libandroidfw: Support loading ApkAssets from a file descriptor

Test: make aapt2_tests
Change-Id: I041f9e9e3d3f6a10684cbd8baa49f4dda7d6dc40
diff --git a/libs/androidfw/ApkAssets.cpp b/libs/androidfw/ApkAssets.cpp
index 158df13..da0205d 100644
--- a/libs/androidfw/ApkAssets.cpp
+++ b/libs/androidfw/ApkAssets.cpp
@@ -47,12 +47,12 @@
 }
 
 std::unique_ptr<const ApkAssets> ApkAssets::Load(const std::string& path, bool system) {
-  return ApkAssets::LoadImpl(path, nullptr, nullptr, system, false /*load_as_shared_library*/);
+  return LoadImpl({} /*fd*/, path, nullptr, nullptr, system, false /*load_as_shared_library*/);
 }
 
 std::unique_ptr<const ApkAssets> ApkAssets::LoadAsSharedLibrary(const std::string& path,
                                                                 bool system) {
-  return ApkAssets::LoadImpl(path, nullptr, nullptr, system, true /*load_as_shared_library*/);
+  return LoadImpl({} /*fd*/, path, nullptr, nullptr, system, true /*load_as_shared_library*/);
 }
 
 std::unique_ptr<const ApkAssets> ApkAssets::LoadOverlay(const std::string& idmap_path,
@@ -70,8 +70,15 @@
     LOG(ERROR) << "failed to load IDMAP " << idmap_path;
     return {};
   }
-  return LoadImpl(loaded_idmap->OverlayApkPath(), std::move(idmap_asset), std::move(loaded_idmap),
-                  system, false /*load_as_shared_library*/);
+  return LoadImpl({} /*fd*/, loaded_idmap->OverlayApkPath(), std::move(idmap_asset),
+                  std::move(loaded_idmap), system, false /*load_as_shared_library*/);
+}
+
+std::unique_ptr<const ApkAssets> ApkAssets::LoadFromFd(unique_fd fd,
+                                                       const std::string& friendly_name,
+                                                       bool system, bool force_shared_lib) {
+  return LoadImpl(std::move(fd), friendly_name, nullptr /*idmap_asset*/, nullptr /*loaded_idmap*/,
+                  system, force_shared_lib);
 }
 
 std::unique_ptr<Asset> ApkAssets::CreateAssetFromFile(const std::string& path) {
@@ -96,11 +103,19 @@
 }
 
 std::unique_ptr<const ApkAssets> ApkAssets::LoadImpl(
-    const std::string& path, std::unique_ptr<Asset> idmap_asset,
+    unique_fd fd, const std::string& path, std::unique_ptr<Asset> idmap_asset,
     std::unique_ptr<const LoadedIdmap> loaded_idmap, bool system, bool load_as_shared_library) {
   ATRACE_CALL();
+
   ::ZipArchiveHandle unmanaged_handle;
-  int32_t result = ::OpenArchive(path.c_str(), &unmanaged_handle);
+  int32_t result;
+  if (fd >= 0) {
+    result =
+        ::OpenArchiveFd(fd.release(), path.c_str(), &unmanaged_handle, true /*assume_ownership*/);
+  } else {
+    result = ::OpenArchive(path.c_str(), &unmanaged_handle);
+  }
+
   if (result != 0) {
     LOG(ERROR) << "Failed to open APK '" << path << "' " << ::ErrorCodeString(result);
     return {};
diff --git a/libs/androidfw/include/androidfw/ApkAssets.h b/libs/androidfw/include/androidfw/ApkAssets.h
index 3a307fc..69702e3 100644
--- a/libs/androidfw/include/androidfw/ApkAssets.h
+++ b/libs/androidfw/include/androidfw/ApkAssets.h
@@ -21,6 +21,7 @@
 #include <string>
 
 #include "android-base/macros.h"
+#include "android-base/unique_fd.h"
 
 #include "androidfw/Asset.h"
 #include "androidfw/LoadedArsc.h"
@@ -51,6 +52,16 @@
   static std::unique_ptr<const ApkAssets> LoadOverlay(const std::string& idmap_path,
                                                       bool system = false);
 
+  // Creates an ApkAssets from the given file descriptor, and takes ownership of the file
+  // descriptor. The `friendly_name` is some name that will be used to identify the source of
+  // this ApkAssets in log messages and other debug scenarios.
+  // If `system` is true, the package is marked as a system package, and allows some functions to
+  // filter out this package when computing what configurations/resources are available.
+  // If `force_shared_lib` is true, any package with ID 0x7f is loaded as a shared library.
+  static std::unique_ptr<const ApkAssets> LoadFromFd(base::unique_fd fd,
+                                                     const std::string& friendly_name, bool system,
+                                                     bool force_shared_lib);
+
   std::unique_ptr<Asset> Open(const std::string& path,
                               Asset::AccessMode mode = Asset::AccessMode::ACCESS_RANDOM) const;
 
@@ -69,7 +80,7 @@
  private:
   DISALLOW_COPY_AND_ASSIGN(ApkAssets);
 
-  static std::unique_ptr<const ApkAssets> LoadImpl(const std::string& path,
+  static std::unique_ptr<const ApkAssets> LoadImpl(base::unique_fd fd, const std::string& path,
                                                    std::unique_ptr<Asset> idmap_asset,
                                                    std::unique_ptr<const LoadedIdmap> loaded_idmap,
                                                    bool system, bool load_as_shared_library);
diff --git a/libs/androidfw/tests/ApkAssets_test.cpp b/libs/androidfw/tests/ApkAssets_test.cpp
index d65d93f..ba5844b 100644
--- a/libs/androidfw/tests/ApkAssets_test.cpp
+++ b/libs/androidfw/tests/ApkAssets_test.cpp
@@ -24,6 +24,7 @@
 #include "TestHelpers.h"
 #include "data/basic/R.h"
 
+using ::android::base::unique_fd;
 using ::com::android::basic::R;
 
 namespace android {
@@ -44,6 +45,26 @@
   ASSERT_NE(nullptr, asset);
 }
 
+TEST(ApkAssetsTest, LoadApkFromFd) {
+  const std::string path = GetTestDataPath() + "/basic/basic.apk";
+  unique_fd fd(::open(path.c_str(), O_RDONLY | O_BINARY));
+  ASSERT_GE(fd.get(), 0);
+
+  std::unique_ptr<const ApkAssets> loaded_apk =
+      ApkAssets::LoadFromFd(std::move(fd), path, false /*system*/, false /*force_shared_lib*/);
+  ASSERT_NE(nullptr, loaded_apk);
+
+  const LoadedArsc* loaded_arsc = loaded_apk->GetLoadedArsc();
+  ASSERT_NE(nullptr, loaded_arsc);
+
+  const LoadedPackage* loaded_package = loaded_arsc->GetPackageForId(0x7f010000);
+  ASSERT_NE(nullptr, loaded_package);
+  EXPECT_TRUE(loaded_package->IsVerified());
+
+  std::unique_ptr<Asset> asset = loaded_apk->Open("res/layout/main.xml");
+  ASSERT_NE(nullptr, asset);
+}
+
 TEST(ApkAssetsTest, LoadApkAsSharedLibrary) {
   std::unique_ptr<const ApkAssets> loaded_apk =
       ApkAssets::Load(GetTestDataPath() + "/appaslib/appaslib.apk");
@@ -132,7 +153,7 @@
   ASSERT_NE(nullptr, asset);
 
   off64_t start, length;
-  base::unique_fd fd(asset->openFileDescriptor(&start, &length));
+  unique_fd fd(asset->openFileDescriptor(&start, &length));
   EXPECT_GE(fd.get(), 0);
 
   lseek64(fd.get(), start, SEEK_SET);