./libbar.so: undefined symbol: __gxx_personality_v0, how to solve it? - c++

Question

While making a simple test case I met with another problem. Please help me.
Here are the files.
<<< bar.cpp >>>
#include <stdint.h>
#include <stdio.h>
extern "C" {
uint64_t var_from_lib;
}
class BC;
class BC {
public:
void bar(void);
BC();
~BC();
};
BC::BC()
{
}
BC::~BC()
{
}
void BC::bar(void)
{
printf("class function : var_from_lib = %lx\n", var_from_lib);
}
extern "C" {
void bar(void)
{
printf("global function : var_from_lib = %lx\n", var_from_lib);
BC tmp;
tmp.bar();
}
}
<<< main1.c >>>
#include <dlfcn.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
extern uint64_t var_from_lib; // = 0x12345678;
int main1(void)
{
void * dlh = dlopen("./libbar.so", RTLD_NOW);
if (!dlh) {
fprintf(stderr, "%s\n", dlerror());
exit(EXIT_FAILURE);
}
void (*bar)(void) = dlsym(dlh,"bar");
if (!bar) {
fprintf(stderr, "%s\n", dlerror());
exit(EXIT_FAILURE);
}
var_from_lib = 0x12341111;
bar();
return 0;
}
<<< main2.c >>>
#include <dlfcn.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
extern uint64_t var_from_lib; // = 0x12345678;
int main2(void)
{
void * dlh = dlopen("./libbar.so", RTLD_NOW);
if (!dlh) {
fprintf(stderr, "%s\n", dlerror());
exit(EXIT_FAILURE);
}
void (*bar)(void) = dlsym(dlh,"bar");
if (!bar) {
fprintf(stderr, "%s\n", dlerror());
exit(EXIT_FAILURE);
}
var_from_lib = 0x12342222;
bar();
return 0;
}
<<< main.c >>>
#include <dlfcn.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
extern uint64_t var_from_lib; // = 0x12345678;
uint64_t __attribute__((weak)) var_from_lib; // = 0x12345678;
extern int main1();
extern int main2();
int main(int argc, char *argv[])
{
if (atoi(argv[1]) == 1) {
main1();
}
else if (atoi(argv[1]) == 2) {
main2();
}
else {
printf("usage : main [1|2]\n");
}
return 0;
}
<<< Makefile >>>
.PHONY: all clean test
LDEXTRAFLAGS ?=
all: prog
%.o: %.c
gcc -c -Wall -fpic -o $# -ldl $<
%.o: %.cpp
g++ -c -Wall -fpic -o $# $<
libbar.so: bar.o
gcc -shared -o $# $<
main: main.o main1.o main2.o
gcc -c -Wall -o $# $< -rdynamic
prog: main.o main1.o main2.o | libbar.so
gcc $(LDEXTRAFLAGS) -o $# $^ -ldl
clean:
rm -f *.o *.so prog
Here is the execution result.
ckim#ckim-ubuntu:~/testdir$ make
gcc -c -Wall -fpic -o main.o -ldl main.c
gcc -c -Wall -fpic -o main1.o -ldl main1.c
gcc -c -Wall -fpic -o main2.o -ldl main2.c
g++ -c -Wall -fpic -o bar.o bar.cpp
gcc -shared -o libbar.so bar.o
gcc -o prog main.o main1.o main2.o -ldl
ckim#ckim-ubuntu:~/testdir$ prog 1
./libbar.so: undefined symbol: __gxx_personality_v0
How can I remove the error?

Answer 1

How can I remove the error?
Link your application with C++ library. Link with g++ or GLOBAL dlopen the libstdc++.so library. Overall, gcc -shared -o libbar.so bar.o should be g++ -shared -o libbar.so bar.o - it's a C++ library. gcc -Wl,--no-undefined -shared -o libbar.so bar.o catches the problem.