deadlock/hang when calling close()/connect() at the same time on the same socket

[Ed Martin <lists at edman007 dot com>]

It appears that opening a socket, and then calling connect() on it and
from another thread calling close() on the socket while it's still in
connect() results in a deadlock. Furthermore in this state the thread
cannot be canceled and connect() will never return (my testcase uses
pthread_cancel(), but it happens without that as well)


This does not happen on linux. I tested this with the latest snapshot,
same problem. I'm running Win7 and I've attached a test case.

#include <pthread.h>
#include <string.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <stdio.h>

int sock;
struct sockaddr_in addr;

void* my_thread(void *arg);
int main(int argc, char **argv){
    printf("Test started\n");
    pthread_t thread;
    sock = socket(AF_INET, SOCK_STREAM, 0);
    addr.sin_family = AF_INET;
    addr.sin_port = htons(8676);
    addr.sin_addr.s_addr = inet_addr("10.0.0.3");

    pthread_create(&thread, NULL, my_thread, NULL);
    sleep(1);
    
    if (close(sock)){
        perror("close");
    }
    
    pthread_cancel(thread);
    pthread_join(thread, NULL);
    printf("no bug\n");
    return 0;
}


void* my_thread(void *arg){

    if (connect(sock, (struct sockaddr*)&addr, sizeof(addr)) == -1){
        perror("connect");
    } else {
        printf("Returned success\n");
    }

    return NULL;
}

Attachment: cygcheck.out
Description: Text document

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