From 3fa66c7283279632526e8f1bc231389fd0415de7 Mon Sep 17 00:00:00 2001
From: David Anderson <dvander@google.com>
Date: Mon, 26 Oct 2020 18:21:08 -0700
Subject: [PATCH] libsnapshot: Add a tool for inspecting COW files.

This simple tool will dump the COW header and included ops to stdout.

Bug: N/A
Test: mm inspect_cow && inspect_cow <file>
Change-Id: I369c4a21a84c95ffc10670bd9eeb2ceccb2a56d6
---
 fs_mgr/libsnapshot/Android.bp      | 24 ++++++++
 fs_mgr/libsnapshot/inspect_cow.cpp | 90 ++++++++++++++++++++++++++++++
 2 files changed, 114 insertions(+)
 create mode 100644 fs_mgr/libsnapshot/inspect_cow.cpp

diff --git a/fs_mgr/libsnapshot/Android.bp b/fs_mgr/libsnapshot/Android.bp
index f154138ad..4e5a0def3 100644
--- a/fs_mgr/libsnapshot/Android.bp
+++ b/fs_mgr/libsnapshot/Android.bp
@@ -572,3 +572,27 @@ cc_test {
     auto_gen_config: true,
     require_root: false,
 }
+
+cc_binary {
+    name: "inspect_cow",
+    host_supported: true,
+    device_supported: true,
+    cflags: [
+        "-D_FILE_OFFSET_BITS=64",
+        "-Wall",
+        "-Werror",
+    ],
+    static_libs: [
+        "libbase",
+        "libbrotli",
+        "libcrypto_static",
+        "liblog",
+        "libsnapshot_cow",
+        "libz",
+    ],
+    shared_libs: [
+    ],
+    srcs: [
+        "inspect_cow.cpp",
+    ],
+}
diff --git a/fs_mgr/libsnapshot/inspect_cow.cpp b/fs_mgr/libsnapshot/inspect_cow.cpp
new file mode 100644
index 000000000..6046bad66
--- /dev/null
+++ b/fs_mgr/libsnapshot/inspect_cow.cpp
@@ -0,0 +1,90 @@
+//
+// Copyright (C) 2020 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 <stdio.h>
+
+#include <iostream>
+#include <string>
+
+#include <android-base/logging.h>
+#include <android-base/unique_fd.h>
+#include <libsnapshot/cow_reader.h>
+
+namespace android {
+namespace snapshot {
+
+void MyLogger(android::base::LogId, android::base::LogSeverity severity, const char*, const char*,
+              unsigned int, const char* message) {
+    if (severity == android::base::ERROR) {
+        fprintf(stderr, "%s\n", message);
+    } else {
+        fprintf(stdout, "%s\n", message);
+    }
+}
+
+static bool Inspect(const std::string& path) {
+    android::base::unique_fd fd(open(path.c_str(), O_RDONLY));
+    if (fd < 0) {
+        PLOG(ERROR) << "open failed: " << path;
+        return false;
+    }
+
+    CowReader reader;
+    if (!reader.Parse(fd)) {
+        LOG(ERROR) << "parse failed: " << path;
+        return false;
+    }
+
+    CowHeader header;
+    if (!reader.GetHeader(&header)) {
+        LOG(ERROR) << "could not get header: " << path;
+        return false;
+    }
+
+    std::cout << "Major version: " << header.major_version << "\n";
+    std::cout << "Minor version: " << header.minor_version << "\n";
+    std::cout << "Header size: " << header.header_size << "\n";
+    std::cout << "Footer size: " << header.footer_size << "\n";
+    std::cout << "Block size: " << header.block_size << "\n";
+    std::cout << "\n";
+
+    auto iter = reader.GetOpIter();
+    while (!iter->Done()) {
+        const CowOperation& op = iter->Get();
+
+        std::cout << op << "\n";
+
+        iter->Next();
+    }
+
+    return true;
+}
+
+}  // namespace snapshot
+}  // namespace android
+
+int main(int argc, char** argv) {
+    android::base::InitLogging(argv, android::snapshot::MyLogger);
+
+    if (argc < 2) {
+        LOG(ERROR) << "Usage: inspect_cow <COW_FILE>";
+        return 1;
+    }
+
+    if (!android::snapshot::Inspect(argv[1])) {
+        return 1;
+    }
+    return 0;
+}