diff --git a/contrib/win32/w32-posix-prototype/win32posix/win32posix/debug.c b/contrib/win32/w32-posix-prototype/win32posix/win32posix/debug.c
new file mode 100644
index 0000000..b74a541
--- /dev/null
+++ b/contrib/win32/w32-posix-prototype/win32posix/win32posix/debug.c
@@ -0,0 +1,33 @@
+#include <Windows.h>
+#include <stdarg.h>
+#include <stdio.h>
+
+
+FILE* log;
+
+void debug_initialize() {
+    char filename[MAX_PATH];
+    int len = 0;
+    SYSTEMTIME time;
+
+    len = GetModuleFileNameA(NULL, filename, MAX_PATH);
+    GetLocalTime(&time);
+    
+    sprintf(filename + len, "_%d_%d_%d.log", time.wHour, time.wMinute, time.wSecond);
+
+    log = fopen(filename, "w");
+}
+
+void debug_done() {
+    fclose(log);
+}
+
+
+void write_log(const char *source_name, const char *function_name, int line_num, const char *fmt, ...) {
+    va_list args;
+    fprintf(log,"\n%s:%s:%d: ", source_name, function_name, line_num);
+    va_start(args, fmt);
+    fprintf(log,fmt, args);
+    va_end(args);
+    fflush(log);
+}
\ No newline at end of file
diff --git a/contrib/win32/w32-posix-prototype/win32posix/win32posix/debug.h b/contrib/win32/w32-posix-prototype/win32posix/win32posix/debug.h
new file mode 100644
index 0000000..0694b18
--- /dev/null
+++ b/contrib/win32/w32-posix-prototype/win32posix/win32posix/debug.h
@@ -0,0 +1,7 @@
+
+
+#define debug(cformat, ...) write_log(__FILE__, __FUNCTION__, __LINE__, cformat, __VA_ARGS__)
+
+void debug_initialize();
+void debug_done();
+void write_log(const char *source_name,const char *function_name, int line_num, const char *fmt, ...);
diff --git a/contrib/win32/w32-posix-prototype/win32posix/win32posix/fileio.c b/contrib/win32/w32-posix-prototype/win32posix/win32posix/fileio.c
index d72f68c..00f0f9b 100644
--- a/contrib/win32/w32-posix-prototype/win32posix/win32posix/fileio.c
+++ b/contrib/win32/w32-posix-prototype/win32posix/win32posix/fileio.c
@@ -31,7 +31,13 @@ int fileio_pipe(struct w32_io* pio[2]) {
     char pipe_name[MAX_PATH];
     SECURITY_ATTRIBUTES sec_attributes;
     
-    if (-1 == sprintf_s(pipe_name, MAX_PATH, "\\\\.\\Pipe\\RemoteExeAnon.%08x.%08x", GetCurrentProcessId(), pipe_number++))
+    if (pio == NULL) {
+        errno = EFAULT;
+        return -1;
+    }
+
+
+    if (-1 == sprintf_s(pipe_name, MAX_PATH, "\\\\.\\Pipe\\W32PosixPipe.%08x.%08x", GetCurrentProcessId(), pipe_number++))
         goto error;
 
     sec_attributes.bInheritHandle = TRUE;
@@ -200,8 +206,13 @@ int fileio_read(struct w32_io* pio, void *dst, unsigned int max) {
     if (fileio_is_io_available(pio, TRUE) == FALSE)
     {
 
-        if (-1 == fileio_ReadFileEx(pio))
+        if (-1 == fileio_ReadFileEx(pio)) {
+            if ((pio->type == PIPE_FD) && (errno == ERROR_NEGATIVE_SEEK))  {//write end of the pipe closed
+                errno = 0;
+                return 0;
+            }
             return -1;
+        }
 
         //Pick up APC if IO has completed
         SleepEx(0, TRUE);
@@ -228,7 +239,11 @@ int fileio_read(struct w32_io* pio, void *dst, unsigned int max) {
     }
 
     if (pio->read_details.error) {
-        errno = EOTHER;
+        errno = errno_from_Win32Error(pio->read_details.error);
+        if (errno == ERROR_BROKEN_PIPE) { //write end of the pipe is closed or pipe broken
+            errno = 0;
+            return 0;
+        }
         return -1;
     }
 
@@ -256,12 +271,23 @@ int fileio_write(struct w32_io* pio, const void *buf, unsigned int max) {
     int bytes_copied;
 
     if (pio->write_details.pending) {
-        errno = EAGAIN;
-        return -1;
+        if (w32_io_is_blocking(pio))
+        {
+            //this covers the scenario when the fd was previously non blocking (and hence io is still pending)
+            //wait for previous io to complete
+            while (pio->write_details.pending) {
+                if (wait_for_any_event(NULL, 0, INFINITE) == -1)
+                    return -1;
+            }
+        }
+        else {
+            errno = EAGAIN;
+            return -1;
+        }
     }
 
     if (pio->write_details.error) {
-        errno = EOTHER;
+        errno = errno_from_Win32Error(pio->write_details.error);
         return -1;
     }
 
@@ -297,6 +323,8 @@ int fileio_write(struct w32_io* pio, const void *buf, unsigned int max) {
     else
     {
         errno = errno_from_Win32Error();
+        if ((pio->type == PIPE_FD) && (errno == ERROR_NEGATIVE_SEEK)) //read end of the pipe closed
+            errno = EPIPE;
         return -1;
     }
 
diff --git a/contrib/win32/w32-posix-prototype/win32posix/win32posix/socketio.c b/contrib/win32/w32-posix-prototype/win32posix/win32posix/socketio.c
index d469f03..788d50c 100644
--- a/contrib/win32/w32-posix-prototype/win32posix/win32posix/socketio.c
+++ b/contrib/win32/w32-posix-prototype/win32posix/win32posix/socketio.c
@@ -127,8 +127,6 @@ int socketio_acceptEx(struct w32_io* pio) {
     return 0;
 }
 
-#define RECV_CONNECTION_CLOSED 1234
-
 void CALLBACK WSARecvCompletionRoutine(
     IN DWORD dwError,
     IN DWORD cbTransferred,
@@ -138,7 +136,7 @@ void CALLBACK WSARecvCompletionRoutine(
 {
     struct w32_io* pio = (struct w32_io*)((char*)lpOverlapped - offsetof(struct w32_io, read_overlapped));
     if (!dwError && !cbTransferred)
-        dwError = RECV_CONNECTION_CLOSED;
+        dwError = ERROR_GRACEFUL_DISCONNECT;
     pio->read_details.error = dwError;
     pio->read_details.remaining = cbTransferred;
     pio->read_details.completed = 0;
@@ -270,7 +268,7 @@ int socketio_recv(struct w32_io* pio, void *buf, size_t len, int flags) {
 
     //if there was an error on async call, return
     if (pio->read_details.error) {
-        if (pio->read_details.error == RECV_CONNECTION_CLOSED) {
+        if (pio->read_details.error == ERROR_GRACEFUL_DISCONNECT) {
             //connection is closed
             return 0;
         }
@@ -313,7 +311,7 @@ int socketio_recv(struct w32_io* pio, void *buf, size_t len, int flags) {
     //by this time we should have some bytes in internal buffer or an error from callback
     if (pio->read_details.error)
     {
-        if (pio->read_details.error == RECV_CONNECTION_CLOSED) {
+        if (pio->read_details.error == ERROR_GRACEFUL_DISCONNECT) {
             //connection is closed
             return 0;
         }
@@ -361,12 +359,24 @@ int socketio_send(struct w32_io* pio, const void *buf, size_t len, int flags) {
     //if io is already pending
     if (pio->write_details.pending)
     {
-        errno = EAGAIN;
-        return -1;
+        if (w32_io_is_blocking(pio))
+        {
+            //this covers the scenario when the fd was previously non blocking (and hence io is still pending)
+            //wait for previous io to complete
+            while (pio->write_details.pending) {
+                if (wait_for_any_event(NULL, 0, INFINITE) == -1)
+                    return -1;
+            }
+        }
+        else {
+            errno = EAGAIN;
+            return -1;
+        }
     }
 
+
     if (pio->write_details.error) {
-        errno = EOTHER;
+        errno = errno_from_WSAError(pio->write_details.error);
         return -1;
     }
 
diff --git a/contrib/win32/w32-posix-prototype/win32posix/win32posix/w32fd.c b/contrib/win32/w32-posix-prototype/win32posix/win32posix/w32fd.c
index daa36a6..8a68ec9 100644
--- a/contrib/win32/w32-posix-prototype/win32posix/win32posix/w32fd.c
+++ b/contrib/win32/w32-posix-prototype/win32posix/win32posix/w32fd.c
@@ -16,13 +16,13 @@ int fd_table_initialize() {
     memset(&fd_table, 0, sizeof(fd_table));
     memset(&w32_io_stdin, 0, sizeof(w32_io_stdin));
     w32_io_stdin.handle = STD_INPUT_HANDLE;
-    fd_table_set(&w32_io_stdin, stdin);
+    fd_table_set(&w32_io_stdin, STDIN_FILENO);
     memset(&w32_io_stdout, 0, sizeof(w32_io_stdout));
     w32_io_stdout.handle = STD_OUTPUT_HANDLE;
-    fd_table_set(&w32_io_stdout, stdout);
+    fd_table_set(&w32_io_stdout, STDOUT_FILENO);
     memset(&w32_io_stderr, 0, sizeof(w32_io_stderr));
     w32_io_stderr.handle = STD_ERROR_HANDLE;
-    fd_table_set(&w32_io_stderr, stderr);
+    fd_table_set(&w32_io_stderr, STDERR_FILENO);
     return 0;
 }
 
@@ -36,7 +36,8 @@ int fd_table_get_min_index() {
         bitmap++;
         min_index += 8;
         if (min_index >= MAX_FDS) {
-            errno = ENOMEM;
+            errno = EMFILE;
+            debug("ERROR: MAX_FDS limit reached");
             return -1;
         }
     }
@@ -53,7 +54,6 @@ int fd_table_get_min_index() {
 }
 
 void fd_table_set(struct w32_io* pio, int index) {
-
     fd_table.w32_ios[index] = pio;
     pio->table_index = index;
     FD_SET(index, &(fd_table.occupied));
@@ -67,11 +67,13 @@ void fd_table_clear(int index)
 }
 
 void w32posix_initialize() {
+    debug_initialize();
     fd_table_initialize();
     socketio_initialize();
 }
 
 void w32posix_done() {
+    debug_done();
     socketio_done();
 }
 
@@ -114,6 +116,7 @@ int w32_socket(int domain, int type, int protocol) {
     }
 
     fd_table_set(pio, min_index);
+    debug("socket:%p, io:%p, fd:%d ", pio->sock, pio, min_index);
     return min_index;
 }
 
@@ -131,93 +134,71 @@ int w32_accept(int fd, struct sockaddr* addr, int* addrlen)
     }
 
     fd_table_set(pio, min_index);
+    debug("socket:%p, io:%p, fd:%d ", pio->sock, pio, min_index);
     return min_index;
 }
 
+#define CHECK_FD(fd) \
+do { \
+    if ((fd > MAX_FDS - 1) || fd_table.w32_ios[fd] == NULL) { \
+         errno = EBADF; \
+         debug("bad fd: %d", fd); \
+         return -1; \
+    } \
+} while (0)
+
 int w32_setsockopt(int fd, int level, int optname, const char* optval, int optlen) {
-    if (fd_table.w32_ios[fd] == NULL) {
-        errno = EBADF;
-        return -1;
-    }
+    CHECK_FD(fd);
     return socketio_setsockopt(fd_table.w32_ios[fd], level, optname, optval, optlen);
 }
 
 int w32_getsockopt(int fd, int level, int optname, char* optval, int* optlen) {
-    if (fd_table.w32_ios[fd] == NULL) {
-        errno = EBADF;
-        return -1;
-    }
+    CHECK_FD(fd);
     return socketio_getsockopt(fd_table.w32_ios[fd], level, optname, optval, optlen);
 }
 
 int w32_getsockname(int fd, struct sockaddr* name, int* namelen) {
-    if (fd_table.w32_ios[fd] == NULL) {
-        errno = EBADF;
-        return -1;
-    }
+    CHECK_FD(fd);
     return socketio_getsockname(fd_table.w32_ios[fd], name, namelen);
 }
 
 int w32_getpeername(int fd, struct sockaddr* name, int* namelen) {
-    if (fd_table.w32_ios[fd] == NULL) {
-        errno = EBADF;
-        return -1;
-    }
+    CHECK_FD(fd);
     return socketio_getpeername(fd_table.w32_ios[fd], name, namelen);
 }
 
 int w32_listen(int fd, int backlog) {
-    if (fd_table.w32_ios[fd] == NULL) {
-        errno = EBADF;
-        return -1;
-    }
+    CHECK_FD(fd);
     return socketio_listen(fd_table.w32_ios[fd], backlog);
 }
 
 int w32_bind(int fd, const struct sockaddr *name, int namelen) {
-    if (fd_table.w32_ios[fd] == NULL) {
-        errno = EBADF;
-        return -1;
-    }
+    CHECK_FD(fd);
     return socketio_bind(fd_table.w32_ios[fd], name, namelen);
 }
 
 int w32_connect(int fd, const struct sockaddr* name, int namelen) {
-    if (fd_table.w32_ios[fd] == NULL) {
-        errno = EBADF;
-        return -1;
-    }
+    CHECK_FD(fd);
     return socketio_connect(fd_table.w32_ios[fd], name, namelen);
 }
 
 int w32_recv(int fd, void *buf, size_t len, int flags) {
-    if (fd_table.w32_ios[fd] == NULL) {
-        errno = EBADF;
-        return -1;
-    }
+    CHECK_FD(fd);
     return socketio_recv(fd_table.w32_ios[fd], buf, len, flags);
 }
 
 int w32_send(int fd, const void *buf, size_t len, int flags) {
-    if (fd_table.w32_ios[fd] == NULL) {
-        errno = EBADF;
-        return -1;
-    }
+    CHECK_FD(fd);
     return socketio_send(fd_table.w32_ios[fd], buf, len, flags);
 }
 
 
 int w32_shutdown(int fd, int how) {
-    if (fd_table.w32_ios[fd] == NULL) {
-        errno = EBADF;
-        return -1;
-    }
+    CHECK_FD(fd);
     return socketio_shutdown(fd_table.w32_ios[fd], how);
 }
 
 
-
-
 //file io
 int w32_pipe(int *pfds){
     int read_index, write_index;
@@ -241,6 +222,8 @@ int w32_pipe(int *pfds){
     fd_table_set(pio[1], write_index);
     pfds[0] = read_index;
     pfds[1] = write_index;
+    debug("read end: handle:%p, io:%p, fd:%d", pio[0]->handle, pio[0], read_index);
+    debug("write end: handle:%p, io:%p, fd:%d", pio[1]->handle, pio[1], write_index);
     return 0;
 }
 
@@ -256,60 +239,44 @@ int w32_open(const char *pathname, int flags, ...) {
         return -1;
 
     fd_table_set(pio, min_index);
+    debug("handle:%p, io:%p, fd:%d", pio->handle, pio, min_index);
     return min_index;
 }
 
 int w32_read(int fd, void *dst, unsigned int max) {
-    if (fd_table.w32_ios[fd] == NULL) {
-        errno = EBADF;
-        return -1;
-    }
+    CHECK_FD(fd);
     return fileio_read(fd_table.w32_ios[fd], dst, max);
 }
 
 int w32_write(int fd, const void *buf, unsigned int max) {
-    if (fd_table.w32_ios[fd] == NULL) {
-        errno = EBADF;
-        return -1;
-    }
+    CHECK_FD(fd);
     return fileio_write(fd_table.w32_ios[fd], buf, max);
 }
 
 int w32_fstat(int fd, struct stat *buf) {
-    if (fd_table.w32_ios[fd] == NULL) {
-        errno = EBADF;
-        return -1;
-    }
+    CHECK_FD(fd);
     return fileio_fstat(fd_table.w32_ios[fd], buf);
 }
 
 int w32_isatty(int fd) {
-    if (fd_table.w32_ios[fd] == NULL) {
-        errno = EBADF;
-        return -1;
-    }
-
+    CHECK_FD(fd);
     return fileio_isatty(fd_table.w32_ios[fd]);
 }
 
 FILE* w32_fdopen(int fd, const char *mode) {
-    if (fd_table.w32_ios[fd] == NULL) {
-        errno = EBADF;
-        return NULL;
-    }
-
+    CHECK_FD(fd);
     return fileio_fdopen(fd_table.w32_ios[fd], mode);
 }
 
 //Common IO
 int w32_close(int fd) {
-    struct w32_io* pio = fd_table.w32_ios[fd];
 
-    if (pio == NULL) {
-        errno = EBADF;
-        return -1;
-    }
+    struct w32_io* pio;
 
+    CHECK_FD(fd);
+    pio = fd_table.w32_ios[fd];
+    
+    debug("io:%p, type:%d, fd:%d, table_index:%d", pio, pio->type, fd, pio->table_index);
     fd_table_clear(pio->table_index);
     if ((pio->type == LISTEN_FD) || (pio->type == SOCK_FD)) {
         return socketio_close(pio);
@@ -322,10 +289,7 @@ int w32_fcntl(int fd, int cmd, ... /* arg */) {
     va_list valist;
     va_start(valist, cmd);
 
-    if (fd_table.w32_ios[fd] == NULL) {
-        errno = EBADF;
-        return -1;
-    }
+    CHECK_FD(fd);
 
     switch (cmd){
     case F_GETFL:
@@ -341,39 +305,55 @@ int w32_fcntl(int fd, int cmd, ... /* arg */) {
         return 0;
     default:
         errno = EINVAL;
+        debug("ERROR: cmd:%d", cmd);
         return -1;
     }
 }
 
 int w32_select(int fds, fd_set* readfds, fd_set* writefds, fd_set* exceptfds, const struct timeval *timeout) {
-    int in_ready_fds = 0, out_ready_fds = 0;
+    int in_ready_fds = 0, out_ready_fds = 0, i;
     fd_set read_ready_fds, write_ready_fds;
-    HANDLE events[10];
+    HANDLE events[32];
     int num_events = 0;
 
     memset(&read_ready_fds, 0, sizeof(fd_set));
     memset(&write_ready_fds, 0, sizeof(fd_set));
 
-    if (fds > MAX_FDS - 1) {
+    if (fds > MAX_FDS ) {
         errno = EINVAL;
+        debug("ERROR: fds: %d", fds);
         return -1;
     }
 
-    if (!readfds && !writefds && !exceptfds) {
+    if (!readfds && !writefds) {
         errno = EINVAL;
+        debug("ERROR: null fd_sets");
         return -1;
     }
 
+    if (exceptfds) {
+        errno = EOPNOTSUPP;
+        debug("ERROR: exceptfds not supported");
+        return -1;
+    }
+
+    if (readfds) {
+        for (i = 0; i < fds; i++) 
+            if (FD_ISSET(i, readfds))
+                CHECK_FD(i);
+    }
+
+    if (writefds) {
+        for (i = 0; i < fds; i++) 
+            if (FD_ISSET(i, writefds))
+                CHECK_FD(i);
+    }
+
 
     //see if any io is ready
-    for (int i = 0; i < fds; i++) {
+    for (i = 0; i < fds; i++) {
 
         if (readfds && FD_ISSET(i, readfds)) {
-            if (fd_table.w32_ios[i] == NULL) {
-                errno = EBADF;
-                return -1;
-            }
-
             in_ready_fds++;
             if (w32_io_is_io_available(fd_table.w32_ios[i], TRUE)) {
                 FD_SET(i, &read_ready_fds);
@@ -382,33 +362,29 @@ int w32_select(int fds, fd_set* readfds, fd_set* writefds, fd_set* exceptfds, co
         }
 
         if (writefds && FD_ISSET(i, writefds)) {
-            if (fd_table.w32_ios[i] == NULL) {
-                errno = EBADF;
-                return -1;
-            }
-
             in_ready_fds++;
             if (w32_io_is_io_available(fd_table.w32_ios[i], FALSE)) {
                 FD_SET(i, &write_ready_fds);
                 out_ready_fds++;
             }
         }
-
     }
 
     //if none of input fds are set return error
     if (in_ready_fds == 0) {
         errno = EINVAL;
+        debug("ERROR: empty fd_sets");
         return -1;
     }
 
-    //if some fds are already ready, return
+    //if io on some fds is already ready, return
     if (out_ready_fds)
     {
         if (readfds)
             *readfds = read_ready_fds;
         if (writefds)
             *writefds = write_ready_fds;
+        debug("IO ready:%d, no wait", out_ready_fds);
         return out_ready_fds;
     }
 
diff --git a/contrib/win32/w32-posix-prototype/win32posix/win32posix/w32fd.h b/contrib/win32/w32-posix-prototype/win32posix/win32posix/w32fd.h
index f2ddaaa..a6f8b4f 100644
--- a/contrib/win32/w32-posix-prototype/win32posix/win32posix/w32fd.h
+++ b/contrib/win32/w32-posix-prototype/win32posix/win32posix/w32fd.h
@@ -1,5 +1,6 @@
 #include <Windows.h>
 #include <stdio.h>
+#include "debug.h"
 
 enum w32_io_type {
     UNKOWN_FD = 0,