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From: Florian Weimer <fw@deneb.enyo.de>
To: "Wangbing(wangbing, RTOS/Poincare Lab) via Libc-alpha"
 <libc-alpha@sourceware.org>
Cc: "Wangbing(wangbing,RTOS/Poincare Lab)" <wangbing6@huawei.com>,
  Nixiaoming <nixiaoming@huawei.com>
Subject: Re: [PATCH] dlsym: Add RTLD_PROBE for situation when dlsym only
 wants to probe a symbol but not use it
References: <efbc56f827194b87878392540b88fa12@huawei.com>
Date: Tue, 27 Sep 2022 12:40:31 +0200
In-Reply-To: <efbc56f827194b87878392540b88fa12@huawei.com> (Wangbing via
	Libc-alpha's message of "Tue, 27 Sep 2022 09:21:04 +0000")
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* Wangbing via Libc-alpha:

> dlsym with RTLD_DEFAULT add dependency for target symbol, if program
> use dlsym only to detect if a symbol exist, and will not use it.
>
> this operation will make unable to dlclose so file containing target
> symbol, add RTLD_PROBE to support symbol probe.

I'd appreciate if you could write a test case for this functionality.

I'm not sure if the new functionality is needed.  If we document that
a struct link_map * obtained from _dl_find_object or via
_r_debug.r_map can be used as an argument to dlsym (and other places
where a DSO handle is currently accepted), programmers could use that
to get this effect.  I believe this works today (as an undocumented
feature) and does not record the dependency.