2 files changed, 23 insertions, 6 deletions
diff --git a/src/wasm/wasm-binary.cpp b/src/wasm/wasm-binary.cpp
index 514b489a9..44ce9a2d1 100644
--- a/src/wasm/wasm-binary.cpp
+++ b/src/wasm/wasm-binary.cpp
@@ -61,6 +61,9 @@ void WasmBinaryWriter::write() {
   if (sourceMap) {
     writeSourceMapEpilog();
   }
+
+  writeUserSections();
+
   finishUp();
 }
 
@@ -551,6 +554,17 @@ static void writeBase64VLQ(std::ostream& out, int32_t n) {
   }
 }
 
+void WasmBinaryWriter::writeUserSections() {
+  for (auto& section : wasm->userSections) {
+    auto start = startSection(0);
+    writeInlineString(section.name.c_str());
+    for (size_t i = 0; i < section.data.size(); i++) {
+      o << uint8_t(section.data[i]);
+    }
+    finishSection(start);
+  }
+}
+
 void WasmBinaryWriter::writeDebugLocation(size_t offset, const Function::DebugLocation& loc) {
   if (lastBytecodeOffset > 0) {
     *sourceMap << ",";
@@ -1626,9 +1640,9 @@ void WasmBinaryBuilder::readImports() {
       case ExternalKind::Global: {
         curr->globalType = getWasmType();
         auto globalMutable = getU32LEB();
-        if (globalMutable) {
-          throw ParseException("imported globals cannot be mutable");
-        }
+        // TODO: actually use the globalMutable flag. Currently mutable global
+        // imports is a future feature, to be implemented with thread support.
+        (void)globalMutable;
         break;
       }
       default: {
diff --git a/src/wasm/wasm-io.cpp b/src/wasm/wasm-io.cpp
index ebc9af8de..1f50d7140 100644
--- a/src/wasm/wasm-io.cpp
+++ b/src/wasm/wasm-io.cpp
@@ -46,15 +46,18 @@ void ModuleReader::readBinary(std::string filename, Module& wasm) {
   parser.read();
 }
 
-void ModuleReader::read(std::string filename, Module& wasm) {
-  // see if this is a wasm binary
+bool ModuleReader::isBinaryFile(std::string filename) {
   std::ifstream infile;
   std::ios_base::openmode flags = std::ifstream::in | std::ifstream::binary;
   infile.open(filename, flags);
   char buffer[4] = { 1, 2, 3, 4 };
   infile.read(buffer, 4);
   infile.close();
-  if (buffer[0] == '\0' && buffer[1] == 'a' && buffer[2] == 's' && buffer[3] == 'm') {
+  return buffer[0] == '\0' && buffer[1] == 'a' && buffer[2] == 's' && buffer[3] == 'm';
+}
+
+void ModuleReader::read(std::string filename, Module& wasm) {
+  if (isBinaryFile(filename)) {
     readBinary(filename, wasm);
   } else {
     // default to text