[aapt2] Parse --feature-flags parameter values

Bug: 297373084
Test: atest aapt2_tests
Change-Id: I7567aa8f41e6fde7334430446a940eb6b04c1446

5 files changed, 139 insertions, 0 deletions

diff --git a/tools/aapt2/cmd/Link.cpp b/tools/aapt2/cmd/Link.cpp
index 97404fc69af2..aacf9199239e 100644
--- a/tools/aapt2/cmd/Link.cpp
+++ b/tools/aapt2/cmd/Link.cpp
@@ -2512,6 +2512,28 @@ int LinkCommand::Action(const std::vector<std::string>& args) {
     }
   }
 
+  // Parse the feature flag values. An argument that starts with '@' points to a file to read flag
+  // values from.
+  std::vector<std::string> all_feature_flags_args;
+  for (const std::string& arg : feature_flags_args_) {
+    if (util::StartsWith(arg, "@")) {
+      const std::string path = arg.substr(1, arg.size() - 1);
+      std::string error;
+      if (!file::AppendArgsFromFile(path, &all_feature_flags_args, &error)) {
+        context.GetDiagnostics()->Error(android::DiagMessage(path) << error);
+        return 1;
+      }
+    } else {
+      all_feature_flags_args.push_back(arg);
+    }
+  }
+
+  for (const std::string& arg : all_feature_flags_args) {
+    if (ParseFeatureFlagsParameter(arg, context.GetDiagnostics(), &options_.feature_flag_values)) {
+      return 1;
+    }
+  }
+
   if (context.GetPackageType() != PackageType::kStaticLib && stable_id_file_path_) {
     if (!LoadStableIdMap(context.GetDiagnostics(), stable_id_file_path_.value(),
         &options_.stable_id_map)) {
diff --git a/tools/aapt2/cmd/Link.h b/tools/aapt2/cmd/Link.h
index a08f385b2270..26713fd92264 100644
--- a/tools/aapt2/cmd/Link.h
+++ b/tools/aapt2/cmd/Link.h
@@ -17,11 +17,17 @@
 #ifndef AAPT2_LINK_H
 #define AAPT2_LINK_H
 
+#include <optional>
 #include <regex>
+#include <string>
+#include <unordered_map>
+#include <unordered_set>
+#include <vector>
 
 #include "Command.h"
 #include "Resource.h"
 #include "androidfw/IDiagnostics.h"
+#include "cmd/Util.h"
 #include "format/binary/TableFlattener.h"
 #include "format/proto/ProtoSerialize.h"
 #include "link/ManifestFixer.h"
@@ -72,6 +78,7 @@ struct LinkOptions {
   bool use_sparse_encoding = false;
   std::unordered_set<std::string> extensions_to_not_compress;
   std::optional<std::regex> regex_to_not_compress;
+  FeatureFlagValues feature_flag_values;
 
   // Static lib options.
   bool no_static_lib_packages = false;
diff --git a/tools/aapt2/cmd/Util.cpp b/tools/aapt2/cmd/Util.cpp
index a92f24b82547..678d84628015 100644
--- a/tools/aapt2/cmd/Util.cpp
+++ b/tools/aapt2/cmd/Util.cpp
@@ -113,6 +113,56 @@ std::unique_ptr<IConfigFilter> ParseConfigFilterParameters(const std::vector<std
   return std::move(filter);
 }
 
+bool ParseFeatureFlagsParameter(StringPiece arg, android::IDiagnostics* diag,
+                                FeatureFlagValues* out_feature_flag_values) {
+  if (arg.empty()) {
+    return true;
+  }
+
+  for (StringPiece flag_and_value : util::Tokenize(arg, ',')) {
+    std::vector<std::string> parts = util::Split(flag_and_value, '=');
+    if (parts.empty()) {
+      continue;
+    }
+
+    if (parts.size() > 2) {
+      diag->Error(android::DiagMessage()
+                  << "Invalid feature flag and optional value '" << flag_and_value
+                  << "'. Must be in the format 'flag_name[=true|false]");
+      return false;
+    }
+
+    StringPiece flag_name = util::TrimWhitespace(parts[0]);
+    if (flag_name.empty()) {
+      diag->Error(android::DiagMessage() << "No name given for one or more flags in: " << arg);
+      return false;
+    }
+
+    std::optional<bool> flag_value = {};
+    if (parts.size() == 2) {
+      StringPiece str_flag_value = util::TrimWhitespace(parts[1]);
+      if (!str_flag_value.empty()) {
+        flag_value = ResourceUtils::ParseBool(parts[1]);
+        if (!flag_value.has_value()) {
+          diag->Error(android::DiagMessage() << "Invalid value for feature flag '" << flag_and_value
+                                             << "'. Value must be 'true' or 'false'");
+          return false;
+        }
+      }
+    }
+
+    if (auto [it, inserted] =
+            out_feature_flag_values->try_emplace(std::string(flag_name), flag_value);
+        !inserted) {
+      // We are allowing the same flag to appear multiple times, last value wins.
+      diag->Note(android::DiagMessage()
+                 << "Value for feature flag '" << flag_name << "' was given more than once");
+      it->second = flag_value;
+    }
+  }
+  return true;
+}
+
 // Adjust the SplitConstraints so that their SDK version is stripped if it
 // is less than or equal to the minSdk. Otherwise the resources that have had
 // their SDK version stripped due to minSdk won't ever match.
diff --git a/tools/aapt2/cmd/Util.h b/tools/aapt2/cmd/Util.h
index 712c07b71695..9ece5dd4d720 100644
--- a/tools/aapt2/cmd/Util.h
+++ b/tools/aapt2/cmd/Util.h
@@ -17,8 +17,13 @@
 #ifndef AAPT_SPLIT_UTIL_H
 #define AAPT_SPLIT_UTIL_H
 
+#include <functional>
+#include <map>
+#include <memory>
+#include <optional>
 #include <regex>
 #include <set>
+#include <string>
 #include <unordered_set>
 
 #include "AppInfo.h"
@@ -32,6 +37,8 @@
 
 namespace aapt {
 
+using FeatureFlagValues = std::map<std::string, std::optional<bool>, std::less<>>;
+
 // Parses a configuration density (ex. hdpi, xxhdpi, 234dpi, anydpi, etc).
 // Returns Nothing and logs a human friendly error message if the string was not legal.
 std::optional<uint16_t> ParseTargetDensityParameter(android::StringPiece arg,
@@ -48,6 +55,13 @@ bool ParseSplitParameter(android::StringPiece arg, android::IDiagnostics* diag,
 std::unique_ptr<IConfigFilter> ParseConfigFilterParameters(const std::vector<std::string>& args,
                                                            android::IDiagnostics* diag);
 
+// Parses a feature flags parameter, which can contain one or more pairs of flag names and optional
+// values, and fills in `out_feature_flag_values` with the parsed values. The pairs in the argument
+// are separated by ',' and the name is separated from the value by '=' if there is a value given.
+// Example arg: "flag1=true,flag2=false,flag3=,flag4" where flag3 and flag4 have no given value.
+bool ParseFeatureFlagsParameter(android::StringPiece arg, android::IDiagnostics* diag,
+                                FeatureFlagValues* out_feature_flag_values);
+
 // Adjust the SplitConstraints so that their SDK version is stripped if it
 // is less than or equal to the min_sdk. Otherwise the resources that have had
 // their SDK version stripped due to min_sdk won't ever match.
diff --git a/tools/aapt2/cmd/Util_test.cpp b/tools/aapt2/cmd/Util_test.cpp
index 139bfbcd0f41..723d87ed0af3 100644
--- a/tools/aapt2/cmd/Util_test.cpp
+++ b/tools/aapt2/cmd/Util_test.cpp
@@ -25,6 +25,7 @@
 #include "util/Files.h"
 
 using ::android::ConfigDescription;
+using testing::Pair;
 using testing::UnorderedElementsAre;
 
 namespace aapt {
@@ -354,6 +355,51 @@ TEST (UtilTest, ParseSplitParameters) {
   EXPECT_CONFIG_EQ(constraints, expected_configuration);
 }
 
+TEST(UtilTest, ParseFeatureFlagsParameter_Empty) {
+  auto diagnostics = test::ContextBuilder().Build()->GetDiagnostics();
+  FeatureFlagValues feature_flag_values;
+  ASSERT_TRUE(ParseFeatureFlagsParameter("", diagnostics, &feature_flag_values));
+  EXPECT_TRUE(feature_flag_values.empty());
+}
+
+TEST(UtilTest, ParseFeatureFlagsParameter_TooManyParts) {
+  auto diagnostics = test::ContextBuilder().Build()->GetDiagnostics();
+  FeatureFlagValues feature_flag_values;
+  ASSERT_FALSE(ParseFeatureFlagsParameter("foo=bar=baz", diagnostics, &feature_flag_values));
+}
+
+TEST(UtilTest, ParseFeatureFlagsParameter_NoNameGiven) {
+  auto diagnostics = test::ContextBuilder().Build()->GetDiagnostics();
+  FeatureFlagValues feature_flag_values;
+  ASSERT_FALSE(ParseFeatureFlagsParameter("foo=true,=false", diagnostics, &feature_flag_values));
+}
+
+TEST(UtilTest, ParseFeatureFlagsParameter_InvalidValue) {
+  auto diagnostics = test::ContextBuilder().Build()->GetDiagnostics();
+  FeatureFlagValues feature_flag_values;
+  ASSERT_FALSE(ParseFeatureFlagsParameter("foo=true,bar=42", diagnostics, &feature_flag_values));
+}
+
+TEST(UtilTest, ParseFeatureFlagsParameter_DuplicateFlag) {
+  auto diagnostics = test::ContextBuilder().Build()->GetDiagnostics();
+  FeatureFlagValues feature_flag_values;
+  ASSERT_TRUE(
+      ParseFeatureFlagsParameter("foo=true,bar=true,foo=false", diagnostics, &feature_flag_values));
+  EXPECT_THAT(feature_flag_values, UnorderedElementsAre(Pair("foo", std::optional<bool>(false)),
+                                                        Pair("bar", std::optional<bool>(true))));
+}
+
+TEST(UtilTest, ParseFeatureFlagsParameter_Valid) {
+  auto diagnostics = test::ContextBuilder().Build()->GetDiagnostics();
+  FeatureFlagValues feature_flag_values;
+  ASSERT_TRUE(ParseFeatureFlagsParameter("foo= true, bar =FALSE,baz=, quux", diagnostics,
+                                         &feature_flag_values));
+  EXPECT_THAT(feature_flag_values,
+              UnorderedElementsAre(Pair("foo", std::optional<bool>(true)),
+                                   Pair("bar", std::optional<bool>(false)),
+                                   Pair("baz", std::nullopt), Pair("quux", std::nullopt)));
+}
+
 TEST (UtilTest, AdjustSplitConstraintsForMinSdk) {
   std::unique_ptr<IAaptContext> context = test::ContextBuilder().Build();