[LinuxBIOS] [PATCH][LAR] New LAR access functions

Peter Stuge peter at stuge.se
Thu Jul 12 19:41:41 CEST 2007

On Thu, Jul 12, 2007 at 07:26:23PM +0200, Stefan Reinauer wrote:
> > > Rather check the path before mkdir()ing.
> > 
> > Exactly the idea.

Maybe I should explain mkdirp_below() a bit more.

It parses the new path one subdir at a time (as separated by / or \)
and calls realpath() to resolve it into an absolute path.

If realpath() fails for some other reason than the path not existing,
return an error.

If the resolved absolute path is outside the specified parent
directory, also return an error.

Otherwise, the new dir is created (no error if it already exists) and
iterate to the next subdir.

Since realpath() only works with existing paths, only one dir can be
checked at a time. This means subdir/../subdir will be considered to
be outside subdir because subdir/.. in the second iteration tests

The only way to properly handle this is to do full path resolution
per path_resolution(2) but that is too big of a wheel to re-invent.

subdir/.. constructs could be removed, but symlinks must also be
checked then.

> Great. Instead of calling mkdirp with ".", can we assume "." is
> always the starting point? (I think it is not called differently
> at any other point)

It's not, but it might be with a new -C option? Or should that call
chdir() before extracting any files? I generally avoid chdir() since
all of a sudden something needs to be done back in the startup
working directory.

Simpler to chdir() and use ready-made paths (if they're relative)
than to copy stuff around to create "relocated" paths though.

Maybe I'm too strict?


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