问题
I'm in a situation that's quite similar to the following. There's libA.so
that depending on some compile time flags exhibits slightly different behaviour (it's an external lib, and I can't modify the source). Then, I have libB.so
that depends on libA.so
(compiled with say -DVALUE=1
), and in my executable I depend both on libB.so
, as well as on libA.so
, but compiled with -DVALUE=0
. However, once I launch it, ld resolves all symbols with one of libA.so
versions, so both my executable and libB.so
are using the same functions.
Is there any way to specify that I want to load resolve undefined symbols of libB.so
only using its dependencies? I've tried using -Wl,-Bgroup
flag when building libB.so
, but it didn't change anything. I know there's dlmopen
that can load the library in a new namespace, but I'd like to have it loaded automatically at startup.
I'm attaching a set of files that reproduce the behaviour:
libA.so:
#include <stdio.h>
#define _STR(x) #x
#define STR(x) _STR(x)
#ifndef VALUE
#define VALUE default
#endif
void func2() {
printf(STR(VALUE) "\n");
}
void func() {
func2();
}
libB.so:
#include <stdio.h>
extern void func(void);
void b_func() {
func();
}
executable:
#include <stdio.h>
extern void b_func(void);
extern void func(void);
int main() {
func(); // should print "default"
b_func(); // should print "other"
}
build commands:
gcc -fPIC -shared A.c -o libA.so
gcc -fPIC -shared -DVALUE=other A.c -o libA2.so
gcc -fPIC -shared B.c -L. -lA2 -o libB.so
gcc main.c -L. -lA -lB -o main
Curiously, it all works fine on OS X.
来源:https://stackoverflow.com/questions/40629041/loading-two-different-versions-of-the-same-shared-library