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/src/Main.java b/test/922-properties/src/Main.java
new file mode 100644
index 0000000..6cec6e9
--- /dev/null
+++ b/test/922-properties/src/Main.java
@@ -0,0 +1,155 @@
+/*
+ * 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.
+ */
+
+import java.util.Set;
+import java.util.TreeSet;
+
+public class Main {
+  public static void main(String[] args) throws Exception {
+    System.loadLibrary(args[1]);
+
+    doTest();
+  }
+
+  public static void doTest() throws Exception {
+    Set<String> recommendedProperties = getRecommendedProperties();
+
+    System.out.println("Recommended properties:");
+    for (String key : recommendedProperties) {
+      checkProperty(key);
+    }
+
+    Set<String> allProperties = getAllProperties();
+
+    Set<String> retained = new TreeSet<String>(recommendedProperties);
+    retained.retainAll(allProperties);
+    if (!retained.equals(recommendedProperties)) {
+      Set<String> missing = new TreeSet<String>(recommendedProperties);
+      missing.removeAll(retained);
+      System.out.println("Missing recommended properties: " + missing);
+    }
+
+    Set<String> nonRecommended = new TreeSet<String>(allProperties);
+    nonRecommended.removeAll(recommendedProperties);
+
+    System.out.println("Other properties:");
+    for (String key : nonRecommended) {
+      checkProperty(key);
+    }
+
+    System.out.println("Non-specified property:");
+    String key = generate(allProperties);
+    checkProperty(key);
+
+    System.out.println("Non-specified property (2):");
+    String key2 = generateUnique(allProperties);
+    checkProperty(key2);
+  }
+
+  private static Set<String> getRecommendedProperties() {
+    Set<String> keys = new TreeSet<String>();
+    keys.add("java.vm.vendor");
+    keys.add("java.vm.version");
+    keys.add("java.vm.name");
+    keys.add("java.vm.info");
+    keys.add("java.library.path");
+    keys.add("java.class.path");
+    return keys;
+  }
+
+  private static Set<String> getAllProperties() {
+    Set<String> keys = new TreeSet<String>();
+    String[] props = getSystemProperties();
+    for (String p : props) {
+      keys.add(p);
+    }
+    return keys;
+  }
+
+  private static boolean equals(String s1, String s2) {
+    if (s1 == null && s2 == null) {
+      return true;
+    } else if (s1 != null) {
+      return s1.equals(s2);
+    } else {
+      return false;
+    }
+  }
+
+  private static void checkProperty(String key) {
+    System.out.print(" \"" + key + "\": ");
+    String err = null;
+    String value = null;
+    try {
+      value = getSystemProperty(key);
+    } catch (RuntimeException e) {
+      err = e.getMessage();
+    }
+    String sysValue = System.getProperty(key);
+    if (equals(value, sysValue)) {
+      System.out.print("OK");
+      if (err != null) {
+        System.out.println(" !!!" + err);
+      } else {
+        System.out.println();
+      }
+    } else {
+      System.out.println("ERROR !!!" + err);
+    }
+
+    System.out.print("  Setting value to \"abc\": ");
+    try {
+      setSystemProperty(key, "abc");
+      System.out.println("SUCCEEDED");
+    } catch (RuntimeException e) {
+      System.out.println("!!!" + e.getMessage());
+    }
+  }
+
+  private static String generateUnique(Set<String> others) {
+    // Construct something. To be deterministic, just use "a+".
+    StringBuilder sb = new StringBuilder("a");
+    for (;;) {
+      String key = sb.toString();
+      if (!others.contains(key)) {
+        return key;
+      }
+      sb.append('a');
+    }
+  }
+
+  private static String generate(Set<String> others) {
+    // First check for something in the overall System properties.
+    TreeSet<String> sysProps = new TreeSet<String>(System.getProperties().stringPropertyNames());
+    sysProps.removeAll(others);
+    if (!sysProps.isEmpty()) {
+      // Find something that starts with "java" or "os," trying to be platform-independent.
+      for (String s: sysProps) {
+        if (s.startsWith("java.") || s.startsWith("os.")) {
+          return s;
+        }
+      }
+      // Just return the first thing.
+      return sysProps.iterator().next();
+    }
+
+    return generateUnique(others);
+  }
+
+  private static native String[] getSystemProperties();
+  private static native String getSystemProperty(String key);
+  private static native void setSystemProperty(String key, String value);
+}