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.

cdc_fuse_fs/mock_libfuse.cc

@@ -0,0 +1,111 @@
+// 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 "cdc_fuse_fs/mock_libfuse.h"
+
+#include <cassert>
+#include <cstring>
+
+namespace cdc_ft {
+namespace {
+MockLibFuse* g_fuse;
+}
+
+MockLibFuse::MockLibFuse() {
+  assert(!g_fuse);
+  g_fuse = this;
+}
+
+MockLibFuse::~MockLibFuse() {
+  assert(g_fuse == this);
+  g_fuse = nullptr;
+}
+
+void MockLibFuse::SetUid(int uid) {
+  assert(g_fuse == this);
+  g_fuse->context.uid = uid;
+}
+
+void MockLibFuse::SetGid(int gid) {
+  assert(g_fuse == this);
+  g_fuse->context.gid = gid;
+}
+
+size_t fuse_add_direntry(fuse_req_t req, char* buf, size_t bufsize,
+                         const char* name, const struct stat* stbuf,
+                         off_t off) {
+  assert(g_fuse);
+  if (bufsize >= sizeof(MockLibFuse::DirEntry)) {
+    assert(stbuf);
+    auto* entry = reinterpret_cast<MockLibFuse::DirEntry*>(buf);
+    strncpy(entry->name, name, sizeof(entry->name));
+    entry->name[sizeof(entry->name) - 1] = 0;
+    entry->ino = stbuf->st_ino;
+    entry->mode = stbuf->st_mode;
+    entry->off = off;
+  }
+  return sizeof(MockLibFuse::DirEntry);
+}
+
+int fuse_reply_attr(fuse_req_t req, const struct stat* attr,
+                    double attr_timeout) {
+  assert(g_fuse);
+  assert(attr);
+  g_fuse->attrs.emplace_back(*attr, attr_timeout);
+  return 0;
+}
+
+int fuse_reply_buf(fuse_req_t req, const char* buf, size_t size) {
+  assert(g_fuse);
+  std::vector<char> data;
+  if (buf && size > 0) {
+    data.insert(data.end(), buf, buf + size);
+  }
+  g_fuse->buffers.push_back(std::move(data));
+  return 0;
+}
+
+int fuse_reply_entry(fuse_req_t req, const struct fuse_entry_param* e) {
+  assert(g_fuse);
+  assert(e);
+  g_fuse->entries.push_back(*e);
+  return 0;
+}
+
+int fuse_reply_err(fuse_req_t req, int err) {
+  assert(g_fuse);
+  g_fuse->errors.push_back(err);
+  return 0;
+}
+
+int fuse_reply_open(fuse_req_t req, const struct fuse_file_info* fi) {
+  assert(g_fuse);
+  assert(fi);
+  g_fuse->open_files.push_back(*fi);
+  return 0;
+}
+
+void fuse_reply_none(fuse_req_t req) {
+  assert(g_fuse);
+  ++g_fuse->none_counter;
+}
+
+int fuse_reply_statfs(fuse_req_t req, const struct statvfs* stbuf) { return 0; }
+
+struct fuse_context* fuse_get_context() {
+  assert(g_fuse);
+  return &g_fuse->context;
+}
+
+}  // namespace cdc_ft