require_file.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <fcntl.h>

#define BUF_SIZE 1024


void error_handling(char *message);

int main(int argc, char * argv[])
{
    int sock;
    char file_name[32];
    char message[BUF_SIZE];
    mode_t filePerms;
    int inputFd, outputFd, openFlags, read_len;

    struct sockaddr_in serv_adr;
    if(argc!=3){
        printf("Usage: %s <IP> <port>\n", argv[0]);
        exit(1);
    }

    sock = socket(PF_INET, SOCK_STREAM, 0);
    if(sock==-1)
        error_handling("socket() error");
    memset(&serv_adr, 0, sizeof(serv_adr));
    serv_adr.sin_family=AF_INET;
    serv_adr.sin_addr.s_addr=inet_addr(argv[1]);
    serv_adr.sin_port=htons(atoi(argv[2]));

    if(connect(sock, (struct sockaddr*)&serv_adr, sizeof(serv_adr))==-1)
        error_handling("connect() error!");
    else
        puts("Connected......");

    fputs("Input file name: ", stdout);
    // 获取文件名
    // 传送给服务器
    fgets(file_name, 32, stdin);

    printf("require file %s\n", file_name);
    if(write(sock, file_name, strlen(file_name))==-1)
        error_handling("send file name error");

    for(int i=0;i<3000;i++)
    {
    }

    openFlags = O_CREAT|O_WRONLY|O_TRUNC;
    filePerms = S_IRUSR| S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH; // rw-rw-rw-
    outputFd = open(file_name, openFlags, filePerms);
    printf("require file %s\n", file_name);
    while((read_len=read(sock, &message, BUF_SIZE)) > 0)
    {
        if(write(outputFd, message, read_len) != read_len)
            error_handling("couldn't write whole buffer");
    }
    if(read_len == -1)
        error_handling("read() error");
    close(sock);
    close(outputFd);
    return 0;
}

void error_handling(char *message)
{
    fputs(message, stderr);
    fputc('\n', stderr);
    exit(1);
}