Re: Huge File read and send via socket

From:
Norbert Unterberg <nunterberg@newsgroups.nospam>
Newsgroups:
microsoft.public.cn.vc++,microsoft.public.usasalesinfo.developer.visualc++,microsoft.public.vc.language,microsoft.public.vc.stl
Date:
Wed, 23 Jan 2008 16:38:18 +0100
Message-ID:
<O1jU7XdXIHA.4140@TK2MSFTNGP04.phx.gbl>
Gamesh,

you should select the newsgroups where you post this question more
carefully. This is neither a sales nor an stl question. And you might as
well ask in the platformsdk.networking group as well.

Ganesh schrieb:

I am new to c++ and socket programming, I have a situvation that my
function have to a binary read ( whole file as 1 chunk ) and keep the
buffer, and send the buffrer via socket by chunk by chunk as user
specified. I have written a code sample, but I am not getting the
correct out out.
 
can some one pls look in to the code and fix it ?


No, we can show you your errors, but it is your code, you do the work
and fix it.

You did not show all the relevant code, so there remain some questions:

What exactly is your problem? Does the send loop finish cleanly or does
it return with an error code? Does it finish without error but the data
on the wire is wrong? Does it hang?

You do not show how you create and open the socket. I assume it's a tcp
socket. Does it operate in blocking or non-blocking mode? If it operates
in non-blocking mode, then you should use select() or some other method
before calling send() to check/wait that you can send more data.

You do not do any meaningful error checking on the value returned by
send(). If send() returns 0 then the socket has been closed by the
receiving side. A negative value means a socket error.
send() returns the number of bytes sent for a reason. It might return
with less bytes sent as you requested, but that does not automatically
indicate an error. So you should be prepared that iSendStatus can be
!=chunkSize/bufsize and this is not an error.

Norbert

FILE *fp23 = fopen( "c:\\hpfile.prn", "rb" );
 
fseek (fp23 , 0 , SEEK_END);
int m_jobSize = ftell (fp23);
rewind (fp23);
 
char* m_buffer = new char[m_jobSize+1];
 
int m_result = fread( m_buffer, 1, m_jobSize, fp23 );
 
 
///////////////////////////////////////////////
 
 int BytesIndex = 0;
 
 while( bufsize > 0)
 {
 
  // Send some bytes
  if ( bufsize < (unsigned long)iSendStatus )
  {
   iSendStatus = send(*sock, &m_buffer[BytesIndex], bufsize, 0); //
Socket is of type
   
   //
   // Call Back Function
   //
   set += iSendStatus;
   ptr(jobid,set);
   
 
   if ( iSendStatus != bufsize )
   {
    cpError = SocketErrorHandler();
    return cpError;
   }
 
  }
  else
  {
   iSendStatus = send(*sock, &m_buffer[BytesIndex], chunkSize, 0); //
Socket is of type
 
   //
   // Call Back Function
   //
   set += iSendStatus;
   ptr(jobid,set);
 

   if ( iSendStatus != chunkSize )
   {
    cpError = SocketErrorHandler();
    return cpError;
   }
 
  }
 
  // Update buffer and counter
  if ( bufsize < (unsigned long)iSendStatus )
  {
   bufsize -= bufsize;
   BytesIndex += bufsize;
  }
  else
  {
   bufsize -= iSendStatus;
   BytesIndex +=iSendStatus;
  }
 

//////////////////////////////
regards
Ganesh
 

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