Parcelable versioning

2 files changed, 71 insertions, 2 deletions

diff --git a/OpenPGP-Keychain-API/libraries/openpgp-api-library/src/org/openintents/openpgp/OpenPgpError.java b/OpenPGP-Keychain-API/libraries/openpgp-api-library/src/org/openintents/openpgp/OpenPgpError.java
index 4dd2cc641..b894a4609 100644
--- a/OpenPGP-Keychain-API/libraries/openpgp-api-library/src/org/openintents/openpgp/OpenPgpError.java
+++ b/OpenPGP-Keychain-API/libraries/openpgp-api-library/src/org/openintents/openpgp/OpenPgpError.java
@@ -19,12 +19,22 @@ package org.openintents.openpgp;
 import android.os.Parcel;
 import android.os.Parcelable;
 
+/**
+ * Parcelable versioning has been copied from Dashclock Widget
+ * https://code.google.com/p/dashclock/source/browse/api/src/main/java/com/google/android/apps/dashclock/api/ExtensionData.java
+ */
 public class OpenPgpError implements Parcelable {
+    /**
+     * Since there might be a case where new versions of the client using the library getting
+     * old versions of the protocol (and thus old versions of this class), we need a versioning
+     * system for the parcels sent between the clients and the providers.
+     */
+    public static final int PARCELABLE_VERSION = 1;
+
+    // possible values for errorId
     public static final int CLIENT_SIDE_ERROR = -1;
-
     public static final int GENERIC_ERROR = 0;
     public static final int INCOMPATIBLE_API_VERSIONS = 1;
-
     public static final int NO_OR_WRONG_PASSPHRASE = 2;
     public static final int NO_USER_IDS = 3;
 
@@ -65,15 +75,39 @@ public class OpenPgpError implements Parcelable {
     }
 
     public void writeToParcel(Parcel dest, int flags) {
+        /**
+         * NOTE: When adding fields in the process of updating this API, make sure to bump
+         * {@link #PARCELABLE_VERSION}.
+         */
+        dest.writeInt(PARCELABLE_VERSION);
+        // Inject a placeholder that will store the parcel size from this point on
+        // (not including the size itself).
+        int sizePosition = dest.dataPosition();
+        dest.writeInt(0);
+        int startPosition = dest.dataPosition();
+        // version 1
         dest.writeInt(errorId);
         dest.writeString(message);
+        // Go back and write the size
+        int parcelableSize = dest.dataPosition() - startPosition;
+        dest.setDataPosition(sizePosition);
+        dest.writeInt(parcelableSize);
+        dest.setDataPosition(startPosition + parcelableSize);
     }
 
     public static final Creator<OpenPgpError> CREATOR = new Creator<OpenPgpError>() {
         public OpenPgpError createFromParcel(final Parcel source) {
+            int parcelableVersion = source.readInt();
+            int parcelableSize = source.readInt();
+            int startPosition = source.dataPosition();
+
             OpenPgpError error = new OpenPgpError();
             error.errorId = source.readInt();
             error.message = source.readString();
+
+            // skip over all fields added in future versions of this parcel
+            source.setDataPosition(startPosition + parcelableSize);
+
             return error;
         }
 
diff --git a/OpenPGP-Keychain-API/libraries/openpgp-api-library/src/org/openintents/openpgp/OpenPgpSignatureResult.java b/OpenPGP-Keychain-API/libraries/openpgp-api-library/src/org/openintents/openpgp/OpenPgpSignatureResult.java
index cb220cf6d..157dd1aad 100644
--- a/OpenPGP-Keychain-API/libraries/openpgp-api-library/src/org/openintents/openpgp/OpenPgpSignatureResult.java
+++ b/OpenPGP-Keychain-API/libraries/openpgp-api-library/src/org/openintents/openpgp/OpenPgpSignatureResult.java
@@ -19,7 +19,18 @@ package org.openintents.openpgp;
 import android.os.Parcel;
 import android.os.Parcelable;
 
+/**
+ * Parcelable versioning has been copied from Dashclock Widget
+ * https://code.google.com/p/dashclock/source/browse/api/src/main/java/com/google/android/apps/dashclock/api/ExtensionData.java
+ */
 public class OpenPgpSignatureResult implements Parcelable {
+    /**
+     * Since there might be a case where new versions of the client using the library getting
+     * old versions of the protocol (and thus old versions of this class), we need a versioning
+     * system for the parcels sent between the clients and the providers.
+     */
+    public static final int PARCELABLE_VERSION = 1;
+
     // generic error on signature verification
     public static final int SIGNATURE_ERROR = 0;
     // successfully verified signature, with certified public key
@@ -90,19 +101,43 @@ public class OpenPgpSignatureResult implements Parcelable {
     }
 
     public void writeToParcel(Parcel dest, int flags) {
+        /**
+         * NOTE: When adding fields in the process of updating this API, make sure to bump
+         * {@link #PARCELABLE_VERSION}.
+         */
+        dest.writeInt(PARCELABLE_VERSION);
+        // Inject a placeholder that will store the parcel size from this point on
+        // (not including the size itself).
+        int sizePosition = dest.dataPosition();
+        dest.writeInt(0);
+        int startPosition = dest.dataPosition();
+        // version 1
         dest.writeInt(status);
         dest.writeByte((byte) (signatureOnly ? 1 : 0));
         dest.writeString(userId);
         dest.writeLong(keyId);
+        // Go back and write the size
+        int parcelableSize = dest.dataPosition() - startPosition;
+        dest.setDataPosition(sizePosition);
+        dest.writeInt(parcelableSize);
+        dest.setDataPosition(startPosition + parcelableSize);
     }
 
     public static final Creator<OpenPgpSignatureResult> CREATOR = new Creator<OpenPgpSignatureResult>() {
         public OpenPgpSignatureResult createFromParcel(final Parcel source) {
+            int parcelableVersion = source.readInt();
+            int parcelableSize = source.readInt();
+            int startPosition = source.dataPosition();
+
             OpenPgpSignatureResult vr = new OpenPgpSignatureResult();
             vr.status = source.readInt();
             vr.signatureOnly = source.readByte() == 1;
             vr.userId = source.readString();
             vr.keyId = source.readLong();
+
+            // skip over all fields added in future versions of this parcel
+            source.setDataPosition(startPosition + parcelableSize);
+
             return vr;
         }