ART: Add system properties support

Add simple support for GetSystemProperties, GetSystemProperty and
SetSystemProperty. Add a test.

Bug: 31455788
Test: m test-art-host-run-test-922-properties
Change-Id: I02914f04643f0f8fab96f1b372925c2c5306fc9b
diff --git a/test/922-properties/properties.cc b/test/922-properties/properties.cc
new file mode 100644
index 0000000..b1e7fce
--- /dev/null
+++ b/test/922-properties/properties.cc
@@ -0,0 +1,107 @@
+/*
+ * Copyright (C) 2017 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.
+ */
+
+#include "properties.h"
+
+#include <stdio.h>
+
+#include "base/macros.h"
+#include "jni.h"
+#include "openjdkjvmti/jvmti.h"
+#include "ScopedUtfChars.h"
+
+#include "ti-agent/common_helper.h"
+#include "ti-agent/common_load.h"
+
+namespace art {
+namespace Test922Properties {
+
+extern "C" JNIEXPORT jobjectArray JNICALL Java_Main_getSystemProperties(
+    JNIEnv* env, jclass Main_klass ATTRIBUTE_UNUSED) {
+  jint count;
+  char** properties;
+  jvmtiError result = jvmti_env->GetSystemProperties(&count, &properties);
+  if (JvmtiErrorToException(env, result)) {
+    return nullptr;
+  }
+
+  auto callback = [&](jint i) -> jstring {
+    char* data = properties[i];
+    if (data == nullptr) {
+      return nullptr;
+    }
+    jstring ret = env->NewStringUTF(data);
+    jvmti_env->Deallocate(reinterpret_cast<unsigned char*>(data));
+    return ret;
+  };
+  jobjectArray ret = CreateObjectArray(env, count, "java/lang/String", callback);
+
+  jvmti_env->Deallocate(reinterpret_cast<unsigned char*>(properties));
+
+  return ret;
+}
+
+extern "C" JNIEXPORT jstring JNICALL Java_Main_getSystemProperty(
+    JNIEnv* env, jclass Main_klass ATTRIBUTE_UNUSED, jstring key) {
+  ScopedUtfChars string(env, key);
+  if (string.c_str() == nullptr) {
+    return nullptr;
+  }
+
+  char* value = nullptr;
+  jvmtiError result = jvmti_env->GetSystemProperty(string.c_str(), &value);
+  if (JvmtiErrorToException(env, result)) {
+    return nullptr;
+  }
+
+  jstring ret = (value == nullptr) ? nullptr : env->NewStringUTF(value);
+
+  jvmti_env->Deallocate(reinterpret_cast<unsigned char*>(value));
+
+  return ret;
+}
+
+extern "C" JNIEXPORT void JNICALL Java_Main_setSystemProperty(
+    JNIEnv* env, jclass Main_klass ATTRIBUTE_UNUSED, jstring key, jstring value) {
+  ScopedUtfChars key_string(env, key);
+  if (key_string.c_str() == nullptr) {
+    return;
+  }
+  ScopedUtfChars value_string(env, value);
+  if (value_string.c_str() == nullptr) {
+    return;
+  }
+
+  jvmtiError result = jvmti_env->SetSystemProperty(key_string.c_str(), value_string.c_str());
+  if (JvmtiErrorToException(env, result)) {
+    return;
+  }
+}
+
+// Don't do anything
+jint OnLoad(JavaVM* vm,
+            char* options ATTRIBUTE_UNUSED,
+            void* reserved ATTRIBUTE_UNUSED) {
+  if (vm->GetEnv(reinterpret_cast<void**>(&jvmti_env), JVMTI_VERSION_1_0)) {
+    printf("Unable to get jvmti env!\n");
+    return 1;
+  }
+  SetAllCapabilities(jvmti_env);
+  return 0;
+}
+
+}  // namespace Test922Properties
+}  // namespace art