Linux系统编程：客户端-服务器用FIFO进行通信

先放下代码  回来在解释

头文件：

clientinfo.h

struct CLIENTINFO{
    char myfifo[500];
    int leftarg;
    int rightarg;
    char op;
}; 
typedef struct CLIENTINFO CLIENTINFO, *CLINTINFOPTR;

client.c

#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <fcntl.h>
#include <signal.h>
#include "clientinfo.h"

#define FIFO_NAME "/home/levi/chatapplication/data/server_fifo/chat_server_fifo"
#define BUFF_SZ 100

char mypipename[BUFF_SZ];
void handler(int sig){
    unlink(mypipename);
    exit(1);
}

int main(int argc, char const *argv[])
{
    int res;
    int fifo_fd, my_fifo;
    int fd;
    CLIENTINFO info;
    char buffer[BUFF_SZ];

    signal(SIGKILL, handler);
    signal(SIGINT, handler);
    signal(SIGTERM, handler);

    if(argc != 4){
        printf("Usage: %s op1 operation op2
", argv[0]);
        exit(1);
    }
    if(access(FIFO_NAME, F_OK) == -1){
        printf("Could not open FIFO %s
", FIFO_NAME);
        exit(EXIT_FAILURE);
    }
    fifo_fd = open(FIFO_NAME, O_WRONLY);
    if(fifo_fd == -1){
        printf("Could not open %s for write access
", FIFO_NAME);
        exit(EXIT_FAILURE);
    }
    sprintf(mypipename, "/home/levi/chat_client_%d_fifo", getpid());
    res = mkfifo(mypipename, 0777);
    if(res != 0){
        printf("FIFO %s was not created
", buffer);
        exit(EXIT_FAILURE);
    }

    my_fifo = open(mypipename, O_RDONLY | O_NONBLOCK);
    if(my_fifo == -1){
        printf("Could not open %s for read only access
", FIFO_NAME);
        exit(EXIT_FAILURE);
    }

    strcpy(info.myfifo, mypipename);
    info.leftarg = atoi(argv[1]);
    info.op = argv[2][0];
    info.rightarg = atoi(argv[3]);

    write(fifo_fd, &info, sizeof(CLIENTINFO));
    close(fifo_fd);

    memset(buffer, '', BUFF_SZ);
    while(1){
        res = read(my_fifo, buffer, BUFF_SZ);
        if(res > 0){
            printf("Received from server : %s
", buffer);
            break;
        }
    }
    printf("Client %d is terminating
", getpid());
    close(my_fifo);
    (void)unlink(mypipename);
    return 0;
}

server.c

#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <fcntl.h>
#include <signal.h>
#include "clientinfo.h"

#define FIFO_NAME "/home/levi/server_fifo/chat_server_fifo"
void handler(int sig){
    unlink(FIFO_NAME);
    exit(1);
}

int calc(CLIENTINFOPTR info){
    switch(info->op){
        case '+' : return info->leftarg + info->rightarg;
        case '-' : return info->leftarg - info->rightarg;
        case '*' : return info->leftarg * info->rightarg;
        case '/' : return info->leftarg / info->rightarg;
    }
    return 0;
}

int main(int argc, char const *argv[])
{
    int res, i, fifo_fd, fd1;
    CLIENTINFO info;
    char buffer[100];
    signal(SIGKILL, handler);
    signal(SIGINT, handler);
    signal(SIGTERM, handler);
    if(access(FIFO_NAME, F_OK) == -1){
        res = mkfifo(FIFO_NAME, 0777);
        if(res != 0){
            printf("FIFO %s was not created
", FIFO_NAME);
            exit(EXIT_FAILURE);
        }
    }
    fifo_fd = open(FIFO_NAME, O_RDONLY);
    if(fifo_fd == -1){
        printf("Could not open %s for read only access
", FIFO_NAME);
        exit(EXIT_FAILURE);
    }
    printf("
Server is rarin to go !
");
    while(1){
        res = read(fifo_fd, &info, sizeof(CLIENTINFO));
        if(res != 0){
            printf("Client arrived!!
");
            sprintf(buffer, "The result is %d", calc(&info));
            fd1 = open(info.myfifo, O_WRONLY | O_NONBLOCK);
            write (fd1, buffer, strlen(buffer) + 1);
            close(fd1);
        }

    }
    return 0;
}

OK！

./server.c &

./client 3 + 5

　　看输出吧！