On Mon, Sep 13, 2010 at 12:59:40PM -0400, Steven Bellovin wrote: > > On Sep 13, 2010, at 12:58 39PM, David Laight wrote: > > > On Sat, Sep 11, 2010 at 02:01:43PM -0700, Chuck Silvers wrote: > >> hi folks, > >> > >> the remaining missing bit that prevents acroread from working with the new > >> linux emulation code (PR 43695) is support for the O_DIRECTORY flag to > >> open(). > > > > Is there a way to open a directory on which you have neither read nor > > write access (maybe not even search access) ? > > You can only open something for which you have *some* access right. > Traditionally, Unix has done access rights checking only at open time, > not at read/write/chdir time. > > > Sometimes it is necessary to open "." in order to do a later fchdir(). > > And if/when we support openat() then you have a good justification for > > only requiring 'x' access. > > > This poses an interesting question -- what flags should go in the open() > call to permit search path but not read?
the POSIX-2008 web page that mentioned in my original mail describes additional open() flags that address these issues. -Chuck
