git/lib/compat/poll/poll.c

/* Emulation for poll(2)
   Contributed by Paolo Bonzini.

   Copyright 2001-2003, 2006-2011 Free Software Foundation, Inc.

   This file is part of gnulib.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License along
   with this program; if not, see <http://www.gnu.org/licenses/>.  */

#define DISABLE_SIGN_COMPARE_WARNINGS

/* To bump the minimum Windows version to Windows 8.1 */
#include "git-compat-util.h"

/* Tell gcc not to warn about the (nfd < 0) tests, below.  */
#if (__GNUC__ == 4 && 3 <= __GNUC_MINOR__) || 4 < __GNUC__
# pragma GCC diagnostic ignored "-Wtype-limits"
#endif

#if defined(WIN32)
# include <malloc.h>
#endif

#include <sys/types.h>

#include <errno.h>
#include <limits.h>
#include <assert.h>

#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
# define WIN32_NATIVE
# if defined (_MSC_VER) && !defined(_WIN32_WINNT)
#  define _WIN32_WINNT 0x0603
# endif
# include <winsock2.h>
# include <windows.h>
# include <io.h>
# include <stdio.h>
# include <conio.h>
#else
# include <sys/time.h>
# include <sys/socket.h>
# ifndef NO_SYS_SELECT_H
#  include <sys/select.h>
# endif
# include <unistd.h>
#endif

/* Specification.  */
#include "poll.h"

#ifdef HAVE_SYS_IOCTL_H
# include <sys/ioctl.h>
#endif
#ifdef HAVE_SYS_FILIO_H
# include <sys/filio.h>
#endif

#include <time.h>

#ifndef INFTIM
# define INFTIM (-1)
#endif

/* BeOS does not have MSG_PEEK.  */
#ifndef MSG_PEEK
# define MSG_PEEK 0
#endif

#ifdef WIN32_NATIVE

#define IsConsoleHandle(h) (((long) (intptr_t) (h) & 3) == 3)

static BOOL
IsSocketHandle (HANDLE h)
{
  WSANETWORKEVENTS ev;

  if (IsConsoleHandle (h))
    return FALSE;

  /* 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);
  return ev.lNetworkEvents != 0xDEADBEEF;
}

/* 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.  If some events cannot happen
   for the handle, eliminate them from *P_SOUGHT.  */

static int
win32_compute_revents (HANDLE h, int *p_sought)
{
  int i, ret, happened;
  INPUT_RECORD *irbuffer;
  DWORD avail, nbuffer;
  BOOL bRet;

  switch (GetFileType (h))
    {
    case FILE_TYPE_PIPE:
      happened = 0;
      if (PeekNamedPipe (h, NULL, 0, NULL, &avail, NULL) != 0)
	{
	  if (avail)
	    happened |= *p_sought & (POLLIN | POLLRDNORM);
	}
      else if (GetLastError () == ERROR_BROKEN_PIPE)
	happened |= POLLHUP;

      else
	{
	  /* It was the write-end of the pipe. Unfortunately there is no
	     reliable way of knowing if it can be written without blocking.
	     Just say that it's all good. */
	    happened |= *p_sought & (POLLOUT | POLLWRNORM | POLLWRBAND);
	}
      return happened;

    case FILE_TYPE_CHAR:
      ret = WaitForSingleObject (h, 0);
      if (!IsConsoleHandle (h))
	return ret == WAIT_OBJECT_0 ? *p_sought & ~(POLLPRI | POLLRDBAND) : 0;

      nbuffer = avail = 0;
      bRet = GetNumberOfConsoleInputEvents (h, &nbuffer);
      if (bRet)
	{
	  /* Input buffer.  */
	  *p_sought &= POLLIN | POLLRDNORM;
	  if (nbuffer == 0)
	    return POLLHUP;
	  if (!*p_sought)
	    return 0;

	  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 *p_sought;
	  return 0;
	}
      else
	{
	  /* Screen buffer.  */
	  *p_sought &= POLLOUT | POLLWRNORM | POLLWRBAND;
	  return *p_sought;
	}

    default:
      ret = WaitForSingleObject (h, 0);
      if (ret == WAIT_OBJECT_0)
	return *p_sought & ~(POLLPRI | POLLRDBAND);

      return *p_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;

      /* some systems can't use recv() on non-socket, including HP NonStop */
      else if (/* (r == -1) && */ socket_errno == ENOTSOCK)
	happened |= (POLLIN | POLLRDNORM) & sought;

      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 (struct pollfd *pfd, nfds_t nfd, int timeout)
{
#ifndef WIN32_NATIVE
  fd_set rfds, wfds, efds;
  struct timeval tv;
  struct timeval *ptv;
  int maxfd, rc;
  nfds_t i;

# ifdef _SC_OPEN_MAX
  static int sc_open_max = -1;

  if (nfd < 0
      || (nfd > sc_open_max
	  && (sc_open_max != -1
	      || nfd > (sc_open_max = sysconf (_SC_OPEN_MAX)))))
    {
      errno = EINVAL;
      return -1;
    }
# else /* !_SC_OPEN_MAX */
#  ifdef OPEN_MAX
  if (nfd < 0 || nfd > OPEN_MAX)
    {
      errno = EINVAL;
      return -1;
    }
#  endif /* OPEN_MAX -- else, no check is needed */
# endif /* !_SC_OPEN_MAX */

  /* EFAULT is not necessary to implement, but let's do it in the
     simplest case. */
  if (!pfd && nfd)
    {
      errno = EFAULT;
      return -1;
    }

  /* convert timeout number into a timeval structure */
  if (timeout == 0)
    {
      ptv = &tv;
      ptv->tv_sec = 0;
      ptv->tv_usec = 0;
    }
  else if (timeout > 0)
    {
      ptv = &tv;
      ptv->tv_sec = timeout / 1000;
      ptv->tv_usec = (timeout % 1000) * 1000;
    }
  else if (timeout == INFTIM)
    /* wait forever */
    ptv = NULL;
  else
    {
      errno = EINVAL;
      return -1;
    }

  /* create fd sets and determine max fd */
  maxfd = -1;
  FD_ZERO (&rfds);
  FD_ZERO (&wfds);
  FD_ZERO (&efds);
  for (i = 0; i < nfd; i++)
    {
      if (pfd[i].fd < 0)
	continue;

      if (pfd[i].events & (POLLIN | POLLRDNORM))
	FD_SET (pfd[i].fd, &rfds);

      /* see select(2): "the only exceptional condition detectable
	 is out-of-band data received on a socket", hence we push
	 POLLWRBAND events onto wfds instead of efds. */
      if (pfd[i].events & (POLLOUT | POLLWRNORM | POLLWRBAND))
	FD_SET (pfd[i].fd, &wfds);
      if (pfd[i].events & (POLLPRI | POLLRDBAND))
	FD_SET (pfd[i].fd, &efds);
      if (pfd[i].fd >= maxfd
	  && (pfd[i].events & (POLLIN | POLLOUT | POLLPRI
			       | POLLRDNORM | POLLRDBAND
			       | POLLWRNORM | POLLWRBAND)))
	{
	  maxfd = pfd[i].fd;
	  if (maxfd > FD_SETSIZE)
	    {
	      errno = EOVERFLOW;
	      return -1;
	    }
	}
    }

  /* examine fd sets */
  rc = select (maxfd + 1, &rfds, &wfds, &efds, ptv);
  if (rc < 0)
    return rc;

  /* establish results */
  rc = 0;
  for (i = 0; i < nfd; i++)
    if (pfd[i].fd < 0)
      pfd[i].revents = 0;
    else
      {
	int happened = compute_revents (pfd[i].fd, pfd[i].events,
					&rfds, &wfds, &efds);
	if (happened)
	  {
	    pfd[i].revents = happened;
	    rc++;
	  }
	else
	  {
	    pfd[i].revents = 0;
	  }
      }

  return rc;
#else
  static struct timeval tv0;
  static HANDLE hEvent;
  WSANETWORKEVENTS ev;
  HANDLE h, handle_array[FD_SETSIZE + 2];
  DWORD ret, wait_timeout, nhandles, orig_timeout = 0;
  ULONGLONG start = 0;
  fd_set rfds, wfds, xfds;
  BOOL poll_again;
  MSG msg;
  int rc = 0;
  nfds_t i;

  if (nfd < 0 || timeout < -1)
    {
      errno = EINVAL;
      return -1;
    }

  if (timeout != INFTIM)
    {
      orig_timeout = timeout;
      start = GetTickCount64();
    }

  if (!hEvent)
    hEvent = CreateEvent (NULL, FALSE, FALSE, NULL);

restart:
  handle_array[0] = hEvent;
  nhandles = 1;
  FD_ZERO (&rfds);
  FD_ZERO (&wfds);
  FD_ZERO (&xfds);

  /* Classify socket handles and create fd sets. */
  for (i = 0; i < nfd; i++)
    {
      int sought = pfd[i].events;
      pfd[i].revents = 0;
      if (pfd[i].fd < 0)
	continue;
      if (!(sought & (POLLIN | POLLRDNORM | POLLOUT | POLLWRNORM | POLLWRBAND
		      | POLLPRI | POLLRDBAND)))
	continue;

      h = (HANDLE) _get_osfhandle (pfd[i].fd);
      assert (h != NULL);
      if (IsSocketHandle (h))
	{
	  int requested = FD_CLOSE;

	  /* see above; socket handles are mapped onto select.  */
	  if (sought & (POLLIN | POLLRDNORM))
	    {
	      requested |= FD_READ | FD_ACCEPT;
	      FD_SET ((SOCKET) h, &rfds);
	    }
	  if (sought & (POLLOUT | POLLWRNORM | POLLWRBAND))
	    {
	      requested |= FD_WRITE | FD_CONNECT;
	      FD_SET ((SOCKET) h, &wfds);
	    }
	  if (sought & (POLLPRI | POLLRDBAND))
	    {
	      requested |= FD_OOB;
	      FD_SET ((SOCKET) h, &xfds);
	    }

	  if (requested)
	    WSAEventSelect ((SOCKET) h, hEvent, requested);
	}
      else
	{
	  /* Poll now.  If we get an event, do not poll again.  Also,
	     screen buffer handles are waitable, and they'll block until
	     a character is available.  win32_compute_revents eliminates
	     bits for the "wrong" direction. */
	  pfd[i].revents = win32_compute_revents (h, &sought);
	  if (sought)
	    handle_array[nhandles++] = h;
	  if (pfd[i].revents)
	    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, NULL, 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.  */
	  int sought = pfd[i].events;
	  happened = win32_compute_revents (h, &sought);
	  nhandles++;
	}

       if ((pfd[i].revents |= happened) != 0)
	rc++;
    }

  if (!rc && orig_timeout && timeout != INFTIM)
    {
      ULONGLONG elapsed = GetTickCount64() - start;
      timeout = elapsed >= orig_timeout ? 0 : (int)(orig_timeout - elapsed);
    }

  if (!rc && timeout)
    {
      SleepEx (1, TRUE);
      goto restart;
    }

  return rc;
#endif
}