Joe Orton wrote:
On Fri, Jan 06, 2006 at 08:04:53AM -0800, Jonathan wrote:
Comments?
This adds apr_dso_open(). Its intention is to only open a dynamic shared
library and to do so without any further process to automatically bind
global symbols, unlike apr_dso_load().
Splitting the differrent implementations into separate files should be
done separately to adding any new interfaces; if you wanted to submit a
patch for that it's probably be a good idea.
That can be done.
For the new interface: offering GLOBAL|NOW and LAZY|LOCAL as the only
two options is just odd; the most common uses I'd see would be
GLOBAL|NOW and LOCAL|NOW, LAZY is useful only in rare cases.
RTLD_NOW is useful for DLLs that expect to export symbols and to debug
code. It does not work well for DLLs that are set-up to import symbols
and that take advantage of private/local DLL namespace, especially when
mixed with code that expects exported symbols. RTLD_LAZY is not
uncommon. It is, perhaps, less used because it requires a bit more work
to code properly. Some systems do the equivalent of RTLD_LAZY, by
default, and require a explicit flag or such to bind everything
immediately. With RTLD_LAZY, it is possible to not export any symbols
and not cause any bind and still access the code in a library through
dlsym(), yet, with RTLD_NOW, it can be done automatically or automated
with compiler options. That automatic bind is not always desirable.
LOCAL|NOW and GLOBAL|NOW only changes symbol depth. GLOBAL|NOW and
LOCAL|LAZY allows symbol breadth and namespace breadth. I suggest
another function, apr_dso_open_ex(), if we want more OS specific
options. LOCAL|LAZY, however, is portable in likeness across other
supported systems without dlopen().
I think any new function should just use flags to allow the user to
choose any of the four combinations where possible. (I don't understand
the vetoes on previous patches which did that, so I can't offer any
advice on how to do this without still incurring a veto; try it and see
I guess)
Regards,
joe
Not all systems have only four options and the same likeness in options.
We can, however, limit it to two functions, for now, instead of just the
only one that we have.
Best,
Jonathan
