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Date: Wed, 19 Feb 2014 14:38:52 +0100
Message-ID: <CAMzR4E4jeO45W5wn4ehdwTaZ_gSKPrrEV49OjnfWwjAj3k0ZDg@mail.gmail.com>
Subject: Fwd: Bug with dlopen() and fork()
From: Jaime Fabregas Fernandez <jaime DOT fabregas AT tarlogic DOT com>
To: cygwin AT cygwin DOT com
Content-Type: text/plain; charset=ISO-8859-1

Library references loaded by a process using dlopen() and dlsym() are
no more valid in child processes after running a fork(). Calls from
child process will never return.

I've searched for a similar problem in the mailing lists and found
this unanswered thread from 2001:

http://cygwin.com/ml/cygwin/2001-02/msg01225.html


I'm running cygwin64. This behaviour can be checked with the following
test program:

========================================================
#include <stdio.h>
#include <dlfcn.h>

int (*myopen)(const char *);

main(){
        void *handle;
        int ret;
        handle = dlopen("my_lib.dll", RTLD_LAZY);
        myopen = dlsym(handle, "mylib_open");

        if( ! fork() ){
                ret = myopen("");
                printf("This printf never shows, call to myopen will
block for ever\n");
        }
        else{
                ret = myopen("");
                printf("%i\n", ret);
                sleep(1);
        }
}
========================================================

Same program runs correctly (showing the two printf's) in a Linux environment.

Thanks

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