Revert "Cleanup add_emscripten_metadata. NFC. (emscripten-core#8482)"

This reverts commit 32d5af6.

emcc.py

@@ -2739,7 +2739,8 @@ def do_binaryen(target, asm_target, options, memfile, wasm_binary_target,
 
   # after generating the wasm, do some final operations
   if shared.Settings.EMIT_EMSCRIPTEN_METADATA:
-    shared.WebAssembly.add_emscripten_metadata(final, wasm_binary_target)
+    wso = shared.WebAssembly.add_emscripten_metadata(final, wasm_binary_target)
+    shutil.move(wso, wasm_binary_target)
 
   if shared.Settings.SIDE_MODULE:
     sys.exit(0) # and we are done.

tools/shared.py

@@ -2978,10 +2978,26 @@ def delebify(buf, offset):
     return (result, offset)
 
   @staticmethod
-  def add_emscripten_metadata(js_file, wasm_file):
+  def get_js_data(js_file, shared=False):
     mem_size = Settings.STATIC_BUMP
     table_size = Settings.WASM_TABLE_SIZE
+    if shared:
+      mem_align = Settings.MAX_GLOBAL_ALIGN
+    else:
+      mem_align = None
+    return (mem_size, table_size, mem_align)
+
+  @staticmethod
+  def add_emscripten_metadata(js_file, wasm_file):
+    (mem_size, table_size, _) = WebAssembly.get_js_data(js_file)
     logger.debug('creating wasm emscripten metadata section with mem size %d, table size %d' % (mem_size, table_size,))
+    wso = js_file + '.wso'
+    wasm = open(wasm_file, 'rb').read()
+    f = open(wso, 'wb')
+    f.write(wasm[0:8]) # copy magic number and version
+    # write the special section
+    f.write(b'\0') # user section is code 0
+    # need to find the size of this section
     name = b'\x13emscripten_metadata' # section name, including prefixed size
     contents = (
       # metadata section version
@@ -3003,25 +3019,19 @@ def add_emscripten_metadata(js_file, wasm_file):
       #     the EMSCRIPTEN_METADATA_MINOR
     )
 
-    orig = open(wasm_file, 'rb').read()
-    with open(wasm_file, 'wb') as f:
-      f.write(orig[0:8]) # copy magic number and version
-      # write the special section
-      f.write(b'\0') # user section is code 0
-      # need to find the size of this section
-      size = len(name) + len(contents)
-      f.write(WebAssembly.lebify(size))
-      f.write(name)
-      f.write(contents)
-      f.write(orig[8:])
+    size = len(name) + len(contents)
+    f.write(WebAssembly.lebify(size))
+    f.write(name)
+    f.write(contents)
+    f.write(wasm[8:])
+    f.close()
+    return wso
 
   @staticmethod
   def make_shared_library(js_file, wasm_file, needed_dynlibs):
     # a wasm shared library has a special "dylink" section, see tools-conventions repo
     assert not Settings.WASM_BACKEND
-    mem_align = Settings.MAX_GLOBAL_ALIGN
-    mem_size = Settings.STATIC_BUMP
-    table_size = Settings.WASM_TABLE_SIZE
+    mem_size, table_size, mem_align = WebAssembly.get_js_data(js_file, True)
     mem_align = int(math.log(mem_align, 2))
     logger.debug('creating wasm dynamic library with mem size %d, table size %d, align %d' % (mem_size, table_size, mem_align))