[Gnu-arch-users] Re: recover deleted files

[Miles Bader]

Charles Duffy <address@hidden> writes:
> > It appears to be attempting to determine the file id from the working 
> > tree, not from the library revision.
> 
> Yes, that's what it looks like -- but "cp `file-find myfile.c`
> myfile.c" is a common meme for recovering deleted files (from trees in
> which said files' deletion has not yet been committed to the archive),
> so that behaviour doesn't really make sense.

None-the-less, that's the way it seems to work.  It may be that it will
find and use the explicit id for a deleted file, in which case whether
it works or not depends on what tagging method you use.

The `tla library-find' command, on the other hand, _does_ work even if
all traces of a file are removed from the working directory, but it's a
bit annoying because it doesn't do automatic adding to greedy revlibs,
etc.

Here's the crap my `tla-update-ids' command goes through to try to find
a pristine copy of a file that's been deleted:

   # Return the path to FILE in a pristine version (either a revision
   # library entry or a pristine tree) of the latest revision, or 0 if one
   # cannot be found.
   function pristine_file(file  
,latest_rev,revlib,revlibs_cmd,revlibs_cmd_status,greedy)
   {
     if (! pristine_root) {
       # Find the latest revision and make sure we have a pristine tree for
       # it; by `pristine tree' we really mean revlib entry or pristine tree

       latest_rev = run_cmd_first_line("$TLA logs -f | sed -n '$p'")

       # See if we've got a revlib entry handy
       pristine_root = run_cmd_first_line("$TLA library-find --silent", 
latest_rev)

       if (! pristine_root) {
         # No revlib entry; can we add one to a greedy library?

         # Search for a greedy revision library
         revlibs_cmd = make_cmd("$TLA my-revision-library 2>/dev/null")
         while ((revlibs_cmd_status = (revlibs_cmd |getline revlib)) > 0) {
           greedy = run_cmd_first_line(make_cmd("$TLA library-config", revlib) \
                                       "| grep '^greedy[?]'")
           if (greedy ~ /yes$/)
             break
         }
         if (revlibs_cmd_status >= 0)
           close (revlibs_cmd)

         if (revlibs_cmd_status > 0) {
           # Found a greedy library, add an entry for this revision to it

           if (run_cmd("$TLA library-add", latest_rev))
             pristine_root = run_cmd_first_line("$TLA library-find", latest_rev)
         }

         if (! pristine_root) {
           # Give up with revlibs and try to add a pristine tree

           if (run_cmd("$TLA add-pristine", latest_rev))
             pristine_root = run_cmd_first_line("$TLA find-pristine", 
latest_rev)
         }
       }
     }

     if (pristine_root)
       return pristine_root "/" file
     else
       return 0
   }

I suspect the behavior of this function may not be quite the same as tla's
normal greedy revlib behavior in corner cases too.

It would be nice if there was a simpler way to do this, e.g., if you
could do something like `tla library-find --add-greedy ...' or something.

-Miles
-- 
Love is a snowmobile racing across the tundra.  Suddenly it flips over,
pinning you underneath.  At night the ice weasels come.  --Nietzsche