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  1. #include <signal.h>
  2. #include <stdio.h>
  3. #include <stdlib.h>
  4. #include <inttypes.h>
  5. #include <unistd.h>
  6. #include <sys/types.h>
  7.  
  8. #define MAGIC 42
  9. #define P 2048
  10.  
  11. int *f(void) {
  12.     static unsigned offset = 0;
  13.     volatile int data[P];
  14.     offset = (offset + 1) % P;
  15.     data[offset] = MAGIC;
  16.     return &data[offset];
  17. }
  18.  
  19. int check() {
  20.     int value;
  21.     int *m = f();
  22.     value = *m;
  23.     return value == MAGIC;
  24. }
  25.  
  26. void loop() {
  27.     do {} while (check());
  28.     puts("Oops.");
  29. }
  30.  
  31. static void catch_function(int signal) {
  32.     int foo[100], i;
  33.     if (signal == SIGCHLD) {
  34.         printf("Caught the SIGCHLD signal. Exiting.\n");
  35.         exit(EXIT_SUCCESS);
  36.     }
  37.     for (i = 0; i < 100; i++)
  38.         foo[i] = i * i;
  39. }
  40.  
  41.  
  42. int main(void) {
  43.     if (signal(SIGUSR1, catch_function) == SIG_ERR || signal(SIGCHLD, catch_function) == SIG_ERR) {
  44.         fputs("An error occurred while setting a signal handler.\n", stderr);
  45.         return EXIT_FAILURE;
  46.     }
  47.  
  48.     pid_t chpid = fork();
  49.     if (chpid == -1) {
  50.         fputs("An error occurred while forking child process.\n", stderr);
  51.         return EXIT_FAILURE;
  52.     }
  53.  
  54.     if (chpid == 0) {
  55.         pid_t parent = getppid();
  56.         do {} while(kill(parent, SIGUSR1) == 0);
  57.         perror("Kill");
  58.     } else {
  59.         loop();
  60.     }
  61.     puts("Exiting.");
  62.     return 0;
  63. }
  64.  
Success #stdin #stdout 2.63s 1720KB
comments (?)
stdin 
Standard input is empty
stdout 
Oops.
Exiting.
https://ideone.com/3wHAj
language:
C (gcc 8.3)
created:
12 years ago
visibility:
secret

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