From: Austin Ziegler <halostatue@...>
Date: 2005-09-14T04:45:48+09:00
Subject: Re: File.split edge cases

On 9/13/05, Berger, Daniel <Daniel.Berger@qwest.com> wrote:
>>> # pseudo-code
>>> if path.root? or path.empty?
>>>     return path, ""
>>> else
>>>     return File.dirname(path), File.basename(path)
>>> end
>> Hmmm. I don't think that's right, still. "ls //" is valid on Unix, so
>> the existing behaviour is *correct*, if mildly unnerving.
> I don't know that just because "ls" handles it one can conclude that
> it's correct behavior on Unix.  But, again, without a POSIX document
> sitting in front of me, I'm just not sure.  My Google skills are
> failing me.

  #include <sys/types.h>
  #include <dirent.h>
  #include <stdlib.h>
  #include <stdio.h>
  #include <string.h>
  #include <errno.h>

  int main(int argc, char* argv)
  {
      struct dirent*  entry;
      DIR*            dir = opendir("//tmp");

      if (!dir)
      {
          fprintf(stderr, "Error opening //tmp (%s).\n",
                  strerror(errno));
          return 1;
      }

      errno = 0;

      while (entry = readdir(dir))
      {
          printf("% 40s\n", entry->d_name);
      }

      if (errno)
      {
          fprintf(stderr, "Error reading //tmp (%s).\n",
                  strerror(errno));
          return 2;
      }

      if (dir)
      {
          closedir(dir);
      }

      return 0;
  }

This should always work on POSIX systems, per:

 http://www.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap03.html

See 3.266 specifically. Also:

  http://www.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap04.html

See 4.11 specifically.

>> However, on Windows, "dir \\" is not correct just as "dir C:\\" will
>> not be correct. Better to specifically check for the UNC-path and
>> drive-path cases. Ruby should also be smart enough to handle the \\.\
>> and \\?\ special prefixes. I can write up a summary of what these are
>> for and how they should be handled, if that would help.
> I think that would be good, along with a series of test cases that
> could be incorporated as part of the Ruby distro.  I already have
> quite a few for File.basename and File.dirname (as part of
> win32-file), though I have to admit I didn't test with "\\.\" or
> "\\?\", though I do have generic UNC path tests.

I'll go through my notes and put something together; it may take a
little time, as \\?\C:\ is valid, but \\?\\server\share isn't; it's
subtly different for \\.\ and \\?\ use with UNC paths.

-austin
-- 
Austin Ziegler * halostatue@gmail.com
               * Alternate: austin@halostatue.ca