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Date: Fri, 24 Aug 2012 13:46:40 -0400
From: Rich Felker <dalias@...ifal.cx>
To: musl@...ts.openwall.com
Subject: Re: ldso: dlclose.

On Fri, Aug 24, 2012 at 03:54:25PM +0200, musl wrote:
> I was talking about this specific case :
> 1) unloding a plugin
> 2) updating the plugin (new plugin.so)
> 3) reloading the plugin
> 
> During the whole sequence the application is up and running.
> 
> Here is how I should do it if dlclose is implemented per posix :
> 1) stop the application
> 2) update the plugin
> 3) restart the application

To clarify on "per POSIX", POSIX allows but does not require dlclose
on the last reference to remove the library from the process's address
space, but requires that this not happen if the library has been used
to resolve undefined symbols.

> The application is not available during this sequence.

If the application just re-execs itself rather than exiting, there is
no window during which it's unavailable. See how irssi handles the
/upgrade command for an example. That might be the cleanest way to
handle what you want to do.

Rich

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