text: // RUN: %clang_scudo %s -o %t
  // RUN: %run %t after  2>&1 | FileCheck %s
  // RUN: %run %t before 2>&1 | FileCheck %s
  
  // Test that we hit a guard page when writing past the end of a chunk
  // allocated by the Secondary allocator, or writing too far in front of it.
  
  #include <assert.h>
  #include <malloc.h>
  #include <signal.h>
  #include <stdlib.h>
  #include <string.h>
  #include <unistd.h>
  
  void handler(int signo, siginfo_t *info, void *uctx) {
    if (info->si_code == SEGV_ACCERR) {
      fprintf(stderr, "SCUDO SIGSEGV\n");
      exit(0);
    }
    exit(1);
  }
  
  int main(int argc, char **argv)
  {
    // The size must be large enough to be serviced by the secondary allocator.
    long page_size = sysconf(_SC_PAGESIZE);
    size_t size = (1U << 17) + page_size;
    struct sigaction a;
  
    assert(argc == 2);
    memset(&a, 0, sizeof(a));
    a.sa_sigaction = handler;
    a.sa_flags = SA_SIGINFO;
  
    char *p = (char *)malloc(size);
    assert(p);
    memset(p, 'A', size); // This should not trigger anything.
    // Set up the SIGSEGV handler now, as the rest should trigger an AV.
    sigaction(SIGSEGV, &a, NULL);
    if (!strcmp(argv[1], "after")) {
      for (int i = 0; i < page_size; i++)
        p[size + i] = 'A';
    }
    if (!strcmp(argv[1], "before")) {
      for (int i = 1; i < page_size; i++)
        p[-i] = 'A';
    }
    free(p);
  
    return 1; // A successful test means we shouldn't reach this.
  }
  
  // CHECK: SCUDO SIGSEGV
  