c - 使用C语言进行Linux网络编程

Question

我写了一个关于从服务器向客户端传输文件的程序。但问题是，如果文件大于2G，我只能传输2G文件，只有2G传输成功。

客户端

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <unistd.h>
#include <stdio.h>
#include <stdarg.h>
#include <string.h>
#include <fcntl.h>
#include <math.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#define  MAXLINE  1000
#define  SA struct sockaddr
typedef struct
{
    int     oft;
    int len;
     char data[MAXLINE];
}Mem;
Mem Dat;
int main(int argc,char *argv[])
{
    int     sockfd = socket(AF_INET,SOCK_STREAM,0);
    int     complete;
    struct  sockaddr_in cli;
    ssize_t recv_l,send_l;
    size_t block_len;
    socklen_t   len;
    char buf[MAXLINE];
    char filename[MAXLINE];
    FILE *fp;
    bzero(&cli,sizeof(cli));
    cli.sin_family = AF_INET;
    if (argv[1] == NULL)
        argv[1] = "172.16.42.22";

    cli.sin_port = htons(5001);
    inet_pton(AF_INET,argv[1],&cli.sin_addr.s_addr);
    bind(sockfd,(struct sockaddr*)&cli,sizeof(cli));
    if (connect(sockfd,(SA*)&cli,sizeof(cli)) == -1)
    {
        perror("connect");
        close(sockfd);
        exit(1);
    }
    //接收文件名列表   
    while((recv_l = recv(sockfd,buf,sizeof(buf),0)) > 0)
    {
        buf[recv_l] = '\0';
        fputs(buf,stdout);
        if(strcmp(buf+recv_l-5,"name\n") == 0)
            break;
    }
//  exit(0);
    bzero(filename,sizeof(filename));
    while(fgets(filename,sizeof(filename),stdin) != NULL)
//  while(gets(filename) != NULL)
    {
        int i = 0;
        for(i = strlen(filename) - 1;i >= 0;i --)
            if(filename[i] == '\n'){
                filename[i] = '\0';
                break;
            }
        send_l  = send(sockfd,filename, strlen(filename),0);
        recv_l = recv(sockfd,buf, sizeof(buf),0);
        buf[recv_l] = '\0';
        puts(buf);
        if (strcmp(buf,"success") == 0)
            break;
        fputs(buf,stdout);
    }
    puts("filename send success");
    //接收文件
    if ((fp = fopen(filename,"wb")) == NULL)
    {
        perror("fopen");
        exit(1);
    }
    while((recv_l = recv(sockfd,&Dat,sizeof(Dat),MSG_WAITALL)))
    {
        if (recv_l < 0){
            perror("recv");
            exit(1);
        }
        fwrite(Dat.data,sizeof(char),Dat.len,fp);
    }
    puts("file receive success");
    fclose(fp);
    close(sockfd);
    return 0;
}

服务器

#include <sys/types.h>
#include <errno.h>
#include <signal.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <unistd.h>
#include <stdio.h>
#include <stdarg.h>
#include <string.h>
#include <fcntl.h>
#include <math.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#define  MAXLINE 1000
#define  SA struct sockaddr
typedef struct
{
    int     oft;
    int len;
    char data[MAXLINE];
}Mem;
Mem Dat;
    long long sum = 0;
int sendall(int sockfd, void *buf, int *len)
{

    int total = 0;        // how many bytes we've sent
    int bytesleft = *len; // how many we have left to send
    int n;
    while(total < *len) {

        n = send(sockfd, buf+total, bytesleft, 0);
        sum += n;
        if(sum >= 1073741824){
            puts("1G");
            sum = 0;
        }
        if (n != bytesleft) return -1;
        if (n == -1) {
            break; }
        total += n;
        bytesleft -= n;
    }

    *len = total; // return number actually sent here

    return n==-1?-1:0; // return -1 on failure, 0 on success
} 
int main(int argc,char *argv[])
{
    int     sockfd = socket(AF_INET,SOCK_STREAM,0);
    socklen_t   len;
    size_t  block_len;
    int     complete;
    ssize_t send_l,recv_l;
    struct sockaddr_in  serv,cli;
    char buf[MAXLINE];
    char filename[100];
    FILE *fp;
    bzero(&serv,sizeof(serv));
    serv.sin_family = AF_INET;

    if (argv[1] == NULL)
        argv[1] = "5001";

    serv.sin_port = htons(atoi(argv[1]));
    serv.sin_addr.s_addr = htonl(0);

    bind(sockfd,(SA*)&serv,sizeof(serv));
    listen(sockfd,5);
    //  for( ; ; )
    {
        len = sizeof(cli);
        complete = accept(sockfd,(SA*)&cli,&len);
        //发送文件名列表
        fp = popen("ls","r");
        while( fgets(buf,MAXLINE,fp) != NULL)
        {
            send(complete,buf,strlen(buf),0);
        }
        strcpy(buf,"input file name\n");
        send(complete,buf, strlen(buf),0);
        puts("send list success");
        pclose(fp);
        //exit(0);      
        //获取文件名
        while( (recv_l = recv(complete,filename,sizeof(filename),0) ) > 0)
        {
            filename[recv_l] = '\0';
            if ((fp = fopen(filename,"rb")) == NULL)
            {
                strcpy(buf,"filename error please input again");
                puts("filename error");
                send(complete,buf,strlen(buf),0);
            }else{
                puts("get filename success");
                break;
            }
        }
        //文件名对了
        strcpy(buf,"success");
        send(complete,buf,strlen(buf),0);
        puts("get correct filename");
        //传文件
        int all = 0;
        long long sa = 0;
            int len = sizeof(Dat);
        while((block_len = fread(Dat.data,sizeof(char),MAXLINE,fp)) > 0)
        {
            Dat.len = block_len;

            if (sendall(complete,&Dat,&len) < 0){
                puts("send error");
                exit(1);
            }
//          if (send(complete,&Dat ,sizeof(Dat),0) < 0)
//          {
//              perror("send");
//              exit(1);
//          }
        }
        printf("%lld\n",sum);
        printf("%s Tranfer finished\n",filename);
        fclose(fp);
        close(complete);
    }
    return 0;
}

Answer 1

在 32 位系统上，默认最大文件大小为 2 GB。您可以使用开关 -D_FILE_OFFSET_BITS=64 编译程序以创建大于 2 GB 的文件或使用 64 位。