[PATCH 3/3] Add a native win32 implementation of poll

[Paolo Bonzini]

Finally, this one works.  The previous version worked on Wine but not on
native Win32 because of a difference in how WSAEnumNetworkEvents works.
 The Win32 manual is clear that calling WSAEnumNetworkEvents *clears*
the events until a further system call is issued (the system call is
recv/read for FD_READ, send/write for FD_WRITE, accept for FD_ACCEPT).
So the sequence needs to be:

1) poll all non-socket handles using win32_compute_revents

2) poll sockets using select

3) if neither 1 nor 2 gives a result, use MsgWaitForMultipleObjects and
then again win32_compute_revents+select

4) look at the result


This finally works under native Win32 (giving the same result as Cygwin)
and under Wine (except for a crash in test_pipe, bug 15272 in Wine's
bugzilla).  I tested it also with -DINTERACTIVE.

I will commit it together with patch 2/3.

Paolo

2008-09-23  Paolo Bonzini  <address@hidden>

        * lib/poll.c: Rewrite.
        * modules/poll: Depend on alloca.
---
 ChangeLog         |    6 +
 lib/poll.c        |  445 ++++++++++++++++++++++++++++++++++++++++++++++------
 modules/poll      |    1 +
 tests/test-poll.c |    9 +-
 4 files changed, 406 insertions(+), 55 deletions(-)

diff --git a/lib/poll.c b/lib/poll.c
index e0714f0..b400128 100644
--- a/lib/poll.c
+++ b/lib/poll.c
@@ -20,14 +20,27 @@
    Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
 
 #include <config.h>
+#include <alloca.h>
 
 #include <sys/types.h>
 #include "poll.h"
 #include <errno.h>
 #include <limits.h>
+#include <assert.h>
+
+#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
+#define WIN32_NATIVE
+#include <winsock2.h>
+#include <windows.h>
+#include <io.h>
+#include <stdio.h>
+#include <conio.h>
+#else
+#include <sys/time.h>
 #include <sys/socket.h>
 #include <sys/select.h>
 #include <unistd.h>
+#endif
 
 #ifdef HAVE_SYS_IOCTL_H
 #include <sys/ioctl.h>
@@ -36,7 +49,6 @@
 #include <sys/filio.h>
 #endif
 
-#include <sys/time.h>
 #include <time.h>
 
 #ifndef INFTIM
@@ -48,12 +60,228 @@
 #define MSG_PEEK 0
 #endif
 
+#ifdef WIN32_NATIVE
+
+/* Declare data structures for ntdll functions.  */
+typedef struct _FILE_PIPE_LOCAL_INFORMATION {
+  ULONG NamedPipeType;
+  ULONG NamedPipeConfiguration;
+  ULONG MaximumInstances;
+  ULONG CurrentInstances;
+  ULONG InboundQuota;
+  ULONG ReadDataAvailable;
+  ULONG OutboundQuota;
+  ULONG WriteQuotaAvailable;
+  ULONG NamedPipeState;
+  ULONG NamedPipeEnd;
+} FILE_PIPE_LOCAL_INFORMATION, *PFILE_PIPE_LOCAL_INFORMATION;
+
+typedef struct _IO_STATUS_BLOCK
+{
+  union {
+    DWORD Status;
+    PVOID Pointer;
+  } u;
+  ULONG_PTR Information;
+} IO_STATUS_BLOCK, *PIO_STATUS_BLOCK;
+
+typedef enum _FILE_INFORMATION_CLASS {
+  FilePipeLocalInformation = 24
+} FILE_INFORMATION_CLASS, *PFILE_INFORMATION_CLASS;
+
+typedef DWORD (WINAPI *PNtQueryInformationFile)
+        (HANDLE, IO_STATUS_BLOCK *, VOID *, ULONG, FILE_INFORMATION_CLASS);
+
+#ifndef PIPE_BUF
+#define PIPE_BUF       512
+#endif
+
+/* Compute revents values for file handle H.  */
+
+static int
+win32_compute_revents (HANDLE h, int sought)
+{
+  int i, ret, happened;
+  INPUT_RECORD *irbuffer;
+  DWORD avail, nbuffer;
+  BOOL bRet;
+  IO_STATUS_BLOCK iosb;
+  FILE_PIPE_LOCAL_INFORMATION fpli;
+  static PNtQueryInformationFile NtQueryInformationFile;
+  static BOOL once_only;
+
+  switch (GetFileType (h))
+    {
+    case FILE_TYPE_PIPE:
+      if (!once_only)
+       {
+         NtQueryInformationFile = (PNtQueryInformationFile)
+           GetProcAddress (GetModuleHandle ("ntdll.dll"),
+                           "NtQueryInformationFile");
+         once_only = TRUE;
+       }
+
+      happened = 0;
+      if (PeekNamedPipe (h, NULL, 0, NULL, &avail, NULL) != 0)
+       {
+         if (avail)
+           happened |= sought & (POLLIN | POLLRDNORM);
+       }
+
+      else
+       {
+         /* It was the write-end of the pipe.  Check if it is writable.
+            If NtQueryInformationFile fails, optimistically assume the pipe is
+            writable.  This could happen on Win9x, where NtQueryInformationFile
+            is not available, or if we inherit a pipe that doesn't permit
+            FILE_READ_ATTRIBUTES access on the write end (I think this should
+            not happen since WinXP SP2; WINE seems fine too).  Otherwise,
+            ensure that enough space is available for atomic writes.  */
+          memset (&iosb, 0, sizeof (iosb));
+          memset (&fpli, 0, sizeof (fpli));
+
+          if (!NtQueryInformationFile
+              || NtQueryInformationFile (h, &iosb, &fpli, sizeof (fpli),
+                                        FilePipeLocalInformation)
+             || fpli.WriteQuotaAvailable >= PIPE_BUF
+             || (fpli.OutboundQuota < PIPE_BUF &&
+                 fpli.WriteQuotaAvailable == fpli.OutboundQuota))
+           happened |= sought & (POLLOUT | POLLWRNORM | POLLWRBAND);
+       }
+      return happened;
+
+    case FILE_TYPE_CHAR:
+      ret = WaitForSingleObject (h, 0);
+      if (ret == WAIT_OBJECT_0)
+        {
+         nbuffer = avail = 0;
+         bRet = GetNumberOfConsoleInputEvents (h, &nbuffer);
+         if (!bRet || nbuffer == 0)
+           return POLLHUP;
+
+         irbuffer = (INPUT_RECORD *) alloca (nbuffer * sizeof (INPUT_RECORD));
+         bRet = PeekConsoleInput (h, irbuffer, nbuffer, &avail);
+         if (!bRet || avail == 0)
+           return POLLHUP;
+
+         for (i = 0; i < avail; i++)
+           if (irbuffer[i].EventType == KEY_EVENT)
+             return sought & ~(POLLPRI | POLLRDBAND);
+       }
+      break;
+
+    default:
+      ret = WaitForSingleObject (h, 0);
+      if (ret == WAIT_OBJECT_0)
+        return sought & ~(POLLPRI | POLLRDBAND);
+
+      break;
+    }
+
+  return sought & (POLLOUT | POLLWRNORM | POLLWRBAND);
+}
+
+/* Convert fd_sets returned by select into revents values.  */
+
+static int
+win32_compute_revents_socket (SOCKET h, int sought, long lNetworkEvents)
+{
+  int happened = 0;
+
+  if ((lNetworkEvents & (FD_READ | FD_ACCEPT | FD_CLOSE)) == FD_ACCEPT)
+    happened |= (POLLIN | POLLRDNORM) & sought;
+
+  else if (lNetworkEvents & (FD_READ | FD_ACCEPT | FD_CLOSE))
+    {
+      int r, error;
+
+      char data[64];
+      WSASetLastError (0);
+      r = recv (h, data, sizeof (data), MSG_PEEK);
+      error = WSAGetLastError ();
+      WSASetLastError (0);
+
+      if (r > 0 || error == WSAENOTCONN)
+        happened |= (POLLIN | POLLRDNORM) & sought;
+
+      /* Distinguish hung-up sockets from other errors.  */
+      else if (r == 0 || error == WSAESHUTDOWN || error == WSAECONNRESET
+              || error == WSAECONNABORTED || error == WSAENETRESET)
+        happened |= POLLHUP;
+
+      else
+        happened |= POLLERR;
+    }
+
+  if (lNetworkEvents & (FD_WRITE | FD_CONNECT))
+    happened |= (POLLOUT | POLLWRNORM | POLLWRBAND) & sought;
+
+  if (lNetworkEvents & FD_OOB)
+    happened |= (POLLPRI | POLLRDBAND) & sought;
+
+  return happened;
+}
+
+#else /* !MinGW */
+
+/* Convert select(2) returned fd_sets into poll(2) revents values.  */
+static int
+compute_revents (int fd, int sought, fd_set *rfds, fd_set *wfds, fd_set *efds)
+{
+  int happened = 0;
+  if (FD_ISSET (fd, rfds))
+    {
+      int r;
+      int socket_errno;
+
+#if defined __MACH__ && defined __APPLE__
+      /* There is a bug in Mac OS X that causes it to ignore MSG_PEEK
+         for some kinds of descriptors.  Detect if this descriptor is a
+         connected socket, a server socket, or something else using a
+         0-byte recv, and use ioctl(2) to detect POLLHUP.  */
+      r = recv (fd, NULL, 0, MSG_PEEK);
+      socket_errno = (r < 0) ? errno : 0;
+      if (r == 0 || socket_errno == ENOTSOCK)
+       ioctl (fd, FIONREAD, &r);
+#else
+      char data[64];
+      r = recv (fd, data, sizeof (data), MSG_PEEK);
+      socket_errno = (r < 0) ? errno : 0;
+#endif
+      if (r == 0)
+       happened |= POLLHUP;
+
+      /* If the event happened on an unconnected server socket,
+         that's fine. */
+      else if (r > 0 || ( /* (r == -1) && */ socket_errno == ENOTCONN))
+       happened |= (POLLIN | POLLRDNORM) & sought;
+
+      /* Distinguish hung-up sockets from other errors.  */
+      else if (socket_errno == ESHUTDOWN || socket_errno == ECONNRESET
+              || socket_errno == ECONNABORTED || socket_errno == ENETRESET)
+       happened |= POLLHUP;
+
+      else
+       happened |= POLLERR;
+    }
+
+  if (FD_ISSET (fd, wfds))
+    happened |= (POLLOUT | POLLWRNORM | POLLWRBAND) & sought;
+
+  if (FD_ISSET (fd, efds))
+    happened |= (POLLPRI | POLLRDBAND) & sought;
+
+  return happened;
+}
+#endif /* !MinGW */
+
 int
 poll (pfd, nfd, timeout)
      struct pollfd *pfd;
      nfds_t nfd;
      int timeout;
 {
+#ifndef WIN32_NATIVE
   fd_set rfds, wfds, efds;
   struct timeval tv;
   struct timeval *ptv;
@@ -137,16 +365,11 @@ poll (pfd, nfd, timeout)
                               | POLLWRNORM | POLLWRBAND)))
        {
          maxfd = pfd[i].fd;
-
-         /* Windows use a linear array of sockets (of size FD_SETSIZE). The
-            descriptor value is not used to address the array.  */
-#if defined __CYGWIN__ || (!defined _WIN32 && !defined __WIN32__)
          if (maxfd > FD_SETSIZE)
            {
              errno = EOVERFLOW;
              return -1;
            }
-#endif
        }
     }
 
@@ -162,61 +385,179 @@ poll (pfd, nfd, timeout)
       pfd[i].revents = 0;
     else
       {
-       int happened = 0, sought = pfd[i].events;
-       if (FD_ISSET (pfd[i].fd, &rfds))
+        int happened = compute_revents (pfd[i].fd, pfd[i].events,
+                                        &rfds, &wfds, &efds);
+       if (happened)
          {
-           int r;
-           int socket_errno;
+           pfd[i].revents = happened;
+           rc++;
+         }
+      }
 
-#if defined __MACH__ && defined __APPLE__
-           /* There is a bug in Mac OS X that causes it to ignore MSG_PEEK
-              for some kinds of descriptors.  Detect if this descriptor is a
-              connected socket, a server socket, or something else using a
-              0-byte recv, and use ioctl(2) to detect POLLHUP.  */
-           r = recv (pfd[i].fd, NULL, 0, MSG_PEEK);
-           socket_errno = (r < 0) ? errno : 0;
-           if (r == 0 || socket_errno == ENOTSOCK)
-             ioctl(pfd[i].fd, FIONREAD, &r);
+  return rc;
 #else
-           char data[64];
-           r = recv (pfd[i].fd, data, sizeof (data), MSG_PEEK);
-            
-# ifdef WIN32
-           if (r < 0 && GetLastError() == 10057) /* server socket */
-              socket_errno = ENOTCONN;
-           else
-# endif
-           socket_errno = (r < 0) ? errno : 0;
-#endif
-           if (r == 0)
-             happened |= POLLHUP;
+  static struct timeval tv0;
+  static HANDLE hEvent;
+  WSANETWORKEVENTS ev;
+  HANDLE h, handle_array[FD_SETSIZE + 2];
+  DWORD ret, wait_timeout, nhandles;
+  fd_set rfds, wfds, xfds;
+  BOOL poll_again;
+  MSG msg;
+  char sockbuf[256];
+  int rc;
+  nfds_t i;
 
-           /* If the event happened on an unconnected server socket,
-              that's fine. */
-           else if (r > 0 || ( /* (r == -1) && */ socket_errno == ENOTCONN))
-             happened |= (POLLIN | POLLRDNORM) & sought;
+  if (nfd < 0 || timeout < -1)
+    {
+      errno = EINVAL;
+      return -1;
+    }
 
-           /* Distinguish hung-up sockets from other errors.  */
-           else if (socket_errno == ESHUTDOWN || socket_errno == ECONNRESET
-                    || socket_errno == ECONNABORTED || socket_errno == 
ENETRESET)
-             happened |= POLLHUP;
+  if (!hEvent)
+    hEvent = CreateEvent (NULL, FALSE, FALSE, NULL);
 
-           else
-             happened |= POLLERR;
-         }
+  handle_array[0] = hEvent;
+  nhandles = 1;
+  FD_ZERO (&rfds);
+  FD_ZERO (&wfds);
+  FD_ZERO (&xfds);
 
-       if (FD_ISSET (pfd[i].fd, &wfds))
-         happened |= (POLLOUT | POLLWRNORM | POLLWRBAND) & sought;
+  /* Classify socket handles and create fd sets. */
+  for (i = 0; i < nfd; i++)
+    {
+      size_t optlen = sizeof(sockbuf);
+      pfd[i].revents = 0;
+      if (pfd[i].fd < 0)
+        continue;
+      if (!(pfd[i].events & (POLLIN | POLLRDNORM |
+                             POLLOUT | POLLWRNORM | POLLWRBAND)))
+       continue;
 
-       if (FD_ISSET (pfd[i].fd, &efds))
-         happened |= (POLLPRI | POLLRDBAND) & sought;
+      h = (HANDLE) _get_osfhandle (pfd[i].fd);
+      assert (h != NULL);
 
-       if (happened)
-         {
-           pfd[i].revents = happened;
-           rc++;
-         }
-      }
+      /* Under Wine, it seems that getsockopt returns 0 for pipes too.
+        WSAEnumNetworkEvents instead distinguishes the two correctly.  */
+      ev.lNetworkEvents = 0xDEADBEEF;
+      WSAEnumNetworkEvents ((SOCKET) h, NULL, &ev);
+      if (ev.lNetworkEvents != 0xDEADBEEF)
+        {
+          int requested = FD_CLOSE;
+
+          /* see above; socket handles are mapped onto select.  */
+          if (pfd[i].events & (POLLIN | POLLRDNORM))
+           {
+              requested |= FD_READ | FD_ACCEPT;
+             FD_SET ((SOCKET) h, &rfds);
+           }
+          if (pfd[i].events & (POLLOUT | POLLWRNORM | POLLWRBAND))
+           {
+              requested |= FD_WRITE | FD_CONNECT;
+             FD_SET ((SOCKET) h, &wfds);
+           }
+          if (pfd[i].events & (POLLPRI | POLLRDBAND))
+           {
+              requested |= FD_OOB;
+             FD_SET ((SOCKET) h, &xfds);
+           }
+
+          if (requested)
+            WSAEventSelect ((SOCKET) h, hEvent, requested);
+        }
+      else
+        {
+          handle_array[nhandles++] = h;
+
+         /* Poll now.  If we get an event, do not poll again.  */
+          pfd[i].revents = win32_compute_revents (h, pfd[i].events);
+          if (pfd[i].revents)
+           wait_timeout = 0;
+        }
+    }
+
+  if (select (0, &rfds, &wfds, &xfds, &tv0) > 0)
+    {
+      /* Do MsgWaitForMultipleObjects anyway to dispatch messages, but
+        no need to call select again.  */
+      poll_again = FALSE;
+      wait_timeout = 0;
+    }
+  else
+    {
+      poll_again = TRUE;
+      if (timeout == INFTIM)
+        wait_timeout = INFINITE;
+      else
+        wait_timeout = timeout;
+    }
+
+  for (;;)
+    {
+      ret = MsgWaitForMultipleObjects (nhandles, handle_array, FALSE,
+                                      wait_timeout, QS_ALLINPUT);
+
+      if (ret == WAIT_OBJECT_0 + nhandles)
+       {
+          /* new input of some other kind */
+         BOOL bRet;
+          while ((bRet = PeekMessage (&msg, NULL, 0, 0, PM_REMOVE)) != 0)
+            {
+              TranslateMessage (&msg);
+              DispatchMessage (&msg);
+            }
+       }
+      else
+       break;
+    }
+
+  if (poll_again)
+    select (0, &rfds, &wfds, &xfds, &tv0);
+
+  /* Place a sentinel at the end of the array.  */
+  handle_array[nhandles] = NULL;
+  nhandles = 1;
+  for (i = 0; i < nfd; i++)
+    {
+      int happened;
+
+      if (pfd[i].fd < 0)
+        continue;
+      if (!(pfd[i].events & (POLLIN | POLLRDNORM |
+                             POLLOUT | POLLWRNORM | POLLWRBAND)))
+       continue;
+
+      h = (HANDLE) _get_osfhandle (pfd[i].fd);
+      if (h != handle_array[nhandles])
+        {
+          /* It's a socket.  */
+          WSAEnumNetworkEvents ((SOCKET) h, NULL, &ev);
+         WSAEventSelect ((SOCKET) h, 0, 0);
+
+         /* If we're lucky, WSAEnumNetworkEvents already provided a way
+            to distinguish FD_READ and FD_ACCEPT; this saves a recv later.  */
+         if (FD_ISSET ((SOCKET) h, &rfds)
+             && !(ev.lNetworkEvents & (FD_READ | FD_ACCEPT)))
+           ev.lNetworkEvents |= FD_READ | FD_ACCEPT;
+         if (FD_ISSET ((SOCKET) h, &wfds))
+           ev.lNetworkEvents |= FD_WRITE | FD_CONNECT;
+         if (FD_ISSET ((SOCKET) h, &xfds))
+           ev.lNetworkEvents |= FD_OOB;
+            
+          happened = win32_compute_revents_socket ((SOCKET) h, pfd[i].events,
+                                                  ev.lNetworkEvents);
+        }
+      else
+        {
+          /* Not a socket.  */
+          nhandles++;
+          happened = win32_compute_revents (h, pfd[i].events);
+        }
+
+       if ((pfd[i].revents |= happened) != 0)
+        rc++;
+    }
 
   return rc;
+#endif
 }
diff --git a/modules/poll b/modules/poll
index 35f3fc6..1d1c0ff 100644
--- a/modules/poll
+++ b/modules/poll
@@ -7,6 +7,7 @@ lib/poll.in.h
 m4/poll.m4
 
 Depends-on:
+alloca
 sys_select
 sys_time
 errno