLAG_H_
+
+#include <string>
+
+#include "absl/flags/flag.h"
+#include "absl/flags/marshalling.h"
+#include "absl/strings/string_view.h"
+
+namespace cdc_ft {
+
+// Supported JEDEC unit suffixes.
+enum class JedecUnit : char {
+  Unkown = 0,
+  Byte = 'B',  // optional
+  Kilo = 'K',
+  Mega = 'M',
+  Giga = 'G',
+  Tera = 'T',
+  Peta = 'P',
+};
+
+// This class parses flag arguments that represent human readable data sizes,
+// such as 1024, 2K, 3M, 4G, or 5T.
+//
+// See https://en.wikipedia.org/wiki/JEDEC_memory_standards.
+class JedecSize {
+ public:
+  explicit JedecSize(uint64_t size = 0) : size_(size) {}
+  uint64_t Size() const { return size_; }
+  void SetSize(uint64_t size) { size_ = size; }
+
+ private:
+  uint64_t size_;
+};
+
+// Abseil flags parser for JedecSize.
+bool AbslParseFlag(absl::string_view text, JedecSize* flag, std::string* err);
+
+// Abseil flags unparser for JedecSize.
+std::string AbslUnparseFlag(const JedecSize& size);
+
+};  // namespace cdc_ft
+
+#endif  // ABSL_HELPER_JEDEC_SIZE_FLAG_H_