C-插座：编写一个客户机/服务器应用程序发送一个文件 [英] C- Socket : Programming a Client/Server-Application to send a file

问题描述

我想要的应用程序发送一个文件，插座：

I want to program an application to send a file with sockets:

下面我的服务器：

   void str_server(int sock)
    {
            char buf[1025];
            const char* filename="test.text";
            FILE *file = fopen(filename, "rb");
            err_abort("Test");
            while (!feof(file))
            {
                int rval = fread(buf, 1, sizeof(buf), file);
                send(sock, buf, rval, 0);
            }
    }

在这里我的客户：

and here my client:

void RecvFile(int sock, const char* filename)
{
    int rval;
    char buf[0x1000];
    FILE *file = fopen(filename, "wb");
    while ((rval = recv(sock, buf, sizeof(buf), 0)) > 0)
    {
        fwrite(buf, 1, rval, file);
    }
    close(sock);
}

我的问题是，我的客户创建一个文件....但不写在文件中的内容！

My problem is that my client create a file....but dont write the content in the file!

推荐答案

添加一些错误处理到code，应该帮助你追踪问题。还要注意的是发送（），的recv（）， FREAD（）和的fwrite（），不能保证写入/读取指定的整个缓冲区，所以你应该考虑到这一点为好。

Add some error handling to your code, that should help you track down the problem. Also note that send(), recv(), fread() and fwrite() are not guaranteed to write/read the entire buffer you specify, so you should take that into account as well.

试试这个：

void str_server(int sock) 
{ 
    char buf[1025]; 
    const char* filename = "test.text"; 
    FILE *file = fopen(filename, "rb"); 
    if (!file)
    {
        printf("Can't open file for reading"); 
        return;
    }
    while (!feof(file)) 
    { 
        int rval = fread(buf, 1, sizeof(buf), file); 
        if (rval < 1)
        {
            printf("Can't read from file");
            fclose(file);
            return;
        }

        int off = 0;
        do
        {
            int sent = send(sock, &buf[off], rval - off, 0);
            if (sent < 1)
            {
                // if the socket is non-blocking, then check
                // the socket error for WSAEWOULDBLOCK/EAGAIN
                // (depending on platform) and if true then
                // use select() to wait for a small period of
                // time to see if the socket becomes writable
                // again before failing the transfer...

                printf("Can't write to socket");
                fclose(file);
                return;
            }

            off += sent;
        }
        while (off < rval);
    } 

    fclose(file);
} 

void RecvFile(int sock, const char* filename) 
{ 
    int rval; 
    char buf[0x1000]; 
    FILE *file = fopen(filename, "wb"); 
    if (!file)
    {
        printf("Can't open file for writing");
        return;
    }

    do
    {
        rval = recv(sock, buf, sizeof(buf), 0);
        if (rval < 0)
        {
            // if the socket is non-blocking, then check
            // the socket error for WSAEWOULDBLOCK/EAGAIN
            // (depending on platform) and if true then
            // use select() to wait for a small period of
            // time to see if the socket becomes readable
            // again before failing the transfer...

            printf("Can't read from socket");
            fclose(file);
            return;
        }

        if (rval == 0)
            break;

        int off = 0;
        do
        {
            int written = fwrite(&buf[off], 1, rval - off, file);
            if (written < 1)
            {
                printf("Can't write to file");
                fclose(file);
                return;
            }

            off += written;
        }
        while (off < rval)
    } 

    fclose(file); 
} 

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