进程间通信的例子-消息队列

haoningabc

root@ubuntu:~/test/SourceCode/ch14# cat msg1.c /* Here's the receiver program. */#include <stdlib.h>#include <stdio.h>#include <string.h>#include <errno.h>#include <unistd.h>#include <sys/msg.h>struct my_msg_st {    long int my_msg_type;    char some_text[BUFSIZ];};int main(){    int running = 1;    int msgid;    struct my_msg_st some_data;    long int msg_to_receive = 0;/* First, we set up the message queue. */    msgid = msgget((key_t)1234, 0666 | IPC_CREAT);    if (msgid == -1) {        fprintf(stderr, "msgget failed with error: %d\n", errno);        exit(EXIT_FAILURE);    }/* Then the messages are retrieved from the queue, until an end message is encountered. Lastly, the message queue is deleted. */    while(running) {        if (msgrcv(msgid, (void *)&some_data, BUFSIZ,                   msg_to_receive, 0) == -1) {            fprintf(stderr, "msgrcv failed with error: %d\n", errno);            exit(EXIT_FAILURE);        }        printf("You wrote: %s", some_data.some_text);        if (strncmp(some_data.some_text, "end", 3) == 0) {            running = 0;        }    }    if (msgctl(msgid, IPC_RMID, 0) == -1) {        fprintf(stderr, "msgctl(IPC_RMID) failed\n");        exit(EXIT_FAILURE);    }    exit(EXIT_SUCCESS);}root@ubuntu:~/test/SourceCode/ch14#
root@ubuntu:~/test/SourceCode/ch14# cat msg2.c  /* The sender program is very similar to msg1.c. In the main set up, delete the msg_to_receive declaration and replace it with buffer[BUFSIZ], remove the message queue delete and make the following changes to the running loop. We now have a call to msgsnd to send the entered text to the queue. */#include <stdlib.h>#include <stdio.h>#include <string.h>#include <errno.h>#include <unistd.h>#include <sys/msg.h>#define MAX_TEXT 512struct my_msg_st {    long int my_msg_type;    char some_text[MAX_TEXT];};int main(){    int running = 1;    struct my_msg_st some_data;    int msgid;    char buffer[BUFSIZ];    msgid = msgget((key_t)1234, 0666 | IPC_CREAT);    if (msgid == -1) {        fprintf(stderr, "msgget failed with error: %d\n", errno);        exit(EXIT_FAILURE);    }    while(running) {        printf("Enter some text: ");        fgets(buffer, BUFSIZ, stdin);        some_data.my_msg_type = 1;        strcpy(some_data.some_text, buffer);        if (msgsnd(msgid, (void *)&some_data, MAX_TEXT, 0) == -1) {            fprintf(stderr, "msgsnd failed\n");            exit(EXIT_FAILURE);        }        if (strncmp(buffer, "end", 3) == 0) {            running = 0;        }    }    exit(EXIT_SUCCESS);}root@ubuntu:~/test/SourceCode/ch14#