Expected token error in file RecvFile function

Question

I'm learning some examples about C++ socket. One of the code here has an error : "expect token while got fclose" at the line above the last line

The code seems fine with me, so I can't figure out what is wrong here.

Any ideas are appreciated.

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); 
}

Joseph Mansfield · Accepted Answer · 2013-04-05 21:32:53Z

3

You have a do with no corresponding while:

do
{
    // ...
    do
    {
        // ...
    }
    while (off < rval);
} 
// No while here

fclose(file);

It appears that it should just be while (true), which you might as well just stick at the top, instead of doing a do while. Execution will break from the loop if recv returns 0 or less, which indicate an orderly shutdown and an error respectively. So change it to:

while (true)
{
    // ...
    do
    {
        // ...
    }
    while (off < rval);
}

fclose(file);

edited Apr 5, 2013 at 21:32

answered Apr 5, 2013 at 21:26

Joseph Mansfield

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1 Comment

Tiana987642 Over a year ago

Thank you, your answer is helpful. Voted!

Andy Prowl · Accepted Answer · 2013-04-05 21:46:01Z

2

You have a do statement without a corresponding while:

do // <== THERE IS NO CORRESPONDING while FOR THIS do
{
    rval = recv(sock, buf, sizeof(buf), 0);
    if (rval < 0)
    {
        // ...
    }

    // ...

    do
    {
        // ...
    }
    while (off < rval); // <== This is OK: the "do" has a matching "while"
}
// Nothing here! Should have a "while (condition)"

If you just want to repeat your loop indefinitely, then you should use while (true) - either replacing the do keyword (preferably), or adding it where the missing while should go (as indicated by the above comments).

edited Apr 5, 2013 at 21:46

answered Apr 5, 2013 at 21:26

Andy Prowl

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Comments

bash.d · Accepted Answer · 2013-04-05 21:26:34Z

You started a do without actually supplying a while();

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);
} //while() Needs to go here

fclose(file);

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