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From Mark Taylor <>
Subject Re: dlopen a .so from a module
Date Fri, 08 Jan 2016 01:45:20 GMT
Thanks Nick,

Replacing ap_rputs with ap_rwrite in my .so worked although I'm not clear
on why?

Right now I'm just using dlopen/dlsym for test/proof of concept.  The .so
could change externally and require reloading at runtime so that's why I'm
not using LoadFile.

Incidentally, I bought your book a while back, it's really a hell of a
thing, thanks for writing it!


On Thu, Jan 7, 2016 at 12:16 AM, Nick Kew <> wrote:

> On Wed, 2016-01-06 at 21:30 -0600, Mark Taylor wrote:
> > Hi all,
> >
> > I have a module that dlopens a .so, gets a handle to a function in the so
> > and calls it. The function in the so calls ap_rputs.  dlopen returns the
> > error 'undefined symbol ap_rputs'.
> Looks like you're falling victim to
> which also points to ap_rwrite as an obvious workaround.
> That would've caught me out, too!
> > nm tells me ap_rputs is defined in httpd, and via some dark magic, httpd
> > symbols are available to modules compiles the apxs -c.  But when I
> compile
> > my .so to be loaded into my module, the symbols from httpd aren't
> > available. My hypothesis, now disproven, was that symbols available to my
> > module would be visible to my .so.
> Does your module use dlopen or apr_dso_load/family?
> Is your module loading/unloading anything per-request or
> per-connection?  If not, why not use LoadFile in httpd.conf
> to load the .so?
> --
> Nick Kew

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