Retry directory creation when ERROR_ALREADY_EXISTS is returned.

[masamitsu-murase]

First of all, let me thank you for your great work.

This is a bug fix for a corner case.

Issue:

• When I ran multiple *.exe files simultaneously, which was packaged by Ocra, I faced a fatal error, "Failed to create installation directory.", in rare cases.

Cause:

• This issue is caused by the following source code in OpCreateInstDirectory:

   UINT tempResult = GetTempFileName(TempPath, _T("ocrastub"), 0, InstDir);
   if (tempResult == 0u)
   {
      FATAL("Failed to get temp file name.");
      return FALSE;
   }

   DEBUG("Creating installation directory: '%s'", InstDir);

   /* Attempt to delete the temp file created by GetTempFileName.
      Ignore errors, i.e. if it doesn't exist. */
   (void)DeleteFile(InstDir);

   if (!CreateDirectory(InstDir, NULL))
   {
      FATAL("Failed to create installation directory.");
      return FALSE;
   }
   return TRUE;

In the above function, the function may fail to create a directory.
Let's assume that we run 2 *exe files packaged by Ocra.

1. Run exe 1 and exe 2 simultaneously.
2. Exe 1 calls GetTempFileName to create a temporary file.
   Let's assume that the name of the file is "ocr0123.tmp".
3. Exe 1 removes the file immediately.
4. Exe 2 calls GetTempFileName.
   In rare cases, it creates a temporary file, "ocr0123.tmp", whose file name is same as step 2.
5. Then, exe 1 fails to create a directory because step 4 already created "ocr0123.tmp".

Let me explain the detailed background.

• Windows generates a temporary file name based on the system time in millisecond.
• Therefore, step 2 and step 4 may generate identical file name because recent CPUs are so fast...

My changeset retries directory creation when ERROR_ALREADY_EXISTS is returned.

Regards,
Murase