WhyCan Forum(哇酷开发者社区)

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <pthread.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/mman.h>

#define MMAP_DATA_SIZE  1024
char *data = NULL;
pthread_t pid_sub;

//子线程
void *subthread(void *arg) 
{
   if( data ) {
       memset(data, 0xff, 20); // 发生segment fault
       printf("subthread memset.\n");
   }
}

//主线程
 int main(void)
{
    int rc=0;
    int fd = shm_open("shm0001", O_CREAT|O_RDWR, 0777);

    if (fd < 0) {
            printf("shm_open failed!\n");
            return -1;
    }

    ftruncate(fd, MMAP_DATA_SIZE);
    data = (char*)mmap(NULL, 1024, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);

    // 创建子线程
    rc = pthread_create(&pid_sub, NULL, subthread, NULL);

    while(1) {
        sleep(1);
    }
}