[Rd] Overriding InitTempDir

[Prof Brian Ripley]

It is conventional for people proposing changes to R to set out a 
compelling case as to why they are needed.  I have not seen any case here.
Can we please have one?

Someone will have to think through the ramifications of such a change (and 
BTW using edit() in an R console is not at all unlikely), and continue to 
maintain it for years to come.  I have to say that in the past I have 
accepted quite a few user suggestions that became maintenance nightmares, 
so I have become very wary.

It's not really a good time: R-devel is about to start solidifying towards 
2.4.0, and we have quite a few issues to work through (e.g. the internal 
changes to S4 methods).


On Fri, 1 Sep 2006, Jeffrey Horner wrote:

> Jeffrey Horner wrote:
> > For embedded projects, one may want to eliminate the per-session temp 
> > directory created by InitTempDir() and just use a system-specific temp 
> > directory. Here's my solution:
> > 
> > extern char *R_TempDir;
> > 
> > void my_InitTempDir()
> > {
> >      char *tmp;
> > 
> >      if (R_TempDir){
> >          if (rmdir(R_TempDir) != 0){
> >              perror("Fatal Error: could not remove R's TempDir!");
> >              exit(1);
> >          }
> >      }
> > 
> >      tmp = getenv("TMPDIR");
> >      if (tmp == NULL) {
> >          tmp = getenv("TMP");
> >              if (tmp == NULL) {
> >                  tmp = getenv("TEMP");
> >                  if (tmp == NULL)
> >                      tmp = "/tmp";
> >              }
> >      }
> > 
> >      R_TempDir=tmp;
> > 
> >      if (setenv("R_SESSION_TMPDIR",tmp,1) != 0){
> >          perror("Fatal Error: couldn't set/replace R_SESSION_TMPDIR!");
> >          exit(1);
> >      }
> > }
> > 
> > This function is called after Rf_initEmbeddedR; it's seems like a hack 
> > but it works. Does anyone have other solutions?
> 
> I just found a fault with the above solution, but only if a program that 
> embeds R calls the R edit function; highly unlikely. Nevertheless, It 
> turns out that soon after InitTempDir is called, InitEd is called and 
> sets the variable DefaultFileName (which is hidden by storage class 
> static, unlike R_TempDir) to a temporary filename located in the 
> directory which was just deleted by my_initTempDir.
> 
> > Maybe InitTempDir could check if R_TempDir was not NULL and then just 
> > return.
> 
> So it would be nice if the above (InitTempDir only creating a directory 
> when R_TempDir is NULL) could be added to R-trunk.
> 
> Note also that in the case that R_TempDir is set to a system-specific 
> temp directory, the program would then have to set it back to NULL as 
> the new function Rf_endEmbeddedR now tests to see if R_TempDir has been set:
> 
> /* use fatal !=0 for emergency bail out */
> void Rf_endEmbeddedR(int fatal)
> {
>      unsigned char buf[1024];
>      char * tmpdir;
> 
>      R_RunExitFinalizers();
>      CleanEd();
>      if(!fatal) KillAllDevices();
>      if((tmpdir = R_TempDir)) {
>      snprintf((char *)buf, 1024, "rm -rf %s", tmpdir);
>      R_system((char *)buf);
>      }
>      if(!fatal && R_CollectWarnings)
>      PrintWarnings();    /* from device close and .Last */
>      fpu_setup(FALSE);
> }
> 
> Jeff
> 

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595