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segv when thread exits after throw/catch of C++ exception
- From: "Ed Connell" <Ed dot Connell at sas dot com>
- To: <libstdc++ at gcc dot gnu dot org>
- Date: Mon, 7 Nov 2005 13:57:04 -0500
- Subject: segv when thread exits after throw/catch of C++ exception
I have a simple C program that spawns a thread; the thread calls into a dlopen'd
shared library. The shared library is in C++ and its lone entry point just does
a throw and catch before returning. We return back into the thread and when the
thread exits it crashes. This happens on at least x86, x86_64 and ia64 on both
SLES 9 and RHEL 4. I originally posted this to a glibc list and Ulrich Drepper
said:
That's a problem in libstdc++. They use pthread_key_create to create a TSD
key but never call pthread_key_delete if the libstdc++ DSO is unloaded.
Thanks
Ed
$ gcc -o threadtest threadtest.c -pthread -lpthread -ldl -g
$ g++ -shared -o libthrow.so throw.cpp -lstdc++ -g
$ export LD_LIBRARY_PATH=.
$ ./threadtest
thread done, program should exit
Segmentation fault
threadtest.c
********
#include <pthread.h>
#include <stdio.h>
#include <dlfcn.h>
int ThreadFn(void *arg)
{
int (*throw_entry)(void);
void *handle;
handle = dlopen("libthrow.so", RTLD_NOW);
throw_entry = dlsym(handle, "throw_entry");
if (throw_entry() != 123) {
printf("throw_entry() didn't return 123 as expected\n");
}
dlclose(handle);
printf("thread done, program should exit\n");
return 0;
}
int main(int argc, char* argv[])
{
pthread_t thread;
void *ret;
pthread_create(&thread, NULL, (void *(*)(void *))ThreadFn, 0);
pthread_join(thread, &ret);
return 0;
}
********
throw.cpp
********
extern "C" {
int throw_entry(void);
};
class foo {};
int throw_entry(void)
{
try
{
throw foo();
}
catch(foo)
{
return 123;
}
return 0;
}
********