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two instances of global from shared lib linked with -Bsymbolic

From: Rafal Dabrowa
Subject: two instances of global from shared lib linked with -Bsymbolic
Date: Tue, 6 Apr 2004 11:20:34 +0200
User-agent: KMail/1.6.1

Earlier I have sent the bug to sources.redhat.com (bug #105), but
I see that it is probably a linker bug. Namely:
        I have created a global (integer) variable in shared library. 
The library is linked with -Bsymbolic option. Main program 
sees this variable as a separate copy: any changes of this 
variable aren't seen in library and vice versa. 
How to repeat: see code below. 
file: mylib.c 
     int MyGlob;        /* variable with two instances at runtime */ 
     void libf() { printf("libf: &MyGlob = %p\n", &MyGlob); } 
file: ts.c 
     extern int MyGlob;         /* extern only ! Defined in libmy.a */ 
     int main() { 
         printf("main: &MyGlob = %p\n", &MyGlob); 
        ts: libmy.a ts.o 
            gcc ts.o -o ts -L. -lmy 
        libmy.a: mylib.o 
            gcc -o libmy.a -shared -Wl,-Bsymbolic mylib.o 
            gcc -g -c $< 
After compile and run I see: 
      main: &MyGlob = 0x8049714 
      libf: &MyGlob = 0x4001a8e8 
The variable has really two different instances, as I have mentioned 
When I use readelf program to read ts program symbol table, I see:

     3: 080483d0    29 FUNC    GLOBAL DEFAULT  UND libf
     6: 0804970c     4 OBJECT  GLOBAL DEFAULT   22 MyGlob

A "libf" symbol is undefined, but "MyGlob" symbol *is* defined. Is this 
correct ?


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