Fix a race condition in llvm::sys::path::unique_file: when we end up

failing to create the unique file because the path doesn't exist,
don't fail if someone else manages to create the path before we do.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@172032 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 7 insertions, 4 deletions

diff --git a/lib/Support/Unix/PathV2.inc b/lib/Support/Unix/PathV2.inc
index 25712a8..741f44a 100644
--- a/lib/Support/Unix/PathV2.inc
+++ b/lib/Support/Unix/PathV2.inc
@@ -421,11 +421,12 @@ retry_random_path:
 rety_open_create:
   int RandomFD = ::open(RandomPath.c_str(), O_RDWR | O_CREAT | O_EXCL, mode);
   if (RandomFD == -1) {
+    int SavedErrno = errno;
     // If the file existed, try again, otherwise, error.
-    if (errno == errc::file_exists)
+    if (SavedErrno == errc::file_exists)
       goto retry_random_path;
     // If path prefix doesn't exist, try to create it.
-    if (errno == errc::no_such_file_or_directory &&
+    if (SavedErrno == errc::no_such_file_or_directory &&
         !exists(path::parent_path(RandomPath))) {
       StringRef p(RandomPath);
       SmallString<64> dir_to_create;
@@ -440,13 +441,15 @@ rety_open_create:
                                (*i)[1] == '/' &&
                                (*i)[2] != '/')
             return make_error_code(errc::no_such_file_or_directory);
-          if (::mkdir(dir_to_create.c_str(), 0700) == -1)
+          if (::mkdir(dir_to_create.c_str(), 0700) == -1 &&
+              errno != errc::file_exists)
             return error_code(errno, system_category());
         }
       }
       goto rety_open_create;
     }
-    return error_code(errno, system_category());
+
+    return error_code(SavedErrno, system_category());
   }
 
    // Make the path absolute.