Set errno=0 in read_block. On Win32 there is no errno and this makes the

do..while loop execute only once. Also set the return value to -1 in
_xcb_open if control reaches the end - if all goes well it shouldn't
reach there.

src/xcb_in.c

@@ -297,15 +297,12 @@ static int read_block(const int fd, void *buf, const ssize_t len)
             fd_set fds;
             FD_ZERO(&fds);
             FD_SET(fd, &fds);
-#ifndef _WIN32
+
+	    /* Initializing errno here makes sure that for Win32 this loop will execute only once */
+	    errno = 0;  
 	    do {
 		ret = select(fd + 1, &fds, 0, 0, 0);
 	    } while (ret == -1 && errno == EINTR);
-#else
-	    /* the do while loop used for the non-windows version isn't required*/
-	    /* for windows since there are no signals in Windows hence no EINTR*/	    
-	    ret = select(fd + 1, &fds, 0, 0, 0);
-#endif /* !_WIN32 */
 #endif /* USE_POLL */
         }
         if(ret <= 0)

src/xcb_util.c

@@ -180,10 +180,10 @@ static int _xcb_open(char *host, char *protocol, const int display)
     fd = _xcb_open_abstract(protocol, file, filelen);
     if (fd >= 0 || (errno != ENOENT && errno != ECONNREFUSED))
         return fd;
-
 #endif
     return  _xcb_open_unix(protocol, file);
 #endif /* !_WIN32 */
+    return -1; /* if control reaches here then something has gone wrong */
 }
 
 static int _xcb_socket(int family, int type, int proto)