util/oslib-win32.c - qemu-android - Git at Google

 /*
  * os-win32.c
  *
  * Copyright (c) 2003-2008 Fabrice Bellard
  * Copyright (c) 2010 Red Hat, Inc.
  *
  * QEMU library functions for win32 which are shared between QEMU and
  * the QEMU tools.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
  * in the Software without restriction, including without limitation the rights
  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  * copies of the Software, and to permit persons to whom the Software is
  * furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  *
  * The implementation of g_poll (functions poll_rest, g_poll) at the end of
  * this file are based on code from GNOME glib-2 and use a different license,
  * see the license comment there.
  */
 #include <windows.h>
 #include <glib.h>
 #include <stdlib.h>
 #include "config-host.h"
 #include "sysemu/sysemu.h"
 #include "qemu/main-loop.h"
 #include "trace.h"
 #include "qemu/sockets.h"

 #ifdef CONFIG_ANDROID
 #include "android/utils/win32_unicode.h"
 #endif  // CONFIG_ANDROID

 /* this must come after including "trace.h" */
 #include <shlobj.h>

 void *qemu_oom_check(void *ptr)
 {
     if (ptr == NULL) {
         fprintf(stderr, "Failed to allocate memory: %lu\n", GetLastError());
         abort();
     }
     return ptr;
 }

 void *qemu_try_memalign(size_t alignment, size_t size)
 {
     void *ptr;

     if (!size) {
         abort();
     }
     ptr = VirtualAlloc(NULL, size, MEM_COMMIT, PAGE_READWRITE);
     trace_qemu_memalign(alignment, size, ptr);
     return ptr;
 }

 void *qemu_memalign(size_t alignment, size_t size)
 {
     return qemu_oom_check(qemu_try_memalign(alignment, size));
 }

 void *qemu_anon_ram_alloc(size_t size, uint64_t *align)
 {
     void *ptr;

     /* FIXME: this is not exactly optimal solution since VirtualAlloc
        has 64Kb granularity, but at least it guarantees us that the
        memory is page aligned. */
     ptr = VirtualAlloc(NULL, size, MEM_COMMIT, PAGE_READWRITE);
     trace_qemu_anon_ram_alloc(size, ptr);
     return ptr;
 }

 void qemu_vfree(void *ptr)
 {
     trace_qemu_vfree(ptr);
     if (ptr) {
         VirtualFree(ptr, 0, MEM_RELEASE);
     }
 }

 void qemu_anon_ram_free(void *ptr, size_t size)
 {
     trace_qemu_anon_ram_free(ptr, size);
     if (ptr) {
         VirtualFree(ptr, 0, MEM_RELEASE);
     }
 }

 /* FIXME: add proper locking */
 struct tm *gmtime_r(const time_t *timep, struct tm *result)
 {
     struct tm *p = gmtime(timep);
     memset(result, 0, sizeof(*result));
     if (p) {
         *result = *p;
         p = result;
     }
     return p;
 }

 /* FIXME: add proper locking */
 struct tm *localtime_r(const time_t *timep, struct tm *result)
 {
     struct tm *p = localtime(timep);
     memset(result, 0, sizeof(*result));
     if (p) {
         *result = *p;
         p = result;
     }
     return p;
 }

 void qemu_set_block(int fd)
 {
     unsigned long opt = 0;
     WSAEventSelect(fd, NULL, 0);
     ioctlsocket(fd, FIONBIO, &opt);
 }

 void qemu_set_nonblock(int fd)
 {
     unsigned long opt = 1;
     ioctlsocket(fd, FIONBIO, &opt);
     qemu_fd_register(fd);
 }

 int socket_set_fast_reuse(int fd)
 {
     /* Enabling the reuse of an endpoint that was used by a socket still in
      * TIME_WAIT state is usually performed by setting SO_REUSEADDR. On Windows
      * fast reuse is the default and SO_REUSEADDR does strange things. So we
      * don't have to do anything here. More info can be found at:
      * http://msdn.microsoft.com/en-us/library/windows/desktop/ms740621.aspx */
     return 0;
 }

 int inet_aton(const char *cp, struct in_addr *ia)
 {
     uint32_t addr = inet_addr(cp);
     if (addr == 0xffffffff) {
         return 0;
     }
     ia->s_addr = addr;
     return 1;
 }

 void qemu_set_cloexec(int fd)
 {
 }

 /* Offset between 1/1/1601 and 1/1/1970 in 100 nanosec units */
 #define _W32_FT_OFFSET (116444736000000000ULL)

 int qemu_gettimeofday(qemu_timeval *tp)
 {
   union {
     unsigned long long ns100; /*time since 1 Jan 1601 in 100ns units */
     FILETIME ft;
   }  _now;

   if(tp) {
       GetSystemTimeAsFileTime (&_now.ft);
       tp->tv_usec=(long)((_now.ns100 / 10ULL) % 1000000ULL );
       tp->tv_sec= (long)((_now.ns100 - _W32_FT_OFFSET) / 10000000ULL);
   }
   /* Always return 0 as per Open Group Base Specifications Issue 6.
      Do not set errno on error.  */
   return 0;
 }

 int qemu_get_thread_id(void)
 {
     return GetCurrentThreadId();
 }

 char *
 qemu_get_local_state_pathname(const char *relative_pathname)
 {
     HRESULT result;
     char base_path[MAX_PATH+1] = "";

     result = SHGetFolderPath(NULL, CSIDL_COMMON_APPDATA, NULL,
                              /* SHGFP_TYPE_CURRENT */ 0, base_path);
     if (result != S_OK) {
         /* misconfigured environment */
         g_critical("CSIDL_COMMON_APPDATA unavailable: %ld", (long)result);
         abort();
     }
     return g_strdup_printf("%s" G_DIR_SEPARATOR_S "%s", base_path,
                            relative_pathname);
 }

 void qemu_set_tty_echo(int fd, bool echo)
 {
     HANDLE handle = (HANDLE)_get_osfhandle(fd);
     DWORD dwMode = 0;

     if (handle == INVALID_HANDLE_VALUE) {
         return;
     }

     GetConsoleMode(handle, &dwMode);

     if (echo) {
         SetConsoleMode(handle, dwMode | ENABLE_ECHO_INPUT | ENABLE_LINE_INPUT);
     } else {
         SetConsoleMode(handle,
                        dwMode & ~(ENABLE_ECHO_INPUT | ENABLE_LINE_INPUT));
     }
 }

 static char exec_dir[PATH_MAX];

 void qemu_init_exec_dir(const char *argv0)
 {

     char *p;
     char buf[MAX_PATH];
     DWORD len;

 #ifdef CONFIG_ANDROID
     wchar_t wideBuf[MAX_PATH];
     len = GetModuleFileNameW(NULL, wideBuf, MAX_PATH);
     if (len == 0 || len >= MAX_PATH) {
         return;
     }
     int written = win32_utf16_to_utf8_buf(wideBuf, buf, sizeof(buf));
     if (written < 0) {
         return;
     }
     len = written;
 #else
     len = GetModuleFileName(NULL, buf, sizeof(buf) - 1);
     if (len == 0) {
         return;
     }
 #endif

     buf[len] = 0;
     p = buf + len - 1;
     while (p != buf && *p != '\\') {
         p--;
     }
     *p = 0;
     if (access(buf, R_OK) == 0) {
         pstrcpy(exec_dir, sizeof(exec_dir), buf);
     }
 }

 char *qemu_get_exec_dir(void)
 {
     return g_strdup(exec_dir);
 }

 /*
  * The original implementation of g_poll from glib has a problem on Windows
  * when using timeouts < 10 ms.
  *
  * Whenever g_poll is called with timeout < 10 ms, it does a quick poll instead
  * of wait. This causes significant performance degradation of QEMU.
  *
  * The following code is a copy of the original code from glib/gpoll.c
  * (glib commit 20f4d1820b8d4d0fc4447188e33efffd6d4a88d8 from 2014-02-19).
  * Some debug code was removed and the code was reformatted.
  * All other code modifications are marked with 'QEMU'.
  */

 /*
  * gpoll.c: poll(2) abstraction
  * Copyright 1998 Owen Taylor
  * Copyright 2008 Red Hat, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library 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
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  */

 static int poll_rest(gboolean poll_msgs, HANDLE *handles, gint nhandles,
                      GPollFD *fds, guint nfds, gint timeout)
 {
     DWORD ready;
     GPollFD *f;
     int recursed_result;

     if (poll_msgs) {
         /* Wait for either messages or handles
          * -> Use MsgWaitForMultipleObjectsEx
          */
         ready = MsgWaitForMultipleObjectsEx(nhandles, handles, timeout,
                                             QS_ALLINPUT, MWMO_ALERTABLE);

         if (ready == WAIT_FAILED) {
             gchar *emsg = g_win32_error_message(GetLastError());
             g_warning("MsgWaitForMultipleObjectsEx failed: %s", emsg);
             g_free(emsg);
         }
     } else if (nhandles == 0) {
         /* No handles to wait for, just the timeout */
         if (timeout == INFINITE) {
             ready = WAIT_FAILED;
         } else {
             SleepEx(timeout, TRUE);
             ready = WAIT_TIMEOUT;
         }
     } else {
         /* Wait for just handles
          * -> Use WaitForMultipleObjectsEx
          */
         ready =
             WaitForMultipleObjectsEx(nhandles, handles, FALSE, timeout, TRUE);
         if (ready == WAIT_FAILED) {
             gchar *emsg = g_win32_error_message(GetLastError());
             g_warning("WaitForMultipleObjectsEx failed: %s", emsg);
             g_free(emsg);
         }
     }

     if (ready == WAIT_FAILED) {
         return -1;
     } else if (ready == WAIT_TIMEOUT || ready == WAIT_IO_COMPLETION) {
         return 0;
     } else if (poll_msgs && ready == WAIT_OBJECT_0 + nhandles) {
         for (f = fds; f < &fds[nfds]; ++f) {
             if (f->fd == G_WIN32_MSG_HANDLE && f->events & G_IO_IN) {
                 f->revents |= G_IO_IN;
             }
         }

         /* If we have a timeout, or no handles to poll, be satisfied
          * with just noticing we have messages waiting.
          */
         if (timeout != 0 || nhandles == 0) {
             return 1;
         }

         /* If no timeout and handles to poll, recurse to poll them,
          * too.
          */
         recursed_result = poll_rest(FALSE, handles, nhandles, fds, nfds, 0);
         return (recursed_result == -1) ? -1 : 1 + recursed_result;
     } else if (/* QEMU: removed the following unneeded statement which causes
                 * a compiler warning: ready >= WAIT_OBJECT_0 && */
                ready < WAIT_OBJECT_0 + nhandles) {
         for (f = fds; f < &fds[nfds]; ++f) {
             if ((HANDLE) f->fd == handles[ready - WAIT_OBJECT_0]) {
                 f->revents = f->events;
             }
         }

         /* If no timeout and polling several handles, recurse to poll
          * the rest of them.
          */
         if (timeout == 0 && nhandles > 1) {
             /* Remove the handle that fired */
             int i;
             if (ready < nhandles - 1) {
                 for (i = ready - WAIT_OBJECT_0 + 1; i < nhandles; i++) {
                     handles[i-1] = handles[i];
                 }
             }
             nhandles--;
             recursed_result = poll_rest(FALSE, handles, nhandles, fds, nfds, 0);
             return (recursed_result == -1) ? -1 : 1 + recursed_result;
         }
         return 1;
     }

     return 0;
 }

 gint g_poll(GPollFD *fds, guint nfds, gint timeout)
 {
     HANDLE handles[MAXIMUM_WAIT_OBJECTS];
     gboolean poll_msgs = FALSE;
     GPollFD *f;
     gint nhandles = 0;
     int retval;

     for (f = fds; f < &fds[nfds]; ++f) {
         if (f->fd == G_WIN32_MSG_HANDLE && (f->events & G_IO_IN)) {
             poll_msgs = TRUE;
         } else if (f->fd > 0) {
             /* Don't add the same handle several times into the array, as
              * docs say that is not allowed, even if it actually does seem
              * to work.
              */
             gint i;

             for (i = 0; i < nhandles; i++) {
                 if (handles[i] == (HANDLE) f->fd) {
                     break;
                 }
             }

             if (i == nhandles) {
                 if (nhandles == MAXIMUM_WAIT_OBJECTS) {
                     g_warning("Too many handles to wait for!\n");
                     break;
                 } else {
                     handles[nhandles++] = (HANDLE) f->fd;
                 }
             }
         }
     }

     for (f = fds; f < &fds[nfds]; ++f) {
         f->revents = 0;
     }

     if (timeout == -1) {
         timeout = INFINITE;
     }

     /* Polling for several things? */
     if (nhandles > 1 || (nhandles > 0 && poll_msgs)) {
         /* First check if one or several of them are immediately
          * available
          */
         retval = poll_rest(poll_msgs, handles, nhandles, fds, nfds, 0);

         /* If not, and we have a significant timeout, poll again with
          * timeout then. Note that this will return indication for only
          * one event, or only for messages. We ignore timeouts less than
          * ten milliseconds as they are mostly pointless on Windows, the
          * MsgWaitForMultipleObjectsEx() call will timeout right away
          * anyway.
          *
          * Modification for QEMU: replaced timeout >= 10 by timeout > 0.
          */
         if (retval == 0 && (timeout == INFINITE || timeout > 0)) {
             retval = poll_rest(poll_msgs, handles, nhandles,
                                fds, nfds, timeout);
         }
     } else {
         /* Just polling for one thing, so no need to check first if
          * available immediately
          */
         retval = poll_rest(poll_msgs, handles, nhandles, fds, nfds, timeout);
     }

     if (retval == -1) {
         for (f = fds; f < &fds[nfds]; ++f) {
             f->revents = 0;
         }
     }

     return retval;
 }

 size_t getpagesize(void)
 {
     SYSTEM_INFO system_info;

     GetSystemInfo(&system_info);
     return system_info.dwPageSize;
 }

 void os_mem_prealloc(int fd, char *area, size_t memory)
 {
     int i;
     size_t pagesize = getpagesize();

     memory = (memory + pagesize - 1) & -pagesize;
     for (i = 0; i < memory / pagesize; i++) {
         memset(area + pagesize * i, 0, 1);
     }
 }

 #ifdef CONFIG_ANDROID
 // Required by the debug Android build.
 int ffs(int x) {
     int result = 0;
     unsigned ux = (unsigned)x;
     while (ux) {
         if (ux & 1)
             return result + 1;
         ux >>= 1;
         ++result;
     }
     return 0;
 }

 int ffsl(long x) {
     int result = 0;
     unsigned long ux = (unsigned long)x;
     while (ux) {
         if (ux & 1)
             return result + 1;
         ux >>= 1;
         ++result;
     }
     return 0;
 }
 #endif
	/*
	* os-win32.c
	*
	* Copyright (c) 2003-2008 Fabrice Bellard
	* Copyright (c) 2010 Red Hat, Inc.
	*
	* QEMU library functions for win32 which are shared between QEMU and
	* the QEMU tools.
	*
	* Permission is hereby granted, free of charge, to any person obtaining a copy
	* of this software and associated documentation files (the "Software"), to deal
	* in the Software without restriction, including without limitation the rights
	* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	* copies of the Software, and to permit persons to whom the Software is
	* furnished to do so, subject to the following conditions:
	*
	* The above copyright notice and this permission notice shall be included in
	* all copies or substantial portions of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
	* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
	* THE SOFTWARE.
	*
	* The implementation of g_poll (functions poll_rest, g_poll) at the end of
	* this file are based on code from GNOME glib-2 and use a different license,
	* see the license comment there.
	*/
	#include <windows.h>
	#include <glib.h>
	#include <stdlib.h>
	#include "config-host.h"
	#include "sysemu/sysemu.h"
	#include "qemu/main-loop.h"
	#include "trace.h"
	#include "qemu/sockets.h"

	#ifdef CONFIG_ANDROID
	#include "android/utils/win32_unicode.h"
	#endif // CONFIG_ANDROID

	/* this must come after including "trace.h" */
	#include <shlobj.h>

	void qemu_oom_check(void ptr)
	{
	if (ptr == NULL) {
	fprintf(stderr, "Failed to allocate memory: %lu\n", GetLastError());
	abort();
	}
	return ptr;
	}

	void *qemu_try_memalign(size_t alignment, size_t size)
	{
	void *ptr;

	if (!size) {
	abort();
	}
	ptr = VirtualAlloc(NULL, size, MEM_COMMIT, PAGE_READWRITE);
	trace_qemu_memalign(alignment, size, ptr);
	return ptr;
	}

	void *qemu_memalign(size_t alignment, size_t size)
	{
	return qemu_oom_check(qemu_try_memalign(alignment, size));
	}

	void qemu_anon_ram_alloc(size_t size, uint64_t align)
	{
	void *ptr;

	/* FIXME: this is not exactly optimal solution since VirtualAlloc
	has 64Kb granularity, but at least it guarantees us that the
	memory is page aligned. */
	ptr = VirtualAlloc(NULL, size, MEM_COMMIT, PAGE_READWRITE);
	trace_qemu_anon_ram_alloc(size, ptr);
	return ptr;
	}

	void qemu_vfree(void *ptr)
	{
	trace_qemu_vfree(ptr);
	if (ptr) {
	VirtualFree(ptr, 0, MEM_RELEASE);
	}
	}

	void qemu_anon_ram_free(void *ptr, size_t size)
	{
	trace_qemu_anon_ram_free(ptr, size);
	if (ptr) {
	VirtualFree(ptr, 0, MEM_RELEASE);
	}
	}

	/* FIXME: add proper locking */
	struct tm gmtime_r(const time_t timep, struct tm *result)
	{
	struct tm *p = gmtime(timep);
	memset(result, 0, sizeof(*result));
	if (p) {
	result = p;
	p = result;
	}
	return p;
	}

	/* FIXME: add proper locking */
	struct tm localtime_r(const time_t timep, struct tm *result)
	{
	struct tm *p = localtime(timep);
	memset(result, 0, sizeof(*result));
	if (p) {
	result = p;
	p = result;
	}
	return p;
	}

	void qemu_set_block(int fd)
	{
	unsigned long opt = 0;
	WSAEventSelect(fd, NULL, 0);
	ioctlsocket(fd, FIONBIO, &opt);
	}

	void qemu_set_nonblock(int fd)
	{
	unsigned long opt = 1;
	ioctlsocket(fd, FIONBIO, &opt);
	qemu_fd_register(fd);
	}

	int socket_set_fast_reuse(int fd)
	{
	/* Enabling the reuse of an endpoint that was used by a socket still in
	* TIME_WAIT state is usually performed by setting SO_REUSEADDR. On Windows
	* fast reuse is the default and SO_REUSEADDR does strange things. So we
	* don't have to do anything here. More info can be found at:
	* http://msdn.microsoft.com/en-us/library/windows/desktop/ms740621.aspx */
	return 0;
	}

	int inet_aton(const char cp, struct in_addr ia)
	{
	uint32_t addr = inet_addr(cp);
	if (addr == 0xffffffff) {
	return 0;
	}
	ia->s_addr = addr;
	return 1;
	}

	void qemu_set_cloexec(int fd)
	{
	}

	/* Offset between 1/1/1601 and 1/1/1970 in 100 nanosec units */
	#define _W32_FT_OFFSET (116444736000000000ULL)

	int qemu_gettimeofday(qemu_timeval *tp)
	{
	union {
	unsigned long long ns100; /time since 1 Jan 1601 in 100ns units /
	FILETIME ft;
	} _now;

	if(tp) {
	GetSystemTimeAsFileTime (&_now.ft);
	tp->tv_usec=(long)((_now.ns100 / 10ULL) % 1000000ULL );
	tp->tv_sec= (long)((_now.ns100 - _W32_FT_OFFSET) / 10000000ULL);
	}
	/* Always return 0 as per Open Group Base Specifications Issue 6.
	Do not set errno on error. */
	return 0;
	}

	int qemu_get_thread_id(void)
	{
	return GetCurrentThreadId();
	}

	char *
	qemu_get_local_state_pathname(const char *relative_pathname)
	{
	HRESULT result;
	char base_path[MAX_PATH+1] = "";

	result = SHGetFolderPath(NULL, CSIDL_COMMON_APPDATA, NULL,
	/* SHGFP_TYPE_CURRENT */ 0, base_path);
	if (result != S_OK) {
	/* misconfigured environment */
	g_critical("CSIDL_COMMON_APPDATA unavailable: %ld", (long)result);
	abort();
	}
	return g_strdup_printf("%s" G_DIR_SEPARATOR_S "%s", base_path,
	relative_pathname);
	}

	void qemu_set_tty_echo(int fd, bool echo)
	{
	HANDLE handle = (HANDLE)_get_osfhandle(fd);
	DWORD dwMode = 0;

	if (handle == INVALID_HANDLE_VALUE) {
	return;
	}

	GetConsoleMode(handle, &dwMode);

	if (echo) {
	SetConsoleMode(handle, dwMode \| ENABLE_ECHO_INPUT \| ENABLE_LINE_INPUT);
	} else {
	SetConsoleMode(handle,
	dwMode & ~(ENABLE_ECHO_INPUT \| ENABLE_LINE_INPUT));
	}
	}

	static char exec_dir[PATH_MAX];

	void qemu_init_exec_dir(const char *argv0)
	{

	char *p;
	char buf[MAX_PATH];
	DWORD len;

	#ifdef CONFIG_ANDROID
	wchar_t wideBuf[MAX_PATH];
	len = GetModuleFileNameW(NULL, wideBuf, MAX_PATH);
	if (len == 0 \|\| len >= MAX_PATH) {
	return;
	}
	int written = win32_utf16_to_utf8_buf(wideBuf, buf, sizeof(buf));
	if (written < 0) {
	return;
	}
	len = written;
	#else
	len = GetModuleFileName(NULL, buf, sizeof(buf) - 1);
	if (len == 0) {
	return;
	}
	#endif

	buf[len] = 0;
	p = buf + len - 1;
	while (p != buf && *p != '\\') {
	p--;
	}
	*p = 0;
	if (access(buf, R_OK) == 0) {
	pstrcpy(exec_dir, sizeof(exec_dir), buf);
	}
	}

	char *qemu_get_exec_dir(void)
	{
	return g_strdup(exec_dir);
	}

	/*
	* The original implementation of g_poll from glib has a problem on Windows
	* when using timeouts < 10 ms.
	*
	* Whenever g_poll is called with timeout < 10 ms, it does a quick poll instead
	* of wait. This causes significant performance degradation of QEMU.
	*
	* The following code is a copy of the original code from glib/gpoll.c
	* (glib commit 20f4d1820b8d4d0fc4447188e33efffd6d4a88d8 from 2014-02-19).
	* Some debug code was removed and the code was reformatted.
	* All other code modifications are marked with 'QEMU'.
	*/

	/*
	* gpoll.c: poll(2) abstraction
	* Copyright 1998 Owen Taylor
	* Copyright 2008 Red Hat, Inc.
	*
	* This library is free software; you can redistribute it and/or
	* modify it under the terms of the GNU Lesser General Public
	* License as published by the Free Software Foundation; either
	* version 2 of the License, or (at your option) any later version.
	*
	* This library 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
	* Lesser General Public License for more details.
	*
	* You should have received a copy of the GNU Lesser General Public
	* License along with this library; if not, see <http://www.gnu.org/licenses/>.
	*/

	static int poll_rest(gboolean poll_msgs, HANDLE *handles, gint nhandles,
	GPollFD *fds, guint nfds, gint timeout)
	{
	DWORD ready;
	GPollFD *f;
	int recursed_result;

	if (poll_msgs) {
	/* Wait for either messages or handles
	* -> Use MsgWaitForMultipleObjectsEx
	*/
	ready = MsgWaitForMultipleObjectsEx(nhandles, handles, timeout,
	QS_ALLINPUT, MWMO_ALERTABLE);

	if (ready == WAIT_FAILED) {
	gchar *emsg = g_win32_error_message(GetLastError());
	g_warning("MsgWaitForMultipleObjectsEx failed: %s", emsg);
	g_free(emsg);
	}
	} else if (nhandles == 0) {
	/* No handles to wait for, just the timeout */
	if (timeout == INFINITE) {
	ready = WAIT_FAILED;
	} else {
	SleepEx(timeout, TRUE);
	ready = WAIT_TIMEOUT;
	}
	} else {
	/* Wait for just handles
	* -> Use WaitForMultipleObjectsEx
	*/
	ready =
	WaitForMultipleObjectsEx(nhandles, handles, FALSE, timeout, TRUE);
	if (ready == WAIT_FAILED) {
	gchar *emsg = g_win32_error_message(GetLastError());
	g_warning("WaitForMultipleObjectsEx failed: %s", emsg);
	g_free(emsg);
	}
	}

	if (ready == WAIT_FAILED) {
	return -1;
	} else if (ready == WAIT_TIMEOUT \|\| ready == WAIT_IO_COMPLETION) {
	return 0;
	} else if (poll_msgs && ready == WAIT_OBJECT_0 + nhandles) {
	for (f = fds; f < &fds[nfds]; ++f) {
	if (f->fd == G_WIN32_MSG_HANDLE && f->events & G_IO_IN) {
	f->revents \|= G_IO_IN;
	}
	}

	/* If we have a timeout, or no handles to poll, be satisfied
	* with just noticing we have messages waiting.
	*/
	if (timeout != 0 \|\| nhandles == 0) {
	return 1;
	}

	/* If no timeout and handles to poll, recurse to poll them,
	* too.
	*/
	recursed_result = poll_rest(FALSE, handles, nhandles, fds, nfds, 0);
	return (recursed_result == -1) ? -1 : 1 + recursed_result;
	} else if (/* QEMU: removed the following unneeded statement which causes
	* a compiler warning: ready >= WAIT_OBJECT_0 && */
	ready < WAIT_OBJECT_0 + nhandles) {
	for (f = fds; f < &fds[nfds]; ++f) {
	if ((HANDLE) f->fd == handles[ready - WAIT_OBJECT_0]) {
	f->revents = f->events;
	}
	}

	/* If no timeout and polling several handles, recurse to poll
	* the rest of them.
	*/
	if (timeout == 0 && nhandles > 1) {
	/* Remove the handle that fired */
	int i;
	if (ready < nhandles - 1) {
	for (i = ready - WAIT_OBJECT_0 + 1; i < nhandles; i++) {
	handles[i-1] = handles[i];
	}
	}
	nhandles--;
	recursed_result = poll_rest(FALSE, handles, nhandles, fds, nfds, 0);
	return (recursed_result == -1) ? -1 : 1 + recursed_result;
	}
	return 1;
	}

	return 0;
	}

	gint g_poll(GPollFD *fds, guint nfds, gint timeout)
	{
	HANDLE handles[MAXIMUM_WAIT_OBJECTS];
	gboolean poll_msgs = FALSE;
	GPollFD *f;
	gint nhandles = 0;
	int retval;

	for (f = fds; f < &fds[nfds]; ++f) {
	if (f->fd == G_WIN32_MSG_HANDLE && (f->events & G_IO_IN)) {
	poll_msgs = TRUE;
	} else if (f->fd > 0) {
	/* Don't add the same handle several times into the array, as
	* docs say that is not allowed, even if it actually does seem
	* to work.
	*/
	gint i;

	for (i = 0; i < nhandles; i++) {
	if (handles[i] == (HANDLE) f->fd) {
	break;
	}
	}

	if (i == nhandles) {
	if (nhandles == MAXIMUM_WAIT_OBJECTS) {
	g_warning("Too many handles to wait for!\n");
	break;
	} else {
	handles[nhandles++] = (HANDLE) f->fd;
	}
	}
	}
	}

	for (f = fds; f < &fds[nfds]; ++f) {
	f->revents = 0;
	}

	if (timeout == -1) {
	timeout = INFINITE;
	}

	/* Polling for several things? */
	if (nhandles > 1 \|\| (nhandles > 0 && poll_msgs)) {
	/* First check if one or several of them are immediately
	* available
	*/
	retval = poll_rest(poll_msgs, handles, nhandles, fds, nfds, 0);

	/* If not, and we have a significant timeout, poll again with
	* timeout then. Note that this will return indication for only
	* one event, or only for messages. We ignore timeouts less than
	* ten milliseconds as they are mostly pointless on Windows, the
	* MsgWaitForMultipleObjectsEx() call will timeout right away
	* anyway.
	*
	* Modification for QEMU: replaced timeout >= 10 by timeout > 0.
	*/
	if (retval == 0 && (timeout == INFINITE \|\| timeout > 0)) {
	retval = poll_rest(poll_msgs, handles, nhandles,
	fds, nfds, timeout);
	}
	} else {
	/* Just polling for one thing, so no need to check first if
	* available immediately
	*/
	retval = poll_rest(poll_msgs, handles, nhandles, fds, nfds, timeout);
	}

	if (retval == -1) {
	for (f = fds; f < &fds[nfds]; ++f) {
	f->revents = 0;
	}
	}

	return retval;
	}

	size_t getpagesize(void)
	{
	SYSTEM_INFO system_info;

	GetSystemInfo(&system_info);
	return system_info.dwPageSize;
	}

	void os_mem_prealloc(int fd, char *area, size_t memory)
	{
	int i;
	size_t pagesize = getpagesize();

	memory = (memory + pagesize - 1) & -pagesize;
	for (i = 0; i < memory / pagesize; i++) {
	memset(area + pagesize * i, 0, 1);
	}
	}

	#ifdef CONFIG_ANDROID
	// Required by the debug Android build.
	int ffs(int x) {
	int result = 0;
	unsigned ux = (unsigned)x;
	while (ux) {
	if (ux & 1)
	return result + 1;
	ux >>= 1;
	++result;
	}
	return 0;
	}

	int ffsl(long x) {
	int result = 0;
	unsigned long ux = (unsigned long)x;
	while (ux) {
	if (ux & 1)
	return result + 1;
	ux >>= 1;
	++result;
	}
	return 0;
	}
	#endif