进程间通信的例子-消息队列
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;};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, 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;};int main(){ int running = 1; struct my_msg_st some_data; int msgid; char buffer; 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#
页:
[1]