/* 服務(wù)器端程序 */

#include <stdio.h>

#include <errno.h>

#include <signal.h>

#include <sys/types.h>

#include <sys/socket.h>



struct sockaddr myname;

char buf[80];

main()

{

  int sock, new_sd, adrlen, cnt;

  sock = socket(AF_UNIX, SOCK_STREAM, 0);		/* 套接字的建立 */

  if (sock < 0) {

    printf("server socket failure %d\n", errno);

    perror("server: ");

    exit(1);  }

  myname.sa_family = AF_UNIX;

  strcpy(myname.sa_data, "/tmp/billb");

  adrlen = strlen(myname.sa_data) + sizeof(myname.sa_family);

  unlink("/tmp/billb");  /* defensive programming */

  if (bind(sock, &myname, adrlen) < 0) {

    printf("server bind failure %d\n", errno);

    perror("server: ");

    exit(1);  }

  if (listen(sock, 5) < 0) {		/* listen函數(shù)調(diào)用 */

    printf("server listen failure %d\n", errno);

    perror("server: ");

    exit(1);  }  



  /* 忽略子進(jìn)程的終止  */

  signal (SIGCHLD, SIG_IGN);

  /*  將服務(wù)器置于死循環(huán)狀態(tài)，等待客戶端的連接請(qǐng)求的到來(lái)。

      實(shí)際上，應(yīng)該用更好的辦法來(lái)結(jié)束這個(gè)死循環(huán)，在這里這

      個(gè)循環(huán)是被連接開(kāi)始信號(hào)或者是超級(jí)用戶終止的。     */



  while (1) {

    if (new_sd = accept(sock, &myname, &adrlen) < 0) {

      printf("server accept failure %d\n", errno);

      perror("server: ");

      exit(1);    }



    /* 建立服務(wù)器端子進(jìn)程。此時(shí)父進(jìn)程將不再運(yùn)行

       --它返回循環(huán)狀態(tài)等待下一個(gè)連接請(qǐng)求     */



    printf("Socket address in server %d is %x, %s\n",

      getpid(), myname.sa_data, myname.sa_data);



    if (fork() == 0) {  /* 建立子進(jìn)程 */

      close (sock);  /* 關(guān)閉套接字，因?yàn)樽舆M(jìn)程不再需要它  */

      /*  . . . . .  */



      cnt = read(new_sd, buf, strlen(buf));

      /* read函數(shù)讀取套接字緩沖區(qū)中的數(shù)據(jù)到應(yīng)用緩沖區(qū)*/

      printf ("Server with pid %d got message %s\n", getpid(), buf);

      strcpy (buf, "Message to client");

      cnt = write(new_sd, buf, strlen(buf));

      printf("Socket address in server %d is %x, %s\n",

        getpid(), myname.sa_data, myname.sa_data);

      /*  . . . . .  */

      close (new_sd); /* close prior to exiting  */

      exit(0);

    }   

  }  

}