Implement sysprop_library API stability check

sysprop_library now checks the API stability itself, cutting dependency
on java_sdk_library. Under the directory {module_dir}/api,
{module_name}-current.txt and {module_name}-latest.txt hold API
signatures.

When sysprop_library is built, or a user run "m {module_name}-check-api"
command, API check is performed. First, current.txt must have exactly
same signature with built sysprop_library module. Second, current.txt
must be compatible with latest.txt.

Build system emits a handy error message to generate/update those API
files, in case of missing or mismatching. Also, a script file for
freezing API files is introduced.

Bug: 131637873
Test: 1) m && boot blueline
Test: 2) m {sysprop_library} performs API check
Test: 3) manual test for check-api, freezing api
Change-Id: I95e0e38a24e78bb9526248ea7efc12d7fbf2d35a

6 files changed, 245 insertions, 78 deletions

diff --git a/Android.bp b/Android.bp
index e91a8d4..9e8aca8 100644
--- a/Android.bp
+++ b/Android.bp
@@ -57,3 +57,23 @@ cc_test_host {
            "JavaGen.cpp",
            "tests/*.cpp"],
 }
+
+java_defaults {
+    name: "sysprop-library-stub-defaults",
+    srcs: [
+        "stub/android/os/SystemProperties.java",
+    ],
+    installable: false,
+    sdk_version: "core_current",
+}
+
+java_library {
+    name: "sysprop-library-stub-platform",
+    defaults: ["sysprop-library-stub-defaults"],
+}
+
+java_library {
+    name: "sysprop-library-stub-vendor",
+    defaults: ["sysprop-library-stub-defaults"],
+    soc_specific: true,
+}
diff --git a/JavaGen.cpp b/JavaGen.cpp
index ba7409d..5cf9c5c 100644
--- a/JavaGen.cpp
+++ b/JavaGen.cpp
@@ -40,8 +40,7 @@ namespace {
 constexpr const char* kIndent = "    ";
 
 constexpr const char* kJavaFileImports =
-    R"(import android.annotation.SystemApi;
-import android.os.SystemProperties;
+    R"(import android.os.SystemProperties;
 
 import java.util.ArrayList;
 import java.util.function.Function;
@@ -157,8 +156,8 @@ std::string GetJavaPackageName(const sysprop::Properties& props);
 std::string GetJavaClassName(const sysprop::Properties& props);
 std::string GetParsingExpression(const sysprop::Property& prop);
 std::string GetFormattingExpression(const sysprop::Property& prop);
-void WriteJavaAnnotation(CodeWriter& writer, sysprop::Scope scope);
-std::string GenerateJavaClass(const sysprop::Properties& props);
+std::string GenerateJavaClass(const sysprop::Properties& props,
+                              sysprop::Scope scope);
 
 std::string GetJavaEnumTypeName(const sysprop::Property& prop) {
   return ApiNameToIdentifier(prop.api_name()) + "_values";
@@ -277,33 +276,8 @@ std::string GetJavaClassName(const sysprop::Properties& props) {
   return module.substr(module.rfind('.') + 1);
 }
 
-void WriteJavaAnnotation(CodeWriter& writer, sysprop::Scope scope) {
-  switch (scope) {
-    // This is to restrict access from modules linking against SDK.
-    // TODO(b/131637873): remove this after cutting dependency on
-    // java_sdk_library
-    case sysprop::Public:
-      writer.Write("/** @hide */\n");
-      writer.Write("@SystemApi\n");
-      break;
-    case sysprop::Internal:
-      writer.Write("/** @hide */\n");
-      break;
-    default:
-      break;
-  }
-}
-
-std::string GenerateJavaClass(const sysprop::Properties& props) {
-  sysprop::Scope classScope = sysprop::Internal;
-
-  for (int i = 0; i < props.prop_size(); ++i) {
-    // Get least restrictive scope among props. For example, if all props
-    // are internal, class can be as well internal. However, class should
-    // be public or system if at least one prop is so.
-    classScope = std::min(classScope, props.prop(i).scope());
-  }
-
+std::string GenerateJavaClass(const sysprop::Properties& props,
+                              sysprop::Scope scope) {
   std::string package_name = GetJavaPackageName(props);
   std::string class_name = GetJavaClassName(props);
 
@@ -311,24 +285,23 @@ std::string GenerateJavaClass(const sysprop::Properties& props) {
   writer.Write("%s", kGeneratedFileFooterComments);
   writer.Write("package %s;\n\n", package_name.c_str());
   writer.Write("%s", kJavaFileImports);
-  WriteJavaAnnotation(writer, classScope);
   writer.Write("public final class %s {\n", class_name.c_str());
   writer.Indent();
   writer.Write("private %s () {}\n\n", class_name.c_str());
   writer.Write("%s", kJavaParsersAndFormatters);
 
   for (int i = 0; i < props.prop_size(); ++i) {
-    writer.Write("\n");
-
     const sysprop::Property& prop = props.prop(i);
 
+    // skip if scope is internal and we are generating public class
+    if (prop.scope() > scope) continue;
+
+    writer.Write("\n");
+
     std::string prop_id = ApiNameToIdentifier(prop.api_name()).c_str();
     std::string prop_type = GetJavaTypeName(prop);
 
     if (prop.type() == sysprop::Enum || prop.type() == sysprop::EnumList) {
-      if (prop.scope() != classScope) {
-        WriteJavaAnnotation(writer, prop.scope());
-      }
       writer.Write("public static enum %s {\n",
                    GetJavaEnumTypeName(prop).c_str());
       writer.Indent();
@@ -361,9 +334,6 @@ std::string GenerateJavaClass(const sysprop::Properties& props) {
       writer.Write("}\n\n");
     }
 
-    if (prop.scope() != classScope) {
-      WriteJavaAnnotation(writer, prop.scope());
-    }
     if (prop.deprecated()) {
       writer.Write("@Deprecated\n");
     }
@@ -389,11 +359,8 @@ std::string GenerateJavaClass(const sysprop::Properties& props) {
       writer.Write("}\n");
     }
 
-    if (prop.access() != sysprop::Readonly) {
+    if (prop.access() != sysprop::Readonly && scope == sysprop::Internal) {
       writer.Write("\n");
-      if (classScope != sysprop::Internal) {
-        WriteJavaAnnotation(writer, sysprop::Internal);
-      }
       if (prop.deprecated()) {
         writer.Write("@Deprecated\n");
       }
@@ -417,6 +384,7 @@ std::string GenerateJavaClass(const sysprop::Properties& props) {
 }  // namespace
 
 Result<void> GenerateJavaLibrary(const std::string& input_file_path,
+                                 sysprop::Scope scope,
                                  const std::string& java_output_dir) {
   sysprop::Properties props;
 
@@ -426,7 +394,7 @@ Result<void> GenerateJavaLibrary(const std::string& input_file_path,
     return res.error();
   }
 
-  std::string java_result = GenerateJavaClass(props);
+  std::string java_result = GenerateJavaClass(props, scope);
   std::string package_name = GetJavaPackageName(props);
   std::string java_package_dir =
       java_output_dir + "/" + std::regex_replace(package_name, kRegexDot, "/");
diff --git a/JavaMain.cpp b/JavaMain.cpp
index 5dc5d27..723e2d3 100644
--- a/JavaMain.cpp
+++ b/JavaMain.cpp
@@ -25,6 +25,7 @@
 #include <getopt.h>
 
 #include "JavaGen.h"
+#include "sysprop.pb.h"
 
 using android::base::Errorf;
 using android::base::Result;
@@ -34,10 +35,14 @@ namespace {
 struct Arguments {
   std::string input_file_path;
   std::string java_output_dir;
+  sysprop::Scope scope;
 };
 
 [[noreturn]] void PrintUsage(const char* exe_name) {
-  std::printf("Usage: %s [--java-output-dir dir] sysprop_file\n", exe_name);
+  std::printf(
+      "Usage: %s --scope (internal|public) --java-output-dir dir "
+      "sysprop_file\n",
+      exe_name);
   std::exit(EXIT_FAILURE);
 }
 
@@ -45,6 +50,7 @@ Result<void> ParseArgs(int argc, char* argv[], Arguments* args) {
   for (;;) {
     static struct option long_options[] = {
         {"java-output-dir", required_argument, 0, 'j'},
+        {"scope", required_argument, 0, 's'},
     };
 
     int opt = getopt_long_only(argc, argv, "", long_options, nullptr);
@@ -54,6 +60,15 @@ Result<void> ParseArgs(int argc, char* argv[], Arguments* args) {
       case 'j':
         args->java_output_dir = optarg;
         break;
+      case 's':
+        if (strcmp(optarg, "public") == 0) {
+          args->scope = sysprop::Scope::Public;
+        } else if (strcmp(optarg, "internal") == 0) {
+          args->scope = sysprop::Scope::Internal;
+        } else {
+          return Errorf("Invalid option {} for scope", optarg);
+        }
+        break;
       default:
         PrintUsage(argv[0]);
     }
@@ -83,7 +98,8 @@ int main(int argc, char* argv[]) {
     PrintUsage(argv[0]);
   }
 
-  if (auto res = GenerateJavaLibrary(args.input_file_path, args.java_output_dir);
+  if (auto res = GenerateJavaLibrary(args.input_file_path, args.scope,
+                                     args.java_output_dir);
       !res) {
     LOG(FATAL) << "Error during generating java sysprop from "
                << args.input_file_path << ": " << res.error();
diff --git a/include/JavaGen.h b/include/JavaGen.h
index 71dc407..9794626 100644
--- a/include/JavaGen.h
+++ b/include/JavaGen.h
@@ -19,5 +19,8 @@
 #include <android-base/result.h>
 #include <string>
 
+#include "sysprop.pb.h"
+
 android::base::Result<void> GenerateJavaLibrary(
-    const std::string& input_file_path, const std::string& java_output_dir);
\ No newline at end of file
+    const std::string& input_file_path, sysprop::Scope scope,
+    const std::string& java_output_dir);
\ No newline at end of file
diff --git a/stub/android/os/SystemProperties.java b/stub/android/os/SystemProperties.java
new file mode 100644
index 0000000..7309abc
--- /dev/null
+++ b/stub/android/os/SystemProperties.java
@@ -0,0 +1,28 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.os;
+
+// Stub for cutting dependency from sysprop_library to framework.jar
+public class SystemProperties {
+    public static String get(String key) {
+        return null;
+    }
+    public static void set(String key, String val) {
+    }
+    private SystemProperties() {
+    }
+}
diff --git a/tests/JavaGenTest.cpp b/tests/JavaGenTest.cpp
index f148e2c..a96d103 100644
--- a/tests/JavaGenTest.cpp
+++ b/tests/JavaGenTest.cpp
@@ -100,12 +100,155 @@ prop {
 }
 )";
 
-constexpr const char* kExpectedJavaOutput =
+constexpr const char* kExpectedPublicOutput =
+    R"(// Generated by the sysprop generator. DO NOT EDIT!
+
+package com.somecompany;
+
+import android.os.SystemProperties;
+
+import java.util.ArrayList;
+import java.util.function.Function;
+import java.util.List;
+import java.util.Locale;
+import java.util.Optional;
+import java.util.StringJoiner;
+import java.util.stream.Collectors;
+
+public final class TestProperties {
+    private TestProperties () {}
+
+    private static Boolean tryParseBoolean(String str) {
+        switch (str.toLowerCase(Locale.US)) {
+            case "1":
+            case "true":
+                return Boolean.TRUE;
+            case "0":
+            case "false":
+                return Boolean.FALSE;
+            default:
+                return null;
+        }
+    }
+
+    private static Integer tryParseInteger(String str) {
+        try {
+            return Integer.valueOf(str);
+        } catch (NumberFormatException e) {
+            return null;
+        }
+    }
+
+    private static Long tryParseLong(String str) {
+        try {
+            return Long.valueOf(str);
+        } catch (NumberFormatException e) {
+            return null;
+        }
+    }
+
+    private static Double tryParseDouble(String str) {
+        try {
+            return Double.valueOf(str);
+        } catch (NumberFormatException e) {
+            return null;
+        }
+    }
+
+    private static String tryParseString(String str) {
+        return "".equals(str) ? null : str;
+    }
+
+    private static <T extends Enum<T>> T tryParseEnum(Class<T> enumType, String str) {
+        try {
+            return Enum.valueOf(enumType, str.toUpperCase(Locale.US));
+        } catch (IllegalArgumentException e) {
+            return null;
+        }
+    }
+
+    private static <T> List<T> tryParseList(Function<String, T> elementParser, String str) {
+        if ("".equals(str)) return new ArrayList<>();
+
+        List<T> ret = new ArrayList<>();
+
+        for (String element : str.split(",")) {
+            ret.add(elementParser.apply(element));
+        }
+
+        return ret;
+    }
+
+    private static <T extends Enum<T>> List<T> tryParseEnumList(Class<T> enumType, String str) {
+        if ("".equals(str)) return new ArrayList<>();
+
+        List<T> ret = new ArrayList<>();
+
+        for (String element : str.split(",")) {
+            ret.add(tryParseEnum(enumType, element));
+        }
+
+        return ret;
+    }
+
+    private static <T> String formatList(List<T> list) {
+        StringJoiner joiner = new StringJoiner(",");
+
+        for (T element : list) {
+            joiner.add(element == null ? "" : element.toString());
+        }
+
+        return joiner.toString();
+    }
+
+    private static <T extends Enum<T>> String formatEnumList(List<T> list, Function<T, String> elementFormatter) {
+        StringJoiner joiner = new StringJoiner(",");
+
+        for (T element : list) {
+            joiner.add(element == null ? "" : elementFormatter.apply(element));
+        }
+
+        return joiner.toString();
+    }
+
+    public static Optional<Integer> test_int() {
+        String value = SystemProperties.get("vendor.test_int");
+        return Optional.ofNullable(tryParseInteger(value));
+    }
+
+    public static Optional<String> test_string() {
+        String value = SystemProperties.get("vendor.test.string");
+        return Optional.ofNullable(tryParseString(value));
+    }
+
+    public static Optional<Boolean> test_BOOLeaN() {
+        String value = SystemProperties.get("ro.vendor.test.b");
+        return Optional.ofNullable(tryParseBoolean(value));
+    }
+
+    public static Optional<Long> vendor_os_test_long() {
+        String value = SystemProperties.get("vendor.vendor.os_test-long");
+        return Optional.ofNullable(tryParseLong(value));
+    }
+
+    public static List<Integer> test_list_int() {
+        String value = SystemProperties.get("vendor.test_list_int");
+        return tryParseList(v -> tryParseInteger(v), value);
+    }
+
+    @Deprecated
+    public static List<String> test_strlist() {
+        String value = SystemProperties.get("vendor.test.strlist");
+        return tryParseList(v -> tryParseString(v), value);
+    }
+}
+)";
+
+constexpr const char* kExpectedInternalOutput =
     R"(// Generated by the sysprop generator. DO NOT EDIT!
 
 package com.somecompany;
 
-import android.annotation.SystemApi;
 import android.os.SystemProperties;
 
 import java.util.ArrayList;
@@ -116,8 +259,6 @@ import java.util.Optional;
 import java.util.StringJoiner;
 import java.util.stream.Collectors;
 
-/** @hide */
-@SystemApi
 public final class TestProperties {
     private TestProperties () {}
 
@@ -214,13 +355,11 @@ public final class TestProperties {
         return joiner.toString();
     }
 
-    /** @hide */
     public static Optional<Double> test_double() {
         String value = SystemProperties.get("vendor.test_double");
         return Optional.ofNullable(tryParseDouble(value));
     }
 
-    /** @hide */
     public static void test_double(Double value) {
         SystemProperties.set("vendor.test_double", value == null ? "" : value.toString());
     }
@@ -230,7 +369,6 @@ public final class TestProperties {
         return Optional.ofNullable(tryParseInteger(value));
     }
 
-    /** @hide */
     public static void test_int(Integer value) {
         SystemProperties.set("vendor.test_int", value == null ? "" : value.toString());
     }
@@ -240,12 +378,10 @@ public final class TestProperties {
         return Optional.ofNullable(tryParseString(value));
     }
 
-    /** @hide */
     public static void test_string(String value) {
         SystemProperties.set("vendor.test.string", value == null ? "" : value.toString());
     }
 
-    /** @hide */
     public static enum test_enum_values {
         A("a"),
         B("b"),
@@ -263,13 +399,11 @@ public final class TestProperties {
         }
     }
 
-    /** @hide */
     public static Optional<test_enum_values> test_enum() {
         String value = SystemProperties.get("vendor.test.enum");
         return Optional.ofNullable(tryParseEnum(test_enum_values.class, value));
     }
 
-    /** @hide */
     public static void test_enum(test_enum_values value) {
         SystemProperties.set("vendor.test.enum", value == null ? "" : value.getPropValue());
     }
@@ -279,7 +413,6 @@ public final class TestProperties {
         return Optional.ofNullable(tryParseBoolean(value));
     }
 
-    /** @hide */
     public static void test_BOOLeaN(Boolean value) {
         SystemProperties.set("ro.vendor.test.b", value == null ? "" : value.toString());
     }
@@ -289,18 +422,15 @@ public final class TestProperties {
         return Optional.ofNullable(tryParseLong(value));
     }
 
-    /** @hide */
     public static void vendor_os_test_long(Long value) {
         SystemProperties.set("vendor.vendor.os_test-long", value == null ? "" : value.toString());
     }
 
-    /** @hide */
     public static List<Double> test_double_list() {
         String value = SystemProperties.get("vendor.test_double_list");
         return tryParseList(v -> tryParseDouble(v), value);
     }
 
-    /** @hide */
     public static void test_double_list(List<Double> value) {
         SystemProperties.set("vendor.test_double_list", value == null ? "" : formatList(value));
     }
@@ -310,7 +440,6 @@ public final class TestProperties {
         return tryParseList(v -> tryParseInteger(v), value);
     }
 
-    /** @hide */
     public static void test_list_int(List<Integer> value) {
         SystemProperties.set("vendor.test_list_int", value == null ? "" : formatList(value));
     }
@@ -321,13 +450,11 @@ public final class TestProperties {
         return tryParseList(v -> tryParseString(v), value);
     }
 
-    /** @hide */
     @Deprecated
     public static void test_strlist(List<String> value) {
         SystemProperties.set("vendor.test.strlist", value == null ? "" : formatList(value));
     }
 
-    /** @hide */
     public static enum el_values {
         ENU("enu"),
         MVA("mva"),
@@ -341,14 +468,12 @@ public final class TestProperties {
         }
     }
 
-    /** @hide */
     @Deprecated
     public static List<el_values> el() {
         String value = SystemProperties.get("vendor.el");
         return tryParseEnumList(el_values.class, value);
     }
 
-    /** @hide */
     @Deprecated
     public static void el(List<el_values> value) {
         SystemProperties.set("vendor.el", value == null ? "" : formatEnumList(value, el_values::getPropValue));
@@ -371,17 +496,24 @@ TEST(SyspropTest, JavaGenTest) {
 
   TemporaryDir temp_dir;
 
-  ASSERT_TRUE(GenerateJavaLibrary(temp_file.path, temp_dir.path));
+  std::pair<sysprop::Scope, const char*> tests[] = {
+      {sysprop::Scope::Internal, kExpectedInternalOutput},
+      {sysprop::Scope::Public, kExpectedPublicOutput},
+  };
+
+  for (auto [scope, expected_output] : tests) {
+    ASSERT_TRUE(GenerateJavaLibrary(temp_file.path, scope, temp_dir.path));
 
-  std::string java_output_path =
-      temp_dir.path + "/com/somecompany/TestProperties.java"s;
+    std::string java_output_path =
+        temp_dir.path + "/com/somecompany/TestProperties.java"s;
 
-  std::string java_output;
-  ASSERT_TRUE(
-      android::base::ReadFileToString(java_output_path, &java_output, true));
-  EXPECT_EQ(java_output, kExpectedJavaOutput);
+    std::string java_output;
+    ASSERT_TRUE(
+        android::base::ReadFileToString(java_output_path, &java_output, true));
+    EXPECT_EQ(java_output, expected_output);
 
-  unlink(java_output_path.c_str());
-  rmdir((temp_dir.path + "/com/somecompany"s).c_str());
-  rmdir((temp_dir.path + "/com"s).c_str());
+    unlink(java_output_path.c_str());
+    rmdir((temp_dir.path + "/com/somecompany"s).c_str());
+    rmdir((temp_dir.path + "/com"s).c_str());
+  }
 }