refactor response file substitution (#6171)

We have the same code in two places, we can make a common function for
the response_file module.

Author: froydnj

emcc.py

@@ -32,7 +32,7 @@
 from subprocess import PIPE
 from tools import shared, jsrun, system_libs
 from tools.shared import execute, suffix, unsuffixed, unsuffixed_basename, WINDOWS, safe_move, run_process, asbytes
-from tools.response_file import read_response_file
+from tools.response_file import substitute_response_files
 import tools.line_endings
 
 try:
@@ -329,17 +329,7 @@ def run():
     exit(1)
 
   # read response files very early on
-  response_file = True
-  while response_file:
-    response_file = None
-    for index in range(1, len(sys.argv)):
-      if sys.argv[index][0] == '@':
-        # found one, loop again next time
-        response_file = True
-        extra_args = read_response_file(sys.argv[index])
-        # slice in extra_args in place of the response file arg
-        sys.argv[index:index+1] = extra_args
-        break
+  substitute_response_files(sys.argv)
 
   if len(sys.argv) == 1 or '--help' in sys.argv:
     # Documentation for emcc and its options must be updated in:

emscripten.py

@@ -20,7 +20,7 @@
 
 from tools import shared
 from tools import jsrun, cache as cache_module, tempfiles
-from tools.response_file import read_response_file
+from tools.response_file import substitute_response_files
 from tools.shared import WINDOWS, asstr
 
 __rootpath__ = os.path.abspath(os.path.dirname(__file__))
@@ -2255,17 +2255,7 @@ def _main(args=None):
   if args is None:
     args = sys.argv[1:]
 
-  response_file = True
-  while response_file:
-    response_file = None
-    for index in range(len(args)):
-      if args[index][0] == '@':
-        # found one, loop again next time
-        response_file = True
-        response_file_args = read_response_file(args[index])
-        # slice in extra_args in place of the response file arg
-        args[index:index+1] = response_file_args
-        break
+  substitute_response_files(args)
 
   parser = argparse.ArgumentParser(
     usage='%(prog)s [-h] [-H HEADERS] [-o OUTFILE] [-c COMPILER_ENGINE] [-s FOO=BAR]* infile',

tools/response_file.py

@@ -44,3 +44,15 @@ def read_response_file(response_filename):
     logging.warning('Read response file ' + response_filename + ': ' + str(args))
 
   return args
+
+def substitute_response_files(args):
+  """Substitute any response files found in args with their contents."""
+  found = True
+  while found:
+    found = False
+    for index in range(len(args)):
+      if args[index].startswith('@'):
+        found = True
+        new_args = read_response_file(args[index])
+        args[index:index+1] = new_args
+        break