On Fri, Oct 23, 2009 at 1:58 AM, Anselm R Garbe <[email protected]> wrote:

>
> 2009/10/23 Anselm R Garbe <[email protected]>:
> > I rebuilt chromium yesterday from yesterday's tip on Linux (last time
> > I did that was about 8 weeks ago or so). I'm involved in developing
> > some NPAPI plugins that used to work well with my older chromium linux
> > build and that work without any issues in all other NPAPI supporting
> > browsers including firefox, Opera and some webkitgtk based ones, such
> > as surf.
> >
> > Anyway, the symptom I see in chromium is this (in about:plugins):
> >
> > Native Client Plugin
> >
> > File name: npfoo.so
> > Native Client Plugin was built on Oct 22 2009 at 12:28:12 and expires
> > on 11/4/2009 (mm/dd/yyyy)
> > MIME Type       Description     Suffixes        Enabled
> > application/x-nacl-srpc NativeClient Simple RPC module   nexe   Yes
> >
> > So the Native Client Plugin somehow overrides the original mime type
> > (application/x-vnd-foo-x and foo as suffix) now and makes it
> > impossible to use the NPAPI plugin as usual. Also note that this
> > Native Client Plugin stuff seems to be totally untested on Linux, at
> > least the borken extension "nexe" (.exe?) hints that there seems to be
> > something not in sync between code that's used on Windows perhaps?
> >
> > On the other hand some plugins seem not to be wrapped by Native Client
> > Plugin, such as Adobe's PDF plugin (nppdf.so) and I wonder why that's
> > the case (is there any hard-coded trusted plugins list somewhere?).
> >
> > Any insight on how to make it work would be really helpful.
>
> Ok, I'm a moron and found the issue. The problem is that the chrome
> executable (in particular statically linked in
> libnpGoogleNaClPluginChrome.a) exports 'char
> *NPP_GetMIMEDescription(void)' as a C symbol, which my plugin code
> also implements and calls when NP_GetMIMEDescription() is called by
> the browser. So chrome's Native Client Plugin's
> NPP_GetMIMEDescription() takes preference and is called by my plugin
> code instead of its own build-in NPP_GetMIMEDescription()
> implementation.
>
> The original pattern came from some initial mozilla NPAPI plugin
> example I started from a long while ago and that contained the pattern
> to call NPP_GetMIMEDescription() on returning from
> NP_GetMIMEDescription entry point. I never bothered to change that
> until now ;)
>
> This might not happen of course if I'd use a C++ compiler that mangles
> the symbols, but my definitions are plain C symbols and hence the
> conflict.
>
> However, I'm not sure if chrome resp. libnpGoogleNaClPluginChrome.a
> does it right with exporting these symbols as plain C symbols because
> this might conflict with other existing plugins as well in the same
> way.
>

http://gcc.gnu.org/wiki/Visibility

Make your plugin compile with -fvisibility=hidden, and only explicitly
export the plugin functions by adding __attribute__((visibility("default")))
That should fix this, and similar problems.

Though agreed, Chrome should aim to do the same...

Antoine

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