Re: [Bug-gnubg] Multiprocessing

[Nardy Pillards]

Example of sockets and Win32
(from http://web.presby.edu/~wasmith/courses/315/samples/sockets/ )

// file: mpclient.cpp
// author: Wayne Smith
// date: March 2003

// To compile this on Solaris (cs2), try:
//     g++ mpclient.cc -o mpclient -lsocket -lnsl

// To compile this on Darwin/MacOS X (titanium), try:
//     c++ mpclient.cc -o mpclient

// To compile this on Windows, try:
//     cl mpclient.cc -GX -DWIN32 ws2_32.lib

#include <iostream>
#include <string>
#include <fstream>
#ifdef WIN32
#include <windows.h>     // this includes winsock2 (among many other things)
#include <io.h>          // needed for read, write
#else
#include <sys/socket.h> // basic socket definitions
#include <netinet/in.h> // sockaddr_in and other Internet defns
#include <arpa/inet.h> // inet(3) functions
#include <unistd.h> // needed for read, write
#include <strings.h> // for bzero
#include <stdlib.h>     // for atoi
#endif
using namespace std;

bool readLine(int sock, string & buf);

int main(int argc, char **argv) {
  int sockfd, n;
  struct sockaddr_in servaddr;
#ifdef WIN32
  WSADATA              wsaData;
  int                  Ret;
#endif

  // process command-line args
  if (argc < 3) {
    cerr << "usage: " << argv[0] << " serverFileName localFileName "
         << "[IPaddress] [serverPort]" << endl;
    return -1;
  }
  char *serverFileName = argv[1],
       *localFileName = argv[2],
       *ipaddress = "10.16.1.20";
  int portnum = 4004;
  if (argc > 3) ipaddress = argv[3];
  if (argc > 4) portnum = atoi(argv[4]);

  // initialize the winsock subsystem
#ifdef WIN32
  if ((Ret = WSAStartup(MAKEWORD(2,2), &wsaData)) != 0) {
    cerr << "winsock startup error" << endl;
    return -1;
  }
#endif

  // do the socket/connect thing as a client
  // winsock note: checking for < 0 may not be best because
  //   socket returns unsigned; try == INVALID_SOCKET
  //   (where INVALID_SOCKET defined in winsock2.h)
  if ( (sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
    cerr << "socket error" << endl;
#ifdef WIN32
    WSACleanup();
#endif
    return -1;
  }
#ifdef WIN32
  servaddr.sin_family = AF_INET;
  servaddr.sin_port   = htons(portnum);
  servaddr.sin_addr.s_addr = inet_addr(ipaddress);
#else
  bzero(&servaddr, sizeof(servaddr));
  servaddr.sin_family = AF_INET;
  servaddr.sin_port   = htons(portnum);
#endif
#ifdef sun
  if (inet_pton(AF_INET, ipaddress, &servaddr.sin_addr) <= 0)
#endif
#ifdef __APPLE__
  if (inet_aton(ipaddress, &servaddr.sin_addr) <= 0)
#endif
#ifndef WIN32
  {
    cerr << "inet_pton error for %s" << ipaddress << endl;
    return -1;
  }
#endif
  // winsock example doesn't check < 0.  Instead checks == SOCKET_ERROR
  if (connect(sockfd, (struct sockaddr *) &servaddr, sizeof(servaddr)) < 0)
{
    cerr << "connect error" << endl;
#ifdef WIN32
    closesocket(sockfd);
    WSACleanup();
#else
    close(sockfd);
#endif
    return -1;
  }

  // create the file that will become a copy
  ofstream myfile(localFileName);
  if (!myfile) {
    cerr << "cannot create " << localFileName << endl;
#ifdef WIN32
    closesocket(sockfd);
    WSACleanup();
#else
    close(sockfd);
#endif
    return -1;
  }

  // send a file name to the server to copy here
  string msg = serverFileName;
  msg += "\n";
#ifdef WIN32
  // winsock apps typically use send (4th arg is flags)
  if (send(sockfd, msg.c_str(), msg.length(), 0) == SOCKET_ERROR)
#else
  if (write(sockfd, msg.c_str(), msg.length()) != msg.length())
#endif
  {
    cerr << "failure to write file name" << endl;
    return -1;
  }
  // now read lines from the remote file and put in a file locally
  int ctr = 0;
  while (readLine(sockfd, msg)) {
    myfile << msg << endl;
    ctr++;
  }
  myfile.close();
  if (ctr == 0) cerr << "Didn't read anything!" << endl;
  else cout << "File copy complete." << endl;

#ifdef WIN32
  closesocket(sockfd);
  WSACleanup();
#else
  close(sockfd);
#endif
  return 0;
}

/*
  Purpose: read a line of text from a socket
  Output: a string containing the line without a newline at end
    (newline is interpreted as "end of transmission")
 */
bool readLine(int sock, string & buf) {
  char cbuf;
  buf = ""; // initialize to the empty string
  bool newlineread = false;
#ifdef WIN32
  // winsock apps typically use recv (4th arg is flags)
  // (note: recv is available on unix side as well)
  while (!newlineread && recv(sock, &cbuf, 1, 0) > 0)
#else
  while (!newlineread && read(sock, &cbuf, 1) > 0)
#endif
  {
    if (cbuf == '\n') newlineread = true;  // quit if newline just read
    else buf = buf + cbuf;
  }
  // if we didn't get a newline, we failed
  return newlineread;
}

Nardy