[sane-devel] signal handling by libsane and backends

[Wittawat Yamwong]

On Friday 15 September 2006 08:39, Gerhard Jaeger wrote:
> [...]
> So the point to fix are inside the backends. If someone could
> provide a testcase, this could be easily fixed.

An example for SIGCHLD (as mentioned by Ryan):

------------- Main program ----------------
int main(int argc, char **argv)
{
    void *so;
    void (*foo)();

    so = dlopen("./test1.so", RTLD_LAZY);
    foo = dlsym(so, "foo");
    foo();
    /* I don't need the library anymore. So I unload it. */
    dlclose(so); 

    system("echo hello");
    /* SIGSEGV here. */
    
    return 0;
}

------------- test1.so -----------------
static void sighandler(int sig)
{
}

void foo(void)
{
    struct sigaction sa;
    
    memset(&sa, 0, sizeof(sa));
    sigemptyset(&sa.sa_mask);
    sa.sa_handler = sighandler;
    sigaction(SIGCHLD, &sa, NULL);

    /* forget to restore SIGCHLD handler. */
}
----------------------------------------

"grep -l SIGCHLD *.c" in the backend directory gives:
artec_eplus48u.c
mustek.c
plustek.c
plustek_pp.c
u12.c


Regards
-- 
Wittawat Yamwong
Hannover, Germany