Re: [RFT/RFH] porting the poll module to win32

[Paolo Bonzini]

> If you believe I should be able to modify the code to use poll
> instead of select,

That's for sure.  I attach an example of a bidirectional I/O loop using 
poll.

> and to use your module successfully for mingw32, I
> could give it a try.

Yes, stdin from the console is a console handle.

The attached patch also works for pipes (if it compiles :-), since I saw 
you needed that functionality in gnutls.

Paolo

#include <sys/socket.h>
#include <sys/poll.h>
#include <fcntl.h>
#include <errno.h>
#include <stddef.h>

#define BUF_SIZE        8192

int
socket_loop (int sock_fd)
{
  char buf_stdin[BUF_SIZE];     /* data buffers */
  char buf_socket[BUF_SIZE];

  char *out_p = buf_stdin, *in_p = buf_socket;
  unsigned int outgoing = 0;
  unsigned int incoming = 0;

  struct pollfd pfd[3];
  int rc;

  /* Setup pollfd structs... */
  pfd[0].fd = sock_fd;
  pfd[0].events = POLLIN | POLLOUT;
  pfd[1].fd = 0;
  pfd[1].events = POLLIN;
  pfd[2].fd = 1;
  pfd[2].events = POLLOUT;

  /* Use nonblocking I/O.  */
  fcntl (0, F_SETFL, fcntl (0, F_GETFL, NULL) | O_NONBLOCK);
  fcntl (1, F_SETFL, fcntl (1, F_GETFL, NULL) | O_NONBLOCK);
  fcntl (sock_fd, F_SETFL, fcntl (sock_fd, F_GETFL, NULL) | O_NONBLOCK);

  while (1)
    {
      pfd[0].revents = 0;
      pfd[1].revents = 0;

      rc = poll (pfd, 2, -1);
      if (rc < 0 && errno == EINTR)
        continue;

      /* Always check for errors */
      if (rc < 0)
        break;

      /* Try to read if there is no pending output... */
      if (!outgoing && (pfd[1].revents & (POLLIN | POLLERR)) == POLLIN)
        outgoing = read (0, buf_stdin, BUF_SIZE);

      /* If there was an error, or if we did not read anything, shut down this
         side of the socket.  After this happens, pfd[1].revents will always
         be zero.  */
      if (!outgoing && (pfd[1].revents & (POLLIN | POLLERR | POLLHUP)))
        {
          pfd[1].fd = -1;
          shutdown (sock_fd, SHUT_WR);
        }

      /* Try to read if there is no pending output... */
      if (!incoming && (pfd[0].revents & (POLLIN | POLLERR)) == POLLIN)
        incoming = read (sock_fd, buf_socket, BUF_SIZE);

      /* If there was an error, or if we did not read anything, quit.  */
      if (!incoming && (pfd[0].revents & (POLLIN | POLLERR | POLLHUP)))
        break;

      if (incoming)
        {
          rc = write (1, in_p, incoming);
          if (rc < 0)
            break;

          incoming -= rc;
          in_p = incoming ? in_p + rc : buf_socket;
        }

      if (outgoing)
        {
          /* Write one line, or the whole buffer */
          rc = write (sock_fd, out_p, outgoing);
          if (rc < 0)
            break;

          outgoing -= rc;
          out_p = outgoing ? out_p + rc : buf_stdin;
        }
    }

  /* Now close it.  */
  return (rc < 0) ? -1 : 0;
}

diff --git a/lib/poll.c b/lib/poll.c
index 4a62dc1..ffa6ab0 100644
--- a/lib/poll.c
+++ b/lib/poll.c
@@ -25,9 +25,18 @@
 #include "poll.h"
 #include <errno.h>
 #include <limits.h>
+
+#ifdef __MSVCRT__
+#include <windows.h>
+#include <winsock2.h>
+#include <io.h>
+#include <stdio.h>
+#include <conio.h>
+#else
 #include <sys/socket.h>
 #include <sys/select.h>
 #include <unistd.h>
+#endif
 
 #ifdef HAVE_SYS_IOCTL_H
 #include <sys/ioctl.h>
@@ -48,12 +57,215 @@
 #define MSG_PEEK 0
 #endif
 
+#ifdef __MSVCRT__
+
+/* 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 u {
+    NTSTATUS Status;
+    PVOID Pointer;
+  };
+  ULONG_PTR Information;
+} IO_STATUS_BLOCK, *PIO_STATUS_BLOCK;
+
+#define FilePipeLocalInformation 24
+
+typedef NTSTATUS (NTAPI *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;
+  IO_STATUS_BLOCK iosb;
+  FILE_PIPE_LOCAL_INFORMATION fpli;
+  static PNtQueryInformationFile NtQueryInformationFile;
+
+  ret = WaitForSingleObject (h, 0);
+  if (ret != WAIT_OBJECT_0)
+    return sought & (POLLOUT | POLLWRNORM | POLLWRBAND);
+
+  switch (GetFileType (h))
+    {
+    case FILE_TYPE_PIPE:
+      if (!NtQueryInformationFile)
+       NtQueryInformationFile = (PNtQueryInformationFile)
+         GetProcAddress (GetModuleHandle ("ntdll.dll"),
+                         "NtQueryInformationFile");
+
+      happened = 0;
+      if (!PeekNamedPipe (h, NULL, 0, NULL, &avail, NULL))
+       return POLLERR;
+
+      if (avail)
+       happened |= sought & (POLLIN | POLLRDNORM);
+
+      memset (&iosb, 0, sizeof (iosb));
+      memset (&fpli, 0, sizeof (fpli));
+
+      /* If NtQueryInformationFile fails, optimistically assume the pipe is
+        writable.  This could happen on Win9x, because 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.  */
+      if (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:
+      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);
+
+      return sought & (POLLOUT | POLLWRNORM | POLLWRBAND);
+
+    default:
+      return sought & ~(POLLPRI | POLLRDBAND);
+    }
+}
+
+/* Convert fd_sets returned by select into revents values.  */
+
+static int
+win32_compute_revents_socket (SOCKET h, int sought,
+                              fd_set *rfds, fd_set *wfds, fd_set *efds)
+{
+  int happened = 0;
+
+  if (FD_ISSET (h, rfds))
+    {
+      int r, error;
+
+      char data[64];
+      WSASetLastError (0);
+      r = recv (h, data, sizeof (data), MSG_PEEK);
+      error = WSAGetLastError ();
+      WSASetLastError (0);
+
+      if (r == 0)
+        happened |= POLLHUP;
+
+      /* If the event happened on an unconnected server socket,
+         that's fine. */
+      else if (r > 0 || ( /* (r == -1) && */ error == ENOTCONN))
+        happened |= (POLLIN | POLLRDNORM) & sought;
+
+      /* Distinguish hung-up sockets from other errors.  */
+      else if (error == WSAESHUTDOWN || error == WSAECONNRESET
+               || error == WSAECONNABORTED || error == WSAENETRESET)
+        happened |= POLLHUP;
+
+      else
+        happened |= POLLERR;
+    }
+
+  if (FD_ISSET (h, wfds))
+    happened |= (POLLOUT | POLLWRNORM | POLLWRBAND) & sought;
+
+  if (FD_ISSET (h, efds))
+    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;
+  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 __MSVCRT__
   fd_set rfds, wfds, efds;
   struct timeval tv;
   struct timeval *ptv;
@@ -162,55 +374,153 @@ 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);
-           socket_errno = (r < 0) ? errno : 0;
-#endif
-           if (r == 0)
-             happened |= POLLHUP;
+  fd_set rfds, wfds, efds;
+  static struct timeval tv0;
+  struct timeval tv = { 0, 0 };
+  struct timeval *ptv;
+  static HANDLE hEvent;
+  HANDLE handle_array[FD_SET_SIZE + 2];
+  DWORD ret, wait_timeout, nhandles;
+  int nsock;
+  BOOL bRet;
+  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 || nfd > FD_SET_SIZE || timeout < 0)
+    {
+      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;
+  nsock = 0;
 
-       if (FD_ISSET (pfd[i].fd, &wfds))
-         happened |= (POLLOUT | POLLWRNORM | POLLWRBAND) & sought;
+  /* Classify socket handles and create fd sets. */
+  FD_ZERO (&rfds);
+  FD_ZERO (&wfds);
+  FD_ZERO (&efds);
+  for (i = 0; i < nfd; i++)
+    {
+      if (pfd[i].fd < 0)
+        continue;
 
-       if (FD_ISSET (pfd[i].fd, &efds))
-         happened |= (POLLPRI | POLLRDBAND) & sought;
+      h = (HANDLE) _get_osfhandle (i);
+      assert (h != NULL);
+      optlen = sizeof(sockbuf);
+      if ((getsockopt ((SOCKET) h, SOL_SOCKET, SO_TYPE, sockbuf, &optlen)
+           != SOCKET_ERROR)
+          || WSAGetLastError() != WSAENOTSOCK)
+        {
+          int ev = 0;
 
-       if (happened)
-         {
-           pfd[i].revents = happened;
-           rc++;
-         }
-      }
+          /* see above; socket handles are mapped onto select.  */
+          if (pfd[i].events & (POLLIN | POLLRDNORM))
+            {
+              FD_SET (pfd[i].fd, &rfds);
+              ev |= FD_READ | FD_ACCEPT;
+            }
+          if (pfd[i].events & (POLLOUT | POLLWRNORM | POLLWRBAND))
+            {
+              FD_SET (pfd[i].fd, &wfds);
+              ev |= FD_WRITE | FD_CONNECT;
+            }
+          if (pfd[i].events & (POLLPRI | POLLRDBAND))
+            {
+              FD_SET (pfd[i].fd, &efds);
+              ev |= FD_OOB;
+            }
+          if (ev)
+            {
+              WSAEventSelect ((SOCKET) h, hEvent, ev);
+              nsock++;
+            }
+        }
+      else
+        {
+          if (pfd[i].events & (POLLIN | POLLRDNORM |
+                               POLLOUT | POLLWRNORM | POLLWRBAND))
+            handle_array[nhandles++] = h;
+        }
+    }
+
+  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 */
+          while ((bRet = PeekMessage (&msg, NULL, 0, 0, PM_REMOVE)) != 0)
+            {
+              TranslateMessage (&msg);
+              DispatchMessage (&msg);
+            }
+       }
+      else
+       break;
+    }
+
+  /* Now check if the sockets have some event set.  */
+  select (nsock + 1, rfds, wfds, efds, &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)
+        {
+          pfd[i].revents = 0;
+          continue;
+        }
+
+      h = (HANDLE) _get_osfhandle (i);
+      if (h != handle_array[nhandles])
+        {
+          /* It's a socket.  */
+          WSAEventSelect (h, 0, 0);
+          happened = win32_compute_revents_socket ((SOCKET) h, pfd[i].events,
+                                                   &rfds, &wfds, &efds);
+        }
+      else
+        {
+          /* Not a socket.  */
+          nhandles++;
+          happened = win32_compute_revents (h, pfd[i].events);
+        }
+
+       if (happened)
+        {
+          pfd[i].revents = happened;
+          rc++;
+        }
+    }
 
   return rc;
+#endif
 }