Small security patches
Pierre A. Humblet
Wed Dec 11 13:16:00 GMT 2002
Christopher Faylor wrote:
> On Wed, Dec 11, 2002 at 03:56:17PM -0500, Pierre A. Humblet wrote:
> >Christopher Faylor wrote:
> >> Shouldn't the global symbols be marked as "NO_COPY"?
> >I am not sure why things are as they are.
> >These symbols are initialized in do_global_ctors and never change.
> >Are the constructors running again after a fork? If so, NO_COPY is fine.
> >It would seem more efficient to copy than to rerun the constructors,
> >but I probably overlook some factors.
> Constructors are always run. If you use a global constructor without a
> NO_COPY then you just end up writing over the contents when the fork
> completes. So, if the constructor is setting things up correctly the
> global should be NO_COPY. Actually, if you can get away without using a
> constructor that would be best. Constructors are a noticeable part of
> cygwin's startup cost.
Thanks for the information. While we are at it, I was looking at the
code and noticed that there were hooks to avoid running the constructors
(things such as "force" and "user_data->run_ctors_p").
Are they ever used or are they history?
In this case we could write a macro to initialize the cygsid structure
without having a constructor. I will look into it.
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