javascript: Switch from deprecated Pointer_stringify() to UTF8toString().

The Pointer_stringify() function is deprecated and has a couple of
issues because it tries to guess the encoding of the buffer. In some
cases it can ignore the length parameter which could end up in
inconsistencies.

Switch to UTF8toString() that takes a length parameter and respects,
that way we don't need to allocate an additional byte for a NULL byte.

1 files changed, 10 insertions, 17 deletions

diff --git a/javascript/olm_inbound_group_session.js b/javascript/olm_inbound_group_session.js
index dd8e493..4aa3201 100644
--- a/javascript/olm_inbound_group_session.js
+++ b/javascript/olm_inbound_group_session.js
@@ -8,7 +8,7 @@ function inbound_group_session_method(wrapped) {
     return function() {
         var result = wrapped.apply(this, arguments);
         if (result === OLM_ERROR) {
-            var message = Pointer_stringify(
+            var message = UTF8ToString(
                 Module['_olm_inbound_group_session_last_error'](arguments[0])
             );
             throw new Error("OLM." + message);
@@ -28,7 +28,7 @@ InboundGroupSession.prototype['pickle'] = restore_stack(function(key) {
         Module['_olm_pickle_inbound_group_session_length']
     )(this.ptr);
     var key_buffer = stack(key_array);
-    var pickle_buffer = stack(pickle_length + NULL_BYTE_PADDING_LENGTH);
+    var pickle_buffer = stack(pickle_length);
     try {
         inbound_group_session_method(Module['_olm_pickle_inbound_group_session'])(
             this.ptr, key_buffer, key_array.length, pickle_buffer, pickle_length
@@ -40,7 +40,7 @@ InboundGroupSession.prototype['pickle'] = restore_stack(function(key) {
             key_array[i] = 0;
         }
     }
-    return Pointer_stringify(pickle_buffer);
+    return UTF8ToString(pickle_buffer, pickle_length);
 });
 
 InboundGroupSession.prototype['unpickle'] = restore_stack(function(key, pickle) {
@@ -112,7 +112,7 @@ InboundGroupSession.prototype['decrypt'] = restore_stack(function(
         // caculating the length destroys the input buffer, so we need to re-copy it.
         writeAsciiToMemory(message, message_buffer, true);
 
-        plaintext_buffer = malloc(max_plaintext_length + NULL_BYTE_PADDING_LENGTH);
+        plaintext_buffer = malloc(max_plaintext_length);
         var message_index = stack(4);
 
         plaintext_length = inbound_group_session_method(
@@ -124,15 +124,8 @@ InboundGroupSession.prototype['decrypt'] = restore_stack(function(
             message_index
         );
 
-        // UTF8ToString requires a null-terminated argument, so add the
-        // null terminator.
-        setValue(
-            plaintext_buffer+plaintext_length,
-            0, "i8"
-        );
-
         return {
-            "plaintext": UTF8ToString(plaintext_buffer),
+            "plaintext": UTF8ToString(plaintext_buffer, plaintext_length),
             "message_index": getValue(message_index, "i32")
         }
     } finally {
@@ -141,7 +134,7 @@ InboundGroupSession.prototype['decrypt'] = restore_stack(function(
         }
         if (plaintext_buffer !== undefined) {
             // don't leave a copy of the plaintext in the heap.
-            bzero(plaintext_buffer, plaintext_length + NULL_BYTE_PADDING_LENGTH);
+            bzero(plaintext_buffer, plaintext_length);
             free(plaintext_buffer);
         }
     }
@@ -151,11 +144,11 @@ InboundGroupSession.prototype['session_id'] = restore_stack(function() {
     var length = inbound_group_session_method(
         Module['_olm_inbound_group_session_id_length']
     )(this.ptr);
-    var session_id = stack(length + NULL_BYTE_PADDING_LENGTH);
+    var session_id = stack(length);
     inbound_group_session_method(Module['_olm_inbound_group_session_id'])(
         this.ptr, session_id, length
     );
-    return Pointer_stringify(session_id);
+    return UTF8ToString(session_id, length);
 });
 
 InboundGroupSession.prototype['first_known_index'] = restore_stack(function() {
@@ -168,11 +161,11 @@ InboundGroupSession.prototype['export_session'] = restore_stack(function(message
     var key_length = inbound_group_session_method(
         Module['_olm_export_inbound_group_session_length']
     )(this.ptr);
-    var key = stack(key_length + NULL_BYTE_PADDING_LENGTH);
+    var key = stack(key_length);
     outbound_group_session_method(Module['_olm_export_inbound_group_session'])(
         this.ptr, key, key_length, message_index
     );
-    var key_str = Pointer_stringify(key);
+    var key_str = UTF8ToString(key, key_length);
     bzero(key, key_length); // clear out a copy of the key
     return key_str;
 });