Add an executable to create a microdroid signature
This is for testing purpose. Creating a microdroid signature and
embedding it in a payload image will be done by VirtManager in the
future.
Bug: 185069443
Test: create a signature following README
create a payload.img with signature
pass --disk=payload.img (check manually /dev/block/vdc1)
Change-Id: I6504dc6b3732c8e00e3bd1ffa5059995962d14b8
diff --git a/microdroid/signature/signature.cc b/microdroid/signature/signature.cc
new file mode 100644
index 0000000..446159e
--- /dev/null
+++ b/microdroid/signature/signature.cc
@@ -0,0 +1,74 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * 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 "microdroid/signature.h"
+
+#include <android-base/endian.h>
+#include <android-base/file.h>
+
+using android::base::ErrnoError;
+using android::base::Error;
+using android::base::Result;
+
+namespace android {
+namespace microdroid {
+
+Result<MicrodroidSignature> ReadMicrodroidSignature(const std::string& path) {
+ std::string content;
+ if (!base::ReadFileToString(path, &content)) {
+ return ErrnoError() << "Failed to read " << path;
+ }
+
+ // read length prefix (4-byte, big-endian)
+ uint32_t size;
+ const size_t length_prefix_bytes = sizeof(size);
+ if (content.size() < length_prefix_bytes) {
+ return Error() << "Invalid signature: size == " << content.size();
+ }
+ size = be32toh(*reinterpret_cast<uint32_t*>(content.data()));
+ if (content.size() < length_prefix_bytes + size) {
+ return Error() << "Invalid signature: size(" << size << ") mimatches to the content size("
+ << content.size() - length_prefix_bytes << ")";
+ }
+ content = content.substr(length_prefix_bytes, size);
+
+ // parse content
+ MicrodroidSignature signature;
+ if (!signature.ParseFromString(content)) {
+ return Error() << "Can't parse MicrodroidSignature from " << path;
+ }
+ return signature;
+}
+
+Result<void> WriteMicrodroidSignature(const MicrodroidSignature& signature, std::ostream& out) {
+ // prepare content
+ std::string content;
+ if (!signature.SerializeToString(&content)) {
+ return Error() << "Failed to write protobuf.";
+ }
+
+ // write length prefix (4-byte, big-endian)
+ uint32_t size = htobe32(static_cast<uint32_t>(content.size()));
+ out.write(reinterpret_cast<const char*>(&size), sizeof(size));
+
+ // write content
+ out << content;
+
+ return {};
+}
+
+} // namespace microdroid
+} // namespace android
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