Merge "Framework: Add API to get zygote PID" am: 1109e2333f

am: 07578c786a

Change-Id: Ibee53631caad0d6ce2108970598f5226d20a849d

core/java/android/os/ZygoteProcess.java

@@ -466,6 +466,35 @@ public class ZygoteProcess {
         }
     }
 
+    /**
+     * Attempt to retrieve the PID of the zygote serving the given abi.
+     */
+    public int getZygotePid(String abi) {
+        try {
+            synchronized (mLock) {
+                ZygoteState state = openZygoteSocketIfNeeded(abi);
+
+                // Each query starts with the argument count (1 in this case)
+                state.writer.write("1");
+                // ... followed by a new-line.
+                state.writer.newLine();
+                // ... followed by our only argument.
+                state.writer.write("--get-pid");
+                state.writer.newLine();
+                state.writer.flush();
+
+                // The response is a length prefixed stream of ASCII bytes.
+                int numBytes = state.inputStream.readInt();
+                byte[] bytes = new byte[numBytes];
+                state.inputStream.readFully(bytes);
+
+                return Integer.parseInt(new String(bytes, StandardCharsets.US_ASCII));
+            }
+        } catch (Exception ex) {
+            throw new RuntimeException("Failure retrieving pid", ex);
+        }
+    }
+
     /**
      * Push hidden API blacklisting exemptions into the zygote process(es).
      *

core/java/com/android/internal/os/ZygoteConnection.java

@@ -150,6 +150,11 @@ class ZygoteConnection {
             return null;
         }
 
+        if (parsedArgs.pidQuery) {
+            handlePidQuery();
+            return null;
+        }
+
         if (parsedArgs.preloadDefault) {
             handlePreload();
             return null;
@@ -271,6 +276,17 @@ class ZygoteConnection {
         }
     }
 
+    private void handlePidQuery() {
+        try {
+            String pidString = String.valueOf(Process.myPid());
+            final byte[] pidStringBytes = pidString.getBytes(StandardCharsets.US_ASCII);
+            mSocketOutStream.writeInt(pidStringBytes.length);
+            mSocketOutStream.write(pidStringBytes);
+        } catch (IOException ioe) {
+            throw new IllegalStateException("Error writing to command socket", ioe);
+        }
+    }
+
     /**
      * Preloads resources if the zygote is in lazily preload mode. Writes the result of the
      * preload operation; {@code 0} when a preload was initiated due to this request and {@code 1}
@@ -468,6 +484,11 @@ class ZygoteConnection {
          */
         boolean startChildZygote;
 
+        /**
+         * Whether the current arguments constitute a request for the zygote's PID.
+         */
+        boolean pidQuery;
+
         /**
          * Exemptions from API blacklisting. These are sent to the pre-forked zygote at boot time,
          * or when they change, via --set-api-blacklist-exemptions.
@@ -622,6 +643,8 @@ class ZygoteConnection {
                     mountExternal = Zygote.MOUNT_EXTERNAL_WRITE;
                 } else if (arg.equals("--query-abi-list")) {
                     abiListQuery = true;
+                } else if (arg.equals("--get-pid")) {
+                    pidQuery = true;
                 } else if (arg.startsWith("--instruction-set=")) {
                     instructionSet = arg.substring(arg.indexOf('=') + 1);
                 } else if (arg.startsWith("--app-data-dir=")) {
@@ -656,7 +679,7 @@ class ZygoteConnection {
                 }
             }
 
-            if (abiListQuery) {
+            if (abiListQuery || pidQuery) {
                 if (args.length - curArg > 0) {
                     throw new IllegalArgumentException("Unexpected arguments after --query-abi-list.");
                 }