Allocate memory for message blobs on the heap

Messages can be very large, so we don't really want to allocate them on the
stack. Switch to using the heap for them, and try to clean up some of the
string handling while we're at it.

1 files changed, 30 insertions, 14 deletions

diff --git a/javascript/olm_outbound_group_session.js b/javascript/olm_outbound_group_session.js
index 88a441d..01fee0b 100644
--- a/javascript/olm_outbound_group_session.js
+++ b/javascript/olm_outbound_group_session.js
@@ -63,20 +63,36 @@ OutboundGroupSession.prototype['create'] = restore_stack(function() {
     );
 });
 
-OutboundGroupSession.prototype['encrypt'] = restore_stack(function(plaintext) {
-    var plaintext_array = array_from_string(plaintext);
-    var message_length = outbound_group_session_method(
-        Module['_olm_group_encrypt_message_length']
-    )(this.ptr, plaintext_array.length);
-    var plaintext_buffer = stack(plaintext_array);
-    var message_buffer = stack(message_length + NULL_BYTE_PADDING_LENGTH);
-    outbound_group_session_method(Module['_olm_group_encrypt'])(
-        this.ptr,
-        plaintext_buffer, plaintext_array.length,
-        message_buffer, message_length
-    );
-    return Pointer_stringify(message_buffer);
-});
+OutboundGroupSession.prototype['encrypt'] = function(plaintext) {
+    var plaintext_buffer, message_buffer;
+    try {
+        var plaintext_length = Module['lengthBytesUTF8'](plaintext);
+
+        var message_length = outbound_group_session_method(
+            Module['_olm_group_encrypt_message_length']
+        )(this.ptr, plaintext_length);
+
+        // need to allow space for the terminator (which stringToUTF8 always
+        // writes), hence + 1.
+        plaintext_buffer = malloc(plaintext_length + 1);
+        Module['stringToUTF8'](plaintext, plaintext_buffer, plaintext_length + 1);
+
+        message_buffer = malloc(message_length + NULL_BYTE_PADDING_LENGTH);
+        outbound_group_session_method(Module['_olm_group_encrypt'])(
+            this.ptr,
+            plaintext_buffer, plaintext_length,
+            message_buffer, message_length
+        );
+        return Module['UTF8ToString'](message_buffer);
+    } finally {
+        if (plaintext_buffer !== undefined) {
+            free(plaintext_buffer);
+        }
+        if (message_buffer !== undefined) {
+            free(message_buffer);
+        }
+    }
+};
 
 OutboundGroupSession.prototype['session_id'] = restore_stack(function() {
     var length = outbound_group_session_method(