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标题: shmdt报错，请大侠帮忙 [打印本页]

作者: xiaoruoax 时间: 2012-12-17 22:23
标题: shmdt报错，请大侠帮忙
GUN/Linux编程指南中的例子，源代码如下：
/*
* atshm.c - Attaching a shared memory segment
*/
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <stdio.h>
#include <stdlib.h>

int main(int argc, char *argv[])
{
int shmid; /* Segment ID */
char *shmbuf; /* Address in process */

/* Expect an segment id on the command line */
if (argc != 2) {
      puts("USAGE: atshm <identifier>");
      exit(EXIT_FAILURE);
}
shmid = atoi(argv[1]);

/* Attach the segment */
if ((shmbuf = shmat(shmid, 0, 0)) < (char *)0) {
      perror("shmat");
      exit(EXIT_FAILURE);
}
/* Where is it attached? */
printf("segment attached at %p\n", shmbuf);

/* See, we really are attached! */
system("ipcs -m");

/* Detach */
if ((shmdt(shmbuf)) < 0) {
      perror("shmdt");
      exit(EXIT_FAILURE);
}
puts("segment detached");

/* Yep, we really did detach it */
system("ipcs -m");

exit(EXIT_SUCCESS);
}

编译：gcc atshm.c -o atshm
执行：./atshm 11137就报错了如图：

作者: crazyhadoop 时间: 2012-12-17 23:43
shmid z这个参数可以随意指定么？ shmat 那返回的就是 -1 吧，貌似已经出错了

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