Fallback to /data/apex/sessions if /metadata partition is absent

There might be devices that support updatable apex, but don't have
/metadata partition. For them we need to fallback to storing sessions on
/data/apex/sessions.

This change implements this logic by introducing GetSessionsDir static
method which will pick first existing directory between
/metadata/apex/sessions and /data/apex/sessions. The evaluation will
happen only once, all other calls to GetSessionsDir will return the
cached value.

Additionally, the logic for migrating sessions from /data/apex/sessions
to /metadata/apex/sessions is changed a little bit. Now apexd will
iterate over entires in /data/apex/sessions, and then recursively
copy their content to the corresponding directory under
/metadata/apex/sessions, and then delete the entry under
/data/apex/sessions. This way a directory created by init
(/data/apex/sessions) is kept, which makes it easier to write unit tests
for apexd.

Logic is implemented as function inside apexd_utils.h for the ease of
unit testing.

Test: atest ApexTestCases
Test: atest apexd_host_tests
Test: atest CtsStagedInstallHostTestCases
Bug: 169932155
Bug: 176314162
Merged-In: Ifea8840ee5f1e56428d80bbb3b4e5e078176a578
Change-Id: Ia5e31e53edb411a023c8b090b7eb53ae977adc3e
(cherry picked from commit 7ffc3f6bd74b0b5567e6425090e9d13b6f5d4172)
(cherry picked from commit 69e06a1ddf509e4fc0734e044655d2b876b2bf45)

1 files changed, 24 insertions, 15 deletions

diff --git a/apexd/apexservice_test.cpp b/apexd/apexservice_test.cpp
index 4c054f1..024cf50 100644
--- a/apexd/apexservice_test.cpp
+++ b/apexd/apexservice_test.cpp
@@ -94,6 +94,26 @@ using MountedApexData = MountedApexDatabase::MountedApexData;
 
 namespace fs = std::filesystem;
 
+static void CleanDir(const std::string& dir) {
+  if (access(dir.c_str(), F_OK) != 0 && errno == ENOENT) {
+    LOG(WARNING) << dir << " does not exist";
+    return;
+  }
+  auto status = WalkDir(dir, [](const fs::directory_entry& p) {
+    std::error_code ec;
+    fs::file_status status = p.status(ec);
+    ASSERT_FALSE(ec) << "Failed to stat " << p.path() << " : " << ec.message();
+    if (fs::is_directory(status)) {
+      fs::remove_all(p.path(), ec);
+    } else {
+      fs::remove(p.path(), ec);
+    }
+    ASSERT_FALSE(ec) << "Failed to delete " << p.path() << " : "
+                     << ec.message();
+  });
+  ASSERT_TRUE(IsOk(status));
+}
+
 class ApexServiceTest : public ::testing::Test {
  public:
   ApexServiceTest() {
@@ -447,21 +467,10 @@ class ApexServiceTest : public ::testing::Test {
 
  private:
   void CleanUp() {
-    auto status = WalkDir(kApexDataDir, [](const fs::directory_entry& p) {
-      std::error_code ec;
-      fs::file_status status = p.status(ec);
-      ASSERT_FALSE(ec) << "Failed to stat " << p.path() << " : "
-                       << ec.message();
-      if (fs::is_directory(status)) {
-        fs::remove_all(p.path(), ec);
-      } else {
-        fs::remove(p.path(), ec);
-      }
-      ASSERT_FALSE(ec) << "Failed to delete " << p.path() << " : "
-                       << ec.message();
-    });
-    fs::remove_all(kApexSessionsDir);
-    ASSERT_TRUE(IsOk(status));
+    CleanDir(kActiveApexPackagesDataDir);
+    CleanDir(kApexBackupDir);
+    CleanDir(kApexHashTreeDir);
+    CleanDir(ApexSession::GetSessionsDir());
 
     DeleteIfExists("/data/misc_ce/0/apexdata/apex.apexd_test");
     DeleteIfExists("/data/misc_ce/0/apexrollback/123456");