add argument to emrun for file dump_out directory

emrun.py

@@ -684,13 +684,12 @@ def do_POST(self):
       # Binary file dump/upload handling. Requests to
       # "stdio.html?file=filename" will write binary data to the given file.
       data = self.rfile.read(int(self.headers['Content-Length']))
-      filename = query[len('file='):]
-      dump_out_directory = 'dump_out'
+      filename = unquote_u(query[len('file='):])
+      filename = os.path.join(emrun_options.dump_out_directory, os.path.normpath(filename))
       try:
-        os.mkdir(dump_out_directory)
+        os.makedirs(os.path.dirname(filename))
       except OSError:
         pass
-      filename = os.path.join(dump_out_directory, os.path.normpath(filename))
       with open(filename, 'wb') as fh:
         fh.write(data)
       logi('Wrote ' + str(len(data)) + ' bytes to file "' + filename + '".')
@@ -1571,6 +1570,9 @@ def run():
   parser.add_argument('--private_browsing', action='store_true',
                       help='If specified, opens browser in private/incognito mode.')
 
+  parser.add_argument('--dump_out_directory', default='dump_out', type=str,
+                      help='If specified, overrides the directory for dump files using emrun_file_dump method.')
+
   parser.add_argument('serve', nargs='?', default='')
 
   parser.add_argument('cmdlineparams', nargs='*')

tests/test_browser.py

@@ -5330,12 +5330,17 @@ def test_emrun(self):
 
     for args in [
         args_base,
-        args_base + ['--private_browsing', '--port', '6941']
+        args_base + ['--private_browsing', '--port', '6941'],
+        args_base + ['--dump_out_directory', 'other dir/multiple', '--port', '6942']
     ]:
       args += [self.in_dir('hello_world.html'), '--', '1', '2', '--3']
       print(shared.shlex_join(args))
       proc = self.run_process(args, check=False)
       self.assertEqual(proc.returncode, 100)
+      dump_dir = 'other dir/multiple' if '--dump_out_directory' in args else 'dump_out'
+      self.assertExists(self.in_dir(f'{dump_dir}/test.dat'))
+      self.assertExists(self.in_dir(f'{dump_dir}/heap.dat'))
+      self.assertExists(self.in_dir(f'{dump_dir}/nested/with space.dat'))
       stdout = read_file(self.in_dir('stdout.txt'))
       stderr = read_file(self.in_dir('stderr.txt'))
       self.assertContained('argc: 4', stdout)

tests/test_emrun.c

@@ -18,6 +18,7 @@ int main(int argc, char **argv) {
   // Dump a file to local filesystem with emrun.
   EM_ASM(emrun_file_dump("test.dat", HEAPU8.subarray(0, 128)););
   EM_ASM(emrun_file_dump("heap.dat", HEAPU8));
+  EM_ASM(emrun_file_dump("nested/with space.dat", HEAPU8.subarray(128, 256)););
 
   if (argc <= 1)
     exit(1);