Trying (not) to crash with libpthread (6.3-RELEASE)

[Oliver Fromme]

Mike <deathjestr at gmail.com> wrote:
 > Jille Timmermans wrote:
 > > void
 > > sigcatcher(int sig) {
 > >  printf("[%p] signal %d\n", pthread_self(), sig);
 > >  printf("Test (probably) succeeded\n");
 > >  fflush(NULL);
 > >  success=1;
 > >  exit(0);
 > > }
 > 
 > Take a look at the man page for sigaction(2). Here's an excerpt:
 > 
 > "All functions not in the above lists are considered to be unsafe with
 > respect to signals.  That is to say, the behaviour of such functions when
 > called from a signal handler is undefined.  In general though, signal
 > handlers should do little more than set a flag; most other actions are
 > not safe."

Additionally, the "success" variable should be
declared as "volatile sig_atomic_t".

By the way, this code ...
 > >  char *x=malloc(1);
 > > [...]
 > >  x[666]=0;
.. does not necessarily cause a SIGSEGV.  It may do so,
but it is not guaranteed.  It may as well write into a
random memory area that happens to belong to your process,
too.  The result is undefined, i.e. it could be anything.

If you need to send a SIGSEGV to yourself reliably, the
best way is to kill(getpid(), SIGSEGV).

Best regards
   Oliver

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