[webnfc] Support NDEFWriteOptions#overwrite

To indicate whether it's allowed to overwrite an NFC tag that already
contains some records.

We do not do any special checks for the case of overwrite = true, just
write into the NFC tag in any cases.

In case of overwrite = false,

- Writing non-formatted tags that are NDEF-formatable
  --> format + write

- Writing (formatted + empty) NDEF tags
  --> write

- Writing (formatted and non-empty) NDEF tags
  --> not allowed

The spec change:
https://github.com/w3c/web-nfc/pull/373/commits/b71a81e33ba568f3a8e3cd3de8271bd45be789e8
https://github.com/w3c/web-nfc/pull/526

BUG=1023231,520391

Change-Id: Ibf271f88e6e395370f994864e966f55ef44f5d2a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2003893
Commit-Queue: Leon Han <leon.han@intel.com>
Reviewed-by: François Beaufort <beaufort.francois@gmail.com>
Reviewed-by: Rijubrata Bhaumik <rijubrata.bhaumik@intel.com>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#734339}

services/device/nfc/android/java/src/org/chromium/device/nfc/NfcImpl.java

@@ -490,6 +490,15 @@ public class NfcImpl implements Nfc {
 
         try {
             mTagHandler.connect();
+
+            if (!mPendingPushOperation.ndefWriteOptions.overwrite
+                    && !mTagHandler.canAlwaysOverwrite()) {
+                Log.w(TAG, "Cannot overwrite the NFC tag due to existing data on it.");
+                pendingPushOperationCompleted(createError(NdefErrorType.NOT_ALLOWED,
+                        "NDEFWriteOptions#overwrite does not allow overwrite."));
+                return;
+            }
+
             mTagHandler.write(NdefMessageUtils.toNdefMessage(mPendingPushOperation.ndefMessage));
             pendingPushOperationCompleted(null);
         } catch (InvalidNdefMessageException e) {
@@ -523,11 +532,9 @@ public class NfcImpl implements Nfc {
             return;
         }
 
-        android.nfc.NdefMessage message = null;
-
         try {
             mTagHandler.connect();
-            message = mTagHandler.read();
+            android.nfc.NdefMessage message = mTagHandler.read();
             if (message == null) {
                 // Tag is formatted to support NDEF but does not contain a message yet.
                 // Let's create one with no records so that watchers can be notified.

services/device/nfc/android/java/src/org/chromium/device/nfc/NfcTagHandler.java

@@ -56,6 +56,8 @@ public class NfcTagHandler {
                 throws IOException, TagLostException, FormatException, IllegalStateException;
         public NdefMessage read()
                 throws IOException, TagLostException, FormatException, IllegalStateException;
+        public boolean canAlwaysOverwrite()
+                throws IOException, TagLostException, FormatException, IllegalStateException;
     }
 
     /**
@@ -80,6 +82,13 @@ public class NfcTagHandler {
                 throws IOException, TagLostException, FormatException, IllegalStateException {
             return mNdef.getNdefMessage();
         }
+
+        @Override
+        public boolean canAlwaysOverwrite()
+                throws IOException, TagLostException, FormatException, IllegalStateException {
+            // Getting null means the tag is empty, overwrite is safe.
+            return mNdef.getNdefMessage() == null;
+        }
     }
 
     /**
@@ -103,6 +112,11 @@ public class NfcTagHandler {
         public NdefMessage read() throws FormatException {
             return NdefMessageUtils.emptyNdefMessage();
         }
+
+        @Override
+        public boolean canAlwaysOverwrite() {
+            return true;
+        }
     }
 
     protected NfcTagHandler(TagTechnology tech, TagTechnologyHandler handler, byte[] id) {
@@ -183,4 +197,13 @@ public class NfcTagHandler {
         }
         return false;
     }
+
+    /**
+     * Returns false only if the tag is already NDEF formatted and contains some records. Otherwise
+     * true.
+     */
+    public boolean canAlwaysOverwrite()
+            throws IOException, TagLostException, FormatException, IllegalStateException {
+        return mTechHandler.canAlwaysOverwrite();
+    }
 }

services/device/nfc/android/junit/src/org/chromium/device/nfc/NFCTest.java

@@ -1279,6 +1279,7 @@ public class NFCTest {
     private NdefWriteOptions createNdefWriteOptions() {
         NdefWriteOptions pushOptions = new NdefWriteOptions();
         pushOptions.ignoreRead = false;
+        pushOptions.overwrite = true;
         return pushOptions;
     }
 

services/device/public/mojom/nfc.mojom

@@ -88,9 +88,15 @@ struct NDEFMessage {
 };
 
 struct NDEFWriteOptions {
-  // If the property is true, the write operation will suspend active watchers
-  // until its completion.
+  // Only the case of |ignore_read| being |true| matters: while this push
+  // operation is pending, even a NFC tag comes in proximity range, do not read
+  // it for all active watchers.
   bool ignore_read;
+
+  // Only the case of |overwrite| being |false| matters: the push operation will
+  // read the NFC tag regardless of |ignore_read| to determine if it has NDEF
+  // records on it, and if yes, do not execute write.
+  bool overwrite;
 };
 
 struct NDEFScanOptions {

third_party/blink/renderer/modules/nfc/ndef_write_options.idl

@@ -6,5 +6,6 @@
 
 dictionary NDEFWriteOptions {
     boolean ignoreRead = true;
+    boolean overwrite = true;
     AbortSignal? signal;
 };

third_party/blink/renderer/modules/nfc/nfc_type_converters.cc

@@ -57,9 +57,10 @@ TypeConverter<NDEFWriteOptionsPtr, const blink::NDEFWriteOptions*>::Convert(
     const blink::NDEFWriteOptions* write_options) {
   // https://w3c.github.io/web-nfc/#the-ndefwriteoptions-dictionary
   // Default values for NDEFWriteOptions dictionary are:
-  // ignoreRead = true
+  // ignoreRead = true, overwrite = true
   NDEFWriteOptionsPtr write_options_ptr = NDEFWriteOptions::New();
   write_options_ptr->ignore_read = write_options->ignoreRead();
+  write_options_ptr->overwrite = write_options->overwrite();
 
   return write_options_ptr;
 }