6_3.cpp

// 用sendfile函数传输文件
#include<sys/socket.h>
#include<netinet/in.h>
#include<arpa/inet.h>
#include<assert.h>
#include<stdio.h>
#include<unistd.h>
#include<stdlib.h>
#include<errno.h>
#include<string.h>
#include<sys/types.h>
#include<sys/stat.h>
#include<fcntl.h>
#include<sys/sendfile.h>

int main(int argc, char* argv[]){
    if(argc <= 3){
        printf("usage: %s IP PORT FILE\n", basename(argv[0]));
        return 1;
    }
    const char* ip = argv[1];
    int port = atoi(argv[2]);
    const char* file_name = argv[3];

    int filefd = open(file_name, O_RDONLY);
    assert(filefd > 0);
    struct stat stat_buf;
    fstat(filefd, &stat_buf);

    struct sockaddr_in address;
    bzero(&address, sizeof(address));
    address.sin_family = AF_INET;
    inet_pton(AF_INET, ip, &address.sin_addr);
    address.sin_port = htons(port);

    int sock = socket(PF_INET, SOCK_STREAM, 0);
    assert(sock >= 0);

    int ret = bind(sock, (struct sockaddr*)&address, sizeof(address));
    assert(ret != -1);

    ret = listen(sock, 5);
    assert(ret != -1);

    struct sockaddr_in client;
    socklen_t client_addrlength = sizeof(client);
    int connfd = accept(sock, (struct sockaddr*)&client, &client_addrlength);
    if(connfd < 0){
        printf("errno is : %d\n", errno);
    }
    else{
        sendfile(connfd, filefd, NULL, stat_buf.st_size);
        close(connfd);
    }

    close(sock);
    return 0;
}