From 2a4afd29a15522ccf3d8ca902214e68445bcac81 Mon Sep 17 00:00:00 2001
From: Yifan Hong <elsk@google.com>
Date: Mon, 27 Apr 2020 20:16:18 -0700
Subject: [PATCH] Detect non-A/B vs. A/B packages correctly.

Check the package metadata to determine whether this is an
A/B or non-A/B update package. This is more accurate.

Also checks ro.virtual_ab.allow_non_ab flag. This is useful for
continuously supporting (and testing) non-A/B.

Bug: 153581609
Test: apply non-A/B update on cuttlefish

Change-Id: I629a533a67966d46d9cd87a59c6b9af26daf1667
---
 install/install.cpp | 27 +++++++++++++++++++--------
 1 file changed, 19 insertions(+), 8 deletions(-)

diff --git a/install/install.cpp b/install/install.cpp
index 1c9bf2fd..d404997d 100644
--- a/install/install.cpp
+++ b/install/install.cpp
@@ -331,15 +331,25 @@ static InstallResult TryUpdateBinary(Package* package, bool* wipe_cache,
     return INSTALL_CORRUPT;
   }
 
-  bool is_ab = android::base::GetBoolProperty("ro.build.ab_update", false);
-  if (is_ab) {
+  bool package_is_ab = get_value(metadata, "ota-type") == OtaTypeToString(OtaType::AB);
+  bool device_supports_ab = android::base::GetBoolProperty("ro.build.ab_update", false);
+  bool ab_device_supports_nonab =
+      android::base::GetBoolProperty("ro.virtual_ab.allow_non_ab", false);
+  bool device_only_supports_ab = device_supports_ab && !ab_device_supports_nonab;
+
+  if (package_is_ab) {
     CHECK(package->GetType() == PackageType::kFile);
   }
 
-  // Verify against the metadata in the package first.
-  if (is_ab && !CheckPackageMetadata(metadata, OtaType::AB)) {
-    log_buffer->push_back(android::base::StringPrintf("error: %d", kUpdateBinaryCommandFailure));
-    return INSTALL_ERROR;
+  // Verify against the metadata in the package first. Expects A/B metadata if:
+  // Package declares itself as an A/B package
+  // Package does not declare itself as an A/B package, but device only supports A/B;
+  //   still calls CheckPackageMetadata to get a meaningful error message.
+  if (package_is_ab || device_only_supports_ab) {
+    if (!CheckPackageMetadata(metadata, OtaType::AB)) {
+      log_buffer->push_back(android::base::StringPrintf("error: %d", kUpdateBinaryCommandFailure));
+      return INSTALL_ERROR;
+    }
   }
 
   ReadSourceTargetBuild(metadata, log_buffer);
@@ -389,8 +399,9 @@ static InstallResult TryUpdateBinary(Package* package, bool* wipe_cache,
 
   std::vector<std::string> args;
   if (auto setup_result =
-          is_ab ? SetUpAbUpdateCommands(package_path, zip, pipe_write.get(), &args)
-                : SetUpNonAbUpdateCommands(package_path, zip, retry_count, pipe_write.get(), &args);
+          package_is_ab
+              ? SetUpAbUpdateCommands(package_path, zip, pipe_write.get(), &args)
+              : SetUpNonAbUpdateCommands(package_path, zip, retry_count, pipe_write.get(), &args);
       !setup_result) {
     log_buffer->push_back(android::base::StringPrintf("error: %d", kUpdateBinaryCommandFailure));
     return INSTALL_CORRUPT;