求大神，什么条件下会执行 cerr << "unknown error: " << errno << "

[QQ594373024]

代码有点多就不都复制上来，我只想知道什么条件会执行
cerr << "unknown error: " << errno << " " << connfd << endl;
exit(-1); // Who knows? Bad foo. Maybe continue for roubustness?
我是用cmd执行exe的

main.h

#ifndef MAIN_H
#define MAIN_H

#include "Listing.h"
#include "Group.h"

#define BACKLOG 11
#define REQ_MAX 8192

extern Listing advertisements;
extern Group users;

extern string active_user;

extern int advertisement_counter;

extern bool create_verified;
extern bool login_failed;

#endif

main.cpp

#include <winsock2.h>
#include <ws2tcpip.h>
#include <signal.h>
#include <cstdio>

#include <string>
#include <fcntl.h>
#include <errno.h>
#include <iostream>
#include <sstream>

#include "Listing.h"
#include "Group.h"
#include "processrequest.h"
#include "main.h"

using namespace std;

Listing advertisements;
Group users;

int advertisement_counter = 0;

string active_user = "";
bool create_verified = true;
bool login_failed = false;


/*
 * Not this is explicitly not concurrent -- the auction data structures
 * are not necessarily concurrency safe
 */

int main (int argc, char *argv[]) {



    /*
     * argv[1] should be the port number
     */
    if (2 != argc) {
        cout << "Usage: " << argv[0] << " [port]" << endl << endl;
        return -1;
    }

    int port = atoi(argv[1]);


    WORD wVersionRequested;
    WSADATA wsaData;
    int err;

    wVersionRequested = MAKEWORD( 2, 2 );

    err = WSAStartup( wVersionRequested, &wsaData );
    if ( err != 0 ) {
        /* Tell the user that we could not find a usable */
        /* WinSock DLL.                                  */
        return 0;
    }



    /*
     * Create and configure the socket
     */
    int connfd = -1;
    int listenfd = -1;

    struct sockaddr_in cliaddr;
    struct sockaddr_in servaddr;
    int clilen = sizeof (cliaddr);

    listenfd = socket (AF_INET, SOCK_STREAM, 0);

    memset(&servaddr, 0, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_addr.s_addr = htonl (INADDR_ANY);
    servaddr.sin_port = htons(port);


    /*
     * Bind to the socket
     */
    bind (listenfd, (struct sockaddr *)&servaddr, sizeof(servaddr));


    /*
     * Configure the listen queue
     */
    listen (listenfd, BACKLOG);

    /*
     * Main work loop:
     * Listen for connection, accept it, process request, print html page
     */


    while (true) {

        // Wait for the knock at the door
        if (0 > (connfd = accept (listenfd,
                                  (struct sockaddr *) &cliaddr, &clilen)) ) {

            if (errno == EINTR)
                continue;
            else {
					//问题在这里
                cerr << "unknown error: " << errno << " " << connfd << endl;
                exit(-1); // Who knows? Bad foo. Maybe continue for roubustness?

            }
			

        }

        // Process the request
        char req_buffer[REQ_MAX];
        int count;



        for (count=0; count<REQ_MAX; count++) {
            recv (connfd, req_buffer+count, 1, 0);

            if (4 == req_buffer[count]) { // 4 is EOT, a.ka. CTRL-D
                req_buffer[count] = '\0';
                break;
            }
        }


        // Move request to stream for C++ style processing
        ostringstream oss;
        oss.str("");
        oss << req_buffer;
        memset (req_buffer, 0, REQ_MAX);

        cerr << oss.str() << endl;

        istringstream iss (oss.str());

        processrequest (iss, connfd, port);

        // Done with this request
        closesocket (connfd);
        connfd = -1;
    }

}

感觉我这样没说清楚，，我也不知道该怎么说，代码那么多