Fix race condition in Directory.create.

runtime/bin/directory_android.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "bin/directory.h"
 
 #include <dirent.h>
 #include <errno.h>
 #include <sys/param.h>
 #include <sys/stat.h>
@@ skipping 373 matching lines @@
     return NULL;
   }
 
   return strdup(buffer);
 }
 
 
 bool Directory::Create(const char* dir_name) {
   // Create the directory with the permissions specified by the
   // process umask.
-  return (TEMP_FAILURE_RETRY(mkdir(dir_name, 0777)) == 0);
+  int result = TEMP_FAILURE_RETRY(mkdir(dir_name, 0777));
+  // If the directory already exists, treat it as a success.
+  if (result == -1 && errno == EEXISTS)  {
+    return (Exists(dir_name) == EXISTS);
+  }
+  return (result == 0);
 }
 
 
 // Android doesn't currently provide mkdtemp.  Once Android provied mkdtemp,
 // remove this function in favor of calling mkdtemp directly.
 static char* MakeTempDirectory(char* path_template) {
   if (mktemp(path_template) == NULL) {
     return NULL;
   }
   if (mkdir(path_template, 0700) != 0) {
@@ skipping 50 matching lines @@
     return DeleteRecursively(dir_name);
   }
 }
 
 
 bool Directory::Rename(const char* path, const char* new_path) {
   ExistsResult exists = Exists(path);
   if (exists != EXISTS) return false;
   return (TEMP_FAILURE_RETRY(rename(path, new_path)) == 0);
 }