From a16436d5d737f65d7dca3335a834ef877b0e9c7b Mon Sep 17 00:00:00 2001
From: Daniel Zheng <zhengdaniel@google.com>
Date: Tue, 26 Sep 2023 17:22:36 -0700
Subject: [PATCH] Adding test for reader compatibility

Reader + Parser v3 should be able to read V2 cow format written to disk.
This test reads in a small cow file written by basic_v2_cow_writer and
parses it to ensure this compatibility checks out.

Test: cow_api_test
Change-Id: I46ebf4e3f12cdb3e4716ca5b624aab5836086733
---
 fs_mgr/libsnapshot/Android.bp                 |  3 ++
 .../libsnapshot/libsnapshot_cow/test_v2.cpp   | 31 +++++++++++++++++++
 2 files changed, 34 insertions(+)

diff --git a/fs_mgr/libsnapshot/Android.bp b/fs_mgr/libsnapshot/Android.bp
index 0131f732e..fe47801f3 100644
--- a/fs_mgr/libsnapshot/Android.bp
+++ b/fs_mgr/libsnapshot/Android.bp
@@ -415,6 +415,9 @@ cc_test {
     test_options: {
         min_shipping_api_level: 30,
     },
+    data: [
+        "tools/testdata/cow_v2",
+    ],
     auto_gen_config: true,
     require_root: false,
     host_supported: true,
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/test_v2.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/test_v2.cpp
index e59bd927f..9676bf9b2 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/test_v2.cpp
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/test_v2.cpp
@@ -1504,6 +1504,37 @@ TEST_F(CowTest, InvalidMergeOrderTest) {
     ASSERT_FALSE(reader.VerifyMergeOps());
 }
 
+unique_fd OpenTestFile(const std::string& file, int flags) {
+    std::string path = "tools/testdata/" + file;
+
+    unique_fd fd(open(path.c_str(), flags));
+    if (fd >= 0) {
+        return fd;
+    }
+
+    path = android::base::GetExecutableDirectory() + "/" + path;
+    return unique_fd{open(path.c_str(), flags)};
+}
+
+TEST_F(CowTest, CompatibilityTest) {
+    std::string filename = "cow_v2";
+    auto fd = OpenTestFile(filename, O_RDONLY);
+    if (fd.get() == -1) {
+        LOG(ERROR) << filename << " not found";
+        GTEST_SKIP();
+    }
+    CowReader reader;
+    reader.Parse(fd);
+
+    const auto& header = reader.GetHeader();
+    ASSERT_EQ(header.prefix.magic, kCowMagicNumber);
+    ASSERT_EQ(header.prefix.major_version, kCowVersionMajor);
+    ASSERT_EQ(header.prefix.minor_version, kCowVersionMinor);
+
+    CowFooter footer;
+    ASSERT_TRUE(reader.GetFooter(&footer));
+}
+
 }  // namespace snapshot
 }  // namespace android