lldb/test/API/functionalities/signal/handle-segv/main.c

   1 #include <sys/mman.h>
   2 #include <signal.h>
   3 #include <stdio.h>
   4 #include <unistd.h>
   5
   6 enum {
   7     kMmapSize = 0x1000,
   8     kMagicValue = 47,
   9 };
  10
  11 void *address;
  12 volatile sig_atomic_t signaled = 0;
  13
  14 void handler(int sig)
  15 {
  16     signaled = 1;
  17     if (munmap(address, kMmapSize) != 0)
  18     {
  19         perror("munmap");
  20         _exit(5);
  21     }
  22
  23     void* newaddr = mmap(address, kMmapSize, PROT_READ | PROT_WRITE,
  24             MAP_ANON | MAP_FIXED | MAP_PRIVATE, -1, 0);
  25     if (newaddr != address)
  26     {
  27         fprintf(stderr, "Newly mmaped address (%p) does not equal old address (%p).\n",
  28                 newaddr, address);
  29         _exit(6);
  30     }
  31     *(int*)newaddr = kMagicValue;
  32 }
  33
  34 int main()
  35 {
  36     if (signal(SIGSEGV, handler) == SIG_ERR)
  37     {
  38         perror("signal");
  39         return 1;
  40     }
  41
  42     address = mmap(NULL, kMmapSize, PROT_NONE, MAP_ANON | MAP_PRIVATE, -1, 0);
  43     if (address == MAP_FAILED)
  44     {
  45         perror("mmap");
  46         return 2;
  47     }
  48
  49     // This should first trigger a segfault. Our handler will make the memory readable and write
  50     // the magic value into memory.
  51     if (*(int*)address != kMagicValue)
  52         return 3;
  53
  54     if (! signaled)
  55         return 4;
  56
  57     return 0;
  58 }