Re: [boost] [filesystem] temp_dir_path()

Subject: Re: [boost] [filesystem] temp_dir_path()
From: Ulrich Eckhardt (doomster_at_[hidden])
Date: 2010-10-10 04:10:39

On Saturday 09 October 2010 18:36:23 Jeff Flinn wrote:
> Posix relies on getEnv("TMPDIR"), which returns 0 if the environment
> variable does not exist.

Question on that: Is it POSIX that actually mandates this very name anywhere? 
If it does, I'd like to hear chapter and verse, because then, lots of software 
doesn't conform to this and could be fixed.

In my experience, there are actually four of these TMP, TEMP, TMPDIR and 
TEMPDIR. On my Debian system, I've redirected these to my homedir at 
~/tmp/{tmp,temp,tmpdir,tempdir} and looking at ~/tmp I see this:

  uli_at_fruitbox:~/tmp$ du 
  24K     ./tmp
  4.0K    ./tempdir
  122M    ./tmpdir
  24M     ./temp

plus a bunch of files under /tmp bearing my ownership, probably from programs 
with a hard-coded path.

> Questions:
> - should Posix return an empty path or an error when empty?

I'd say an error.

> - should Windows provide a more 'temp-path' centric error?

I wouldn't bother. If someone needs this, they will probably file a bug 
ticket.

> - should both verify the path exists?

Yes. Question remains what fallbacks should be tried, e.g. "/tmp" on POSIX 
systems or environment variables on non-embedded win32.

> - if the path does not exist should one be created?

No, the application should define how to handle that, not the library.

Uli