Adding upstream version 1:115.7.0.upstream/1%115.7.0upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 4761 insertions, 0 deletions

diff --git a/nsprpub/pr/src/md/windows/ntio.c b/nsprpub/pr/src/md/windows/ntio.c
new file mode 100644
index 0000000000..40f5200789
--- /dev/null
+++ b/nsprpub/pr/src/md/windows/ntio.c
@@ -0,0 +1,4761 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Windows NT IO module
+ *
+ * This module handles IO for LOCAL_SCOPE and GLOBAL_SCOPE threads.
+ * For LOCAL_SCOPE threads, we're using NT fibers.  For GLOBAL_SCOPE threads
+ * we're using NT-native threads.
+ *
+ * When doing IO, we want to use completion ports for optimal performance
+ * with fibers.  But if we use completion ports for all IO, it is difficult
+ * to project a blocking model with GLOBAL_SCOPE threads.  To handle this
+ * we create an extra thread for completing IO for GLOBAL_SCOPE threads.
+ * We don't really want to complete IO on a separate thread for LOCAL_SCOPE
+ * threads because it means extra context switches, which are really slow
+ * on NT...  Since we're using a single completion port, some IO will
+ * be incorrectly completed on the GLOBAL_SCOPE IO thread; this will mean
+ * extra context switching; but I don't think there is anything I can do
+ * about it.
+ */
+
+#include "primpl.h"
+#include "pprmwait.h"
+#include <direct.h>
+#include <mbstring.h>
+
+static HANDLE                _pr_completion_port;
+static PRThread             *_pr_io_completion_thread;
+
+#define RECYCLE_SIZE 512
+static struct _MDLock        _pr_recycle_lock;
+static PRInt32               _pr_recycle_INET_array[RECYCLE_SIZE];
+static PRInt32               _pr_recycle_INET_tail = 0;
+static PRInt32               _pr_recycle_INET6_array[RECYCLE_SIZE];
+static PRInt32               _pr_recycle_INET6_tail = 0;
+
+__declspec(thread) PRThread *_pr_io_restarted_io = NULL;
+DWORD _pr_io_restartedIOIndex;  /* The thread local storage slot for each
+                                 * thread is initialized to NULL. */
+
+PRBool                       _nt_version_gets_lockfile_completion;
+
+struct _MDLock               _pr_ioq_lock;
+extern _MDLock               _nt_idleLock;
+extern PRCList               _nt_idleList;
+extern PRUint32              _nt_idleCount;
+
+#define CLOSE_TIMEOUT   PR_SecondsToInterval(5)
+
+/*
+ * NSPR-to-NT access right mapping table for files.
+ */
+static DWORD fileAccessTable[] = {
+    FILE_GENERIC_READ,
+    FILE_GENERIC_WRITE,
+    FILE_GENERIC_EXECUTE
+};
+
+/*
+ * NSPR-to-NT access right mapping table for directories.
+ */
+static DWORD dirAccessTable[] = {
+    FILE_GENERIC_READ,
+    FILE_GENERIC_WRITE|FILE_DELETE_CHILD,
+    FILE_GENERIC_EXECUTE
+};
+
+static PRBool IsPrevCharSlash(const char *str, const char *current);
+
+#define _NEED_351_FILE_LOCKING_HACK
+#ifdef _NEED_351_FILE_LOCKING_HACK
+#define _PR_LOCAL_FILE 1
+#define _PR_REMOTE_FILE 2
+PRBool IsFileLocalInit();
+PRInt32 IsFileLocal(HANDLE hFile);
+#endif /* _NEED_351_FILE_LOCKING_HACK */
+
+static PRInt32 _md_MakeNonblock(HANDLE);
+
+static PROsfd _nt_nonblock_accept(PRFileDesc *fd, struct sockaddr *addr, int *addrlen, PRIntervalTime);
+static PRInt32 _nt_nonblock_connect(PRFileDesc *fd, struct sockaddr *addr, int addrlen, PRIntervalTime);
+static PRInt32 _nt_nonblock_recv(PRFileDesc *fd, char *buf, int len, int flags, PRIntervalTime);
+static PRInt32 _nt_nonblock_send(PRFileDesc *fd, char *buf, int len, PRIntervalTime);
+static PRInt32 _nt_nonblock_writev(PRFileDesc *fd, const PRIOVec *iov, int size, PRIntervalTime);
+static PRInt32 _nt_nonblock_sendto(PRFileDesc *, const char *, int, const struct sockaddr *, int, PRIntervalTime);
+static PRInt32 _nt_nonblock_recvfrom(PRFileDesc *, char *, int, struct sockaddr *, int *, PRIntervalTime);
+
+/*
+ * We cannot associate a fd (a socket) with an I/O completion port
+ * if the fd is nonblocking or inheritable.
+ *
+ * Nonblocking socket I/O won't work if the socket is associated with
+ * an I/O completion port.
+ *
+ * An inheritable fd cannot be associated with an I/O completion port
+ * because the completion notification of async I/O initiated by the
+ * child process is still posted to the I/O completion port in the
+ * parent process.
+ */
+#define _NT_USE_NB_IO(fd) \
+    ((fd)->secret->nonblocking || (fd)->secret->inheritable == _PR_TRI_TRUE)
+
+/*
+ * UDP support
+ *
+ * UDP is supported on NT by the continuation thread mechanism.
+ * The code is borrowed from ptio.c in pthreads nspr, hence the
+ * PT and pt prefixes.  This mechanism is in fact general and
+ * not limited to UDP.  For now, only UDP's recvfrom and sendto
+ * go through the continuation thread if they get WSAEWOULDBLOCK
+ * on first try.  Recv and send on a connected UDP socket still
+ * goes through asychronous io.
+ */
+
+#define PT_DEFAULT_SELECT_MSEC 100
+
+typedef struct pt_Continuation pt_Continuation;
+typedef PRBool (*ContinuationFn)(pt_Continuation *op, PRInt16 revent);
+
+typedef enum pr_ContuationStatus
+{
+    pt_continuation_sumbitted,
+    pt_continuation_inprogress,
+    pt_continuation_abort,
+    pt_continuation_done
+} pr_ContuationStatus;
+
+struct pt_Continuation
+{
+    /* These objects are linked in ascending timeout order */
+    pt_Continuation *next, *prev;           /* self linked list of these things */
+
+    /* The building of the continuation operation */
+    ContinuationFn function;                /* what function to continue */
+    union {
+        SOCKET osfd;
+    } arg1;            /* #1 - the op's fd */
+    union {
+        void* buffer;
+    } arg2;           /* #2 - primary transfer buffer */
+    union {
+        PRIntn amount;
+    } arg3;          /* #3 - size of 'buffer' */
+    union {
+        PRIntn flags;
+    } arg4;           /* #4 - read/write flags */
+    union {
+        PRNetAddr *addr;
+    } arg5;        /* #5 - send/recv address */
+
+    PRIntervalTime timeout;                 /* representation of the timeout */
+
+    PRIntn event;                           /* flags for select()'s events */
+
+    /*
+    ** The representation and notification of the results of the operation.
+    ** These function can either return an int return code or a pointer to
+    ** some object.
+    */
+    union {
+        PRIntn code;
+        void *object;
+    } result;
+
+    PRIntn syserrno;                        /* in case it failed, why (errno) */
+    pr_ContuationStatus status;             /* the status of the operation */
+    PRCondVar *complete;                    /* to notify the initiating thread */
+};
+
+static struct pt_TimedQueue
+{
+    PRLock *ml;                             /* a little protection */
+    PRThread *thread;                       /* internal thread's identification */
+    PRCondVar *new_op;                      /* new operation supplied */
+    PRCondVar *finish_op;                   /* an existing operation finished */
+    PRUintn op_count;                       /* number of operations in the list */
+    pt_Continuation *head, *tail;           /* head/tail of list of operations */
+
+    pt_Continuation *op;                    /* timed operation furthest in future */
+    PRIntervalTime epoch;                   /* the epoch of 'timed' */
+} pt_tq;
+
+#if defined(DEBUG)
+static struct pt_debug_s
+{
+    PRIntn predictionsFoiled;
+    PRIntn pollingListMax;
+    PRIntn continuationsServed;
+} pt_debug;
+#endif  /* DEBUG */
+
+static void ContinuationThread(void *arg);
+static PRInt32 pt_SendTo(
+    SOCKET osfd, const void *buf,
+    PRInt32 amount, PRInt32 flags, const PRNetAddr *addr,
+    PRIntn addrlen, PRIntervalTime timeout);
+static PRInt32 pt_RecvFrom(SOCKET osfd, void *buf, PRInt32 amount,
+                           PRInt32 flags, PRNetAddr *addr, PRIntn *addr_len, PRIntervalTime timeout);
+
+
+/* The key returned from GetQueuedCompletionStatus() is used to determine what
+ * type of completion we have.  We differentiate between IO completions and
+ * CVAR completions.
+ */
+#define KEY_IO              0xaaaaaaaa
+#define KEY_CVAR            0xbbbbbbbb
+
+PRInt32
+_PR_MD_PAUSE_CPU(PRIntervalTime ticks)
+{
+    int awoken = 0;
+    unsigned long bytes, key;
+    int rv;
+    LPOVERLAPPED olp;
+    _MDOverlapped *mdOlp;
+    PRUint32 timeout;
+
+    if (_nt_idleCount > 0) {
+        PRThread *deadThread;
+
+        _MD_LOCK(&_nt_idleLock);
+        while( !PR_CLIST_IS_EMPTY(&_nt_idleList) ) {
+            deadThread = _PR_THREAD_PTR(PR_LIST_HEAD(&_nt_idleList));
+            PR_REMOVE_LINK(&deadThread->links);
+
+            PR_ASSERT(deadThread->state == _PR_DEAD_STATE);
+
+            /* XXXMB - cleanup to do here? */
+            if ( !_PR_IS_NATIVE_THREAD(deadThread) ) {
+                /* Spinlock while user thread is still running.
+                 * There is no way to use a condition variable here. The thread
+                 * is dead, and we have to wait until we switch off the dead
+                 * thread before we can kill the fiber completely.
+                 */
+                while ( deadThread->no_sched)
+                    ;
+
+                DeleteFiber(deadThread->md.fiber_id);
+            }
+            memset(deadThread, 0xa, sizeof(PRThread)); /* debugging */
+            if (!deadThread->threadAllocatedOnStack) {
+                PR_DELETE(deadThread);
+            }
+            _nt_idleCount--;
+        }
+        _MD_UNLOCK(&_nt_idleLock);
+    }
+
+    if (ticks == PR_INTERVAL_NO_TIMEOUT)
+#if 0
+        timeout = INFINITE;
+#else
+        /*
+         * temporary hack to poll the runq every 5 seconds because of bug in
+         * native threads creating user threads and not poking the right cpu.
+         *
+         * A local thread that was interrupted is bound to its current
+         * cpu but there is no easy way for the interrupter to poke the
+         * right cpu.  This is a hack to poll the runq every 5 seconds.
+         */
+        timeout = 5000;
+#endif
+    else {
+        timeout = PR_IntervalToMilliseconds(ticks);
+    }
+
+    /*
+     * The idea of looping here is to complete as many IOs as possible before
+     * returning.  This should minimize trips to the idle thread.
+     */
+    while(1) {
+        rv = GetQueuedCompletionStatus(
+                 _pr_completion_port,
+                 &bytes,
+                 &key,
+                 &olp,
+                 timeout);
+        if (rv == 0 && olp == NULL) {
+            /* Error in GetQueuedCompetionStatus */
+            if (GetLastError() != WAIT_TIMEOUT) {
+                /* ARGH - what can we do here? Log an error? XXXMB */
+                return -1;
+            } else {
+                /* If awoken == 0, then we just had a timeout */
+                return awoken;
+            }
+        }
+
+        if (olp == NULL) {
+            return 0;
+        }
+
+        mdOlp = (_MDOverlapped *)olp;
+
+        if (mdOlp->ioModel == _MD_MultiWaitIO) {
+            PRRecvWait *desc;
+            PRWaitGroup *group;
+            PRThread *thred = NULL;
+            PRMWStatus mwstatus;
+
+            desc = mdOlp->data.mw.desc;
+            PR_ASSERT(desc != NULL);
+            mwstatus = rv ? PR_MW_SUCCESS : PR_MW_FAILURE;
+            if (InterlockedCompareExchange((PVOID *)&desc->outcome,
+                                           (PVOID)mwstatus, (PVOID)PR_MW_PENDING)
+                == (PVOID)PR_MW_PENDING) {
+                if (mwstatus == PR_MW_SUCCESS) {
+                    desc->bytesRecv = bytes;
+                } else {
+                    mdOlp->data.mw.error = GetLastError();
+                }
+            }
+            group = mdOlp->data.mw.group;
+            PR_ASSERT(group != NULL);
+
+            _PR_MD_LOCK(&group->mdlock);
+            PR_APPEND_LINK(&mdOlp->data.mw.links, &group->io_ready);
+            PR_ASSERT(desc->fd != NULL);
+            NT_HashRemoveInternal(group, desc->fd);
+            if (!PR_CLIST_IS_EMPTY(&group->wait_list)) {
+                thred = _PR_THREAD_CONDQ_PTR(PR_LIST_HEAD(&group->wait_list));
+                PR_REMOVE_LINK(&thred->waitQLinks);
+            }
+            _PR_MD_UNLOCK(&group->mdlock);
+
+            if (thred) {
+                if (!_PR_IS_NATIVE_THREAD(thred)) {
+                    int pri = thred->priority;
+                    _PRCPU *lockedCPU = _PR_MD_CURRENT_CPU();
+                    _PR_THREAD_LOCK(thred);
+                    if (thred->flags & _PR_ON_PAUSEQ) {
+                        _PR_SLEEPQ_LOCK(thred->cpu);
+                        _PR_DEL_SLEEPQ(thred, PR_TRUE);
+                        _PR_SLEEPQ_UNLOCK(thred->cpu);
+                        _PR_THREAD_UNLOCK(thred);
+                        thred->cpu = lockedCPU;
+                        thred->state = _PR_RUNNABLE;
+                        _PR_RUNQ_LOCK(lockedCPU);
+                        _PR_ADD_RUNQ(thred, lockedCPU, pri);
+                        _PR_RUNQ_UNLOCK(lockedCPU);
+                    } else {
+                        /*
+                         * The thread was just interrupted and moved
+                         * from the pause queue to the run queue.
+                         */
+                        _PR_THREAD_UNLOCK(thred);
+                    }
+                } else {
+                    _PR_THREAD_LOCK(thred);
+                    thred->state = _PR_RUNNABLE;
+                    _PR_THREAD_UNLOCK(thred);
+                    ReleaseSemaphore(thred->md.blocked_sema, 1, NULL);
+                }
+            }
+        } else {
+            PRThread *completed_io;
+
+            PR_ASSERT(mdOlp->ioModel == _MD_BlockingIO);
+            completed_io = _PR_THREAD_MD_TO_PTR(mdOlp->data.mdThread);
+            completed_io->md.blocked_io_status = rv;
+            if (rv == 0) {
+                completed_io->md.blocked_io_error = GetLastError();
+            }
+            completed_io->md.blocked_io_bytes = bytes;
+
+            if ( !_PR_IS_NATIVE_THREAD(completed_io) ) {
+                int pri = completed_io->priority;
+                _PRCPU *lockedCPU = _PR_MD_CURRENT_CPU();
+
+                /* The KEY_CVAR notification only occurs when a native thread
+                 * is notifying a user thread.  For user-user notifications
+                 * the wakeup occurs by having the notifier place the thread
+                 * on the runq directly; for native-native notifications the
+                 * wakeup occurs by calling ReleaseSemaphore.
+                 */
+                if ( key == KEY_CVAR ) {
+                    PR_ASSERT(completed_io->io_pending == PR_FALSE);
+                    PR_ASSERT(completed_io->io_suspended == PR_FALSE);
+                    PR_ASSERT(completed_io->md.thr_bound_cpu == NULL);
+
+                    /* Thread has already been deleted from sleepQ */
+
+                    /* Switch CPU and add to runQ */
+                    completed_io->cpu = lockedCPU;
+                    completed_io->state = _PR_RUNNABLE;
+                    _PR_RUNQ_LOCK(lockedCPU);
+                    _PR_ADD_RUNQ(completed_io, lockedCPU, pri);
+                    _PR_RUNQ_UNLOCK(lockedCPU);
+                } else {
+                    PR_ASSERT(key == KEY_IO);
+                    PR_ASSERT(completed_io->io_pending == PR_TRUE);
+
+                    _PR_THREAD_LOCK(completed_io);
+
+                    completed_io->io_pending = PR_FALSE;
+
+                    /* If io_suspended is true, then this IO has already resumed.
+                     * We don't need to do anything; because the thread is
+                     * already running.
+                     */
+                    if (completed_io->io_suspended == PR_FALSE) {
+                        if (completed_io->flags & (_PR_ON_SLEEPQ|_PR_ON_PAUSEQ)) {
+                            _PR_SLEEPQ_LOCK(completed_io->cpu);
+                            _PR_DEL_SLEEPQ(completed_io, PR_TRUE);
+                            _PR_SLEEPQ_UNLOCK(completed_io->cpu);
+
+                            _PR_THREAD_UNLOCK(completed_io);
+
+                            /*
+                             * If an I/O operation is suspended, the thread
+                             * must be running on the same cpu on which the
+                             * I/O operation was issued.
+                             */
+                            PR_ASSERT(!completed_io->md.thr_bound_cpu ||
+                                      (completed_io->cpu == completed_io->md.thr_bound_cpu));
+
+                            if (!completed_io->md.thr_bound_cpu) {
+                                completed_io->cpu = lockedCPU;
+                            }
+                            completed_io->state = _PR_RUNNABLE;
+                            _PR_RUNQ_LOCK(completed_io->cpu);
+                            _PR_ADD_RUNQ(completed_io, completed_io->cpu, pri);
+                            _PR_RUNQ_UNLOCK(completed_io->cpu);
+                        } else {
+                            _PR_THREAD_UNLOCK(completed_io);
+                        }
+                    } else {
+                        _PR_THREAD_UNLOCK(completed_io);
+                    }
+                }
+            } else {
+                /* For native threads, they are only notified through this loop
+                 * when completing IO.  So, don't worry about this being a CVAR
+                 * notification, because that is not possible.
+                 */
+                _PR_THREAD_LOCK(completed_io);
+                completed_io->io_pending = PR_FALSE;
+                if (completed_io->io_suspended == PR_FALSE) {
+                    completed_io->state = _PR_RUNNABLE;
+                    _PR_THREAD_UNLOCK(completed_io);
+                    rv = ReleaseSemaphore(completed_io->md.blocked_sema,
+                                          1, NULL);
+                    PR_ASSERT(0 != rv);
+                } else {
+                    _PR_THREAD_UNLOCK(completed_io);
+                }
+            }
+        }
+
+        awoken++;
+        timeout = 0;   /* Don't block on subsequent trips through the loop */
+    }
+
+    /* never reached */
+    return 0;
+}
+
+static PRStatus
+_native_thread_md_wait(PRThread *thread, PRIntervalTime ticks)
+{
+    DWORD rv;
+    PRUint32 msecs = (ticks == PR_INTERVAL_NO_TIMEOUT) ?
+                     INFINITE : PR_IntervalToMilliseconds(ticks);
+
+    /*
+     * thread waiting for a cvar or a joining thread
+     */
+    rv = WaitForSingleObject(thread->md.blocked_sema, msecs);
+    switch(rv) {
+        case WAIT_OBJECT_0:
+            return PR_SUCCESS;
+            break;
+        case WAIT_TIMEOUT:
+            _PR_THREAD_LOCK(thread);
+            PR_ASSERT (thread->state != _PR_IO_WAIT);
+            if (thread->wait.cvar != NULL) {
+                PR_ASSERT(thread->state == _PR_COND_WAIT);
+                thread->wait.cvar = NULL;
+                thread->state = _PR_RUNNING;
+                _PR_THREAD_UNLOCK(thread);
+            } else {
+                /* The CVAR was notified just as the timeout
+                 * occurred.  This left the semaphore in the
+                 * signaled state.  Call WaitForSingleObject()
+                 * to clear the semaphore.
+                 */
+                _PR_THREAD_UNLOCK(thread);
+                rv = WaitForSingleObject(thread->md.blocked_sema, INFINITE);
+                PR_ASSERT(rv == WAIT_OBJECT_0);
+            }
+            return PR_SUCCESS;
+            break;
+        default:
+            return PR_FAILURE;
+            break;
+    }
+
+    return PR_SUCCESS;
+}
+
+PRStatus
+_PR_MD_WAIT(PRThread *thread, PRIntervalTime ticks)
+{
+    DWORD rv;
+
+    if (_native_threads_only) {
+        return(_native_thread_md_wait(thread, ticks));
+    }
+    if ( thread->flags & _PR_GLOBAL_SCOPE ) {
+        PRUint32 msecs = (ticks == PR_INTERVAL_NO_TIMEOUT) ?
+                         INFINITE : PR_IntervalToMilliseconds(ticks);
+        rv = WaitForSingleObject(thread->md.blocked_sema, msecs);
+        switch(rv) {
+            case WAIT_OBJECT_0:
+                return PR_SUCCESS;
+                break;
+            case WAIT_TIMEOUT:
+                _PR_THREAD_LOCK(thread);
+                if (thread->state == _PR_IO_WAIT) {
+                    if (thread->io_pending == PR_TRUE) {
+                        thread->state = _PR_RUNNING;
+                        thread->io_suspended = PR_TRUE;
+                        _PR_THREAD_UNLOCK(thread);
+                    } else {
+                        /* The IO completed just at the same time the timeout
+                         * occurred.  This left the semaphore in the signaled
+                         * state.  Call WaitForSingleObject() to clear the
+                         * semaphore.
+                         */
+                        _PR_THREAD_UNLOCK(thread);
+                        rv = WaitForSingleObject(thread->md.blocked_sema, INFINITE);
+                        PR_ASSERT(rv == WAIT_OBJECT_0);
+                    }
+                } else {
+                    if (thread->wait.cvar != NULL) {
+                        PR_ASSERT(thread->state == _PR_COND_WAIT);
+                        thread->wait.cvar = NULL;
+                        thread->state = _PR_RUNNING;
+                        _PR_THREAD_UNLOCK(thread);
+                    } else {
+                        /* The CVAR was notified just as the timeout
+                         * occurred.  This left the semaphore in the
+                         * signaled state.  Call WaitForSingleObject()
+                         * to clear the semaphore.
+                         */
+                        _PR_THREAD_UNLOCK(thread);
+                        rv = WaitForSingleObject(thread->md.blocked_sema, INFINITE);
+                        PR_ASSERT(rv == WAIT_OBJECT_0);
+                    }
+                }
+                return PR_SUCCESS;
+                break;
+            default:
+                return PR_FAILURE;
+                break;
+        }
+    } else {
+        PRInt32 is;
+
+        _PR_INTSOFF(is);
+        _PR_MD_SWITCH_CONTEXT(thread);
+    }
+
+    return PR_SUCCESS;
+}
+
+static void
+_native_thread_io_nowait(
+    PRThread *thread,
+    int rv,
+    int bytes)
+{
+    int rc;
+
+    PR_ASSERT(rv != 0);
+    _PR_THREAD_LOCK(thread);
+    if (thread->state == _PR_IO_WAIT) {
+        PR_ASSERT(thread->io_suspended == PR_FALSE);
+        PR_ASSERT(thread->io_pending == PR_TRUE);
+        thread->state = _PR_RUNNING;
+        thread->io_pending = PR_FALSE;
+        _PR_THREAD_UNLOCK(thread);
+    } else {
+        /* The IO completed just at the same time the
+         * thread was interrupted. This left the semaphore
+         * in the signaled state. Call WaitForSingleObject()
+         * to clear the semaphore.
+         */
+        PR_ASSERT(thread->io_suspended == PR_TRUE);
+        PR_ASSERT(thread->io_pending == PR_TRUE);
+        thread->io_pending = PR_FALSE;
+        _PR_THREAD_UNLOCK(thread);
+        rc = WaitForSingleObject(thread->md.blocked_sema, INFINITE);
+        PR_ASSERT(rc == WAIT_OBJECT_0);
+    }
+
+    thread->md.blocked_io_status = rv;
+    thread->md.blocked_io_bytes = bytes;
+    rc = ResetEvent(thread->md.thr_event);
+    PR_ASSERT(rc != 0);
+    return;
+}
+
+static PRStatus
+_native_thread_io_wait(PRThread *thread, PRIntervalTime ticks)
+{
+    DWORD rv, bytes;
+#define _NATIVE_IO_WAIT_HANDLES     2
+#define _NATIVE_WAKEUP_EVENT_INDEX  0
+#define _NATIVE_IO_EVENT_INDEX      1
+
+    HANDLE wait_handles[_NATIVE_IO_WAIT_HANDLES];
+
+    PRUint32 msecs = (ticks == PR_INTERVAL_NO_TIMEOUT) ?
+                     INFINITE : PR_IntervalToMilliseconds(ticks);
+
+    PR_ASSERT(thread->flags & _PR_GLOBAL_SCOPE);
+
+    wait_handles[0] = thread->md.blocked_sema;
+    wait_handles[1] = thread->md.thr_event;
+    rv = WaitForMultipleObjects(_NATIVE_IO_WAIT_HANDLES, wait_handles,
+                                FALSE, msecs);
+
+    switch(rv) {
+        case WAIT_OBJECT_0 + _NATIVE_IO_EVENT_INDEX:
+            /*
+             * I/O op completed
+             */
+            _PR_THREAD_LOCK(thread);
+            if (thread->state == _PR_IO_WAIT) {
+
+                PR_ASSERT(thread->io_suspended == PR_FALSE);
+                PR_ASSERT(thread->io_pending == PR_TRUE);
+                thread->state = _PR_RUNNING;
+                thread->io_pending = PR_FALSE;
+                _PR_THREAD_UNLOCK(thread);
+            } else {
+                /* The IO completed just at the same time the
+                 * thread was interrupted. This led to us being
+                 * notified twice. Call WaitForSingleObject()
+                 * to clear the semaphore.
+                 */
+                PR_ASSERT(thread->io_suspended == PR_TRUE);
+                PR_ASSERT(thread->io_pending == PR_TRUE);
+                thread->io_pending = PR_FALSE;
+                _PR_THREAD_UNLOCK(thread);
+                rv = WaitForSingleObject(thread->md.blocked_sema,
+                                         INFINITE);
+                PR_ASSERT(rv == WAIT_OBJECT_0);
+            }
+
+            rv = GetOverlappedResult((HANDLE) thread->io_fd,
+                                     &thread->md.overlapped.overlapped, &bytes, FALSE);
+
+            thread->md.blocked_io_status = rv;
+            if (rv != 0) {
+                thread->md.blocked_io_bytes = bytes;
+            } else {
+                thread->md.blocked_io_error = GetLastError();
+                PR_ASSERT(ERROR_IO_PENDING != thread->md.blocked_io_error);
+            }
+            rv = ResetEvent(thread->md.thr_event);
+            PR_ASSERT(rv != 0);
+            break;
+        case WAIT_OBJECT_0 + _NATIVE_WAKEUP_EVENT_INDEX:
+            /*
+             * I/O interrupted;
+             */
+#ifdef DEBUG
+            _PR_THREAD_LOCK(thread);
+            PR_ASSERT(thread->io_suspended == PR_TRUE);
+            _PR_THREAD_UNLOCK(thread);
+#endif
+            break;
+        case WAIT_TIMEOUT:
+            _PR_THREAD_LOCK(thread);
+            if (thread->state == _PR_IO_WAIT) {
+                thread->state = _PR_RUNNING;
+                thread->io_suspended = PR_TRUE;
+                _PR_THREAD_UNLOCK(thread);
+            } else {
+                /*
+                 * The thread was interrupted just as the timeout
+                 * occurred. This left the semaphore in the signaled
+                 * state. Call WaitForSingleObject() to clear the
+                 * semaphore.
+                 */
+                PR_ASSERT(thread->io_suspended == PR_TRUE);
+                _PR_THREAD_UNLOCK(thread);
+                rv = WaitForSingleObject(thread->md.blocked_sema, INFINITE);
+                PR_ASSERT(rv == WAIT_OBJECT_0);
+            }
+            break;
+        default:
+            return PR_FAILURE;
+            break;
+    }
+
+    return PR_SUCCESS;
+}
+
+
+static PRStatus
+_NT_IO_WAIT(PRThread *thread, PRIntervalTime timeout)
+{
+    PRBool fWait = PR_TRUE;
+
+    if (_native_threads_only) {
+        return(_native_thread_io_wait(thread, timeout));
+    }
+    if (!_PR_IS_NATIVE_THREAD(thread))  {
+
+        _PR_THREAD_LOCK(thread);
+
+        /* The IO may have already completed; if so, don't add to sleepQ,
+         * since we are already on the runQ!
+         */
+        if (thread->io_pending == PR_TRUE) {
+            _PR_SLEEPQ_LOCK(thread->cpu);
+            _PR_ADD_SLEEPQ(thread, timeout);
+            _PR_SLEEPQ_UNLOCK(thread->cpu);
+        } else {
+            fWait = PR_FALSE;
+        }
+        _PR_THREAD_UNLOCK(thread);
+    }
+    if (fWait) {
+        return _PR_MD_WAIT(thread, timeout);
+    }
+    else {
+        return PR_SUCCESS;
+    }
+}
+
+/*
+ * Unblock threads waiting for I/O
+ * used when interrupting threads
+ *
+ * NOTE: The thread lock should held when this function is called.
+ * On return, the thread lock is released.
+ */
+void _PR_Unblock_IO_Wait(PRThread *thr)
+{
+    PRStatus rv;
+    _PRCPU *cpu = thr->cpu;
+
+    PR_ASSERT(thr->state == _PR_IO_WAIT);
+    /*
+     * A thread for which an I/O timed out or was interrupted cannot be
+     * in an IO_WAIT state except as a result of calling PR_Close or
+     * PR_NT_CancelIo for the FD. For these two cases, _PR_IO_WAIT state
+     * is not interruptible
+     */
+    if (thr->md.interrupt_disabled == PR_TRUE) {
+        _PR_THREAD_UNLOCK(thr);
+        return;
+    }
+    thr->io_suspended = PR_TRUE;
+    thr->state = _PR_RUNNABLE;
+
+    if (!_PR_IS_NATIVE_THREAD(thr)) {
+        PRThread *me = _PR_MD_CURRENT_THREAD();
+        PR_ASSERT(thr->flags & (_PR_ON_SLEEPQ | _PR_ON_PAUSEQ));
+        _PR_SLEEPQ_LOCK(cpu);
+        _PR_DEL_SLEEPQ(thr, PR_TRUE);
+        _PR_SLEEPQ_UNLOCK(cpu);
+        /*
+         * this thread will continue to run on the same cpu until the
+         * I/O is aborted by closing the FD or calling CancelIO
+         */
+        thr->md.thr_bound_cpu = cpu;
+
+        PR_ASSERT(!(thr->flags & _PR_IDLE_THREAD));
+        _PR_AddThreadToRunQ(me, thr);
+    }
+    _PR_THREAD_UNLOCK(thr);
+    rv = _PR_MD_WAKEUP_WAITER(thr);
+    PR_ASSERT(PR_SUCCESS == rv);
+}
+
+/* Resume an outstanding IO; requires that after the switch, we disable */
+static PRStatus
+_NT_ResumeIO(PRThread *thread, PRIntervalTime ticks)
+{
+    PRBool fWait = PR_TRUE;
+
+    if (!_PR_IS_NATIVE_THREAD(thread)) {
+        if (_pr_use_static_tls) {
+            _pr_io_restarted_io = thread;
+        } else {
+            TlsSetValue(_pr_io_restartedIOIndex, thread);
+        }
+    } else {
+        _PR_THREAD_LOCK(thread);
+        if (!thread->io_pending) {
+            fWait = PR_FALSE;
+        }
+        thread->io_suspended = PR_FALSE;
+
+        _PR_THREAD_UNLOCK(thread);
+    }
+    /* We don't put ourselves back on the sleepQ yet; until we
+     * set the suspended bit to false, we can't do that.  Just save
+     * the sleep time here, and then continue.  The restarted_io handler
+     * will add us to the sleepQ if needed.
+     */
+    thread->sleep = ticks;
+
+    if (fWait) {
+        if (!_PR_IS_NATIVE_THREAD(thread)) {
+            return _PR_MD_WAIT(thread, ticks);
+        }
+        else {
+            return _NT_IO_WAIT(thread, ticks);
+        }
+    }
+    return PR_SUCCESS;
+}
+
+PRStatus
+_PR_MD_WAKEUP_WAITER(PRThread *thread)
+{
+    if (thread == NULL) {
+        /* If thread is NULL, we aren't waking a thread, we're just poking
+         * idle thread
+         */
+        if ( PostQueuedCompletionStatus(_pr_completion_port, 0,
+                                        KEY_CVAR, NULL) == FALSE) {
+            return PR_FAILURE;
+        }
+        return PR_SUCCESS;
+    }
+
+    if ( _PR_IS_NATIVE_THREAD(thread) ) {
+        if (ReleaseSemaphore(thread->md.blocked_sema, 1, NULL) == FALSE) {
+            return PR_FAILURE;
+        }
+        else {
+            return PR_SUCCESS;
+        }
+    } else {
+        PRThread *me = _PR_MD_CURRENT_THREAD();
+
+        /* When a Native thread has to awaken a user thread, it has to poke
+         * the completion port because all user threads might be idle, and
+         * thus the CPUs are just waiting for a completion.
+         *
+         * XXXMB - can we know when we are truely idle (and not checking
+         *         the runq)?
+         */
+        if ((_PR_IS_NATIVE_THREAD(me) || (thread->cpu != me->cpu)) &&
+            (!thread->md.thr_bound_cpu)) {
+            /* The thread should not be in any queue */
+            PR_ASSERT(thread->queueCount == 0);
+            if ( PostQueuedCompletionStatus(_pr_completion_port, 0,
+                                            KEY_CVAR, &(thread->md.overlapped.overlapped)) == FALSE) {
+                return PR_FAILURE;
+            }
+        }
+        return PR_SUCCESS;
+    }
+}
+
+void
+_PR_MD_INIT_IO()
+{
+    WORD WSAVersion = 0x0101;
+    WSADATA WSAData;
+    int err;
+    OSVERSIONINFO OSversion;
+
+    err = WSAStartup( WSAVersion, &WSAData );
+    PR_ASSERT(0 == err);
+
+    _pr_completion_port = CreateIoCompletionPort(INVALID_HANDLE_VALUE,
+                          NULL,
+                          0,
+                          0);
+
+    _MD_NEW_LOCK(&_pr_recycle_lock);
+    _MD_NEW_LOCK(&_pr_ioq_lock);
+
+    OSversion.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);
+    if (GetVersionEx(&OSversion)) {
+        _nt_version_gets_lockfile_completion = PR_FALSE;
+        if (OSversion.dwMajorVersion >= 4) {
+            _nt_version_gets_lockfile_completion = PR_TRUE;
+        }
+    } else {
+        PR_ASSERT(0);
+    }
+
+#ifdef _NEED_351_FILE_LOCKING_HACK
+    IsFileLocalInit();
+#endif /* _NEED_351_FILE_LOCKING_HACK */
+
+    /*
+     * UDP support: start up the continuation thread
+     */
+
+    pt_tq.op_count = 0;
+    pt_tq.head = pt_tq.tail = NULL;
+    pt_tq.ml = PR_NewLock();
+    PR_ASSERT(NULL != pt_tq.ml);
+    pt_tq.new_op = PR_NewCondVar(pt_tq.ml);
+    PR_ASSERT(NULL != pt_tq.new_op);
+#if defined(DEBUG)
+    memset(&pt_debug, 0, sizeof(struct pt_debug_s));
+#endif
+
+    pt_tq.thread = PR_CreateThread(
+                       PR_SYSTEM_THREAD, ContinuationThread, NULL,
+                       PR_PRIORITY_URGENT, PR_GLOBAL_THREAD, PR_JOINABLE_THREAD, 0);
+
+    PR_ASSERT(NULL != pt_tq.thread);
+
+#ifdef DEBUG
+    /* Doublecheck _pr_filetime_offset's hard-coded value is correct. */
+    {
+        SYSTEMTIME systime;
+        union {
+            PRTime prt;
+            FILETIME ft;
+        } filetime;
+        BOOL rv;
+
+        systime.wYear = 1970;
+        systime.wMonth = 1;
+        /* wDayOfWeek is ignored */
+        systime.wDay = 1;
+        systime.wHour = 0;
+        systime.wMinute = 0;
+        systime.wSecond = 0;
+        systime.wMilliseconds = 0;
+
+        rv = SystemTimeToFileTime(&systime, &filetime.ft);
+        PR_ASSERT(0 != rv);
+        PR_ASSERT(filetime.prt == _pr_filetime_offset);
+    }
+#endif /* DEBUG */
+
+    _PR_NT_InitSids();
+}
+
+/* --- SOCKET IO --------------------------------------------------------- */
+
+/* _md_get_recycled_socket()
+ * Get a socket from the recycle bin; if no sockets are in the bin,
+ * create one.  The socket will be passed to AcceptEx() as the
+ * second argument.
+ */
+static SOCKET
+_md_get_recycled_socket(int af)
+{
+    SOCKET rv;
+
+    _MD_LOCK(&_pr_recycle_lock);
+    if (af == AF_INET && _pr_recycle_INET_tail) {
+        _pr_recycle_INET_tail--;
+        rv = _pr_recycle_INET_array[_pr_recycle_INET_tail];
+        _MD_UNLOCK(&_pr_recycle_lock);
+        return rv;
+    }
+    if (af == AF_INET6 && _pr_recycle_INET6_tail) {
+        _pr_recycle_INET6_tail--;
+        rv = _pr_recycle_INET6_array[_pr_recycle_INET6_tail];
+        _MD_UNLOCK(&_pr_recycle_lock);
+        return rv;
+    }
+    _MD_UNLOCK(&_pr_recycle_lock);
+
+    rv = _PR_MD_SOCKET(af, SOCK_STREAM, 0);
+    if (rv != INVALID_SOCKET && _md_Associate((HANDLE)rv) == 0) {
+        closesocket(rv);
+        return INVALID_SOCKET;
+    }
+    return rv;
+}
+
+/* _md_put_recycled_socket()
+ * Add a socket to the recycle bin.
+ */
+static void
+_md_put_recycled_socket(SOCKET newsock, int af)
+{
+    PR_ASSERT(_pr_recycle_INET_tail >= 0);
+    PR_ASSERT(_pr_recycle_INET6_tail >= 0);
+
+    _MD_LOCK(&_pr_recycle_lock);
+    if (af == AF_INET && _pr_recycle_INET_tail < RECYCLE_SIZE) {
+        _pr_recycle_INET_array[_pr_recycle_INET_tail] = newsock;
+        _pr_recycle_INET_tail++;
+        _MD_UNLOCK(&_pr_recycle_lock);
+    } else if (af == AF_INET6 && _pr_recycle_INET6_tail < RECYCLE_SIZE) {
+        _pr_recycle_INET6_array[_pr_recycle_INET6_tail] = newsock;
+        _pr_recycle_INET6_tail++;
+        _MD_UNLOCK(&_pr_recycle_lock);
+    } else {
+        _MD_UNLOCK(&_pr_recycle_lock);
+        closesocket(newsock);
+    }
+
+    return;
+}
+
+/* _md_Associate()
+ * Associates a file with the completion port.
+ * Returns 0 on failure, 1 on success.
+ */
+PRInt32
+_md_Associate(HANDLE file)
+{
+    HANDLE port;
+
+    if (!_native_threads_only) {
+        port = CreateIoCompletionPort((HANDLE)file,
+                                      _pr_completion_port,
+                                      KEY_IO,
+                                      0);
+
+        /* XXX should map error codes on failures */
+        return (port == _pr_completion_port);
+    } else {
+        return 1;
+    }
+}
+
+/*
+ * _md_MakeNonblock()
+ * Make a socket nonblocking.
+ * Returns 0 on failure, 1 on success.
+ */
+static PRInt32
+_md_MakeNonblock(HANDLE file)
+{
+    int rv;
+    u_long one = 1;
+
+    rv = ioctlsocket((SOCKET)file, FIONBIO, &one);
+    /* XXX should map error codes on failures */
+    return (rv == 0);
+}
+
+static int missing_completions = 0;
+static int max_wait_loops = 0;
+
+static PRInt32
+_NT_IO_ABORT(PROsfd sock)
+{
+    PRThread *me = _PR_MD_CURRENT_THREAD();
+    PRBool fWait;
+    PRInt32 rv;
+    int loop_count;
+
+    /* This is a clumsy way to abort the IO, but it is all we can do.
+     * It looks a bit racy, but we handle all the cases.
+     * case 1:  IO completes before calling closesocket
+     *     case 1a:  fWait is set to PR_FALSE
+     *           This should e the most likely case.  We'll properly
+     *           not wait call _NT_IO_WAIT, since the closesocket()
+     *           won't be forcing a completion.
+     *     case 1b: fWait is set to PR_TRUE
+     *           This hopefully won't happen much.  When it does, this
+     *           thread will timeout in _NT_IO_WAIT for CLOSE_INTERVAL
+     *           before cleaning up.
+     * case 2:  IO does not complete before calling closesocket
+     *     case 2a: IO never completes
+     *           This is the likely case.  We'll close it and wait
+     *           for the completion forced by the close.  Return should
+     *           be immediate.
+     *     case 2b: IO completes just after calling closesocket
+     *           Since the closesocket is issued, we'll either get a
+     *           completion back for the real IO or for the close.  We
+     *           don't really care.  It may not even be possible to get
+     *           a real completion here.  In any event, we'll awaken
+     *           from NT_IO_WAIT immediately.
+     */
+
+    _PR_THREAD_LOCK(me);
+    fWait = me->io_pending;
+    if (fWait) {
+        /*
+         * If there's still I/O pending, it should have already timed
+         * out once before this function is called.
+         */
+        PR_ASSERT(me->io_suspended == PR_TRUE);
+
+        /* Set up to wait for I/O completion again */
+        me->state = _PR_IO_WAIT;
+        me->io_suspended = PR_FALSE;
+        me->md.interrupt_disabled = PR_TRUE;
+    }
+    _PR_THREAD_UNLOCK(me);
+
+    /* Close the socket if there is one */
+    if (sock != INVALID_SOCKET) {
+        rv = closesocket((SOCKET)sock);
+    }
+
+    /* If there was I/O pending before the close, wait for it to complete */
+    if (fWait) {
+
+        /* Wait and wait for the I/O to complete */
+        for (loop_count = 0; fWait; ++loop_count) {
+
+            _NT_IO_WAIT(me, CLOSE_TIMEOUT);
+
+            _PR_THREAD_LOCK(me);
+            fWait = me->io_pending;
+            if (fWait) {
+                PR_ASSERT(me->io_suspended == PR_TRUE);
+                me->state = _PR_IO_WAIT;
+                me->io_suspended = PR_FALSE;
+            }
+            _PR_THREAD_UNLOCK(me);
+
+            if (loop_count > max_wait_loops) {
+                max_wait_loops = loop_count;
+            }
+        }
+
+        if (loop_count > 1) {
+            ++missing_completions;
+        }
+
+        me->md.interrupt_disabled = PR_FALSE;
+        me->io_pending = PR_FALSE;
+        me->state = _PR_RUNNING;
+    }
+
+    PR_ASSERT(me->io_pending == PR_FALSE);
+    me->md.thr_bound_cpu = NULL;
+    me->io_suspended = PR_FALSE;
+
+    return rv;
+}
+
+
+PROsfd
+_PR_MD_SOCKET(int af, int type, int flags)
+{
+    SOCKET sock;
+
+    sock = socket(af, type, flags);
+
+    if (sock == INVALID_SOCKET) {
+        _PR_MD_MAP_SOCKET_ERROR(WSAGetLastError());
+    }
+
+    return (PROsfd)sock;
+}
+
+struct connect_data_s {
+    PRInt32 status;
+    PRInt32 error;
+    PROsfd  osfd;
+    struct sockaddr *addr;
+    PRUint32 addrlen;
+    PRIntervalTime timeout;
+};
+
+void
+_PR_MD_connect_thread(void *cdata)
+{
+    struct connect_data_s *cd = (struct connect_data_s *)cdata;
+
+    cd->status = connect(cd->osfd, cd->addr, cd->addrlen);
+
+    if (cd->status == SOCKET_ERROR) {
+        cd->error = WSAGetLastError();
+    }
+
+    return;
+}
+
+
+PRInt32
+_PR_MD_CONNECT(PRFileDesc *fd, const PRNetAddr *addr, PRUint32 addrlen,
+               PRIntervalTime timeout)
+{
+    PROsfd osfd = fd->secret->md.osfd;
+    PRInt32 rv, err;
+    u_long nbio;
+    PRInt32 rc;
+
+    if (fd->secret->nonblocking) {
+        if (!fd->secret->md.io_model_committed) {
+            rv = _md_MakeNonblock((HANDLE)osfd);
+            PR_ASSERT(0 != rv);
+            fd->secret->md.io_model_committed = PR_TRUE;
+        }
+
+        if ((rv = connect(osfd, (struct sockaddr *) addr, addrlen)) == -1) {
+            err = WSAGetLastError();
+            _PR_MD_MAP_CONNECT_ERROR(err);
+        }
+        return rv;
+    }
+
+    /*
+     * Temporarily make the socket non-blocking so that we can
+     * initiate a non-blocking connect and wait for its completion
+     * (with a timeout) in select.
+     */
+    PR_ASSERT(!fd->secret->md.io_model_committed);
+    nbio = 1;
+    rv = ioctlsocket((SOCKET)osfd, FIONBIO, &nbio);
+    PR_ASSERT(0 == rv);
+
+    rc = _nt_nonblock_connect(fd, (struct sockaddr *) addr, addrlen, timeout);
+
+    /* Set the socket back to blocking. */
+    nbio = 0;
+    rv = ioctlsocket((SOCKET)osfd, FIONBIO, &nbio);
+    PR_ASSERT(0 == rv);
+
+    return rc;
+}
+
+PRInt32
+_PR_MD_BIND(PRFileDesc *fd, const PRNetAddr *addr, PRUint32 addrlen)
+{
+    PRInt32 rv;
+#if 0
+    int one = 1;
+#endif
+
+    rv = bind(fd->secret->md.osfd, (const struct sockaddr *)&(addr->inet), addrlen);
+
+    if (rv == SOCKET_ERROR) {
+        _PR_MD_MAP_BIND_ERROR(WSAGetLastError());
+        return -1;
+    }
+
+#if 0
+    /* Disable nagle- so far unknown if this is good or not...
+     */
+    rv = setsockopt(fd->secret->md.osfd,
+                    SOL_SOCKET,
+                    TCP_NODELAY,
+                    (const char *)&one,
+                    sizeof(one));
+    PR_ASSERT(rv == 0);
+#endif
+
+    return 0;
+}
+
+void _PR_MD_UPDATE_ACCEPT_CONTEXT(PROsfd accept_sock, PROsfd listen_sock)
+{
+    /* Sockets accept()'d with AcceptEx need to call this setsockopt before
+     * calling anything other than ReadFile(), WriteFile(), send(), recv(),
+     * Transmitfile(), and closesocket().  In order to call any other
+     * winsock functions, we have to make this setsockopt call.
+     *
+     * XXXMB - For the server, we *NEVER* need this in
+     * the "normal" code path.  But now we have to call it.  This is a waste
+     * of a system call.  We'd like to only call it before calling the
+     * obscure socket calls, but since we don't know at that point what the
+     * original socket was (or even if it is still alive) we can't do it
+     * at that point...
+     */
+    setsockopt((SOCKET)accept_sock,
+               SOL_SOCKET,
+               SO_UPDATE_ACCEPT_CONTEXT,
+               (char *)&listen_sock,
+               sizeof(listen_sock));
+
+}
+
+#define INET_ADDR_PADDED (sizeof(PRNetAddr) + 16)
+PROsfd
+_PR_MD_FAST_ACCEPT(PRFileDesc *fd, PRNetAddr *raddr, PRUint32 *rlen,
+                   PRIntervalTime timeout, PRBool fast,
+                   _PR_AcceptTimeoutCallback callback, void *callbackArg)
+{
+    PROsfd osfd = fd->secret->md.osfd;
+    PRThread *me = _PR_MD_CURRENT_THREAD();
+    SOCKET accept_sock;
+    int bytes;
+    PRNetAddr *Laddr;
+    PRNetAddr *Raddr;
+    PRUint32 llen, err;
+    int rv;
+
+    if (_NT_USE_NB_IO(fd)) {
+        if (!fd->secret->md.io_model_committed) {
+            rv = _md_MakeNonblock((HANDLE)osfd);
+            PR_ASSERT(0 != rv);
+            fd->secret->md.io_model_committed = PR_TRUE;
+        }
+        /*
+         * The accepted socket inherits the nonblocking and
+         * inheritable (HANDLE_FLAG_INHERIT) attributes of
+         * the listening socket.
+         */
+        accept_sock = _nt_nonblock_accept(fd, (struct sockaddr *)raddr, rlen, timeout);
+        if (!fd->secret->nonblocking) {
+            u_long zero = 0;
+
+            rv = ioctlsocket(accept_sock, FIONBIO, &zero);
+            PR_ASSERT(0 == rv);
+        }
+        return accept_sock;
+    }
+
+    if (me->io_suspended) {
+        PR_SetError(PR_INVALID_STATE_ERROR, 0);
+        return -1;
+    }
+
+    if (!fd->secret->md.io_model_committed) {
+        rv = _md_Associate((HANDLE)osfd);
+        PR_ASSERT(0 != rv);
+        fd->secret->md.io_model_committed = PR_TRUE;
+    }
+
+    if (!me->md.acceptex_buf) {
+        me->md.acceptex_buf = PR_MALLOC(2*INET_ADDR_PADDED);
+        if (!me->md.acceptex_buf) {
+            PR_SetError(PR_OUT_OF_MEMORY_ERROR, 0);
+            return -1;
+        }
+    }
+
+    accept_sock = _md_get_recycled_socket(fd->secret->af);
+    if (accept_sock == INVALID_SOCKET) {
+        return -1;
+    }
+
+    memset(&(me->md.overlapped.overlapped), 0, sizeof(OVERLAPPED));
+    if (_native_threads_only) {
+        me->md.overlapped.overlapped.hEvent = me->md.thr_event;
+    }
+
+    _PR_THREAD_LOCK(me);
+    if (_PR_PENDING_INTERRUPT(me)) {
+        me->flags &= ~_PR_INTERRUPT;
+        PR_SetError(PR_PENDING_INTERRUPT_ERROR, 0);
+        _PR_THREAD_UNLOCK(me);
+        closesocket(accept_sock);
+        return -1;
+    }
+    me->io_pending = PR_TRUE;
+    me->state = _PR_IO_WAIT;
+    _PR_THREAD_UNLOCK(me);
+    me->io_fd = osfd;
+
+    rv = AcceptEx((SOCKET)osfd,
+                  accept_sock,
+                  me->md.acceptex_buf,
+                  0,
+                  INET_ADDR_PADDED,
+                  INET_ADDR_PADDED,
+                  &bytes,
+                  &(me->md.overlapped.overlapped));
+
+    if ( (rv == 0) && ((err = WSAGetLastError()) != ERROR_IO_PENDING))  {
+        /* Argh! The IO failed */
+        closesocket(accept_sock);
+        _PR_THREAD_LOCK(me);
+        me->io_pending = PR_FALSE;
+        me->state = _PR_RUNNING;
+        if (_PR_PENDING_INTERRUPT(me)) {
+            me->flags &= ~_PR_INTERRUPT;
+            PR_SetError(PR_PENDING_INTERRUPT_ERROR, 0);
+            _PR_THREAD_UNLOCK(me);
+            return -1;
+        }
+        _PR_THREAD_UNLOCK(me);
+
+        _PR_MD_MAP_ACCEPTEX_ERROR(err);
+        return -1;
+    }
+
+    if (_native_threads_only && rv) {
+        _native_thread_io_nowait(me, rv, bytes);
+    } else if (_NT_IO_WAIT(me, timeout) == PR_FAILURE) {
+        PR_ASSERT(0);
+        closesocket(accept_sock);
+        return -1;
+    }
+
+    PR_ASSERT(me->io_pending == PR_FALSE || me->io_suspended == PR_TRUE);
+
+    if (me->io_suspended) {
+        closesocket(accept_sock);
+        if (_PR_PENDING_INTERRUPT(me)) {
+            me->flags &= ~_PR_INTERRUPT;
+            PR_SetError(PR_PENDING_INTERRUPT_ERROR, 0);
+        } else {
+            PR_SetError(PR_IO_TIMEOUT_ERROR, 0);
+        }
+        return -1;
+    }
+
+    if (me->md.blocked_io_status == 0) {
+        closesocket(accept_sock);
+        _PR_MD_MAP_ACCEPTEX_ERROR(me->md.blocked_io_error);
+        return -1;
+    }
+
+    if (!fast) {
+        _PR_MD_UPDATE_ACCEPT_CONTEXT((SOCKET)accept_sock, (SOCKET)osfd);
+    }
+
+    /* IO is done */
+    GetAcceptExSockaddrs(
+        me->md.acceptex_buf,
+        0,
+        INET_ADDR_PADDED,
+        INET_ADDR_PADDED,
+        (LPSOCKADDR *)&(Laddr),
+        &llen,
+        (LPSOCKADDR *)&(Raddr),
+        (unsigned int *)rlen);
+
+    if (raddr != NULL) {
+        memcpy((char *)raddr, (char *)&Raddr->inet, *rlen);
+    }
+
+    PR_ASSERT(me->io_pending == PR_FALSE);
+
+    return accept_sock;
+}
+
+PRInt32
+_PR_MD_FAST_ACCEPT_READ(PRFileDesc *sd, PROsfd *newSock, PRNetAddr **raddr,
+                        void *buf, PRInt32 amount, PRIntervalTime timeout,
+                        PRBool fast, _PR_AcceptTimeoutCallback callback,
+                        void *callbackArg)
+{
+    PROsfd sock = sd->secret->md.osfd;
+    PRThread *me = _PR_MD_CURRENT_THREAD();
+    int bytes;
+    PRNetAddr *Laddr;
+    PRUint32 llen, rlen, err;
+    int rv;
+    PRBool isConnected;
+    PRBool madeCallback = PR_FALSE;
+
+    if (me->io_suspended) {
+        PR_SetError(PR_INVALID_STATE_ERROR, 0);
+        return -1;
+    }
+
+    if (!sd->secret->md.io_model_committed) {
+        rv = _md_Associate((HANDLE)sock);
+        PR_ASSERT(0 != rv);
+        sd->secret->md.io_model_committed = PR_TRUE;
+    }
+
+    *newSock = _md_get_recycled_socket(sd->secret->af);
+    if (*newSock == INVALID_SOCKET) {
+        return -1;
+    }
+
+    memset(&(me->md.overlapped.overlapped), 0, sizeof(OVERLAPPED));
+    if (_native_threads_only) {
+        me->md.overlapped.overlapped.hEvent = me->md.thr_event;
+    }
+
+    _PR_THREAD_LOCK(me);
+    if (_PR_PENDING_INTERRUPT(me)) {
+        me->flags &= ~_PR_INTERRUPT;
+        PR_SetError(PR_PENDING_INTERRUPT_ERROR, 0);
+        _PR_THREAD_UNLOCK(me);
+        closesocket(*newSock);
+        return -1;
+    }
+    me->io_pending = PR_TRUE;
+    me->state = _PR_IO_WAIT;
+    _PR_THREAD_UNLOCK(me);
+    me->io_fd = sock;
+
+    rv = AcceptEx((SOCKET)sock,
+                  *newSock,
+                  buf,
+                  amount,
+                  INET_ADDR_PADDED,
+                  INET_ADDR_PADDED,
+                  &bytes,
+                  &(me->md.overlapped.overlapped));
+
+    if ( (rv == 0) && ((err = GetLastError()) != ERROR_IO_PENDING)) {
+        closesocket(*newSock);
+        _PR_THREAD_LOCK(me);
+        me->io_pending = PR_FALSE;
+        me->state = _PR_RUNNING;
+        if (_PR_PENDING_INTERRUPT(me)) {
+            me->flags &= ~_PR_INTERRUPT;
+            PR_SetError(PR_PENDING_INTERRUPT_ERROR, 0);
+            _PR_THREAD_UNLOCK(me);
+            return -1;
+        }
+        _PR_THREAD_UNLOCK(me);
+
+        _PR_MD_MAP_ACCEPTEX_ERROR(err);
+        return -1;
+    }
+
+    if (_native_threads_only && rv) {
+        _native_thread_io_nowait(me, rv, bytes);
+    } else if (_NT_IO_WAIT(me, timeout) == PR_FAILURE) {
+        PR_ASSERT(0);
+        closesocket(*newSock);
+        return -1;
+    }
+
+retry:
+    if (me->io_suspended) {
+        PRInt32 err;
+        INT seconds;
+        INT bytes = sizeof(seconds);
+
+        PR_ASSERT(timeout != PR_INTERVAL_NO_TIMEOUT);
+
+        err = getsockopt(*newSock,
+                         SOL_SOCKET,
+                         SO_CONNECT_TIME,
+                         (char *)&seconds,
+                         (PINT)&bytes);
+        if ( err == NO_ERROR ) {
+            PRIntervalTime elapsed = PR_SecondsToInterval(seconds);
+
+            if (seconds == 0xffffffff) {
+                isConnected = PR_FALSE;
+            }
+            else {
+                isConnected = PR_TRUE;
+            }
+
+            if (!isConnected) {
+                if (madeCallback == PR_FALSE && callback) {
+                    callback(callbackArg);
+                }
+                madeCallback = PR_TRUE;
+                me->state = _PR_IO_WAIT;
+                if (_NT_ResumeIO(me, timeout) == PR_FAILURE) {
+                    closesocket(*newSock);
+                    return -1;
+                }
+                goto retry;
+            }
+
+            if (elapsed < timeout) {
+                /* Socket is connected but time not elapsed, RESUME IO */
+                timeout -= elapsed;
+                me->state = _PR_IO_WAIT;
+                if (_NT_ResumeIO(me, timeout) == PR_FAILURE) {
+                    closesocket(*newSock);
+                    return -1;
+                }
+                goto retry;
+            }
+        } else {
+            /*  What to do here? Assume socket not open?*/
+            PR_ASSERT(0);
+            isConnected = PR_FALSE;
+        }
+
+        rv = _NT_IO_ABORT(*newSock);
+
+        PR_ASSERT(me->io_pending ==  PR_FALSE);
+        PR_ASSERT(me->io_suspended ==  PR_FALSE);
+        PR_ASSERT(me->md.thr_bound_cpu ==  NULL);
+        /* If the IO is still suspended, it means we didn't get any
+         * completion from NT_IO_WAIT.  This is not disasterous, I hope,
+         * but it may mean we still have an IO outstanding...  Try to
+         * recover by just allowing ourselves to continue.
+         */
+        me->io_suspended = PR_FALSE;
+        if (_PR_PENDING_INTERRUPT(me)) {
+            me->flags &= ~_PR_INTERRUPT;
+            PR_SetError(PR_PENDING_INTERRUPT_ERROR, 0);
+        } else {
+            PR_SetError(PR_IO_TIMEOUT_ERROR, 0);
+        }
+        me->state = _PR_RUNNING;
+        closesocket(*newSock);
+        return -1;
+    }
+
+    PR_ASSERT(me->io_pending == PR_FALSE);
+    PR_ASSERT(me->io_suspended == PR_FALSE);
+    PR_ASSERT(me->md.thr_bound_cpu == NULL);
+
+    if (me->md.blocked_io_status == 0) {
+        _PR_MD_MAP_ACCEPTEX_ERROR(me->md.blocked_io_error);
+        closesocket(*newSock);
+        return -1;
+    }
+
+    if (!fast) {
+        _PR_MD_UPDATE_ACCEPT_CONTEXT((SOCKET)*newSock, (SOCKET)sock);
+    }
+
+    /* IO is done */
+    GetAcceptExSockaddrs(
+        buf,
+        amount,
+        INET_ADDR_PADDED,
+        INET_ADDR_PADDED,
+        (LPSOCKADDR *)&(Laddr),
+        &llen,
+        (LPSOCKADDR *)(raddr),
+        (unsigned int *)&rlen);
+
+    return me->md.blocked_io_bytes;
+}
+
+PRInt32
+_PR_MD_SENDFILE(PRFileDesc *sock, PRSendFileData *sfd,
+                PRInt32 flags, PRIntervalTime timeout)
+{
+    PRThread *me = _PR_MD_CURRENT_THREAD();
+    PRInt32 tflags;
+    int rv, err;
+
+    if (me->io_suspended) {
+        PR_SetError(PR_INVALID_STATE_ERROR, 0);
+        return -1;
+    }
+
+    if (!sock->secret->md.io_model_committed) {
+        rv = _md_Associate((HANDLE)sock->secret->md.osfd);
+        PR_ASSERT(0 != rv);
+        sock->secret->md.io_model_committed = PR_TRUE;
+    }
+    if (!me->md.xmit_bufs) {
+        me->md.xmit_bufs = PR_NEW(TRANSMIT_FILE_BUFFERS);
+        if (!me->md.xmit_bufs) {
+            PR_SetError(PR_OUT_OF_MEMORY_ERROR, 0);
+            return -1;
+        }
+    }
+    me->md.xmit_bufs->Head       = (void *)sfd->header;
+    me->md.xmit_bufs->HeadLength = sfd->hlen;
+    me->md.xmit_bufs->Tail       = (void *)sfd->trailer;
+    me->md.xmit_bufs->TailLength = sfd->tlen;
+
+    memset(&(me->md.overlapped.overlapped), 0, sizeof(OVERLAPPED));
+    me->md.overlapped.overlapped.Offset = sfd->file_offset;
+    if (_native_threads_only) {
+        me->md.overlapped.overlapped.hEvent = me->md.thr_event;
+    }
+
+    tflags = 0;
+    if (flags & PR_TRANSMITFILE_CLOSE_SOCKET) {
+        tflags = TF_DISCONNECT | TF_REUSE_SOCKET;
+    }
+
+    _PR_THREAD_LOCK(me);
+    if (_PR_PENDING_INTERRUPT(me)) {
+        me->flags &= ~_PR_INTERRUPT;
+        PR_SetError(PR_PENDING_INTERRUPT_ERROR, 0);
+        _PR_THREAD_UNLOCK(me);
+        return -1;
+    }
+    me->io_pending = PR_TRUE;
+    me->state = _PR_IO_WAIT;
+    _PR_THREAD_UNLOCK(me);
+    me->io_fd = sock->secret->md.osfd;
+
+    rv = TransmitFile((SOCKET)sock->secret->md.osfd,
+                      (HANDLE)sfd->fd->secret->md.osfd,
+                      (DWORD)sfd->file_nbytes,
+                      (DWORD)0,
+                      (LPOVERLAPPED)&(me->md.overlapped.overlapped),
+                      (TRANSMIT_FILE_BUFFERS *)me->md.xmit_bufs,
+                      (DWORD)tflags);
+    if ( (rv == 0) && ((err = GetLastError()) != ERROR_IO_PENDING) ) {
+        _PR_THREAD_LOCK(me);
+        me->io_pending = PR_FALSE;
+        me->state = _PR_RUNNING;
+        if (_PR_PENDING_INTERRUPT(me)) {
+            me->flags &= ~_PR_INTERRUPT;
+            PR_SetError(PR_PENDING_INTERRUPT_ERROR, 0);
+            _PR_THREAD_UNLOCK(me);
+            return -1;
+        }
+        _PR_THREAD_UNLOCK(me);
+
+        _PR_MD_MAP_TRANSMITFILE_ERROR(err);
+        return -1;
+    }
+
+    if (_NT_IO_WAIT(me, timeout) == PR_FAILURE) {
+        PR_ASSERT(0);
+        return -1;
+    }
+
+    PR_ASSERT(me->io_pending == PR_FALSE || me->io_suspended == PR_TRUE);
+
+    if (me->io_suspended) {
+        if (_PR_PENDING_INTERRUPT(me)) {
+            me->flags &= ~_PR_INTERRUPT;
+            PR_SetError(PR_PENDING_INTERRUPT_ERROR, 0);
+        } else {
+            PR_SetError(PR_IO_TIMEOUT_ERROR, 0);
+        }
+        return -1;
+    }
+
+    if (me->md.blocked_io_status == 0) {
+        _PR_MD_MAP_TRANSMITFILE_ERROR(me->md.blocked_io_error);
+        return -1;
+    }
+
+    if (flags & PR_TRANSMITFILE_CLOSE_SOCKET) {
+        _md_put_recycled_socket(sock->secret->md.osfd, sock->secret->af);
+    }
+
+    PR_ASSERT(me->io_pending == PR_FALSE);
+
+    return me->md.blocked_io_bytes;
+}
+
+PRInt32
+_PR_MD_RECV(PRFileDesc *fd, void *buf, PRInt32 amount, PRIntn flags,
+            PRIntervalTime timeout)
+{
+    PROsfd osfd = fd->secret->md.osfd;
+    PRThread *me = _PR_MD_CURRENT_THREAD();
+    int bytes;
+    int rv, err;
+
+    if (_NT_USE_NB_IO(fd)) {
+        if (!fd->secret->md.io_model_committed) {
+            rv = _md_MakeNonblock((HANDLE)osfd);
+            PR_ASSERT(0 != rv);
+            fd->secret->md.io_model_committed = PR_TRUE;
+        }
+        return _nt_nonblock_recv(fd, buf, amount, flags, timeout);
+    }
+
+    if (me->io_suspended) {
+        PR_SetError(PR_INVALID_STATE_ERROR, 0);
+        return -1;
+    }
+
+    if (!fd->secret->md.io_model_committed) {
+        rv = _md_Associate((HANDLE)osfd);
+        PR_ASSERT(0 != rv);
+        fd->secret->md.io_model_committed = PR_TRUE;
+    }
+
+    memset(&(me->md.overlapped.overlapped), 0, sizeof(OVERLAPPED));
+    if (_native_threads_only) {
+        me->md.overlapped.overlapped.hEvent = me->md.thr_event;
+    }
+
+    _PR_THREAD_LOCK(me);
+    if (_PR_PENDING_INTERRUPT(me)) {
+        me->flags &= ~_PR_INTERRUPT;
+        PR_SetError(PR_PENDING_INTERRUPT_ERROR, 0);
+        _PR_THREAD_UNLOCK(me);
+        return -1;
+    }
+    me->io_pending = PR_TRUE;
+    me->state = _PR_IO_WAIT;
+    _PR_THREAD_UNLOCK(me);
+    me->io_fd = osfd;
+
+    rv = ReadFile((HANDLE)osfd,
+                  buf,
+                  amount,
+                  &bytes,
+                  &(me->md.overlapped.overlapped));
+    if ( (rv == 0) && (GetLastError() != ERROR_IO_PENDING) ) {
+        _PR_THREAD_LOCK(me);
+        me->io_pending = PR_FALSE;
+        me->state = _PR_RUNNING;
+        if (_PR_PENDING_INTERRUPT(me)) {
+            me->flags &= ~_PR_INTERRUPT;
+            PR_SetError(PR_PENDING_INTERRUPT_ERROR, 0);
+            _PR_THREAD_UNLOCK(me);
+            return -1;
+        }
+        _PR_THREAD_UNLOCK(me);
+
+        if ((err = GetLastError()) == ERROR_HANDLE_EOF) {
+            return 0;
+        }
+        _PR_MD_MAP_READ_ERROR(err);
+        return -1;
+    }
+
+    if (_native_threads_only && rv) {
+        _native_thread_io_nowait(me, rv, bytes);
+    } else if (_NT_IO_WAIT(me, timeout) == PR_FAILURE) {
+        PR_ASSERT(0);
+        return -1;
+    }
+
+    PR_ASSERT(me->io_pending == PR_FALSE || me->io_suspended == PR_TRUE);
+
+    if (me->io_suspended) {
+        if (_PR_PENDING_INTERRUPT(me)) {
+            me->flags &= ~_PR_INTERRUPT;
+            PR_SetError(PR_PENDING_INTERRUPT_ERROR, 0);
+        } else {
+            PR_SetError(PR_IO_TIMEOUT_ERROR, 0);
+        }
+        return -1;
+    }
+
+    if (me->md.blocked_io_status == 0) {
+        if (me->md.blocked_io_error == ERROR_HANDLE_EOF) {
+            return 0;
+        }
+        _PR_MD_MAP_READ_ERROR(me->md.blocked_io_error);
+        return -1;
+    }
+
+    PR_ASSERT(me->io_pending == PR_FALSE);
+
+    return me->md.blocked_io_bytes;
+}
+
+PRInt32
+_PR_MD_SEND(PRFileDesc *fd, const void *buf, PRInt32 amount, PRIntn flags,
+            PRIntervalTime timeout)
+{
+    PROsfd osfd = fd->secret->md.osfd;
+    PRThread *me = _PR_MD_CURRENT_THREAD();
+    int bytes;
+    int rv, err;
+
+    if (_NT_USE_NB_IO(fd)) {
+        if (!fd->secret->md.io_model_committed) {
+            rv = _md_MakeNonblock((HANDLE)osfd);
+            PR_ASSERT(0 != rv);
+            fd->secret->md.io_model_committed = PR_TRUE;
+        }
+        return _nt_nonblock_send(fd, (char *)buf, amount, timeout);
+    }
+
+    if (me->io_suspended) {
+        PR_SetError(PR_INVALID_STATE_ERROR, 0);
+        return -1;
+    }
+
+    if (!fd->secret->md.io_model_committed) {
+        rv = _md_Associate((HANDLE)osfd);
+        PR_ASSERT(0 != rv);
+        fd->secret->md.io_model_committed = PR_TRUE;
+    }
+
+    memset(&(me->md.overlapped.overlapped), 0, sizeof(OVERLAPPED));
+    if (_native_threads_only) {
+        me->md.overlapped.overlapped.hEvent = me->md.thr_event;
+    }
+
+    _PR_THREAD_LOCK(me);
+    if (_PR_PENDING_INTERRUPT(me)) {
+        me->flags &= ~_PR_INTERRUPT;
+        PR_SetError(PR_PENDING_INTERRUPT_ERROR, 0);
+        _PR_THREAD_UNLOCK(me);
+        return -1;
+    }
+    me->io_pending = PR_TRUE;
+    me->state = _PR_IO_WAIT;
+    _PR_THREAD_UNLOCK(me);
+    me->io_fd = osfd;
+
+    rv = WriteFile((HANDLE)osfd,
+                   buf,
+                   amount,
+                   &bytes,
+                   &(me->md.overlapped.overlapped));
+    if ( (rv == 0) && ((err = GetLastError()) != ERROR_IO_PENDING) ) {
+        _PR_THREAD_LOCK(me);
+        me->io_pending = PR_FALSE;
+        me->state = _PR_RUNNING;
+        if (_PR_PENDING_INTERRUPT(me)) {
+            me->flags &= ~_PR_INTERRUPT;
+            PR_SetError(PR_PENDING_INTERRUPT_ERROR, 0);
+            _PR_THREAD_UNLOCK(me);
+            return -1;
+        }
+        _PR_THREAD_UNLOCK(me);
+
+        _PR_MD_MAP_WRITE_ERROR(err);
+        return -1;
+    }
+
+    if (_native_threads_only && rv) {
+        _native_thread_io_nowait(me, rv, bytes);
+    } else if (_NT_IO_WAIT(me, timeout) == PR_FAILURE) {
+        PR_ASSERT(0);
+        return -1;
+    }
+
+    PR_ASSERT(me->io_pending == PR_FALSE || me->io_suspended == PR_TRUE);
+
+    if (me->io_suspended) {
+        if (_PR_PENDING_INTERRUPT(me)) {
+            me->flags &= ~_PR_INTERRUPT;
+            PR_SetError(PR_PENDING_INTERRUPT_ERROR, 0);
+        } else {
+            PR_SetError(PR_IO_TIMEOUT_ERROR, 0);
+        }
+        return -1;
+    }
+
+    if (me->md.blocked_io_status == 0) {
+        _PR_MD_MAP_WRITE_ERROR(me->md.blocked_io_error);
+        return -1;
+    }
+
+    PR_ASSERT(me->io_pending == PR_FALSE);
+
+    return me->md.blocked_io_bytes;
+}
+
+PRInt32
+_PR_MD_SENDTO(PRFileDesc *fd, const void *buf, PRInt32 amount, PRIntn flags,
+              const PRNetAddr *addr, PRUint32 addrlen, PRIntervalTime timeout)
+{
+    PROsfd osfd = fd->secret->md.osfd;
+    PRInt32 rv;
+
+    if (!fd->secret->md.io_model_committed) {
+        rv = _md_MakeNonblock((HANDLE)osfd);
+        PR_ASSERT(0 != rv);
+        fd->secret->md.io_model_committed = PR_TRUE;
+    }
+    if (_NT_USE_NB_IO(fd)) {
+        return _nt_nonblock_sendto(fd, buf, amount, (struct sockaddr *)addr, addrlen, timeout);
+    }
+    else {
+        return pt_SendTo(osfd, buf, amount, flags, addr, addrlen, timeout);
+    }
+}
+
+PRInt32
+_PR_MD_RECVFROM(PRFileDesc *fd, void *buf, PRInt32 amount, PRIntn flags,
+                PRNetAddr *addr, PRUint32 *addrlen, PRIntervalTime timeout)
+{
+    PROsfd osfd = fd->secret->md.osfd;
+    PRInt32 rv;
+
+    if (!fd->secret->md.io_model_committed) {
+        rv = _md_MakeNonblock((HANDLE)osfd);
+        PR_ASSERT(0 != rv);
+        fd->secret->md.io_model_committed = PR_TRUE;
+    }
+    if (_NT_USE_NB_IO(fd)) {
+        return _nt_nonblock_recvfrom(fd, buf, amount, (struct sockaddr *)addr, addrlen, timeout);
+    }
+    else {
+        return pt_RecvFrom(osfd, buf, amount, flags, addr, addrlen, timeout);
+    }
+}
+
+/* XXXMB - for now this is a sockets call only */
+PRInt32
+_PR_MD_WRITEV(PRFileDesc *fd, const PRIOVec *iov, PRInt32 iov_size, PRIntervalTime timeout)
+{
+    PROsfd osfd = fd->secret->md.osfd;
+    int index;
+    int sent = 0;
+    int rv;
+
+    if (_NT_USE_NB_IO(fd)) {
+        if (!fd->secret->md.io_model_committed) {
+            rv = _md_MakeNonblock((HANDLE)osfd);
+            PR_ASSERT(0 != rv);
+            fd->secret->md.io_model_committed = PR_TRUE;
+        }
+        return _nt_nonblock_writev(fd, iov, iov_size, timeout);
+    }
+
+    for (index=0; index<iov_size; index++) {
+        rv = _PR_MD_SEND(fd, iov[index].iov_base, iov[index].iov_len, 0,
+                         timeout);
+        if (rv > 0) {
+            sent += rv;
+        }
+        if ( rv != iov[index].iov_len ) {
+            if (sent <= 0) {
+                return -1;
+            }
+            return -1;
+        }
+    }
+
+    return sent;
+}
+
+PRInt32
+_PR_MD_LISTEN(PRFileDesc *fd, PRIntn backlog)
+{
+    PRInt32 rv;
+
+    rv = listen(fd->secret->md.osfd, backlog);
+    if (rv < 0) {
+        _PR_MD_MAP_LISTEN_ERROR(WSAGetLastError());
+    }
+    return(rv);
+}
+
+PRInt32
+_PR_MD_SHUTDOWN(PRFileDesc *fd, PRIntn how)
+{
+    PRInt32 rv;
+
+    rv = shutdown(fd->secret->md.osfd, how);
+    if (rv < 0) {
+        _PR_MD_MAP_SHUTDOWN_ERROR(WSAGetLastError());
+    }
+    return(rv);
+}
+
+PRStatus
+_PR_MD_GETSOCKNAME(PRFileDesc *fd, PRNetAddr *addr, PRUint32 *len)
+{
+    PRInt32 rv;
+
+    rv = getsockname((SOCKET)fd->secret->md.osfd, (struct sockaddr *)addr, len);
+    if (rv==0) {
+        return PR_SUCCESS;
+    }
+    else {
+        _PR_MD_MAP_GETSOCKNAME_ERROR(WSAGetLastError());
+        return PR_FAILURE;
+    }
+}
+
+PRStatus
+_PR_MD_GETPEERNAME(PRFileDesc *fd, PRNetAddr *addr, PRUint32 *len)
+{
+    PRInt32 rv;
+
+    /*
+     * NT has a bug that, when invoked on a socket accepted by
+     * AcceptEx(), getpeername() returns an all-zero peer address.
+     * To work around this bug, we store the peer's address (returned
+     * by AcceptEx()) with the socket fd and use the cached peer
+     * address if the socket is an accepted socket.
+     */
+
+    if (fd->secret->md.accepted_socket) {
+        INT seconds;
+        INT bytes = sizeof(seconds);
+
+        /*
+         * Determine if the socket is connected.
+         */
+
+        rv = getsockopt(fd->secret->md.osfd,
+                        SOL_SOCKET,
+                        SO_CONNECT_TIME,
+                        (char *) &seconds,
+                        (PINT) &bytes);
+        if (rv == NO_ERROR) {
+            if (seconds == 0xffffffff) {
+                PR_SetError(PR_NOT_CONNECTED_ERROR, 0);
+                return PR_FAILURE;
+            }
+            *len = PR_NETADDR_SIZE(&fd->secret->md.peer_addr);
+            memcpy(addr, &fd->secret->md.peer_addr, *len);
+            return PR_SUCCESS;
+        } else {
+            _PR_MD_MAP_GETSOCKOPT_ERROR(WSAGetLastError());
+            return PR_FAILURE;
+        }
+    } else {
+        rv = getpeername((SOCKET)fd->secret->md.osfd,
+                         (struct sockaddr *) addr, len);
+        if (rv == 0) {
+            return PR_SUCCESS;
+        } else {
+            _PR_MD_MAP_GETPEERNAME_ERROR(WSAGetLastError());
+            return PR_FAILURE;
+        }
+    }
+}
+
+PRStatus
+_PR_MD_GETSOCKOPT(PRFileDesc *fd, PRInt32 level, PRInt32 optname, char* optval, PRInt32* optlen)
+{
+    PRInt32 rv;
+
+    rv = getsockopt((SOCKET)fd->secret->md.osfd, level, optname, optval, optlen);
+    if (rv==0) {
+        return PR_SUCCESS;
+    }
+    else {
+        _PR_MD_MAP_GETSOCKOPT_ERROR(WSAGetLastError());
+        return PR_FAILURE;
+    }
+}
+
+PRStatus
+_PR_MD_SETSOCKOPT(PRFileDesc *fd, PRInt32 level, PRInt32 optname, const char* optval, PRInt32 optlen)
+{
+    PRInt32 rv;
+
+    rv = setsockopt((SOCKET)fd->secret->md.osfd, level, optname, optval, optlen);
+    if (rv==0) {
+        return PR_SUCCESS;
+    }
+    else {
+        _PR_MD_MAP_SETSOCKOPT_ERROR(WSAGetLastError());
+        return PR_FAILURE;
+    }
+}
+
+/* --- FILE IO ----------------------------------------------------------- */
+
+PROsfd
+_PR_MD_OPEN(const char *name, PRIntn osflags, PRIntn mode)
+{
+    HANDLE file;
+    PRInt32 access = 0;
+    PRInt32 flags = 0;
+    PRInt32 flag6 = 0;
+
+    if (osflags & PR_SYNC) {
+        flag6 = FILE_FLAG_WRITE_THROUGH;
+    }
+
+    if (osflags & PR_RDONLY || osflags & PR_RDWR) {
+        access |= GENERIC_READ;
+    }
+    if (osflags & PR_WRONLY || osflags & PR_RDWR) {
+        access |= GENERIC_WRITE;
+    }
+
+    if ( osflags & PR_CREATE_FILE && osflags & PR_EXCL ) {
+        flags = CREATE_NEW;
+    }
+    else if (osflags & PR_CREATE_FILE) {
+        flags = (0 != (osflags & PR_TRUNCATE)) ? CREATE_ALWAYS : OPEN_ALWAYS;
+    }
+    else if (osflags & PR_TRUNCATE) {
+        flags = TRUNCATE_EXISTING;
+    }
+    else {
+        flags = OPEN_EXISTING;
+    }
+
+
+    flag6 |= FILE_FLAG_OVERLAPPED;
+
+    file = CreateFile(name,
+                      access,
+                      FILE_SHARE_READ|FILE_SHARE_WRITE,
+                      NULL,
+                      flags,
+                      flag6,
+                      NULL);
+    if (file == INVALID_HANDLE_VALUE) {
+        _PR_MD_MAP_OPEN_ERROR(GetLastError());
+        return -1;
+    }
+
+    if (osflags & PR_APPEND) {
+        if ( SetFilePointer(file, 0, 0, FILE_END) == 0xFFFFFFFF ) {
+            _PR_MD_MAP_LSEEK_ERROR(GetLastError());
+            CloseHandle(file);
+            return -1;
+        }
+    }
+
+    return (PROsfd)file;
+}
+
+PROsfd
+_PR_MD_OPEN_FILE(const char *name, PRIntn osflags, PRIntn mode)
+{
+    HANDLE file;
+    PRInt32 access = 0;
+    PRInt32 flags = 0;
+    PRInt32 flag6 = 0;
+    SECURITY_ATTRIBUTES sa;
+    LPSECURITY_ATTRIBUTES lpSA = NULL;
+    PSECURITY_DESCRIPTOR pSD = NULL;
+    PACL pACL = NULL;
+
+    if (osflags & PR_SYNC) {
+        flag6 = FILE_FLAG_WRITE_THROUGH;
+    }
+
+    if (osflags & PR_RDONLY || osflags & PR_RDWR) {
+        access |= GENERIC_READ;
+    }
+    if (osflags & PR_WRONLY || osflags & PR_RDWR) {
+        access |= GENERIC_WRITE;
+    }
+
+    if ( osflags & PR_CREATE_FILE && osflags & PR_EXCL ) {
+        flags = CREATE_NEW;
+    }
+    else if (osflags & PR_CREATE_FILE) {
+        flags = (0 != (osflags & PR_TRUNCATE)) ? CREATE_ALWAYS : OPEN_ALWAYS;
+    }
+    else if (osflags & PR_TRUNCATE) {
+        flags = TRUNCATE_EXISTING;
+    }
+    else {
+        flags = OPEN_EXISTING;
+    }
+
+
+    flag6 |= FILE_FLAG_OVERLAPPED;
+
+    if (osflags & PR_CREATE_FILE) {
+        if (_PR_NT_MakeSecurityDescriptorACL(mode, fileAccessTable,
+                                             &pSD, &pACL) == PR_SUCCESS) {
+            sa.nLength = sizeof(sa);
+            sa.lpSecurityDescriptor = pSD;
+            sa.bInheritHandle = FALSE;
+            lpSA = &sa;
+        }
+    }
+    file = CreateFile(name,
+                      access,
+                      FILE_SHARE_READ|FILE_SHARE_WRITE,
+                      lpSA,
+                      flags,
+                      flag6,
+                      NULL);
+    if (lpSA != NULL) {
+        _PR_NT_FreeSecurityDescriptorACL(pSD, pACL);
+    }
+    if (file == INVALID_HANDLE_VALUE) {
+        _PR_MD_MAP_OPEN_ERROR(GetLastError());
+        return -1;
+    }
+
+    if (osflags & PR_APPEND) {
+        if ( SetFilePointer(file, 0, 0, FILE_END) == 0xFFFFFFFF ) {
+            _PR_MD_MAP_LSEEK_ERROR(GetLastError());
+            CloseHandle(file);
+            return -1;
+        }
+    }
+
+    return (PROsfd)file;
+}
+
+PRInt32
+_PR_MD_READ(PRFileDesc *fd, void *buf, PRInt32 len)
+{
+    PROsfd f = fd->secret->md.osfd;
+    PRUint32 bytes;
+    int rv, err;
+    LONG hiOffset = 0;
+    LONG loOffset;
+    LARGE_INTEGER offset; /* use for a normalized add of len to offset */
+
+    if (!fd->secret->md.sync_file_io) {
+        PRThread *me = _PR_MD_CURRENT_THREAD();
+
+        if (me->io_suspended) {
+            PR_SetError(PR_INVALID_STATE_ERROR, 0);
+            return -1;
+        }
+
+        memset(&(me->md.overlapped.overlapped), 0, sizeof(OVERLAPPED));
+
+        me->md.overlapped.overlapped.Offset = SetFilePointer((HANDLE)f, 0, &me->md.overlapped.overlapped.OffsetHigh, FILE_CURRENT);
+        PR_ASSERT((me->md.overlapped.overlapped.Offset != 0xffffffff) || (GetLastError() == NO_ERROR));
+
+        if (fd->secret->inheritable == _PR_TRI_TRUE) {
+            rv = ReadFile((HANDLE)f,
+                          (LPVOID)buf,
+                          len,
+                          &bytes,
+                          &me->md.overlapped.overlapped);
+            if (rv != 0) {
+                loOffset = SetFilePointer((HANDLE)f, bytes, &hiOffset, FILE_CURRENT);
+                PR_ASSERT((loOffset != 0xffffffff) || (GetLastError() == NO_ERROR));
+                return bytes;
+            }
+            err = GetLastError();
+            if (err == ERROR_IO_PENDING) {
+                rv = GetOverlappedResult((HANDLE)f,
+                                         &me->md.overlapped.overlapped, &bytes, TRUE);
+                if (rv != 0) {
+                    loOffset = SetFilePointer((HANDLE)f, bytes, &hiOffset, FILE_CURRENT);
+                    PR_ASSERT((loOffset != 0xffffffff) || (GetLastError() == NO_ERROR));
+                    return bytes;
+                }
+                err = GetLastError();
+            }
+            if (err == ERROR_HANDLE_EOF) {
+                return 0;
+            } else {
+                _PR_MD_MAP_READ_ERROR(err);
+                return -1;
+            }
+        } else {
+            if (!fd->secret->md.io_model_committed) {
+                rv = _md_Associate((HANDLE)f);
+                PR_ASSERT(rv != 0);
+                fd->secret->md.io_model_committed = PR_TRUE;
+            }
+
+            if (_native_threads_only) {
+                me->md.overlapped.overlapped.hEvent = me->md.thr_event;
+            }
+
+            _PR_THREAD_LOCK(me);
+            if (_PR_PENDING_INTERRUPT(me)) {
+                me->flags &= ~_PR_INTERRUPT;
+                PR_SetError(PR_PENDING_INTERRUPT_ERROR, 0);
+                _PR_THREAD_UNLOCK(me);
+                return -1;
+            }
+            me->io_pending = PR_TRUE;
+            me->state = _PR_IO_WAIT;
+            _PR_THREAD_UNLOCK(me);
+            me->io_fd = f;
+
+            rv = ReadFile((HANDLE)f,
+                          (LPVOID)buf,
+                          len,
+                          &bytes,
+                          &me->md.overlapped.overlapped);
+            if ( (rv == 0) && ((err = GetLastError()) != ERROR_IO_PENDING) ) {
+                _PR_THREAD_LOCK(me);
+                me->io_pending = PR_FALSE;
+                me->state = _PR_RUNNING;
+                if (_PR_PENDING_INTERRUPT(me)) {
+                    me->flags &= ~_PR_INTERRUPT;
+                    PR_SetError(PR_PENDING_INTERRUPT_ERROR, 0);
+                    _PR_THREAD_UNLOCK(me);
+                    return -1;
+                }
+                _PR_THREAD_UNLOCK(me);
+
+                if (err == ERROR_HANDLE_EOF) {
+                    return 0;
+                }
+                _PR_MD_MAP_READ_ERROR(err);
+                return -1;
+            }
+
+            if (_native_threads_only && rv) {
+                _native_thread_io_nowait(me, rv, bytes);
+            } else if (_NT_IO_WAIT(me, PR_INTERVAL_NO_TIMEOUT) == PR_FAILURE) {
+                PR_ASSERT(0);
+                return -1;
+            }
+
+            PR_ASSERT(me->io_pending == PR_FALSE || me->io_suspended == PR_TRUE);
+
+            if (me->io_suspended) {
+                if (_PR_PENDING_INTERRUPT(me)) {
+                    me->flags &= ~_PR_INTERRUPT;
+                    PR_SetError(PR_PENDING_INTERRUPT_ERROR, 0);
+                } else {
+                    PR_SetError(PR_IO_TIMEOUT_ERROR, 0);
+                }
+                return -1;
+            }
+
+            if (me->md.blocked_io_status == 0) {
+                if (me->md.blocked_io_error == ERROR_HANDLE_EOF) {
+                    return 0;
+                }
+                _PR_MD_MAP_READ_ERROR(me->md.blocked_io_error);
+                return -1;
+            }
+
+            /* Apply the workaround from bug 70765 (see _PR_MD_WRITE)
+             * to the reading code, too. */
+
+            offset.LowPart = me->md.overlapped.overlapped.Offset;
+            offset.HighPart = me->md.overlapped.overlapped.OffsetHigh;
+            offset.QuadPart += me->md.blocked_io_bytes;
+
+            SetFilePointer((HANDLE)f, offset.LowPart, &offset.HighPart, FILE_BEGIN);
+
+            PR_ASSERT(me->io_pending == PR_FALSE);
+
+            return me->md.blocked_io_bytes;
+        }
+    } else {
+
+        rv = ReadFile((HANDLE)f,
+                      (LPVOID)buf,
+                      len,
+                      &bytes,
+                      NULL);
+        if (rv == 0) {
+            err = GetLastError();
+            /* ERROR_HANDLE_EOF can only be returned by async io */
+            PR_ASSERT(err != ERROR_HANDLE_EOF);
+            if (err == ERROR_BROKEN_PIPE) {
+                /* The write end of the pipe has been closed. */
+                return 0;
+            }
+            _PR_MD_MAP_READ_ERROR(err);
+            return -1;
+        }
+        return bytes;
+    }
+}
+
+PRInt32
+_PR_MD_WRITE(PRFileDesc *fd, const void *buf, PRInt32 len)
+{
+    PROsfd f = fd->secret->md.osfd;
+    PRInt32 bytes;
+    int rv, err;
+    LONG hiOffset = 0;
+    LONG loOffset;
+    LARGE_INTEGER offset; /* use for the calculation of the new offset */
+
+    if (!fd->secret->md.sync_file_io) {
+        PRThread *me = _PR_MD_CURRENT_THREAD();
+
+        if (me->io_suspended) {
+            PR_SetError(PR_INVALID_STATE_ERROR, 0);
+            return -1;
+        }
+
+        memset(&(me->md.overlapped.overlapped), 0, sizeof(OVERLAPPED));
+
+        me->md.overlapped.overlapped.Offset = SetFilePointer((HANDLE)f, 0, &me->md.overlapped.overlapped.OffsetHigh, FILE_CURRENT);
+        PR_ASSERT((me->md.overlapped.overlapped.Offset != 0xffffffff) || (GetLastError() == NO_ERROR));
+
+        if (fd->secret->inheritable == _PR_TRI_TRUE) {
+            rv = WriteFile((HANDLE)f,
+                           (LPVOID)buf,
+                           len,
+                           &bytes,
+                           &me->md.overlapped.overlapped);
+            if (rv != 0) {
+                loOffset = SetFilePointer((HANDLE)f, bytes, &hiOffset, FILE_CURRENT);
+                PR_ASSERT((loOffset != 0xffffffff) || (GetLastError() == NO_ERROR));
+                return bytes;
+            }
+            err = GetLastError();
+            if (err == ERROR_IO_PENDING) {
+                rv = GetOverlappedResult((HANDLE)f,
+                                         &me->md.overlapped.overlapped, &bytes, TRUE);
+                if (rv != 0) {
+                    loOffset = SetFilePointer((HANDLE)f, bytes, &hiOffset, FILE_CURRENT);
+                    PR_ASSERT((loOffset != 0xffffffff) || (GetLastError() == NO_ERROR));
+                    return bytes;
+                }
+                err = GetLastError();
+            }
+            _PR_MD_MAP_READ_ERROR(err);
+            return -1;
+        } else {
+            if (!fd->secret->md.io_model_committed) {
+                rv = _md_Associate((HANDLE)f);
+                PR_ASSERT(rv != 0);
+                fd->secret->md.io_model_committed = PR_TRUE;
+            }
+            if (_native_threads_only) {
+                me->md.overlapped.overlapped.hEvent = me->md.thr_event;
+            }
+
+            _PR_THREAD_LOCK(me);
+            if (_PR_PENDING_INTERRUPT(me)) {
+                me->flags &= ~_PR_INTERRUPT;
+                PR_SetError(PR_PENDING_INTERRUPT_ERROR, 0);
+                _PR_THREAD_UNLOCK(me);
+                return -1;
+            }
+            me->io_pending = PR_TRUE;
+            me->state = _PR_IO_WAIT;
+            _PR_THREAD_UNLOCK(me);
+            me->io_fd = f;
+
+            rv = WriteFile((HANDLE)f,
+                           buf,
+                           len,
+                           &bytes,
+                           &(me->md.overlapped.overlapped));
+            if ( (rv == 0) && ((err = GetLastError()) != ERROR_IO_PENDING) ) {
+                _PR_THREAD_LOCK(me);
+                me->io_pending = PR_FALSE;
+                me->state = _PR_RUNNING;
+                if (_PR_PENDING_INTERRUPT(me)) {
+                    me->flags &= ~_PR_INTERRUPT;
+                    PR_SetError(PR_PENDING_INTERRUPT_ERROR, 0);
+                    _PR_THREAD_UNLOCK(me);
+                    return -1;
+                }
+                _PR_THREAD_UNLOCK(me);
+
+                _PR_MD_MAP_WRITE_ERROR(err);
+                return -1;
+            }
+
+            if (_native_threads_only && rv) {
+                _native_thread_io_nowait(me, rv, bytes);
+            } else if (_NT_IO_WAIT(me, PR_INTERVAL_NO_TIMEOUT) == PR_FAILURE) {
+                PR_ASSERT(0);
+                return -1;
+            }
+
+            PR_ASSERT(me->io_pending == PR_FALSE || me->io_suspended == PR_TRUE);
+
+            if (me->io_suspended) {
+                if (_PR_PENDING_INTERRUPT(me)) {
+                    me->flags &= ~_PR_INTERRUPT;
+                    PR_SetError(PR_PENDING_INTERRUPT_ERROR, 0);
+                } else {
+                    PR_SetError(PR_IO_TIMEOUT_ERROR, 0);
+                }
+                return -1;
+            }
+
+            if (me->md.blocked_io_status == 0) {
+                _PR_MD_MAP_WRITE_ERROR(me->md.blocked_io_error);
+                return -1;
+            }
+
+            /*
+             * Moving the file pointer by a relative offset (FILE_CURRENT)
+             * does not work with a file on a network drive exported by a
+             * Win2K system.  We still don't know why.  A workaround is to
+             * move the file pointer by an absolute offset (FILE_BEGIN).
+             * (Bugzilla bug 70765)
+             */
+            offset.LowPart = me->md.overlapped.overlapped.Offset;
+            offset.HighPart = me->md.overlapped.overlapped.OffsetHigh;
+            offset.QuadPart += me->md.blocked_io_bytes;
+
+            SetFilePointer((HANDLE)f, offset.LowPart, &offset.HighPart, FILE_BEGIN);
+
+            PR_ASSERT(me->io_pending == PR_FALSE);
+
+            return me->md.blocked_io_bytes;
+        }
+    } else {
+        rv = WriteFile((HANDLE)f,
+                       buf,
+                       len,
+                       &bytes,
+                       NULL);
+        if (rv == 0) {
+            _PR_MD_MAP_WRITE_ERROR(GetLastError());
+            return -1;
+        }
+        return bytes;
+    }
+}
+
+PRInt32
+_PR_MD_SOCKETAVAILABLE(PRFileDesc *fd)
+{
+    PRInt32 result;
+
+    if (ioctlsocket(fd->secret->md.osfd, FIONREAD, &result) < 0) {
+        PR_SetError(PR_BAD_DESCRIPTOR_ERROR, WSAGetLastError());
+        return -1;
+    }
+    return result;
+}
+
+PRInt32
+_PR_MD_PIPEAVAILABLE(PRFileDesc *fd)
+{
+    if (NULL == fd) {
+        PR_SetError(PR_BAD_DESCRIPTOR_ERROR, 0);
+    }
+    else {
+        PR_SetError(PR_NOT_IMPLEMENTED_ERROR, 0);
+    }
+    return -1;
+}
+
+PROffset32
+_PR_MD_LSEEK(PRFileDesc *fd, PROffset32 offset, PRSeekWhence whence)
+{
+    DWORD moveMethod;
+    PROffset32 rv;
+
+    switch (whence) {
+        case PR_SEEK_SET:
+            moveMethod = FILE_BEGIN;
+            break;
+        case PR_SEEK_CUR:
+            moveMethod = FILE_CURRENT;
+            break;
+        case PR_SEEK_END:
+            moveMethod = FILE_END;
+            break;
+        default:
+            PR_SetError(PR_INVALID_ARGUMENT_ERROR, 0);
+            return -1;
+    }
+
+    rv = SetFilePointer((HANDLE)fd->secret->md.osfd, offset, NULL, moveMethod);
+
+    /*
+     * If the lpDistanceToMoveHigh argument (third argument) is
+     * NULL, SetFilePointer returns 0xffffffff on failure.
+     */
+    if (-1 == rv) {
+        _PR_MD_MAP_LSEEK_ERROR(GetLastError());
+    }
+    return rv;
+}
+
+PROffset64
+_PR_MD_LSEEK64(PRFileDesc *fd, PROffset64 offset, PRSeekWhence whence)
+{
+    DWORD moveMethod;
+    LARGE_INTEGER li;
+    DWORD err;
+
+    switch (whence) {
+        case PR_SEEK_SET:
+            moveMethod = FILE_BEGIN;
+            break;
+        case PR_SEEK_CUR:
+            moveMethod = FILE_CURRENT;
+            break;
+        case PR_SEEK_END:
+            moveMethod = FILE_END;
+            break;
+        default:
+            PR_SetError(PR_INVALID_ARGUMENT_ERROR, 0);
+            return -1;
+    }
+
+    li.QuadPart = offset;
+    li.LowPart = SetFilePointer((HANDLE)fd->secret->md.osfd,
+                                li.LowPart, &li.HighPart, moveMethod);
+
+    if (0xffffffff == li.LowPart && (err = GetLastError()) != NO_ERROR) {
+        _PR_MD_MAP_LSEEK_ERROR(err);
+        li.QuadPart = -1;
+    }
+    return li.QuadPart;
+}
+
+/*
+ * This is documented to succeed on read-only files, but Win32's
+ * FlushFileBuffers functions fails with "access denied" in such a
+ * case.  So we only signal an error if the error is *not* "access
+ * denied".
+ */
+PRInt32
+_PR_MD_FSYNC(PRFileDesc *fd)
+{
+    /*
+     * From the documentation:
+     *
+     *     On Windows NT, the function FlushFileBuffers fails if hFile
+     *     is a handle to console output. That is because console
+     *     output is not buffered. The function returns FALSE, and
+     *     GetLastError returns ERROR_INVALID_HANDLE.
+     *
+     * On the other hand, on Win95, it returns without error.  I cannot
+     * assume that 0, 1, and 2 are console, because if someone closes
+     * System.out and then opens a file, they might get file descriptor
+     * 1.  An error on *that* version of 1 should be reported, whereas
+     * an error on System.out (which was the original 1) should be
+     * ignored.  So I use isatty() to ensure that such an error was
+     * because of this, and if it was, I ignore the error.
+     */
+
+    BOOL ok = FlushFileBuffers((HANDLE)fd->secret->md.osfd);
+
+    if (!ok) {
+        DWORD err = GetLastError();
+
+        if (err != ERROR_ACCESS_DENIED) {   /* from winerror.h */
+            _PR_MD_MAP_FSYNC_ERROR(err);
+            return -1;
+        }
+    }
+    return 0;
+}
+
+PRInt32
+_PR_MD_CLOSE(PROsfd osfd, PRBool socket)
+{
+    PRInt32 rv;
+    PRThread *me = _PR_MD_CURRENT_THREAD();
+
+    if (socket)  {
+        rv = closesocket((SOCKET)osfd);
+        if (rv < 0) {
+            _PR_MD_MAP_CLOSE_ERROR(WSAGetLastError());
+        }
+    } else {
+        rv = CloseHandle((HANDLE)osfd)?0:-1;
+        if (rv < 0) {
+            _PR_MD_MAP_CLOSE_ERROR(GetLastError());
+        }
+    }
+
+    if (rv == 0 && me->io_suspended) {
+        if (me->io_fd == osfd) {
+            PRBool fWait;
+
+            _PR_THREAD_LOCK(me);
+            me->state = _PR_IO_WAIT;
+            /* The IO could have completed on another thread just after
+             * calling closesocket while the io_suspended flag was true.
+             * So we now grab the lock to do a safe check on io_pending to
+             * see if we need to wait or not.
+             */
+            fWait = me->io_pending;
+            me->io_suspended = PR_FALSE;
+            me->md.interrupt_disabled = PR_TRUE;
+            _PR_THREAD_UNLOCK(me);
+
+            if (fWait) {
+                _NT_IO_WAIT(me, PR_INTERVAL_NO_TIMEOUT);
+            }
+            PR_ASSERT(me->io_suspended ==  PR_FALSE);
+            PR_ASSERT(me->io_pending ==  PR_FALSE);
+            /*
+             * I/O operation is no longer pending; the thread can now
+             * run on any cpu
+             */
+            _PR_THREAD_LOCK(me);
+            me->md.interrupt_disabled = PR_FALSE;
+            me->md.thr_bound_cpu = NULL;
+            me->io_suspended = PR_FALSE;
+            me->io_pending = PR_FALSE;
+            me->state = _PR_RUNNING;
+            _PR_THREAD_UNLOCK(me);
+        }
+    }
+    return rv;
+}
+
+PRStatus
+_PR_MD_SET_FD_INHERITABLE(PRFileDesc *fd, PRBool inheritable)
+{
+    BOOL rv;
+
+    if (fd->secret->md.io_model_committed) {
+        PR_SetError(PR_INVALID_ARGUMENT_ERROR, 0);
+        return PR_FAILURE;
+    }
+    rv = SetHandleInformation(
+             (HANDLE)fd->secret->md.osfd,
+             HANDLE_FLAG_INHERIT,
+             inheritable ? HANDLE_FLAG_INHERIT : 0);
+    if (0 == rv) {
+        _PR_MD_MAP_DEFAULT_ERROR(GetLastError());
+        return PR_FAILURE;
+    }
+    return PR_SUCCESS;
+}
+
+void
+_PR_MD_INIT_FD_INHERITABLE(PRFileDesc *fd, PRBool imported)
+{
+    if (imported) {
+        fd->secret->inheritable = _PR_TRI_UNKNOWN;
+    } else {
+        fd->secret->inheritable = _PR_TRI_FALSE;
+    }
+}
+
+void
+_PR_MD_QUERY_FD_INHERITABLE(PRFileDesc *fd)
+{
+    DWORD flags;
+
+    PR_ASSERT(_PR_TRI_UNKNOWN == fd->secret->inheritable);
+    if (fd->secret->md.io_model_committed) {
+        return;
+    }
+    if (GetHandleInformation((HANDLE)fd->secret->md.osfd, &flags)) {
+        if (flags & HANDLE_FLAG_INHERIT) {
+            fd->secret->inheritable = _PR_TRI_TRUE;
+        } else {
+            fd->secret->inheritable = _PR_TRI_FALSE;
+        }
+    }
+}
+
+
+/* --- DIR IO ------------------------------------------------------------ */
+#define GetFileFromDIR(d)       (d)->d_entry.cFileName
+#define FileIsHidden(d)       ((d)->d_entry.dwFileAttributes & FILE_ATTRIBUTE_HIDDEN)
+
+void FlipSlashes(char *cp, int len)
+{
+    while (--len >= 0) {
+        if (cp[0] == '/') {
+            cp[0] = PR_DIRECTORY_SEPARATOR;
+        }
+        cp = _mbsinc(cp);
+    }
+} /* end FlipSlashes() */
+
+/*
+**
+** Local implementations of standard Unix RTL functions which are not provided
+** by the VC RTL.
+**
+*/
+
+PRInt32
+_PR_MD_CLOSE_DIR(_MDDir *d)
+{
+    if ( d ) {
+        if (FindClose( d->d_hdl )) {
+            d->magic = (PRUint32)-1;
+            return 0;
+        } else {
+            _PR_MD_MAP_CLOSEDIR_ERROR(GetLastError());
+            return -1;
+        }
+    }
+    PR_SetError(PR_INVALID_ARGUMENT_ERROR, 0);
+    return -1;
+}
+
+
+PRStatus
+_PR_MD_OPEN_DIR(_MDDir *d, const char *name)
+{
+    char filename[ MAX_PATH ];
+    int len;
+
+    len = strlen(name);
+    /* Need 5 bytes for \*.* and the trailing null byte. */
+    if (len + 5 > MAX_PATH) {
+        PR_SetError(PR_NAME_TOO_LONG_ERROR, 0);
+        return PR_FAILURE;
+    }
+    strcpy(filename, name);
+
+    /*
+     * If 'name' ends in a slash or backslash, do not append
+     * another backslash.
+     */
+    if (IsPrevCharSlash(filename, filename + len)) {
+        len--;
+    }
+    strcpy(&filename[len], "\\*.*");
+    FlipSlashes( filename, strlen(filename) );
+
+    d->d_hdl = FindFirstFile( filename, &(d->d_entry) );
+    if ( d->d_hdl == INVALID_HANDLE_VALUE ) {
+        _PR_MD_MAP_OPENDIR_ERROR(GetLastError());
+        return PR_FAILURE;
+    }
+    d->firstEntry = PR_TRUE;
+    d->magic = _MD_MAGIC_DIR;
+    return PR_SUCCESS;
+}
+
+char *
+_PR_MD_READ_DIR(_MDDir *d, PRIntn flags)
+{
+    PRInt32 err;
+    BOOL rv;
+    char *fileName;
+
+    if ( d ) {
+        while (1) {
+            if (d->firstEntry) {
+                d->firstEntry = PR_FALSE;
+                rv = 1;
+            } else {
+                rv = FindNextFile(d->d_hdl, &(d->d_entry));
+            }
+            if (rv == 0) {
+                break;
+            }
+            fileName = GetFileFromDIR(d);
+            if ( (flags & PR_SKIP_DOT) &&
+                 (fileName[0] == '.') && (fileName[1] == '\0')) {
+                continue;
+            }
+            if ( (flags & PR_SKIP_DOT_DOT) &&
+                 (fileName[0] == '.') && (fileName[1] == '.') &&
+                 (fileName[2] == '\0')) {
+                continue;
+            }
+            if ( (flags & PR_SKIP_HIDDEN) && FileIsHidden(d)) {
+                continue;
+            }
+            return fileName;
+        }
+        err = GetLastError();
+        PR_ASSERT(NO_ERROR != err);
+        _PR_MD_MAP_READDIR_ERROR(err);
+        return NULL;
+    }
+    PR_SetError(PR_INVALID_ARGUMENT_ERROR, 0);
+    return NULL;
+}
+
+PRInt32
+_PR_MD_DELETE(const char *name)
+{
+    if (DeleteFile(name)) {
+        return 0;
+    } else {
+        _PR_MD_MAP_DELETE_ERROR(GetLastError());
+        return -1;
+    }
+}
+
+void
+_PR_FileTimeToPRTime(const FILETIME *filetime, PRTime *prtm)
+{
+    PR_ASSERT(sizeof(FILETIME) == sizeof(PRTime));
+    CopyMemory(prtm, filetime, sizeof(PRTime));
+#ifdef __GNUC__
+    *prtm = (*prtm - _pr_filetime_offset) / 10LL;
+#else
+    *prtm = (*prtm - _pr_filetime_offset) / 10i64;
+#endif
+
+#ifdef DEBUG
+    /* Doublecheck our calculation. */
+    {
+        SYSTEMTIME systime;
+        PRExplodedTime etm;
+        PRTime cmp; /* for comparison */
+        BOOL rv;
+
+        rv = FileTimeToSystemTime(filetime, &systime);
+        PR_ASSERT(0 != rv);
+
+        /*
+         * PR_ImplodeTime ignores wday and yday.
+         */
+        etm.tm_usec = systime.wMilliseconds * PR_USEC_PER_MSEC;
+        etm.tm_sec = systime.wSecond;
+        etm.tm_min = systime.wMinute;
+        etm.tm_hour = systime.wHour;
+        etm.tm_mday = systime.wDay;
+        etm.tm_month = systime.wMonth - 1;
+        etm.tm_year = systime.wYear;
+        /*
+         * It is not well-documented what time zone the FILETIME's
+         * are in.  WIN32_FIND_DATA is documented to be in UTC (GMT).
+         * But BY_HANDLE_FILE_INFORMATION is unclear about this.
+         * By our best judgement, we assume that FILETIME is in UTC.
+         */
+        etm.tm_params.tp_gmt_offset = 0;
+        etm.tm_params.tp_dst_offset = 0;
+        cmp = PR_ImplodeTime(&etm);
+
+        /*
+         * SYSTEMTIME is in milliseconds precision, so we convert PRTime's
+         * microseconds to milliseconds before doing the comparison.
+         */
+        PR_ASSERT((cmp / PR_USEC_PER_MSEC) == (*prtm / PR_USEC_PER_MSEC));
+    }
+#endif /* DEBUG */
+}
+
+PRInt32
+_PR_MD_STAT(const char *fn, struct stat *info)
+{
+    PRInt32 rv;
+
+    rv = _stat(fn, (struct _stat *)info);
+    if (-1 == rv) {
+        /*
+         * Check for MSVC runtime library _stat() bug.
+         * (It's really a bug in FindFirstFile().)
+         * If a pathname ends in a backslash or slash,
+         * e.g., c:\temp\ or c:/temp/, _stat() will fail.
+         * Note: a pathname ending in a slash (e.g., c:/temp/)
+         * can be handled by _stat() on NT but not on Win95.
+         *
+         * We remove the backslash or slash at the end and
+         * try again.
+         */
+
+        int len = strlen(fn);
+        if (len > 0 && len <= _MAX_PATH
+            && IsPrevCharSlash(fn, fn + len)) {
+            char newfn[_MAX_PATH + 1];
+
+            strcpy(newfn, fn);
+            newfn[len - 1] = '\0';
+            rv = _stat(newfn, (struct _stat *)info);
+        }
+    }
+
+    if (-1 == rv) {
+        _PR_MD_MAP_STAT_ERROR(errno);
+    }
+    return rv;
+}
+
+#define _PR_IS_SLASH(ch) ((ch) == '/' || (ch) == '\\')
+
+static PRBool
+IsPrevCharSlash(const char *str, const char *current)
+{
+    const char *prev;
+
+    if (str >= current) {
+        return PR_FALSE;
+    }
+    prev = _mbsdec(str, current);
+    return (prev == current - 1) && _PR_IS_SLASH(*prev);
+}
+
+/*
+ * IsRootDirectory --
+ *
+ * Return PR_TRUE if the pathname 'fn' is a valid root directory,
+ * else return PR_FALSE.  The char buffer pointed to by 'fn' must
+ * be writable.  During the execution of this function, the contents
+ * of the buffer pointed to by 'fn' may be modified, but on return
+ * the original contents will be restored.  'buflen' is the size of
+ * the buffer pointed to by 'fn'.
+ *
+ * Root directories come in three formats:
+ * 1. / or \, meaning the root directory of the current drive.
+ * 2. C:/ or C:\, where C is a drive letter.
+ * 3. \\<server name>\<share point name>\ or
+ *    \\<server name>\<share point name>, meaning the root directory
+ *    of a UNC (Universal Naming Convention) name.
+ */
+
+static PRBool
+IsRootDirectory(char *fn, size_t buflen)
+{
+    char *p;
+    PRBool slashAdded = PR_FALSE;
+    PRBool rv = PR_FALSE;
+
+    if (_PR_IS_SLASH(fn[0]) && fn[1] == '\0') {
+        return PR_TRUE;
+    }
+
+    if (isalpha(fn[0]) && fn[1] == ':' && _PR_IS_SLASH(fn[2])
+        && fn[3] == '\0') {
+        rv = GetDriveType(fn) > 1 ? PR_TRUE : PR_FALSE;
+        return rv;
+    }
+
+    /* The UNC root directory */
+
+    if (_PR_IS_SLASH(fn[0]) && _PR_IS_SLASH(fn[1])) {
+        /* The 'server' part should have at least one character. */
+        p = &fn[2];
+        if (*p == '\0' || _PR_IS_SLASH(*p)) {
+            return PR_FALSE;
+        }
+
+        /* look for the next slash */
+        do {
+            p = _mbsinc(p);
+        } while (*p != '\0' && !_PR_IS_SLASH(*p));
+        if (*p == '\0') {
+            return PR_FALSE;
+        }
+
+        /* The 'share' part should have at least one character. */
+        p++;
+        if (*p == '\0' || _PR_IS_SLASH(*p)) {
+            return PR_FALSE;
+        }
+
+        /* look for the final slash */
+        do {
+            p = _mbsinc(p);
+        } while (*p != '\0' && !_PR_IS_SLASH(*p));
+        if (_PR_IS_SLASH(*p) && p[1] != '\0') {
+            return PR_FALSE;
+        }
+        if (*p == '\0') {
+            /*
+             * GetDriveType() doesn't work correctly if the
+             * path is of the form \\server\share, so we add
+             * a final slash temporarily.
+             */
+            if ((p + 1) < (fn + buflen)) {
+                *p++ = '\\';
+                *p = '\0';
+                slashAdded = PR_TRUE;
+            } else {
+                return PR_FALSE; /* name too long */
+            }
+        }
+        rv = GetDriveType(fn) > 1 ? PR_TRUE : PR_FALSE;
+        /* restore the 'fn' buffer */
+        if (slashAdded) {
+            *--p = '\0';
+        }
+    }
+    return rv;
+}
+
+PRInt32
+_PR_MD_GETFILEINFO64(const char *fn, PRFileInfo64 *info)
+{
+    WIN32_FILE_ATTRIBUTE_DATA findFileData;
+
+    if (NULL == fn || '\0' == *fn) {
+        PR_SetError(PR_INVALID_ARGUMENT_ERROR, 0);
+        return -1;
+    }
+
+    if (!GetFileAttributesEx(fn, GetFileExInfoStandard, &findFileData)) {
+        _PR_MD_MAP_OPENDIR_ERROR(GetLastError());
+        return -1;
+    }
+
+    if (findFileData.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) {
+        info->type = PR_FILE_DIRECTORY;
+    } else {
+        info->type = PR_FILE_FILE;
+    }
+
+    info->size = findFileData.nFileSizeHigh;
+    info->size = (info->size << 32) + findFileData.nFileSizeLow;
+
+    _PR_FileTimeToPRTime(&findFileData.ftLastWriteTime, &info->modifyTime);
+
+    if (0 == findFileData.ftCreationTime.dwLowDateTime &&
+        0 == findFileData.ftCreationTime.dwHighDateTime) {
+        info->creationTime = info->modifyTime;
+    } else {
+        _PR_FileTimeToPRTime(&findFileData.ftCreationTime,
+                             &info->creationTime);
+    }
+
+    return 0;
+}
+
+PRInt32
+_PR_MD_GETFILEINFO(const char *fn, PRFileInfo *info)
+{
+    PRFileInfo64 info64;
+    PRInt32 rv = _PR_MD_GETFILEINFO64(fn, &info64);
+    if (0 == rv)
+    {
+        info->type = info64.type;
+        info->size = (PRUint32) info64.size;
+        info->modifyTime = info64.modifyTime;
+        info->creationTime = info64.creationTime;
+    }
+    return rv;
+}
+
+PRInt32
+_PR_MD_GETOPENFILEINFO64(const PRFileDesc *fd, PRFileInfo64 *info)
+{
+    int rv;
+
+    BY_HANDLE_FILE_INFORMATION hinfo;
+
+    rv = GetFileInformationByHandle((HANDLE)fd->secret->md.osfd, &hinfo);
+    if (rv == FALSE) {
+        _PR_MD_MAP_FSTAT_ERROR(GetLastError());
+        return -1;
+    }
+
+    if (hinfo.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) {
+        info->type = PR_FILE_DIRECTORY;
+    }
+    else {
+        info->type = PR_FILE_FILE;
+    }
+
+    info->size = hinfo.nFileSizeHigh;
+    info->size = (info->size << 32) + hinfo.nFileSizeLow;
+
+    _PR_FileTimeToPRTime(&hinfo.ftLastWriteTime, &(info->modifyTime) );
+    _PR_FileTimeToPRTime(&hinfo.ftCreationTime, &(info->creationTime) );
+
+    return 0;
+}
+
+PRInt32
+_PR_MD_GETOPENFILEINFO(const PRFileDesc *fd, PRFileInfo *info)
+{
+    int rv;
+
+    BY_HANDLE_FILE_INFORMATION hinfo;
+
+    rv = GetFileInformationByHandle((HANDLE)fd->secret->md.osfd, &hinfo);
+    if (rv == FALSE) {
+        _PR_MD_MAP_FSTAT_ERROR(GetLastError());
+        return -1;
+    }
+
+    if (hinfo.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) {
+        info->type = PR_FILE_DIRECTORY;
+    }
+    else {
+        info->type = PR_FILE_FILE;
+    }
+
+    info->size = hinfo.nFileSizeLow;
+
+    _PR_FileTimeToPRTime(&hinfo.ftLastWriteTime, &(info->modifyTime) );
+    _PR_FileTimeToPRTime(&hinfo.ftCreationTime, &(info->creationTime) );
+
+    return 0;
+}
+
+PRInt32
+_PR_MD_RENAME(const char *from, const char *to)
+{
+    /* Does this work with dot-relative pathnames? */
+    if (MoveFile(from, to)) {
+        return 0;
+    } else {
+        _PR_MD_MAP_RENAME_ERROR(GetLastError());
+        return -1;
+    }
+}
+
+PRInt32
+_PR_MD_ACCESS(const char *name, PRAccessHow how)
+{
+    PRInt32 rv;
+
+    switch (how) {
+        case PR_ACCESS_WRITE_OK:
+            rv = _access(name, 02);
+            break;
+        case PR_ACCESS_READ_OK:
+            rv = _access(name, 04);
+            break;
+        case PR_ACCESS_EXISTS:
+            rv = _access(name, 00);
+            break;
+        default:
+            PR_SetError(PR_INVALID_ARGUMENT_ERROR, 0);
+            return -1;
+    }
+    if (rv < 0) {
+        _PR_MD_MAP_ACCESS_ERROR(errno);
+    }
+    return rv;
+}
+
+PRInt32
+_PR_MD_MKDIR(const char *name, PRIntn mode)
+{
+    /* XXXMB - how to translate the "mode"??? */
+    if (CreateDirectory(name, NULL)) {
+        return 0;
+    } else {
+        _PR_MD_MAP_MKDIR_ERROR(GetLastError());
+        return -1;
+    }
+}
+
+PRInt32
+_PR_MD_MAKE_DIR(const char *name, PRIntn mode)
+{
+    BOOL rv;
+    SECURITY_ATTRIBUTES sa;
+    LPSECURITY_ATTRIBUTES lpSA = NULL;
+    PSECURITY_DESCRIPTOR pSD = NULL;
+    PACL pACL = NULL;
+
+    if (_PR_NT_MakeSecurityDescriptorACL(mode, dirAccessTable,
+                                         &pSD, &pACL) == PR_SUCCESS) {
+        sa.nLength = sizeof(sa);
+        sa.lpSecurityDescriptor = pSD;
+        sa.bInheritHandle = FALSE;
+        lpSA = &sa;
+    }
+    rv = CreateDirectory(name, lpSA);
+    if (lpSA != NULL) {
+        _PR_NT_FreeSecurityDescriptorACL(pSD, pACL);
+    }
+    if (rv) {
+        return 0;
+    } else {
+        _PR_MD_MAP_MKDIR_ERROR(GetLastError());
+        return -1;
+    }
+}
+
+PRInt32
+_PR_MD_RMDIR(const char *name)
+{
+    if (RemoveDirectory(name)) {
+        return 0;
+    } else {
+        _PR_MD_MAP_RMDIR_ERROR(GetLastError());
+        return -1;
+    }
+}
+
+PRStatus
+_PR_MD_LOCKFILE(PROsfd f)
+{
+    PRInt32 rv, err;
+    PRThread *me = _PR_MD_CURRENT_THREAD();
+
+    if (me->io_suspended) {
+        PR_SetError(PR_INVALID_STATE_ERROR, 0);
+        return PR_FAILURE;
+    }
+
+    memset(&(me->md.overlapped.overlapped), 0, sizeof(OVERLAPPED));
+
+    _PR_THREAD_LOCK(me);
+    if (_PR_PENDING_INTERRUPT(me)) {
+        me->flags &= ~_PR_INTERRUPT;
+        PR_SetError(PR_PENDING_INTERRUPT_ERROR, 0);
+        _PR_THREAD_UNLOCK(me);
+        return -1;
+    }
+    me->io_pending = PR_TRUE;
+    me->state = _PR_IO_WAIT;
+    _PR_THREAD_UNLOCK(me);
+
+    rv = LockFileEx((HANDLE)f,
+                    LOCKFILE_EXCLUSIVE_LOCK,
+                    0,
+                    0x7fffffff,
+                    0,
+                    &me->md.overlapped.overlapped);
+
+    if (_native_threads_only) {
+        _PR_THREAD_LOCK(me);
+        me->io_pending = PR_FALSE;
+        me->state = _PR_RUNNING;
+        if (_PR_PENDING_INTERRUPT(me)) {
+            me->flags &= ~_PR_INTERRUPT;
+            PR_SetError(PR_PENDING_INTERRUPT_ERROR, 0);
+            _PR_THREAD_UNLOCK(me);
+            return PR_FAILURE;
+        }
+        _PR_THREAD_UNLOCK(me);
+
+        if (rv == FALSE) {
+            err = GetLastError();
+            PR_ASSERT(err != ERROR_IO_PENDING);
+            _PR_MD_MAP_LOCKF_ERROR(err);
+            return PR_FAILURE;
+        }
+        return PR_SUCCESS;
+    }
+
+    /* HACK AROUND NT BUG
+     * NT 3.51 has a bug.  In NT 3.51, if LockFileEx returns true, you
+     * don't get any completion on the completion port.  This is a bug.
+     *
+     * They fixed it on NT4.0 so that you do get a completion.
+     *
+     * If we pretend we won't get a completion, NSPR gets confused later
+     * when the unexpected completion arrives.  If we assume we do get
+     * a completion, we hang on 3.51.  Worse, Microsoft informs me that the
+     * behavior varies on 3.51 depending on if you are using a network
+     * file system or a local disk!
+     *
+     * Solution:  For now, _nt_version_gets_lockfile_completion is set
+     * depending on whether or not this system is EITHER
+     *      - running NT 4.0
+     *      - running NT 3.51 with a service pack greater than 5.
+     *
+     * In the meantime, this code may not work on network file systems.
+     *
+     */
+
+    if ( rv == FALSE && ((err = GetLastError()) != ERROR_IO_PENDING)) {
+        _PR_THREAD_LOCK(me);
+        me->io_pending = PR_FALSE;
+        me->state = _PR_RUNNING;
+        if (_PR_PENDING_INTERRUPT(me)) {
+            me->flags &= ~_PR_INTERRUPT;
+            PR_SetError(PR_PENDING_INTERRUPT_ERROR, 0);
+            _PR_THREAD_UNLOCK(me);
+            return PR_FAILURE;
+        }
+        _PR_THREAD_UNLOCK(me);
+
+        _PR_MD_MAP_LOCKF_ERROR(err);
+        return PR_FAILURE;
+    }
+#ifdef _NEED_351_FILE_LOCKING_HACK
+    else if (rv)  {
+        /* If this is NT 3.51 and the file is local, then we won't get a
+         * completion back from LockFile when it succeeded.
+         */
+        if (_nt_version_gets_lockfile_completion == PR_FALSE) {
+            if ( IsFileLocal((HANDLE)f) == _PR_LOCAL_FILE) {
+                me->io_pending = PR_FALSE;
+                me->state = _PR_RUNNING;
+                return PR_SUCCESS;
+            }
+        }
+    }
+#endif /* _NEED_351_FILE_LOCKING_HACK */
+
+    if (_NT_IO_WAIT(me, PR_INTERVAL_NO_TIMEOUT) == PR_FAILURE) {
+        _PR_THREAD_LOCK(me);
+        me->io_pending = PR_FALSE;
+        me->state = _PR_RUNNING;
+        _PR_THREAD_UNLOCK(me);
+        return PR_FAILURE;
+    }
+
+    if (me->md.blocked_io_status == 0) {
+        _PR_MD_MAP_LOCKF_ERROR(me->md.blocked_io_error);
+        return PR_FAILURE;
+    }
+
+    return PR_SUCCESS;
+}
+
+PRStatus
+_PR_MD_TLOCKFILE(PROsfd f)
+{
+    PRInt32 rv, err;
+    PRThread *me = _PR_MD_CURRENT_THREAD();
+
+    if (me->io_suspended) {
+        PR_SetError(PR_INVALID_STATE_ERROR, 0);
+        return PR_FAILURE;
+    }
+
+    memset(&(me->md.overlapped.overlapped), 0, sizeof(OVERLAPPED));
+
+    _PR_THREAD_LOCK(me);
+    if (_PR_PENDING_INTERRUPT(me)) {
+        me->flags &= ~_PR_INTERRUPT;
+        PR_SetError(PR_PENDING_INTERRUPT_ERROR, 0);
+        _PR_THREAD_UNLOCK(me);
+        return -1;
+    }
+    me->io_pending = PR_TRUE;
+    me->state = _PR_IO_WAIT;
+    _PR_THREAD_UNLOCK(me);
+
+    rv = LockFileEx((HANDLE)f,
+                    LOCKFILE_FAIL_IMMEDIATELY|LOCKFILE_EXCLUSIVE_LOCK,
+                    0,
+                    0x7fffffff,
+                    0,
+                    &me->md.overlapped.overlapped);
+    if (_native_threads_only) {
+        _PR_THREAD_LOCK(me);
+        me->io_pending = PR_FALSE;
+        me->state = _PR_RUNNING;
+        if (_PR_PENDING_INTERRUPT(me)) {
+            me->flags &= ~_PR_INTERRUPT;
+            PR_SetError(PR_PENDING_INTERRUPT_ERROR, 0);
+            _PR_THREAD_UNLOCK(me);
+            return PR_FAILURE;
+        }
+        _PR_THREAD_UNLOCK(me);
+
+        if (rv == FALSE) {
+            err = GetLastError();
+            PR_ASSERT(err != ERROR_IO_PENDING);
+            _PR_MD_MAP_LOCKF_ERROR(err);
+            return PR_FAILURE;
+        }
+        return PR_SUCCESS;
+    }
+    if ( rv == FALSE && ((err = GetLastError()) != ERROR_IO_PENDING)) {
+        _PR_THREAD_LOCK(me);
+        me->io_pending = PR_FALSE;
+        me->state = _PR_RUNNING;
+        if (_PR_PENDING_INTERRUPT(me)) {
+            me->flags &= ~_PR_INTERRUPT;
+            PR_SetError(PR_PENDING_INTERRUPT_ERROR, 0);
+            _PR_THREAD_UNLOCK(me);
+            return PR_FAILURE;
+        }
+        _PR_THREAD_UNLOCK(me);
+
+        _PR_MD_MAP_LOCKF_ERROR(err);
+        return PR_FAILURE;
+    }
+#ifdef _NEED_351_FILE_LOCKING_HACK
+    else if (rv)  {
+        /* If this is NT 3.51 and the file is local, then we won't get a
+         * completion back from LockFile when it succeeded.
+         */
+        if (_nt_version_gets_lockfile_completion == PR_FALSE) {
+            if ( IsFileLocal((HANDLE)f) == _PR_LOCAL_FILE) {
+                _PR_THREAD_LOCK(me);
+                me->io_pending = PR_FALSE;
+                me->state = _PR_RUNNING;
+                if (_PR_PENDING_INTERRUPT(me)) {
+                    me->flags &= ~_PR_INTERRUPT;
+                    PR_SetError(PR_PENDING_INTERRUPT_ERROR, 0);
+                    _PR_THREAD_UNLOCK(me);
+                    return PR_FAILURE;
+                }
+                _PR_THREAD_UNLOCK(me);
+
+                return PR_SUCCESS;
+            }
+        }
+    }
+#endif /* _NEED_351_FILE_LOCKING_HACK */
+
+    if (_NT_IO_WAIT(me, PR_INTERVAL_NO_TIMEOUT) == PR_FAILURE) {
+        _PR_THREAD_LOCK(me);
+        me->io_pending = PR_FALSE;
+        me->state = _PR_RUNNING;
+        if (_PR_PENDING_INTERRUPT(me)) {
+            me->flags &= ~_PR_INTERRUPT;
+            PR_SetError(PR_PENDING_INTERRUPT_ERROR, 0);
+            _PR_THREAD_UNLOCK(me);
+            return PR_FAILURE;
+        }
+        _PR_THREAD_UNLOCK(me);
+
+        return PR_FAILURE;
+    }
+
+    if (me->md.blocked_io_status == 0) {
+        _PR_MD_MAP_LOCKF_ERROR(me->md.blocked_io_error);
+        return PR_FAILURE;
+    }
+
+    return PR_SUCCESS;
+}
+
+
+PRStatus
+_PR_MD_UNLOCKFILE(PROsfd f)
+{
+    PRInt32 rv;
+    PRThread *me = _PR_MD_CURRENT_THREAD();
+
+    if (me->io_suspended) {
+        PR_SetError(PR_INVALID_STATE_ERROR, 0);
+        return PR_FAILURE;
+    }
+
+    memset(&(me->md.overlapped.overlapped), 0, sizeof(OVERLAPPED));
+
+    rv = UnlockFileEx((HANDLE)f,
+                      0,
+                      0x7fffffff,
+                      0,
+                      &me->md.overlapped.overlapped);
+
+    if (rv) {
+        return PR_SUCCESS;
+    }
+    else {
+        int err = GetLastError();
+        _PR_MD_MAP_LOCKF_ERROR(err);
+        return PR_FAILURE;
+    }
+}
+
+void
+_PR_MD_MAKE_NONBLOCK(PRFileDesc *f)
+{
+    /*
+     * On NT, we either call _md_Associate() or _md_MakeNonblock(),
+     * depending on whether the socket is blocking or not.
+     *
+     * Once we associate a socket with the io completion port,
+     * there is no way to disassociate it from the io completion
+     * port.  So we have to call _md_Associate/_md_MakeNonblock
+     * lazily.
+     */
+}
+
+#ifdef _NEED_351_FILE_LOCKING_HACK
+/***************
+**
+** Lockfile hacks
+**
+** The following code is a hack to work around a microsoft bug with lockfile.
+** The problem is that on NT 3.51, if LockFileEx() succeeds, you never
+** get a completion back for files that are on local disks.  So, we need to
+** know if a file is local or remote so we can tell if we should expect
+** a completion.
+**
+** The only way to check if a file is local or remote based on the handle is
+** to get the serial number for the volume it is mounted on and then to
+** compare that with mounted drives.  This code caches the volume numbers of
+** fixed disks and does a relatively quick check.
+**
+** Locking:  Since the only thing we ever do when multithreaded is a 32bit
+**           assignment, we probably don't need locking.  It is included just
+**           case anyway.
+**
+** Limitations:  Does not work on floppies because they are too slow
+**               Unknown if it will work on wierdo 3rd party file systems
+**
+****************
+*/
+
+/* There can only be 26 drive letters on NT */
+#define _PR_MAX_DRIVES 26
+
+_MDLock cachedVolumeLock;
+DWORD dwCachedVolumeSerialNumbers[_PR_MAX_DRIVES] = {0};
+DWORD dwLastCachedDrive = 0;
+DWORD dwRemoveableDrivesToCheck = 0; /* bitmask for removeable drives */
+
+PRBool IsFileLocalInit()
+{
+    TCHAR lpBuffer[_PR_MAX_DRIVES*5];
+    DWORD nBufferLength = _PR_MAX_DRIVES*5;
+    DWORD nBufferNeeded = GetLogicalDriveStrings(0, NULL);
+    DWORD dwIndex = 0;
+    DWORD dwDriveType;
+    DWORD dwVolumeSerialNumber;
+    DWORD dwDriveIndex = 0;
+    DWORD oldmode = (DWORD) -1;
+
+    _MD_NEW_LOCK(&cachedVolumeLock);
+
+    nBufferNeeded = GetLogicalDriveStrings(nBufferLength, lpBuffer);
+    if (nBufferNeeded == 0 || nBufferNeeded > nBufferLength) {
+        return PR_FALSE;
+    }
+
+    // Calling GetVolumeInformation on a removeable drive where the
+    // disk is currently removed will cause a dialog box to the
+    // console.  This is not good.
+    // Temporarily disable the SEM_FAILCRITICALERRORS to avoid the
+    // damn dialog.
+
+    dwCachedVolumeSerialNumbers[dwDriveIndex] = 0;
+    oldmode = SetErrorMode(SEM_FAILCRITICALERRORS);
+
+    // now loop through the logical drives
+    while(lpBuffer[dwIndex] != TEXT('\0'))
+    {
+        // skip the floppy drives.  This is *SLOW*
+        if ((lpBuffer[dwIndex] == TEXT('A')) || (lpBuffer[dwIndex] == TEXT('B')))
+            /* Skip over floppies */;
+        else
+        {
+            dwDriveIndex = (lpBuffer[dwIndex] - TEXT('A'));
+
+            dwDriveType = GetDriveType(&lpBuffer[dwIndex]);
+
+            switch(dwDriveType)
+            {
+                // Ignore these drive types
+                case 0:
+                case 1:
+                case DRIVE_REMOTE:
+                default: // If the drive type is unknown, ignore it.
+                    break;
+
+                // Removable media drives can have different serial numbers
+                // at different times, so cache the current serial number
+                // but keep track of them so they can be rechecked if necessary.
+                case DRIVE_REMOVABLE:
+
+                // CDROM is a removable media
+                case DRIVE_CDROM:
+
+                // no idea if ramdisks can change serial numbers or not
+                // but it doesn't hurt to treat them as removable.
+
+                case DRIVE_RAMDISK:
+
+
+                    // Here is where we keep track of removable drives.
+                    dwRemoveableDrivesToCheck |= 1 << dwDriveIndex;
+
+                // removable drives fall through to fixed drives and get cached.
+
+                case DRIVE_FIXED:
+
+                    // cache volume serial numbers.
+                    if (GetVolumeInformation(
+                            &lpBuffer[dwIndex],
+                            NULL, 0,
+                            &dwVolumeSerialNumber,
+                            NULL, NULL, NULL, 0)
+                       )
+                    {
+                        if (dwLastCachedDrive < dwDriveIndex) {
+                            dwLastCachedDrive = dwDriveIndex;
+                        }
+                        dwCachedVolumeSerialNumbers[dwDriveIndex] = dwVolumeSerialNumber;
+                    }
+
+                    break;
+            }
+        }
+
+        dwIndex += lstrlen(&lpBuffer[dwIndex]) +1;
+    }
+
+    if (oldmode != (DWORD) -1) {
+        SetErrorMode(oldmode);
+        oldmode = (DWORD) -1;
+    }
+
+    return PR_TRUE;
+}
+
+PRInt32 IsFileLocal(HANDLE hFile)
+{
+    DWORD dwIndex = 0, dwMask;
+    BY_HANDLE_FILE_INFORMATION Info;
+    TCHAR szDrive[4] = TEXT("C:\\");
+    DWORD dwVolumeSerialNumber;
+    DWORD oldmode = (DWORD) -1;
+    int rv = _PR_REMOTE_FILE;
+
+    if (!GetFileInformationByHandle(hFile, &Info)) {
+        return -1;
+    }
+
+    // look to see if the volume serial number has been cached.
+    _MD_LOCK(&cachedVolumeLock);
+    while(dwIndex <= dwLastCachedDrive)
+        if (dwCachedVolumeSerialNumbers[dwIndex++] == Info.dwVolumeSerialNumber)
+        {
+            _MD_UNLOCK(&cachedVolumeLock);
+            return _PR_LOCAL_FILE;
+        }
+    _MD_UNLOCK(&cachedVolumeLock);
+
+    // volume serial number not found in the cache.  Check removable files.
+    // removable drives are noted as a bitmask.  If the bit associated with
+    // a specific drive is set, then we should query its volume serial number
+    // as its possible it has changed.
+    dwMask = dwRemoveableDrivesToCheck;
+    dwIndex = 0;
+
+    while(dwMask)
+    {
+        while(!(dwMask & 1))
+        {
+            dwIndex++;
+            dwMask = dwMask >> 1;
+        }
+
+        szDrive[0] = TEXT('A')+ (TCHAR) dwIndex;
+
+        // Calling GetVolumeInformation on a removeable drive where the
+        // disk is currently removed will cause a dialog box to the
+        // console.  This is not good.
+        // Temporarily disable the SEM_FAILCRITICALERRORS to avoid the
+        // dialog.
+
+        oldmode = SetErrorMode(SEM_FAILCRITICALERRORS);
+
+        if (GetVolumeInformation(
+                szDrive,
+                NULL, 0,
+                &dwVolumeSerialNumber,
+                NULL, NULL, NULL, 0)
+           )
+        {
+            if (dwVolumeSerialNumber == Info.dwVolumeSerialNumber)
+            {
+                _MD_LOCK(&cachedVolumeLock);
+                if (dwLastCachedDrive < dwIndex) {
+                    dwLastCachedDrive = dwIndex;
+                }
+                dwCachedVolumeSerialNumbers[dwIndex] = dwVolumeSerialNumber;
+                _MD_UNLOCK(&cachedVolumeLock);
+                rv = _PR_LOCAL_FILE;
+            }
+        }
+        if (oldmode != (DWORD) -1) {
+            SetErrorMode(oldmode);
+            oldmode = (DWORD) -1;
+        }
+
+        if (rv == _PR_LOCAL_FILE) {
+            return _PR_LOCAL_FILE;
+        }
+
+        dwIndex++;
+        dwMask = dwMask >> 1;
+    }
+
+    return _PR_REMOTE_FILE;
+}
+#endif /* _NEED_351_FILE_LOCKING_HACK */
+
+PR_IMPLEMENT(PRStatus) PR_NT_CancelIo(PRFileDesc *fd)
+{
+    PRThread *me = _PR_MD_CURRENT_THREAD();
+    PRBool fWait;
+    PRFileDesc *bottom;
+
+    bottom = PR_GetIdentitiesLayer(fd, PR_NSPR_IO_LAYER);
+    if (!me->io_suspended || (NULL == bottom) ||
+        (me->io_fd != bottom->secret->md.osfd)) {
+        PR_SetError(PR_INVALID_STATE_ERROR, 0);
+        return PR_FAILURE;
+    }
+    /*
+     * The CancelIO operation has to be issued by the same NT thread that
+     * issued the I/O operation
+     */
+    PR_ASSERT(_PR_IS_NATIVE_THREAD(me) || (me->cpu == me->md.thr_bound_cpu));
+    if (me->io_pending) {
+        if (!CancelIo((HANDLE)bottom->secret->md.osfd)) {
+            PR_SetError(PR_INVALID_STATE_ERROR, GetLastError());
+            return PR_FAILURE;
+        }
+    }
+    _PR_THREAD_LOCK(me);
+    fWait = me->io_pending;
+    me->io_suspended = PR_FALSE;
+    me->state = _PR_IO_WAIT;
+    me->md.interrupt_disabled = PR_TRUE;
+    _PR_THREAD_UNLOCK(me);
+    if (fWait) {
+        _NT_IO_WAIT(me, PR_INTERVAL_NO_TIMEOUT);
+    }
+    PR_ASSERT(me->io_suspended ==  PR_FALSE);
+    PR_ASSERT(me->io_pending ==  PR_FALSE);
+
+    _PR_THREAD_LOCK(me);
+    me->md.interrupt_disabled = PR_FALSE;
+    me->md.thr_bound_cpu = NULL;
+    me->io_suspended = PR_FALSE;
+    me->io_pending = PR_FALSE;
+    me->state = _PR_RUNNING;
+    _PR_THREAD_UNLOCK(me);
+    return PR_SUCCESS;
+}
+
+static PROsfd _nt_nonblock_accept(PRFileDesc *fd, struct sockaddr *addr, int *addrlen, PRIntervalTime timeout)
+{
+    PROsfd osfd = fd->secret->md.osfd;
+    SOCKET sock;
+    PRInt32 rv, err;
+    fd_set rd;
+    struct timeval tv, *tvp;
+
+    FD_ZERO(&rd);
+    FD_SET((SOCKET)osfd, &rd);
+    if (timeout == PR_INTERVAL_NO_TIMEOUT) {
+        while ((sock = accept(osfd, addr, addrlen)) == -1) {
+            if (((err = WSAGetLastError()) == WSAEWOULDBLOCK)
+                && (!fd->secret->nonblocking)) {
+                if ((rv = _PR_NTFiberSafeSelect(0, &rd, NULL, NULL,
+                                                NULL)) == -1) {
+                    _PR_MD_MAP_SELECT_ERROR(WSAGetLastError());
+                    break;
+                }
+            } else {
+                _PR_MD_MAP_ACCEPT_ERROR(err);
+                break;
+            }
+        }
+    } else if (timeout == PR_INTERVAL_NO_WAIT) {
+        if ((sock = accept(osfd, addr, addrlen)) == -1) {
+            if (((err = WSAGetLastError()) == WSAEWOULDBLOCK)
+                && (!fd->secret->nonblocking)) {
+                PR_SetError(PR_IO_TIMEOUT_ERROR, 0);
+            } else {
+                _PR_MD_MAP_ACCEPT_ERROR(err);
+            }
+        }
+    } else {
+retry:
+        if ((sock = accept(osfd, addr, addrlen)) == -1) {
+            if (((err = WSAGetLastError()) == WSAEWOULDBLOCK)
+                && (!fd->secret->nonblocking)) {
+                tv.tv_sec = PR_IntervalToSeconds(timeout);
+                tv.tv_usec = PR_IntervalToMicroseconds(
+                                 timeout - PR_SecondsToInterval(tv.tv_sec));
+                tvp = &tv;
+
+                rv = _PR_NTFiberSafeSelect(0, &rd, NULL, NULL, tvp);
+                if (rv > 0) {
+                    goto retry;
+                } else if (rv == 0) {
+                    PR_SetError(PR_IO_TIMEOUT_ERROR, 0);
+                } else {
+                    _PR_MD_MAP_SELECT_ERROR(WSAGetLastError());
+                }
+            } else {
+                _PR_MD_MAP_ACCEPT_ERROR(err);
+            }
+        }
+    }
+    return (PROsfd)sock;
+}
+
+static PRInt32 _nt_nonblock_connect(PRFileDesc *fd, struct sockaddr *addr, int addrlen, PRIntervalTime timeout)
+{
+    PROsfd osfd = fd->secret->md.osfd;
+    PRInt32 rv;
+    int err;
+    fd_set wr, ex;
+    struct timeval tv, *tvp;
+    int len;
+
+    if ((rv = connect(osfd, addr, addrlen)) == -1) {
+        if ((err = WSAGetLastError()) == WSAEWOULDBLOCK) {
+            if ( timeout == PR_INTERVAL_NO_TIMEOUT ) {
+                tvp = NULL;
+            } else {
+                tv.tv_sec = PR_IntervalToSeconds(timeout);
+                tv.tv_usec = PR_IntervalToMicroseconds(
+                                 timeout - PR_SecondsToInterval(tv.tv_sec));
+                tvp = &tv;
+            }
+            FD_ZERO(&wr);
+            FD_ZERO(&ex);
+            FD_SET((SOCKET)osfd, &wr);
+            FD_SET((SOCKET)osfd, &ex);
+            if ((rv = _PR_NTFiberSafeSelect(0, NULL, &wr, &ex,
+                                            tvp)) == -1) {
+                _PR_MD_MAP_SELECT_ERROR(WSAGetLastError());
+                return rv;
+            }
+            if (rv == 0) {
+                PR_SetError(PR_IO_TIMEOUT_ERROR, 0);
+                return -1;
+            }
+            /* Call Sleep(0) to work around a Winsock timeing bug. */
+            Sleep(0);
+            if (FD_ISSET((SOCKET)osfd, &ex)) {
+                len = sizeof(err);
+                if (getsockopt(osfd, SOL_SOCKET, SO_ERROR,
+                               (char *) &err, &len) == SOCKET_ERROR) {
+                    _PR_MD_MAP_GETSOCKOPT_ERROR(WSAGetLastError());
+                    return -1;
+                }
+                _PR_MD_MAP_CONNECT_ERROR(err);
+                return -1;
+            }
+            PR_ASSERT(FD_ISSET((SOCKET)osfd, &wr));
+            rv = 0;
+        } else {
+            _PR_MD_MAP_CONNECT_ERROR(err);
+        }
+    }
+    return rv;
+}
+
+static PRInt32 _nt_nonblock_recv(PRFileDesc *fd, char *buf, int len, int flags, PRIntervalTime timeout)
+{
+    PROsfd osfd = fd->secret->md.osfd;
+    PRInt32 rv, err;
+    struct timeval tv, *tvp;
+    fd_set rd;
+    int osflags;
+
+    if (0 == flags) {
+        osflags = 0;
+    } else {
+        PR_ASSERT(PR_MSG_PEEK == flags);
+        osflags = MSG_PEEK;
+    }
+    while ((rv = recv(osfd,buf,len,osflags)) == -1) {
+        if (((err = WSAGetLastError()) == WSAEWOULDBLOCK)
+            && (!fd->secret->nonblocking)) {
+            FD_ZERO(&rd);
+            FD_SET((SOCKET)osfd, &rd);
+            if (timeout == PR_INTERVAL_NO_TIMEOUT) {
+                tvp = NULL;
+            } else {
+                tv.tv_sec = PR_IntervalToSeconds(timeout);
+                tv.tv_usec = PR_IntervalToMicroseconds(
+                                 timeout - PR_SecondsToInterval(tv.tv_sec));
+                tvp = &tv;
+            }
+            if ((rv = _PR_NTFiberSafeSelect(0, &rd, NULL, NULL,
+                                            tvp)) == -1) {
+                _PR_MD_MAP_SELECT_ERROR(WSAGetLastError());
+                break;
+            } else if (rv == 0) {
+                PR_SetError(PR_IO_TIMEOUT_ERROR, 0);
+                rv = -1;
+                break;
+            }
+        } else {
+            _PR_MD_MAP_RECV_ERROR(err);
+            break;
+        }
+    }
+    return(rv);
+}
+
+static PRInt32 _nt_nonblock_send(PRFileDesc *fd, char *buf, int len, PRIntervalTime timeout)
+{
+    PROsfd osfd = fd->secret->md.osfd;
+    PRInt32 rv, err;
+    struct timeval tv, *tvp;
+    fd_set wd;
+    PRInt32 bytesSent = 0;
+
+    while(bytesSent < len) {
+        while ((rv = send(osfd,buf,len,0)) == -1) {
+            if (((err = WSAGetLastError()) == WSAEWOULDBLOCK)
+                && (!fd->secret->nonblocking)) {
+                if ( timeout == PR_INTERVAL_NO_TIMEOUT ) {
+                    tvp = NULL;
+                } else {
+                    tv.tv_sec = PR_IntervalToSeconds(timeout);
+                    tv.tv_usec = PR_IntervalToMicroseconds(
+                                     timeout - PR_SecondsToInterval(tv.tv_sec));
+                    tvp = &tv;
+                }
+                FD_ZERO(&wd);
+                FD_SET((SOCKET)osfd, &wd);
+                if ((rv = _PR_NTFiberSafeSelect(0, NULL, &wd, NULL,
+                                                tvp)) == -1) {
+                    _PR_MD_MAP_SELECT_ERROR(WSAGetLastError());
+                    return -1;
+                }
+                if (rv == 0) {
+                    PR_SetError(PR_IO_TIMEOUT_ERROR, 0);
+                    return -1;
+                }
+            } else {
+                _PR_MD_MAP_SEND_ERROR(err);
+                return -1;
+            }
+        }
+        bytesSent += rv;
+        if (fd->secret->nonblocking) {
+            break;
+        }
+        if (bytesSent < len) {
+            if ( timeout == PR_INTERVAL_NO_TIMEOUT ) {
+                tvp = NULL;
+            } else {
+                tv.tv_sec = PR_IntervalToSeconds(timeout);
+                tv.tv_usec = PR_IntervalToMicroseconds(
+                                 timeout - PR_SecondsToInterval(tv.tv_sec));
+                tvp = &tv;
+            }
+            FD_ZERO(&wd);
+            FD_SET((SOCKET)osfd, &wd);
+            if ((rv = _PR_NTFiberSafeSelect(0, NULL, &wd, NULL,
+                                            tvp)) == -1) {
+                _PR_MD_MAP_SELECT_ERROR(WSAGetLastError());
+                return -1;
+            }
+            if (rv == 0) {
+                PR_SetError(PR_IO_TIMEOUT_ERROR, 0);
+                return -1;
+            }
+        }
+    }
+    return bytesSent;
+}
+
+static PRInt32 _nt_nonblock_writev(PRFileDesc *fd, const PRIOVec *iov, int size, PRIntervalTime timeout)
+{
+    int index;
+    int sent = 0;
+    int rv;
+
+    for (index=0; index<size; index++) {
+        rv = _nt_nonblock_send(fd, iov[index].iov_base, iov[index].iov_len, timeout);
+        if (rv > 0) {
+            sent += rv;
+        }
+        if ( rv != iov[index].iov_len ) {
+            if (rv < 0) {
+                if (fd->secret->nonblocking
+                    && (PR_GetError() == PR_WOULD_BLOCK_ERROR)
+                    && (sent > 0)) {
+                    return sent;
+                } else {
+                    return -1;
+                }
+            }
+            /* Only a nonblocking socket can have partial sends */
+            PR_ASSERT(fd->secret->nonblocking);
+            return sent;
+        }
+    }
+
+    return sent;
+}
+
+static PRInt32 _nt_nonblock_sendto(
+    PRFileDesc *fd, const char *buf, int len,
+    const struct sockaddr *addr, int addrlen, PRIntervalTime timeout)
+{
+    PROsfd osfd = fd->secret->md.osfd;
+    PRInt32 rv, err;
+    struct timeval tv, *tvp;
+    fd_set wd;
+    PRInt32 bytesSent = 0;
+
+    while(bytesSent < len) {
+        while ((rv = sendto(osfd,buf,len,0, addr, addrlen)) == -1) {
+            if (((err = WSAGetLastError()) == WSAEWOULDBLOCK)
+                && (!fd->secret->nonblocking)) {
+                if ( timeout == PR_INTERVAL_NO_TIMEOUT ) {
+                    tvp = NULL;
+                } else {
+                    tv.tv_sec = PR_IntervalToSeconds(timeout);
+                    tv.tv_usec = PR_IntervalToMicroseconds(
+                                     timeout - PR_SecondsToInterval(tv.tv_sec));
+                    tvp = &tv;
+                }
+                FD_ZERO(&wd);
+                FD_SET((SOCKET)osfd, &wd);
+                if ((rv = _PR_NTFiberSafeSelect(0, NULL, &wd, NULL,
+                                                tvp)) == -1) {
+                    _PR_MD_MAP_SELECT_ERROR(WSAGetLastError());
+                    return -1;
+                }
+                if (rv == 0) {
+                    PR_SetError(PR_IO_TIMEOUT_ERROR, 0);
+                    return -1;
+                }
+            } else {
+                _PR_MD_MAP_SENDTO_ERROR(err);
+                return -1;
+            }
+        }
+        bytesSent += rv;
+        if (fd->secret->nonblocking) {
+            break;
+        }
+        if (bytesSent < len) {
+            if ( timeout == PR_INTERVAL_NO_TIMEOUT ) {
+                tvp = NULL;
+            } else {
+                tv.tv_sec = PR_IntervalToSeconds(timeout);
+                tv.tv_usec = PR_IntervalToMicroseconds(
+                                 timeout - PR_SecondsToInterval(tv.tv_sec));
+                tvp = &tv;
+            }
+            FD_ZERO(&wd);
+            FD_SET((SOCKET)osfd, &wd);
+            if ((rv = _PR_NTFiberSafeSelect(0, NULL, &wd, NULL,
+                                            tvp)) == -1) {
+                _PR_MD_MAP_SELECT_ERROR(WSAGetLastError());
+                return -1;
+            }
+            if (rv == 0) {
+                PR_SetError(PR_IO_TIMEOUT_ERROR, 0);
+                return -1;
+            }
+        }
+    }
+    return bytesSent;
+}
+
+static PRInt32 _nt_nonblock_recvfrom(PRFileDesc *fd, char *buf, int len, struct sockaddr *addr, int *addrlen, PRIntervalTime timeout)
+{
+    PROsfd osfd = fd->secret->md.osfd;
+    PRInt32 rv, err;
+    struct timeval tv, *tvp;
+    fd_set rd;
+
+    while ((rv = recvfrom(osfd,buf,len,0,addr, addrlen)) == -1) {
+        if (((err = WSAGetLastError()) == WSAEWOULDBLOCK)
+            && (!fd->secret->nonblocking)) {
+            if (timeout == PR_INTERVAL_NO_TIMEOUT) {
+                tvp = NULL;
+            } else {
+                tv.tv_sec = PR_IntervalToSeconds(timeout);
+                tv.tv_usec = PR_IntervalToMicroseconds(
+                                 timeout - PR_SecondsToInterval(tv.tv_sec));
+                tvp = &tv;
+            }
+            FD_ZERO(&rd);
+            FD_SET((SOCKET)osfd, &rd);
+            if ((rv = _PR_NTFiberSafeSelect(0, &rd, NULL, NULL,
+                                            tvp)) == -1) {
+                _PR_MD_MAP_SELECT_ERROR(WSAGetLastError());
+                break;
+            } else if (rv == 0) {
+                PR_SetError(PR_IO_TIMEOUT_ERROR, 0);
+                rv = -1;
+                break;
+            }
+        } else {
+            _PR_MD_MAP_RECVFROM_ERROR(err);
+            break;
+        }
+    }
+    return(rv);
+}
+
+/*
+ * UDP support: the continuation thread functions and recvfrom and sendto.
+ */
+
+static void pt_InsertTimedInternal(pt_Continuation *op)
+{
+    PRInt32 delta = 0;
+    pt_Continuation *t_op = NULL;
+    PRIntervalTime now = PR_IntervalNow(), op_tmo, qd_tmo;
+
+    /*
+     * If this element operation isn't timed, it gets queued at the
+     * end of the list (just after pt_tq.tail) and we're
+     * finishd early.
+     */
+    if (PR_INTERVAL_NO_TIMEOUT == op->timeout)
+    {
+        t_op = pt_tq.tail;  /* put it at the end */
+        goto done;
+    }
+
+    /*
+     * The rest of this routine actaully deals with timed ops.
+     */
+
+    if (NULL != pt_tq.op)
+    {
+        /*
+         * To find where in the list to put the new operation, form
+         * the absolute time the operations in question will expire.
+         *
+         * The new operation ('op') will expire at now() + op->timeout.
+         *
+         * The operation that will time out furthest in the future will
+         * do so at pt_tq.epoch + pt_tq.op->timeout.
+         *
+         * Subsequently earlier timeouts are computed based on the latter
+         * knowledge by subracting the timeout deltas that are stored in
+         * the operation list. There are operation[n]->timeout ticks
+         * between the expiration of operation[n-1] and operation[n].e e
+         *
+         * Therefore, the operation[n-1] will expire operation[n]->timeout
+         * ticks prior to operation[n].
+         *
+         * This should be easy!
+         */
+        t_op = pt_tq.op;  /* running pointer to queued op */
+        op_tmo = now + op->timeout;  /* that's in absolute ticks */
+        qd_tmo = pt_tq.epoch + t_op->timeout;  /* likewise */
+
+        do
+        {
+            /*
+             * If 'op' expires later than t_op, then insert 'op' just
+             * ahead of t_op. Otherwise, compute when operation[n-1]
+             * expires and try again.
+             *
+             * The actual different between the expiriation of 'op'
+             * and the current operation what becomes the new operaton's
+             * timeout interval. That interval is also subtracted from
+             * the interval of the operation immediately following where
+             * we stick 'op' (unless the next one isn't timed). The new
+             * timeout assigned to 'op' takes into account the values of
+             * now() and when the previous intervals were compured.
+             */
+            delta = op_tmo - qd_tmo;
+            if (delta >= 0)
+            {
+                op->timeout += (now - pt_tq.epoch);
+                goto done;
+            }
+
+            qd_tmo -= t_op->timeout;  /* previous operaton expiration */
+            t_op = t_op->prev;  /* point to previous operation */
+            if (NULL != t_op) {
+                qd_tmo += t_op->timeout;
+            }
+        } while (NULL != t_op);
+
+        /*
+         * If we got here we backed off the head of the list. That means that
+         * this timed entry has to go at the head of the list. This is just
+         * about like having an empty timer list.
+         */
+        delta = op->timeout;  /* $$$ is this right? */
+    }
+
+done:
+
+    /*
+     * Insert 'op' into the queue just after t_op or if t_op is null,
+     * at the head of the list.
+     *
+     * If t_op is NULL, the list is currently empty and this is pretty
+     * easy.
+     */
+    if (NULL == t_op)
+    {
+        op->prev = NULL;
+        op->next = pt_tq.head;
+        pt_tq.head = op;
+        if (NULL == pt_tq.tail) {
+            pt_tq.tail = op;
+        }
+        else {
+            op->next->prev = op;
+        }
+    }
+    else
+    {
+        op->prev = t_op;
+        op->next = t_op->next;
+        if (NULL != op->prev) {
+            op->prev->next = op;
+        }
+        if (NULL != op->next) {
+            op->next->prev = op;
+        }
+        if (t_op == pt_tq.tail) {
+            pt_tq.tail = op;
+        }
+    }
+
+    /*
+     * Are we adjusting our epoch, etc? Are we replacing
+     * what was previously the element due to expire furthest
+     * out in the future? Is this even a timed operation?
+     */
+    if (PR_INTERVAL_NO_TIMEOUT != op->timeout)
+    {
+        if ((NULL == pt_tq.op)  /* we're the one and only */
+            || (t_op == pt_tq.op))  /* we're replacing */
+        {
+            pt_tq.op = op;
+            pt_tq.epoch = now;
+        }
+    }
+
+    pt_tq.op_count += 1;
+
+}  /* pt_InsertTimedInternal */
+
+/*
+ * function: pt_FinishTimed
+ *
+ * Takes the finished operation out of the timed queue. It
+ * notifies the initiating thread that the opertions is
+ * complete and returns to the caller the value of the next
+ * operation in the list (or NULL).
+ */
+static pt_Continuation *pt_FinishTimedInternal(pt_Continuation *op)
+{
+    pt_Continuation *next;
+
+    /* remove this one from the list */
+    if (NULL == op->prev) {
+        pt_tq.head = op->next;
+    }
+    else {
+        op->prev->next = op->next;
+    }
+    if (NULL == op->next) {
+        pt_tq.tail = op->prev;
+    }
+    else {
+        op->next->prev = op->prev;
+    }
+
+    /* did we happen to hit the timed op? */
+    if (op == pt_tq.op) {
+        pt_tq.op = op->prev;
+    }
+
+    next = op->next;
+    op->next = op->prev = NULL;
+    op->status = pt_continuation_done;
+
+    pt_tq.op_count -= 1;
+#if defined(DEBUG)
+    pt_debug.continuationsServed += 1;
+#endif
+    PR_NotifyCondVar(op->complete);
+
+    return next;
+}  /* pt_FinishTimedInternal */
+
+static void ContinuationThread(void *arg)
+{
+    /* initialization */
+    fd_set readSet, writeSet, exceptSet;
+    struct timeval tv;
+    SOCKET *pollingList = 0;                /* list built for polling */
+    PRIntn pollingListUsed;                 /* # entries used in the list */
+    PRIntn pollingListNeeded;               /* # entries needed this time */
+    PRIntn pollingSlotsAllocated = 0;       /* # entries available in list */
+    PRIntervalTime mx_select_ticks = PR_MillisecondsToInterval(PT_DEFAULT_SELECT_MSEC);
+
+    /* do some real work */
+    while (1)
+    {
+        PRIntn rv;
+        PRStatus status;
+        PRIntn pollIndex;
+        pt_Continuation *op;
+        PRIntervalTime now = PR_IntervalNow();
+        PRIntervalTime timeout = PR_INTERVAL_NO_TIMEOUT;
+
+        PR_Lock(pt_tq.ml);
+        while (NULL == pt_tq.head)
+        {
+            status = PR_WaitCondVar(pt_tq.new_op, PR_INTERVAL_NO_TIMEOUT);
+            if ((PR_FAILURE == status)
+                && (PR_PENDING_INTERRUPT_ERROR == PR_GetError())) {
+                break;
+            }
+        }
+        pollingListNeeded = pt_tq.op_count;
+        PR_Unlock(pt_tq.ml);
+
+        /* Okay. We're history */
+        if ((PR_FAILURE == status)
+            && (PR_PENDING_INTERRUPT_ERROR == PR_GetError())) {
+            break;
+        }
+
+        /*
+         * We are not holding the pt_tq.ml lock now, so more items may
+         * get added to pt_tq during this window of time.  We hope
+         * that 10 more spaces in the polling list should be enough.
+         */
+
+        FD_ZERO(&readSet);
+        FD_ZERO(&writeSet);
+        FD_ZERO(&exceptSet);
+        pollingListNeeded += 10;
+        if (pollingListNeeded > pollingSlotsAllocated)
+        {
+            if (NULL != pollingList) {
+                PR_DELETE(pollingList);
+            }
+            pollingList = PR_MALLOC(pollingListNeeded * sizeof(PRPollDesc));
+            PR_ASSERT(NULL != pollingList);
+            pollingSlotsAllocated = pollingListNeeded;
+        }
+
+#if defined(DEBUG)
+        if (pollingListNeeded > pt_debug.pollingListMax) {
+            pt_debug.pollingListMax = pollingListUsed;
+        }
+#endif
+
+        /*
+         * Build up a polling list.
+         * This list is sorted on time. Operations that have been
+         * interrupted are completed and not included in the list.
+         * There is an assertion that the operation is in progress.
+         */
+        pollingListUsed = 0;
+        PR_Lock(pt_tq.ml);
+
+        for (op = pt_tq.head; NULL != op;)
+        {
+            if (pt_continuation_abort == op->status)
+            {
+                op->result.code = -1;
+                op->syserrno = WSAEINTR;
+                op = pt_FinishTimedInternal(op);
+            }
+            else
+            {
+                PR_ASSERT(pt_continuation_done != op->status);
+                op->status = pt_continuation_inprogress;
+                if (op->event & PR_POLL_READ) {
+                    FD_SET(op->arg1.osfd, &readSet);
+                }
+                if (op->event & PR_POLL_WRITE) {
+                    FD_SET(op->arg1.osfd, &writeSet);
+                }
+                if (op->event & PR_POLL_EXCEPT) {
+                    FD_SET(op->arg1.osfd, &exceptSet);
+                }
+                pollingList[pollingListUsed] = op->arg1.osfd;
+                pollingListUsed += 1;
+                if (pollingListUsed == pollingSlotsAllocated) {
+                    break;
+                }
+                op = op->next;
+            }
+        }
+
+        PR_Unlock(pt_tq.ml);
+
+        /*
+         * If 'op' isn't NULL at this point, then we didn't get to
+         * the end of the list. That means that more items got added
+         * to the list than we anticipated. So, forget this iteration,
+         * go around the horn again.
+         * One would hope this doesn't happen all that often.
+         */
+        if (NULL != op)
+        {
+#if defined(DEBUG)
+            pt_debug.predictionsFoiled += 1;  /* keep track */
+#endif
+            continue;  /* make it rethink things */
+        }
+
+        /* there's a chance that all ops got blown away */
+        if (NULL == pt_tq.head) {
+            continue;
+        }
+        /* if not, we know this is the shortest timeout */
+        timeout = pt_tq.head->timeout;
+
+        /*
+         * We don't want to wait forever on this poll. So keep
+         * the interval down. The operations, if they are timed,
+         * still have to timeout, while those that are not timed
+         * should persist forever. But they may be aborted. That's
+         * what this anxiety is all about.
+         */
+        if (timeout > mx_select_ticks) {
+            timeout = mx_select_ticks;
+        }
+
+        if (PR_INTERVAL_NO_TIMEOUT != pt_tq.head->timeout) {
+            pt_tq.head->timeout -= timeout;
+        }
+        tv.tv_sec = PR_IntervalToSeconds(timeout);
+        tv.tv_usec = PR_IntervalToMicroseconds(timeout) % PR_USEC_PER_SEC;
+
+        rv = select(0, &readSet, &writeSet, &exceptSet, &tv);
+
+        if (0 == rv)  /* poll timed out - what about leading op? */
+        {
+            if (0 == pt_tq.head->timeout)
+            {
+                /*
+                 * The leading element of the timed queue has timed
+                 * out. Get rid of it. In any case go around the
+                 * loop again, computing the polling list, checking
+                 * for interrupted operations.
+                 */
+                PR_Lock(pt_tq.ml);
+                do
+                {
+                    pt_tq.head->result.code = -1;
+                    pt_tq.head->syserrno = WSAETIMEDOUT;
+                    op = pt_FinishTimedInternal(pt_tq.head);
+                } while ((NULL != op) && (0 == op->timeout));
+                PR_Unlock(pt_tq.ml);
+            }
+            continue;
+        }
+
+        if (-1 == rv && (WSAGetLastError() == WSAEINTR
+                         || WSAGetLastError() == WSAEINPROGRESS))
+        {
+            continue;               /* go around the loop again */
+        }
+
+        /*
+         * select() says that something in our list is ready for some more
+         * action or is an invalid fd. Find it, load up the operation and
+         * see what happens.
+         */
+
+        PR_ASSERT(rv > 0 || WSAGetLastError() == WSAENOTSOCK);
+
+
+        /*
+         * $$$ There's a problem here. I'm running the operations list
+         * and I'm not holding any locks. I don't want to hold the lock
+         * and do the operation, so this is really messed up..
+         *
+         * This may work out okay. The rule is that only this thread,
+         * the continuation thread, can remove elements from the list.
+         * Therefore, the list is at worst, longer than when we built
+         * the polling list.
+         */
+        op = pt_tq.head;
+        for (pollIndex = 0; pollIndex < pollingListUsed; ++pollIndex)
+        {
+            PRInt16 revents = 0;
+
+            PR_ASSERT(NULL != op);
+
+            /*
+             * This one wants attention. Redo the operation.
+             * We know that there can only be more elements
+             * in the op list than we knew about when we created
+             * the poll list. Therefore, we might have to skip
+             * a few ops to find the right one to operation on.
+             */
+            while (pollingList[pollIndex] != op->arg1.osfd )
+            {
+                op = op->next;
+                PR_ASSERT(NULL != op);
+            }
+
+            if (FD_ISSET(op->arg1.osfd, &readSet)) {
+                revents |= PR_POLL_READ;
+            }
+            if (FD_ISSET(op->arg1.osfd, &writeSet)) {
+                revents |= PR_POLL_WRITE;
+            }
+            if (FD_ISSET(op->arg1.osfd, &exceptSet)) {
+                revents |= PR_POLL_EXCEPT;
+            }
+
+            /*
+             * Sip over all those not in progress. They'll be
+             * pruned next time we build a polling list. Call
+             * the continuation function. If it reports completion,
+             * finish off the operation.
+             */
+            if (revents && (pt_continuation_inprogress == op->status)
+                && (op->function(op, revents)))
+            {
+                PR_Lock(pt_tq.ml);
+                op = pt_FinishTimedInternal(op);
+                PR_Unlock(pt_tq.ml);
+            }
+        }
+    }
+    if (NULL != pollingList) {
+        PR_DELETE(pollingList);
+    }
+}  /* ContinuationThread */
+
+static int pt_Continue(pt_Continuation *op)
+{
+    PRStatus rv;
+    /* Finish filling in the blank slots */
+    op->status = pt_continuation_sumbitted;
+    op->complete = PR_NewCondVar(pt_tq.ml);
+
+    PR_Lock(pt_tq.ml);  /* we provide the locking */
+
+    pt_InsertTimedInternal(op);  /* insert in the structure */
+
+    PR_NotifyCondVar(pt_tq.new_op);  /* notify the continuation thread */
+
+    while (pt_continuation_done != op->status)  /* wait for completion */
+    {
+        rv = PR_WaitCondVar(op->complete, PR_INTERVAL_NO_TIMEOUT);
+        /*
+         * If we get interrupted, we set state the continuation thread will
+         * see and allow it to finish the I/O operation w/ error. That way
+         * the rule that only the continuation thread is removing elements
+         * from the list is still valid.
+         *
+         * Don't call interrupt on the continuation thread. That'll just
+         * piss him off. He's cycling around at least every mx_select_ticks
+         * anyhow and should notice the request in there.
+         */
+        if ((PR_FAILURE == rv)
+            && (PR_PENDING_INTERRUPT_ERROR == PR_GetError())) {
+            op->status = pt_continuation_abort;    /* our status */
+        }
+    }
+
+    PR_Unlock(pt_tq.ml);  /* we provide the locking */
+
+    PR_DestroyCondVar(op->complete);
+
+    return op->result.code;  /* and the primary answer */
+}  /* pt_Continue */
+
+static PRBool pt_sendto_cont(pt_Continuation *op, PRInt16 revents)
+{
+    PRIntn bytes = sendto(
+                       op->arg1.osfd, op->arg2.buffer, op->arg3.amount, op->arg4.flags,
+                       (struct sockaddr*)op->arg5.addr, sizeof(*(op->arg5.addr)));
+    op->syserrno = WSAGetLastError();
+    if (bytes > 0)  /* this is progress */
+    {
+        char *bp = op->arg2.buffer;
+        bp += bytes;  /* adjust the buffer pointer */
+        op->arg2.buffer = bp;
+        op->result.code += bytes;  /* accumulate the number sent */
+        op->arg3.amount -= bytes;  /* and reduce the required count */
+        return (0 == op->arg3.amount) ? PR_TRUE : PR_FALSE;
+    }
+    else return ((-1 == bytes) && (WSAEWOULDBLOCK == op->syserrno)) ?
+                    PR_FALSE : PR_TRUE;
+}  /* pt_sendto_cont */
+
+static PRBool pt_recvfrom_cont(pt_Continuation *op, PRInt16 revents)
+{
+    PRIntn addr_len = sizeof(*(op->arg5.addr));
+    op->result.code = recvfrom(
+                          op->arg1.osfd, op->arg2.buffer, op->arg3.amount,
+                          op->arg4.flags, (struct sockaddr*)op->arg5.addr, &addr_len);
+    op->syserrno = WSAGetLastError();
+    return ((-1 == op->result.code) && (WSAEWOULDBLOCK == op->syserrno)) ?
+           PR_FALSE : PR_TRUE;
+}  /* pt_recvfrom_cont */
+
+static PRInt32 pt_SendTo(
+    SOCKET osfd, const void *buf,
+    PRInt32 amount, PRInt32 flags, const PRNetAddr *addr,
+    PRIntn addrlen, PRIntervalTime timeout)
+{
+    PRInt32 bytes = -1, err;
+    PRBool fNeedContinue = PR_FALSE;
+
+    bytes = sendto(
+                osfd, buf, amount, flags,
+                (struct sockaddr*)addr, PR_NETADDR_SIZE(addr));
+    if (bytes == -1) {
+        if ((err = WSAGetLastError()) == WSAEWOULDBLOCK) {
+            fNeedContinue = PR_TRUE;
+        }
+        else {
+            _PR_MD_MAP_SENDTO_ERROR(err);
+        }
+    }
+    if (fNeedContinue == PR_TRUE)
+    {
+        pt_Continuation op;
+        op.arg1.osfd = osfd;
+        op.arg2.buffer = (void*)buf;
+        op.arg3.amount = amount;
+        op.arg4.flags = flags;
+        op.arg5.addr = (PRNetAddr*)addr;
+        op.timeout = timeout;
+        op.result.code = 0;  /* initialize the number sent */
+        op.function = pt_sendto_cont;
+        op.event = PR_POLL_WRITE | PR_POLL_EXCEPT;
+        bytes = pt_Continue(&op);
+        if (bytes < 0) {
+            WSASetLastError(op.syserrno);
+            _PR_MD_MAP_SENDTO_ERROR(op.syserrno);
+        }
+    }
+    return bytes;
+}  /* pt_SendTo */
+
+static PRInt32 pt_RecvFrom(SOCKET osfd, void *buf, PRInt32 amount,
+                           PRInt32 flags, PRNetAddr *addr, PRIntn *addr_len, PRIntervalTime timeout)
+{
+    PRInt32 bytes = -1, err;
+    PRBool fNeedContinue = PR_FALSE;
+
+    bytes = recvfrom(
+                osfd, buf, amount, flags,
+                (struct sockaddr*)addr, addr_len);
+    if (bytes == -1) {
+        if ((err = WSAGetLastError()) == WSAEWOULDBLOCK) {
+            fNeedContinue = PR_TRUE;
+        }
+        else {
+            _PR_MD_MAP_RECVFROM_ERROR(err);
+        }
+    }
+
+    if (fNeedContinue == PR_TRUE)
+    {
+        pt_Continuation op;
+        op.arg1.osfd = osfd;
+        op.arg2.buffer = buf;
+        op.arg3.amount = amount;
+        op.arg4.flags = flags;
+        op.arg5.addr = addr;
+        op.timeout = timeout;
+        op.function = pt_recvfrom_cont;
+        op.event = PR_POLL_READ | PR_POLL_EXCEPT;
+        bytes = pt_Continue(&op);
+        if (bytes < 0) {
+            WSASetLastError(op.syserrno);
+            _PR_MD_MAP_RECVFROM_ERROR(op.syserrno);
+        }
+    }
+    return bytes;
+}  /* pt_RecvFrom */