在Linux下使用C語言TCPSocket實現簡單檔案傳輸，包括客戶端和伺服器端，其中，伺服器端使用多執行緒實現同時接收多個客戶端傳送的檔案。

傳送檔案內容之前，首先需要將檔名和長度資訊傳送到伺服器，為了便於區分，採用傳送結構體的方式，設定標誌位，1標識資料域為檔名，2標識資料域為檔案內容，3標識傳送結束，4標識傳送檔案長度。這樣便可區分發送的內容。

伺服器端程式碼如下：

/*多執行緒實現接收多個客戶端的檔案*/
#include <stdio.h>
#include <fcntl.h>
#include <pthread.h>
#include <sys/stat.h>
 

#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>

#define PORT 8887
#define BUFF_SIZE 1024

typedef struct{
    char type;
    char data[BUFF_SIZE];
}m_package;

void* process_client();

int main(){
    int ss = create_tcp_server(PORT);
    if(-1 == ss)
        exit
 
(-1);
    while(1){
        //接受客戶端連線
        socklen_t addrlen = sizeof(struct sockaddr);
        struct sockaddr_in client_addr; //客戶端地址結構
        int client_sock = accept(ss, (struct sockaddr*)&client_addr, &addrlen);
        if(client_sock < 0){
            printf("accept error\n");
        }
        printf
 
("accept success\n");

        pthread_t pid;
        if(pthread_create(&pid, NULL, process_client, &client_sock) < 0){
            printf("pthread_create error\n");
        }
    }
}

//處理客戶端程式
void *process_client(void *arg){
    int size = 0, fd, count = 0, sockid = *(int*)arg;
    m_package pac;
    long total = 0, cur = 0;
    //迴圈接收檔案
    while(1) {
        memset(&pac, 0, sizeof(pac));
        size = read(sockid, &pac, sizeof(pac));
        if(size > 0){
            if (pac.type == 1){
                fd = open(pac.data, O_CREAT|O_WRONLY, 0777);
                if(-1 == fd){
                    printf("open file error!\n");
                    continue;
                }
                count = total = cur = 0;
            }
            else if (pac.type == 2){
                cur += write(fd, pac.data, strlen(pac.data));
                if(count++ % 5000 == 0){
                    printf("recv from client < %d > : %.01lf\%\n", sockid, cur * 100.0 / total);
                    count = 0;
                }
            }
            else if (pac.type == 3){
                printf("recv from client < %d > : 100.0\%\n", sockid);
                printf("recv success\n");
                close(fd);
            }
            else if(pac.type == 4){//檔案長度
                total = strtol(pac.data, NULL, 10);
                printf("%ld\n", total);
            }
        }else{
            printf("client disconnected\n");
            close(sockid);
            break;
        }
    }
    return 0;
}

#include <stdio.h>
#include <fcntl.h>
#include <pthread.h>

#define PORT 8888
#define BUFF_SIZE 1024

typedef struct{
    char type;
    char data[BUFF_SIZE];
}m_package;

int main(){
    //建立連線
    int sock_fd = connect_tcp("192.168.134.188", PORT);
    if(-1 == sock_fd)
        return -1;

    m_package pac;
    int fd, cur = 0, count = 0;
    long filesize = 0;
    while(1){
        //開啟檔案
        memset(&pac, 0, sizeof(pac));
        pac.type = 1;
        // strcpy(pac.data, "/home/SKZH/a.txt");
        scanf("%s", pac.data);
        //獲取檔案資訊
        struct stat sfile;
        stat(pac.data, &sfile );
        filesize = sfile.st_size;
        time_t t;
        long begin = time(&t);
        cur = count = 0;

        fd = open(pac.data, O_RDONLY);
        if(-1 == fd){
            printf("file open error\n");
            continue;
        }
        //讀取檔案併發送
        //傳送檔名
        strcpy(pac.data, strrchr(pac.data, '/') + 1);
        write(sock_fd, &pac, sizeof(pac));
        memset(&pac, 0, sizeof(pac));

        //傳送檔案長度
        pac.type = 4;
        sprintf(pac.data,"%ld",filesize);
        write(sock_fd, &pac, sizeof(pac));
        memset(&pac, 0, sizeof(pac));

        int read_len = 0;
        while((read_len = read(fd, pac.data, BUFF_SIZE)) > 0){
            pac.type = 2;
            write(sock_fd, &pac, sizeof(pac));
            memset(&pac, 0, sizeof(pac));
            cur += read_len;
            if(count++ % 5000 == 0){
                count = 0;
                printf("send to server : %.1lf\%\n", cur * 100.0 / filesize);
            }
        }

        //傳送結束標記
        memset(&pac, 3, sizeof(pac));
        write(sock_fd, &pac, BUFF_SIZE + 1);
        close(fd);

        printf("send to server : 100.0\%\n");
        printf("file size : %d B\n", filesize);
        printf("time : %ld ms\n", time(&t) - begin);
        printf("send file success\n");
        printf("------------------------\n");
    }
    close(sock_fd);
}