[Insight-developers] portable temporary file name generator function?

[Luis Ibanez]

Kent, Mathieu,

Could we use the UUID functionalities of GDCM
in order to generate a unique filename ?


   My 2 cents,


        Luis


--------------------------------------------------
On Wed, Jul 29, 2009 at 5:48 PM, kent williams
<norman-k-williams at uiowa.edu>wrote:

> Yeah, you found the conundrum.  If you can't come up with a temporary name
> and create the file in one atomic operation, you're theoretically up
> against
> a race condition -- another process could create that file between choosing
> the filename and opening it.
>
> My 'solution' is robust enough for our purposes, though it's neither
> thread-safe nor secure. It also does nothing to check for things like /tmp
> filling up or being unwritable. And it will fail on Windows as it stands
> unless you've made a '/tmp' directory on every drive. But I will worry
> about
> that if we ever deploy on Windows.
>
> namespace {
>
>  vnl_random randgen;
>  bool randomized(false);
>  // TODO
> std::string NewTempName()
> {
> #if !defined(_WIN32)
>  if(!randomized)
>    {
>    randomized = true;
>    randgen.reseed(static_cast<unsigned long>(getpid()));
>    }
> #endif
>  // it needs to be an image name. None of the standard library functions I
> know
>  // about generate unique filenames with suffixes.
>  for(;;)
>    {
>    std::ostringstream strvalue;
>    strvalue << "/tmp/";
>    strvalue << randgen.lrand32();
>    strvalue << randgen.lrand32();
>    strvalue << ".nii.gz";
>    if(!vtksys::SystemTools::FileExists(strvalue.str().c_str(),true))
>      {
>      return strvalue.str().c_str();
>       }
>    }
> }
>
>
> On 7/29/09 4:26 PM, "Mathieu Malaterre" <mathieu.malaterre at gmail.com>
> wrote:
>
> > On Tue, Jul 28, 2009 at 8:46 PM, kent
> > williams<norman-k-williams at uiowa.edu> wrote:
> >> I have need to generate some temporary filenames, in order to write out
> >> images for external programs to use as inputs.
> >>
> >> I notice there's no temporary file name generator in
> itksys::SystemTools.
> >>
> >> Shouldn't there be?
> >>
> >> I'd can write one, no doubt, but don't have Windows builds to test it
> on.
> >>
> >> Is there one buried somewhere in CMake?
> >
> > The only one I found out to be working on linux and win32 was tempnam:
> >
> >  char *tempnam(const char *dir, const char *pfx);
> >
> > Most documentation will tell you this is a bad idea anyway and should
> > instead request a file (without knowing the actual filename) from the
> > system (eg: tmpfile).
> >
> >
> > HTH
>
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