On Thu, 31 May 2007, Jakub Jelinek wrote:
> On Thu, May 31, 2007 at 11:46:31AM -0700, Davide Libenzi wrote:
> > On Thu, 31 May 2007, Ulrich Drepper wrote:
> > > Davide Libenzi wrote:
> > > > Isn't this better be a global process flag? Default should be, for legacy
> > > > reasons,
> > >
> > > No. Policies are always wrong since it means code that cannot change
> > > the policy (e.g, all runtime libraries) have no access to the
> > > functionality. I cannot set the policy to default to close-on-exit in
> > > glibc all the while the application assumes this is not the case.
> >
> > I was talking for a broader usage, not only glibc centric. Most ppl
> > writing MT+exec apps wants all but (eventually) and handfull of files
> > leaking across the exec boundary.
>
> If open (and all other syscalls that create fds) have O_CLOEXEC (and
> something similar for other syscalls), then such a policy can be easily
> implemented on the userland, if desired.
That, unless you change all the syscalls creating files to accept new
parameters, would require a syscall+fcntl operation. That is not atomic
(ie, another thread might do exec between the syscall and the fcntl).
Again, mine was a general comment, not directed into magically fixing
existing buggy code. What I meant, was that the vast majority of MT+exec
apps wants all their fds (but an handfull, maybe) to be O_CLOEXEC. So a
global, non-inheritable, per-process flag seemed the most straightforward
solution.
- Davide
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