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Re: Difference between -shared, -symbolic, and -G?

From: Todd <todd dot freed at gmail dot com>
To: Andrew Haley <aph at redhat dot com>
Cc: Ian Lance Taylor <iant at google dot com>, gcc-help at gcc dot gnu dot org
Date: Thu, 29 Oct 2009 13:51:44 -0600
Subject: Re: Difference between -shared, -symbolic, and -G?
References: <fea8ac9f0910191302l3be8f886yd6226a3b7990e301@mail.gmail.com> <mcr8wf70zsv.fsf@dhcp-172-17-9-151.mtv.corp.google.com> <fea8ac9f0910200819p36ce95f6lbbe8db5d6e0bbfa4@mail.gmail.com> <mcreioyxbjl.fsf@dhcp-172-17-9-151.mtv.corp.google.com> <4AE8CB9F.5080702@gmail.com> <mcrskd3ax2e.fsf@dhcp-172-17-9-151.mtv.corp.google.com> <4AE9ACB6.70903@gmail.com> <4AE9E3EC.4070100@redhat.com>

Andrew Haley wrote:

I am using gcc version 4.3.3 for x86

-Wl,-Bsymbolic looks like it does what I want.


Be very, very careful.  -Bsymbolic violates the C standard, and all
manner of very weird things can happen to your program.  One symptom
is that data in a shared library that is written by an executable
fails mysteriously to be there when read by the library.  This is
because you end up with two copies of the data, one in the shared
library and one in the executable, even though the data is only
defined once in the library.  It is possible to solve most of these
problems by compiling the executable as PIC.

Andrew.

Hmm. I just need to have a function in my shared library, callable from the executable linked against the shared library, which I can also call from inside the shared library such that calls originating inside always invoke the one defined inside. What is the right way to achieve this, then?

-Todd

Follow-Ups:
- Re: Difference between -shared, -symbolic, and -G?
  - From: Ian Lance Taylor

References:
- Difference between -shared, -symbolic, and -G?
  - From: Joseph Garvin
- Re: Difference between -shared, -symbolic, and -G?
  - From: Ian Lance Taylor
- Re: Difference between -shared, -symbolic, and -G?
  - From: Joseph Garvin
- Re: Difference between -shared, -symbolic, and -G?
  - From: Ian Lance Taylor
- Re: Difference between -shared, -symbolic, and -G?
  - From: Todd
- Re: Difference between -shared, -symbolic, and -G?
  - From: Ian Lance Taylor
- Re: Difference between -shared, -symbolic, and -G?
  - From: Todd
- Re: Difference between -shared, -symbolic, and -G?
  - From: Andrew Haley

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