A brief discussion on simulating multi-threaded and multi-process crashes in Linux

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <pthread.h>
#include <assert.h>

void *fun1(void *arg)
{
 printf("fun1 enter\n");
 while(1)
 {
  printf("%s\n", __FUNCTION__);
  usleep(1000 * 1000);
 }
 printf("fun1 exit\n");
 return ((void *)1);
}

void *fun2(void *arg)
{
 printf("fun1 enter\n");
 usleep(1000 * 3000);
 char * ptr = (char *)malloc(sizeof(char));
 printf("ptr1: 0x%x\n", ptr);
 ptr = NULL;
 printf("ptr2: 0x%x\n", ptr);
 free(ptr);
 memcpy(ptr, "123", 3);
 printf("ptr3: 0x%x\n", ptr);
 printf("fun2 exit\n");
 return ((void *)2);
}

int main(void)
{
 pthread_t tid1, tid2;
 int err;
 
 err = pthread_create(&tid1, NULL, fun1, NULL);
 assert(0 == err);
 err = pthread_create(&tid2, NULL, fun2, NULL);
 assert(0 == err);
 
 printf("main join ...\n");
// getchar();
 pthread_join(tid1, NULL);
 pthread_join(tid2, NULL);
 
 return 0;
}

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <pthread.h>
#include <assert.h>

void fun(void *arg)
{
 printf("fun1 enter\n");
 usleep(1000 * 3000);
 char * ptr = (char *)malloc(sizeof(char));
 printf("ptr1: 0x%x\n", ptr);
 ptr = NULL;
 printf("ptr2: 0x%x\n", ptr);
 free(ptr);
 memcpy(ptr, "123", 3);
 printf("ptr3: 0x%x\n", ptr);
 printf("fun2 exit\n");
 return ;
}

int main(int argc, char *argv[])
{
 assert(2 == argc);
 pid_t pid;
 int i;
 for(i=0; i<atoi(argv[1]); i++)
 {
  pid = fork();
  if(0 > pid)
  {
   printf("fork error");
   exit(1);
  }
  else if(0 == pid)
  {
   printf("child pid is %lu\n", (unsigned long)getpid());
   fun(NULL);
   exit(0);
  }
 }
 
 printf("parent pid is %lu\n", (unsigned long)getpid());
 while(-1 != wait(NULL)); //Wait for all subprocesses to finish printf("main return\n");
 getchar();
 
 return 0;
}