none/tests/sigstackgrowth.c

   1 #include <signal.h>
   2 #include <stdio.h>
   3 #include <stdlib.h>
   4 #include <sys/types.h>
   5 #include <unistd.h>
   6
   7 /* What does this test do?  It checks that valgrind's signal frame
   8    building mechanism can create at least 4MB of signal delivery
   9    frames, hence that it can actually expand the stack by that much
  10    when delivering signals.  A fair-enough thing to want to test.
  11
  12    It does this by getting into the signal handler, and then
  13    recursively invoking the handler by sending itself the signal
  14    again, until the stack has grown to 4MB from the starting frame
  15    (main).
  16
  17    Consequence is: it is essential that we do not disable delivery of
  18    further signals within the handler itself, else the kernel will
  19    wait till the handler exits before delivering the next signal, the
  20    frame will be cleared, the stack will never grow, and we'll be in
  21    an infinite loop.
  22
  23    Hence we *must* give the SA_NODEFER flag when setting up the
  24    handler.
  25 */
  26
  27 static char *deep;
  28
  29 #define SIZE    (4*1024*1024)
  30
  31 static void handler(int sig)
  32 {
  33         char here;
  34
  35         if (&here < deep) {
  36                 printf("PASSED\n");
  37                 exit(0);
  38         }
  39
  40         kill(getpid(), SIGUSR1);
  41 }
  42
  43 int main()
  44 {
  45         struct sigaction sa;
  46
  47         char here;
  48         deep = &here - SIZE;
  49
  50         sa.sa_handler = handler;
  51         sa.sa_flags = SA_NODEFER;
  52         sigemptyset(&sa.sa_mask);
  53
  54         sigaction(SIGUSR1, &sa, NULL);
  55
  56         kill(getpid(), SIGUSR1);
  57
  58         printf("FAILED\n");
  59         exit(1);
  60 }
  61