1 files changed, 192 insertions, 0 deletions
diff --git a/mobile/android/geckoview/src/main/java/org/mozilla/gecko/mozglue/SharedMemory.java b/mobile/android/geckoview/src/main/java/org/mozilla/gecko/mozglue/SharedMemory.java
new file mode 100644
index 0000000000..af8b62c382
--- /dev/null
+++ b/mobile/android/geckoview/src/main/java/org/mozilla/gecko/mozglue/SharedMemory.java
@@ -0,0 +1,192 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package org.mozilla.gecko.mozglue;
+
+import android.annotation.SuppressLint;
+import android.os.MemoryFile;
+import android.os.Parcel;
+import android.os.ParcelFileDescriptor;
+import android.os.Parcelable;
+import android.util.Log;
+import java.io.FileDescriptor;
+import java.io.IOException;
+import java.lang.reflect.Method;
+
+@SuppressLint("DiscouragedPrivateApi")
+public class SharedMemory implements Parcelable {
+  private static final String LOGTAG = "GeckoShmem";
+  private static final Method sGetFDMethod;
+  private ParcelFileDescriptor mDescriptor;
+  private int mSize;
+  private int mId;
+  private long mHandle; // The native pointer.
+  private boolean mIsMapped;
+  private MemoryFile mBackedFile;
+
+  // MemoryFile.getFileDescriptor() is hidden. :(
+  static {
+    Method method = null;
+    try {
+      method = MemoryFile.class.getDeclaredMethod("getFileDescriptor");
+    } catch (final NoSuchMethodException e) {
+      e.printStackTrace();
+    }
+    sGetFDMethod = method;
+  }
+
+  private SharedMemory(final Parcel in) {
+    mDescriptor = in.readFileDescriptor();
+    mSize = in.readInt();
+    mId = in.readInt();
+  }
+
+  public static final Creator<SharedMemory> CREATOR =
+      new Creator<SharedMemory>() {
+        @Override
+        public SharedMemory createFromParcel(final Parcel in) {
+          return new SharedMemory(in);
+        }
+
+        @Override
+        public SharedMemory[] newArray(final int size) {
+          return new SharedMemory[size];
+        }
+      };
+
+  @Override
+  public int describeContents() {
+    return CONTENTS_FILE_DESCRIPTOR;
+  }
+
+  @Override
+  public void writeToParcel(final Parcel dest, final int flags) {
+    // We don't want ParcelFileDescriptor.writeToParcel() to close the fd.
+    dest.writeFileDescriptor(mDescriptor.getFileDescriptor());
+    dest.writeInt(mSize);
+    dest.writeInt(mId);
+  }
+
+  public SharedMemory(final int id, final int size) throws NoSuchMethodException, IOException {
+    if (sGetFDMethod == null) {
+      throw new NoSuchMethodException("MemoryFile.getFileDescriptor() doesn't exist.");
+    }
+    mBackedFile = new MemoryFile(null, size);
+    try {
+      final FileDescriptor fd = (FileDescriptor) sGetFDMethod.invoke(mBackedFile);
+      mDescriptor = ParcelFileDescriptor.dup(fd);
+      mSize = size;
+      mId = id;
+      mBackedFile.allowPurging(false);
+    } catch (final Exception e) {
+      e.printStackTrace();
+      close();
+      throw new IOException(e.getMessage());
+    }
+  }
+
+  public void flush() {
+    if (!mIsMapped) {
+      return;
+    }
+
+    unmap(mHandle, mSize);
+    mHandle = 0;
+    mIsMapped = false;
+  }
+
+  public void close() {
+    flush();
+
+    if (mDescriptor != null) {
+      try {
+        mDescriptor.close();
+      } catch (final IOException e) {
+        e.printStackTrace();
+      }
+      mDescriptor = null;
+    }
+  }
+
+  // Should only be called by process that allocates shared memory.
+  public void dispose() {
+    if (!isValid()) {
+      return;
+    }
+
+    close();
+
+    if (mBackedFile != null) {
+      mBackedFile.close();
+      mBackedFile = null;
+    }
+  }
+
+  private native void unmap(long address, int size);
+
+  public boolean isValid() {
+    return mDescriptor != null;
+  }
+
+  public int getSize() {
+    return mSize;
+  }
+
+  private int getFD() {
+    return isValid() ? mDescriptor.getFd() : -1;
+  }
+
+  public long getPointer() {
+    if (!isValid()) {
+      return 0;
+    }
+
+    if (!mIsMapped) {
+      try {
+        mHandle = map(getFD(), mSize);
+      } catch (final NullPointerException e) {
+        Log.e(LOGTAG, "SharedMemory#" + mId + " error.", e);
+        throw e;
+      }
+      if (mHandle != 0) {
+        mIsMapped = true;
+      }
+    }
+    return mHandle;
+  }
+
+  private native long map(int fd, int size);
+
+  @Override
+  protected void finalize() throws Throwable {
+    if (mBackedFile != null) {
+      Log.w(LOGTAG, "dispose() not called before finalizing");
+    }
+    dispose();
+
+    super.finalize();
+  }
+
+  @Override
+  public String toString() {
+    return "SHM("
+        + getSize()
+        + " bytes): id="
+        + mId
+        + ", backing="
+        + mBackedFile
+        + ",fd="
+        + mDescriptor;
+  }
+
+  @Override
+  public boolean equals(final Object that) {
+    return (this == that) || ((that instanceof SharedMemory) && (hashCode() == that.hashCode()));
+  }
+
+  @Override
+  public int hashCode() {
+    return mId;
+  }
+}