1 files changed, 171 insertions, 0 deletions
diff --git a/mobile/android/base/java/org/mozilla/gecko/mozglue/SharedMemory.java b/mobile/android/base/java/org/mozilla/gecko/mozglue/SharedMemory.java
new file mode 100644
index 000000000..bc43a2755
--- /dev/null
+++ b/mobile/android/base/java/org/mozilla/gecko/mozglue/SharedMemory.java
@@ -0,0 +1,171 @@
+/* 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.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;
+
+public class SharedMemory implements Parcelable {
+    private static final String LOGTAG = "GeckoShmem";
+    private static Method sGetFDMethod = null; // MemoryFile.getFileDescriptor() is hidden. :(
+    private ParcelFileDescriptor mDescriptor;
+    private int mSize;
+    private int mId;
+    private long mHandle; // The native pointer.
+    private boolean mIsMapped;
+    private MemoryFile mBackedFile;
+
+    static {
+        try {
+            sGetFDMethod = MemoryFile.class.getDeclaredMethod("getFileDescriptor");
+        } catch (NoSuchMethodException e) {
+            e.printStackTrace();
+        }
+    }
+
+    private SharedMemory(Parcel in) {
+        mDescriptor = in.readFileDescriptor();
+        mSize = in.readInt();
+        mId = in.readInt();
+    }
+
+    public static final Creator<SharedMemory> CREATOR = new Creator<SharedMemory>() {
+        @Override
+        public SharedMemory createFromParcel(Parcel in) {
+            return new SharedMemory(in);
+        }
+
+        @Override
+        public SharedMemory[] newArray(int size) {
+            return new SharedMemory[size];
+        }
+    };
+
+    @Override
+    public int describeContents() {
+        return 0;
+    }
+
+    @Override
+    public void writeToParcel(Parcel dest, int flags) {
+        // We don't want ParcelFileDescriptor.writeToParcel() to close the fd.
+        dest.writeFileDescriptor(mDescriptor.getFileDescriptor());
+        dest.writeInt(mSize);
+        dest.writeInt(mId);
+    }
+
+    public SharedMemory(int id, int size) throws NoSuchMethodException, IOException {
+        if (sGetFDMethod == null) {
+            throw new NoSuchMethodException("MemoryFile.getFileDescriptor() doesn't exist.");
+        }
+        mBackedFile = new MemoryFile(null, size);
+        try {
+            FileDescriptor fd = (FileDescriptor)sGetFDMethod.invoke(mBackedFile);
+            mDescriptor = ParcelFileDescriptor.dup(fd);
+            mSize = size;
+            mId = id;
+            mBackedFile.allowPurging(false);
+        } catch (Exception e) {
+            e.printStackTrace();
+            close();
+            throw new IOException(e.getMessage());
+        }
+    }
+
+    public void flush() {
+        if (mBackedFile == null) {
+            close();
+        }
+    }
+
+    public void close() {
+        if (mIsMapped) {
+            unmap(mHandle, mSize);
+            mHandle = 0;
+        }
+
+        if (mDescriptor != null) {
+            try {
+                mDescriptor.close();
+            } catch (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) {
+            mHandle = map(getFD(), mSize);
+            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(Object that) {
+        return (this == that) ||
+                ((that instanceof SharedMemory) && (hashCode() == that.hashCode()));
+    }
+
+    @Override
+    public int hashCode() {
+        return mId;
+    }
+}