p11-12.c

SUN Solaris8平台下进程间通信

#include   <stdio.h>
#include   <sys/types.h>
#include   <sys/ipc.h>
#include   <sys/msg.h>
#include   <time.h>
#include  "err_exit.h"
static void do_msgctl();
static char warning_message[] = "If you remove read permission for \
     yourself, this program will fail next time!";
int main(void)
{
    struct msqid_ds buf;     /* 用于IPC_STAT和IP_SET命令的消息队列结构缓冲区 */
    int    cmd,              /* msgctl的命令参数 */
           msqid;            /* 消息队列ID */
    /* 读入消息队列id和控制命令 */
    printf( "Enter the msqid = ");
    scanf("%d", &msqid);
    printf( " Enter the number for the command:\n");
    printf( "\tIPC_RMID = %d\n", IPC_RMID);
    printf( "\tIPC_SET = %d\n", IPC_SET);
    printf( "\tIPC_STAT = %d\n", IPC_STAT);
    scanf("%d", &cmd);
    /* 检查输入值并执行相应命令 */
    switch (cmd) {
    case IPC_STAT:   /* 获取消息队列当前控制结构并报告给用户 */
        do_msgctl(msqid, IPC_STAT, &buf);
        printf( "The USER ID = %d\n", buf.msg_perm.uid);
        printf( "The GROUP ID = %d\n", buf.msg_perm.gid);
        printf( "The CREATOR ID = %d\n", buf.msg_perm.cuid);
        printf( "The CREADTOR's GROUP ID = %d\n", buf.msg_perm.cgid);
        printf( "The operation permissions = %#o, ", buf.msg_perm.mode);
        printf( "access permissions = %#o\n", buf.msg_perm.mode & 0777);
        printf( "msg_cbytes = %d\n", buf.msg_cbytes);
        printf( "msg_qbytes = %d\n", buf.msg_qbytes);
        printf( "msg_qnum = %d\n",  buf.msg_qnum);
        printf( "msg_lspid = %d\n", buf.msg_lspid);
        printf( "msg_lrpid = %d\n", buf.msg_lrpid);
        printf( "msg_stime = %s", buf.msg_stime ? 
                             ctime(&buf.msg_stime) : "Not Set\n");
        printf( "msg_rtime = %s", buf.msg_rtime ?
                             ctime(&buf.msg_rtime) : "Not Set\n");
        printf( "msg_ctime = %s", ctime(&buf.msg_ctime));
        break;
    case IPC_SET: /* 修改消息队列控制结构的设置 */
         /* 先获得消息队列的当前控制结构 */
        do_msgctl(msqid, IPC_STAT, &buf);
        printf( "Enter msg_perm.uid: ");
        scanf ("%d", &buf.msg_perm.uid);
        printf( "Enter msg_perm.gid: ");
        scanf("%d", &buf.msg_perm.gid);
        printf("%s\n", warning_message);
        printf( "Enter msg_perm.mode: ");
        scanf("%d", &buf.msg_perm.mode);
        printf( "Enter msg_qbytes: ");
        scanf("%d", &buf.msg_qbytes);
        do_msgctl(msqid, IPC_SET, &buf);
        break;
    case IPC_RMID:
    default:
         /* 删除消息队列或试着执行未知的命令 */
       do_msgctl(msqid, cmd, (struct msqid_ds *)NULL);
       break;
    }
    exit(0);
}

/* 打印出传递给msgctl的参数，调msgctl并报告结果。
   如果msgctl失败，该函数不返回而是终止执行。*/
static void do_msgctl(int msqid, int cmd, struct msqid_ds  *buf)
{
    register int rtrn;  
    printf( "\nmsgctl: Calling msgctl(%d, %d, %s)\n",
             msqid, cmd, buf ? "&buf" : "(struct msqid_ds *)NULL");
    rtrn = msgctl(msqid, cmd, buf);
    if (rtrn == -1) 
        err_exit("msgctl failed");
    else 
        printf( " msgctl was successful for %d\n", msqid);
}