monitor/fds.c - qemu - Git at Google

 /*
  * QEMU monitor file descriptor passing
  *
  * Copyright (c) 2003-2004 Fabrice Bellard
  *
  * 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.
  */

 #include "qemu/osdep.h"
 #include "monitor-internal.h"
 #include "qapi/error.h"
 #include "qapi/qapi-commands-misc.h"
 #include "qapi/qmp/qerror.h"
 #include "qemu/ctype.h"
 #include "qemu/cutils.h"
 #include "sysemu/runstate.h"

 /* file descriptors passed via SCM_RIGHTS */
 typedef struct mon_fd_t mon_fd_t;
 struct mon_fd_t {
     char *name;
     int fd;
     QLIST_ENTRY(mon_fd_t) next;
 };

 /* file descriptor associated with a file descriptor set */
 typedef struct MonFdsetFd MonFdsetFd;
 struct MonFdsetFd {
     int fd;
     bool removed;
     char *opaque;
     QLIST_ENTRY(MonFdsetFd) next;
 };

 /* file descriptor set containing fds passed via SCM_RIGHTS */
 typedef struct MonFdset MonFdset;
 struct MonFdset {
     int64_t id;
     QLIST_HEAD(, MonFdsetFd) fds;
     QLIST_HEAD(, MonFdsetFd) dup_fds;
     QLIST_ENTRY(MonFdset) next;
 };

 /* Protects mon_fdsets */
 static QemuMutex mon_fdsets_lock;
 static QLIST_HEAD(, MonFdset) mon_fdsets;

 void qmp_getfd(const char *fdname, Error **errp)
 {
     Monitor *cur_mon = monitor_cur();
     mon_fd_t *monfd;
     int fd, tmp_fd;

     fd = qemu_chr_fe_get_msgfd(&cur_mon->chr);
     if (fd == -1) {
         error_setg(errp, "No file descriptor supplied via SCM_RIGHTS");
         return;
     }

     if (qemu_isdigit(fdname[0])) {
         close(fd);
         error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "fdname",
                    "a name not starting with a digit");
         return;
     }

     /* See close() call below. */
     qemu_mutex_lock(&cur_mon->mon_lock);
     QLIST_FOREACH(monfd, &cur_mon->fds, next) {
         if (strcmp(monfd->name, fdname) != 0) {
             continue;
         }

         tmp_fd = monfd->fd;
         monfd->fd = fd;
         qemu_mutex_unlock(&cur_mon->mon_lock);
         /* Make sure close() is outside critical section */
         close(tmp_fd);
         return;
     }

     monfd = g_new0(mon_fd_t, 1);
     monfd->name = g_strdup(fdname);
     monfd->fd = fd;

     QLIST_INSERT_HEAD(&cur_mon->fds, monfd, next);
     qemu_mutex_unlock(&cur_mon->mon_lock);
 }

 void qmp_closefd(const char *fdname, Error **errp)
 {
     Monitor *cur_mon = monitor_cur();
     mon_fd_t *monfd;
     int tmp_fd;

     qemu_mutex_lock(&cur_mon->mon_lock);
     QLIST_FOREACH(monfd, &cur_mon->fds, next) {
         if (strcmp(monfd->name, fdname) != 0) {
             continue;
         }

         QLIST_REMOVE(monfd, next);
         tmp_fd = monfd->fd;
         g_free(monfd->name);
         g_free(monfd);
         qemu_mutex_unlock(&cur_mon->mon_lock);
         /* Make sure close() is outside critical section */
         close(tmp_fd);
         return;
     }

     qemu_mutex_unlock(&cur_mon->mon_lock);
     error_setg(errp, "File descriptor named '%s' not found", fdname);
 }

 int monitor_get_fd(Monitor *mon, const char *fdname, Error **errp)
 {
     mon_fd_t *monfd;

     QEMU_LOCK_GUARD(&mon->mon_lock);
     QLIST_FOREACH(monfd, &mon->fds, next) {
         int fd;

         if (strcmp(monfd->name, fdname) != 0) {
             continue;
         }

         fd = monfd->fd;
         assert(fd >= 0);

         /* caller takes ownership of fd */
         QLIST_REMOVE(monfd, next);
         g_free(monfd->name);
         g_free(monfd);

         return fd;
     }

     error_setg(errp, "File descriptor named '%s' has not been found", fdname);
     return -1;
 }

 static void monitor_fdset_cleanup(MonFdset *mon_fdset)
 {
     MonFdsetFd *mon_fdset_fd;
     MonFdsetFd *mon_fdset_fd_next;

     QLIST_FOREACH_SAFE(mon_fdset_fd, &mon_fdset->fds, next, mon_fdset_fd_next) {
         if ((mon_fdset_fd->removed ||
                 (QLIST_EMPTY(&mon_fdset->dup_fds) && mon_refcount == 0)) &&
                 runstate_is_running()) {
             close(mon_fdset_fd->fd);
             g_free(mon_fdset_fd->opaque);
             QLIST_REMOVE(mon_fdset_fd, next);
             g_free(mon_fdset_fd);
         }
     }

     if (QLIST_EMPTY(&mon_fdset->fds) && QLIST_EMPTY(&mon_fdset->dup_fds)) {
         QLIST_REMOVE(mon_fdset, next);
         g_free(mon_fdset);
     }
 }

 void monitor_fdsets_cleanup(void)
 {
     MonFdset *mon_fdset;
     MonFdset *mon_fdset_next;

     QEMU_LOCK_GUARD(&mon_fdsets_lock);
     QLIST_FOREACH_SAFE(mon_fdset, &mon_fdsets, next, mon_fdset_next) {
         monitor_fdset_cleanup(mon_fdset);
     }
 }

 AddfdInfo *qmp_add_fd(bool has_fdset_id, int64_t fdset_id,
                       const char *opaque, Error **errp)
 {
     int fd;
     Monitor *mon = monitor_cur();
     AddfdInfo *fdinfo;

     fd = qemu_chr_fe_get_msgfd(&mon->chr);
     if (fd == -1) {
         error_setg(errp, "No file descriptor supplied via SCM_RIGHTS");
         goto error;
     }

     fdinfo = monitor_fdset_add_fd(fd, has_fdset_id, fdset_id, opaque, errp);
     if (fdinfo) {
         return fdinfo;
     }

 error:
     if (fd != -1) {
         close(fd);
     }
     return NULL;
 }

 void qmp_remove_fd(int64_t fdset_id, bool has_fd, int64_t fd, Error **errp)
 {
     MonFdset *mon_fdset;
     MonFdsetFd *mon_fdset_fd;
     char fd_str[60];

     QEMU_LOCK_GUARD(&mon_fdsets_lock);
     QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
         if (mon_fdset->id != fdset_id) {
             continue;
         }
         QLIST_FOREACH(mon_fdset_fd, &mon_fdset->fds, next) {
             if (has_fd) {
                 if (mon_fdset_fd->fd != fd) {
                     continue;
                 }
                 mon_fdset_fd->removed = true;
                 break;
             } else {
                 mon_fdset_fd->removed = true;
             }
         }
         if (has_fd && !mon_fdset_fd) {
             goto error;
         }
         monitor_fdset_cleanup(mon_fdset);
         return;
     }

 error:
     if (has_fd) {
         snprintf(fd_str, sizeof(fd_str), "fdset-id:%" PRId64 ", fd:%" PRId64,
                  fdset_id, fd);
     } else {
         snprintf(fd_str, sizeof(fd_str), "fdset-id:%" PRId64, fdset_id);
     }
     error_setg(errp, "File descriptor named '%s' not found", fd_str);
 }

 FdsetInfoList *qmp_query_fdsets(Error **errp)
 {
     MonFdset *mon_fdset;
     MonFdsetFd *mon_fdset_fd;
     FdsetInfoList *fdset_list = NULL;

     QEMU_LOCK_GUARD(&mon_fdsets_lock);
     QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
         FdsetInfo *fdset_info = g_malloc0(sizeof(*fdset_info));

         fdset_info->fdset_id = mon_fdset->id;

         QLIST_FOREACH(mon_fdset_fd, &mon_fdset->fds, next) {
             FdsetFdInfo *fdsetfd_info;

             fdsetfd_info = g_malloc0(sizeof(*fdsetfd_info));
             fdsetfd_info->fd = mon_fdset_fd->fd;
             fdsetfd_info->opaque = g_strdup(mon_fdset_fd->opaque);

             QAPI_LIST_PREPEND(fdset_info->fds, fdsetfd_info);
         }

         QAPI_LIST_PREPEND(fdset_list, fdset_info);
     }

     return fdset_list;
 }

 AddfdInfo *monitor_fdset_add_fd(int fd, bool has_fdset_id, int64_t fdset_id,
                                 const char *opaque, Error **errp)
 {
     MonFdset *mon_fdset = NULL;
     MonFdsetFd *mon_fdset_fd;
     AddfdInfo *fdinfo;

     QEMU_LOCK_GUARD(&mon_fdsets_lock);
     if (has_fdset_id) {
         QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
             /* Break if match found or match impossible due to ordering by ID */
             if (fdset_id <= mon_fdset->id) {
                 if (fdset_id < mon_fdset->id) {
                     mon_fdset = NULL;
                 }
                 break;
             }
         }
     }

     if (mon_fdset == NULL) {
         int64_t fdset_id_prev = -1;
         MonFdset *mon_fdset_cur = QLIST_FIRST(&mon_fdsets);

         if (has_fdset_id) {
             if (fdset_id < 0) {
                 error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "fdset-id",
                            "a non-negative value");
                 return NULL;
             }
             /* Use specified fdset ID */
             QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
                 mon_fdset_cur = mon_fdset;
                 if (fdset_id < mon_fdset_cur->id) {
                     break;
                 }
             }
         } else {
             /* Use first available fdset ID */
             QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
                 mon_fdset_cur = mon_fdset;
                 if (fdset_id_prev == mon_fdset_cur->id - 1) {
                     fdset_id_prev = mon_fdset_cur->id;
                     continue;
                 }
                 break;
             }
         }

         mon_fdset = g_malloc0(sizeof(*mon_fdset));
         if (has_fdset_id) {
             mon_fdset->id = fdset_id;
         } else {
             mon_fdset->id = fdset_id_prev + 1;
         }

         /* The fdset list is ordered by fdset ID */
         if (!mon_fdset_cur) {
             QLIST_INSERT_HEAD(&mon_fdsets, mon_fdset, next);
         } else if (mon_fdset->id < mon_fdset_cur->id) {
             QLIST_INSERT_BEFORE(mon_fdset_cur, mon_fdset, next);
         } else {
             QLIST_INSERT_AFTER(mon_fdset_cur, mon_fdset, next);
         }
     }

     mon_fdset_fd = g_malloc0(sizeof(*mon_fdset_fd));
     mon_fdset_fd->fd = fd;
     mon_fdset_fd->removed = false;
     mon_fdset_fd->opaque = g_strdup(opaque);
     QLIST_INSERT_HEAD(&mon_fdset->fds, mon_fdset_fd, next);

     fdinfo = g_malloc0(sizeof(*fdinfo));
     fdinfo->fdset_id = mon_fdset->id;
     fdinfo->fd = mon_fdset_fd->fd;

     return fdinfo;
 }

 int monitor_fdset_dup_fd_add(int64_t fdset_id, int flags)
 {
 #ifdef _WIN32
     return -ENOENT;
 #else
     MonFdset *mon_fdset;

     QEMU_LOCK_GUARD(&mon_fdsets_lock);
     QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
         MonFdsetFd *mon_fdset_fd;
         MonFdsetFd *mon_fdset_fd_dup;
         int fd = -1;
         int dup_fd;
         int mon_fd_flags;

         if (mon_fdset->id != fdset_id) {
             continue;
         }

         QLIST_FOREACH(mon_fdset_fd, &mon_fdset->fds, next) {
             mon_fd_flags = fcntl(mon_fdset_fd->fd, F_GETFL);
             if (mon_fd_flags == -1) {
                 return -1;
             }

             if ((flags & O_ACCMODE) == (mon_fd_flags & O_ACCMODE)) {
                 fd = mon_fdset_fd->fd;
                 break;
             }
         }

         if (fd == -1) {
             errno = EACCES;
             return -1;
         }

         dup_fd = qemu_dup_flags(fd, flags);
         if (dup_fd == -1) {
             return -1;
         }

         mon_fdset_fd_dup = g_malloc0(sizeof(*mon_fdset_fd_dup));
         mon_fdset_fd_dup->fd = dup_fd;
         QLIST_INSERT_HEAD(&mon_fdset->dup_fds, mon_fdset_fd_dup, next);
         return dup_fd;
     }

     errno = ENOENT;
     return -1;
 #endif
 }

 static int64_t monitor_fdset_dup_fd_find_remove(int dup_fd, bool remove)
 {
     MonFdset *mon_fdset;
     MonFdsetFd *mon_fdset_fd_dup;

     QEMU_LOCK_GUARD(&mon_fdsets_lock);
     QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
         QLIST_FOREACH(mon_fdset_fd_dup, &mon_fdset->dup_fds, next) {
             if (mon_fdset_fd_dup->fd == dup_fd) {
                 if (remove) {
                     QLIST_REMOVE(mon_fdset_fd_dup, next);
                     g_free(mon_fdset_fd_dup);
                     if (QLIST_EMPTY(&mon_fdset->dup_fds)) {
                         monitor_fdset_cleanup(mon_fdset);
                     }
                     return -1;
                 } else {
                     return mon_fdset->id;
                 }
             }
         }
     }

     return -1;
 }

 int64_t monitor_fdset_dup_fd_find(int dup_fd)
 {
     return monitor_fdset_dup_fd_find_remove(dup_fd, false);
 }

 void monitor_fdset_dup_fd_remove(int dup_fd)
 {
     monitor_fdset_dup_fd_find_remove(dup_fd, true);
 }

 int monitor_fd_param(Monitor *mon, const char *fdname, Error **errp)
 {
     int fd;

     if (!qemu_isdigit(fdname[0]) && mon) {
         fd = monitor_get_fd(mon, fdname, errp);
     } else {
         fd = qemu_parse_fd(fdname);
         if (fd < 0) {
             error_setg(errp, "Invalid file descriptor number '%s'",
                        fdname);
         }
     }

     return fd;
 }

 static void __attribute__((__constructor__)) monitor_fds_init(void)
 {
     qemu_mutex_init(&mon_fdsets_lock);
 }
	/*
	* QEMU monitor file descriptor passing
	*
	* Copyright (c) 2003-2004 Fabrice Bellard
	*
	* 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.
	*/

	#include "qemu/osdep.h"
	#include "monitor-internal.h"
	#include "qapi/error.h"
	#include "qapi/qapi-commands-misc.h"
	#include "qapi/qmp/qerror.h"
	#include "qemu/ctype.h"
	#include "qemu/cutils.h"
	#include "sysemu/runstate.h"

	/* file descriptors passed via SCM_RIGHTS */
	typedef struct mon_fd_t mon_fd_t;
	struct mon_fd_t {
	char *name;
	int fd;
	QLIST_ENTRY(mon_fd_t) next;
	};

	/* file descriptor associated with a file descriptor set */
	typedef struct MonFdsetFd MonFdsetFd;
	struct MonFdsetFd {
	int fd;
	bool removed;
	char *opaque;
	QLIST_ENTRY(MonFdsetFd) next;
	};

	/* file descriptor set containing fds passed via SCM_RIGHTS */
	typedef struct MonFdset MonFdset;
	struct MonFdset {
	int64_t id;
	QLIST_HEAD(, MonFdsetFd) fds;
	QLIST_HEAD(, MonFdsetFd) dup_fds;
	QLIST_ENTRY(MonFdset) next;
	};

	/* Protects mon_fdsets */
	static QemuMutex mon_fdsets_lock;
	static QLIST_HEAD(, MonFdset) mon_fdsets;

	void qmp_getfd(const char fdname, Error *errp)
	{
	Monitor *cur_mon = monitor_cur();
	mon_fd_t *monfd;
	int fd, tmp_fd;

	fd = qemu_chr_fe_get_msgfd(&cur_mon->chr);
	if (fd == -1) {
	error_setg(errp, "No file descriptor supplied via SCM_RIGHTS");
	return;
	}

	if (qemu_isdigit(fdname[0])) {
	close(fd);
	error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "fdname",
	"a name not starting with a digit");
	return;
	}

	/* See close() call below. */
	qemu_mutex_lock(&cur_mon->mon_lock);
	QLIST_FOREACH(monfd, &cur_mon->fds, next) {
	if (strcmp(monfd->name, fdname) != 0) {
	continue;
	}

	tmp_fd = monfd->fd;
	monfd->fd = fd;
	qemu_mutex_unlock(&cur_mon->mon_lock);
	/* Make sure close() is outside critical section */
	close(tmp_fd);
	return;
	}

	monfd = g_new0(mon_fd_t, 1);
	monfd->name = g_strdup(fdname);
	monfd->fd = fd;

	QLIST_INSERT_HEAD(&cur_mon->fds, monfd, next);
	qemu_mutex_unlock(&cur_mon->mon_lock);
	}

	void qmp_closefd(const char fdname, Error *errp)
	{
	Monitor *cur_mon = monitor_cur();
	mon_fd_t *monfd;
	int tmp_fd;

	qemu_mutex_lock(&cur_mon->mon_lock);
	QLIST_FOREACH(monfd, &cur_mon->fds, next) {
	if (strcmp(monfd->name, fdname) != 0) {
	continue;
	}

	QLIST_REMOVE(monfd, next);
	tmp_fd = monfd->fd;
	g_free(monfd->name);
	g_free(monfd);
	qemu_mutex_unlock(&cur_mon->mon_lock);
	/* Make sure close() is outside critical section */
	close(tmp_fd);
	return;
	}

	qemu_mutex_unlock(&cur_mon->mon_lock);
	error_setg(errp, "File descriptor named '%s' not found", fdname);
	}

	int monitor_get_fd(Monitor mon, const char fdname, Error **errp)
	{
	mon_fd_t *monfd;

	QEMU_LOCK_GUARD(&mon->mon_lock);
	QLIST_FOREACH(monfd, &mon->fds, next) {
	int fd;

	if (strcmp(monfd->name, fdname) != 0) {
	continue;
	}

	fd = monfd->fd;
	assert(fd >= 0);

	/* caller takes ownership of fd */
	QLIST_REMOVE(monfd, next);
	g_free(monfd->name);
	g_free(monfd);

	return fd;
	}

	error_setg(errp, "File descriptor named '%s' has not been found", fdname);
	return -1;
	}

	static void monitor_fdset_cleanup(MonFdset *mon_fdset)
	{
	MonFdsetFd *mon_fdset_fd;
	MonFdsetFd *mon_fdset_fd_next;

	QLIST_FOREACH_SAFE(mon_fdset_fd, &mon_fdset->fds, next, mon_fdset_fd_next) {
	if ((mon_fdset_fd->removed \|\|
	(QLIST_EMPTY(&mon_fdset->dup_fds) && mon_refcount == 0)) &&
	runstate_is_running()) {
	close(mon_fdset_fd->fd);
	g_free(mon_fdset_fd->opaque);
	QLIST_REMOVE(mon_fdset_fd, next);
	g_free(mon_fdset_fd);
	}
	}

	if (QLIST_EMPTY(&mon_fdset->fds) && QLIST_EMPTY(&mon_fdset->dup_fds)) {
	QLIST_REMOVE(mon_fdset, next);
	g_free(mon_fdset);
	}
	}

	void monitor_fdsets_cleanup(void)
	{
	MonFdset *mon_fdset;
	MonFdset *mon_fdset_next;

	QEMU_LOCK_GUARD(&mon_fdsets_lock);
	QLIST_FOREACH_SAFE(mon_fdset, &mon_fdsets, next, mon_fdset_next) {
	monitor_fdset_cleanup(mon_fdset);
	}
	}

	AddfdInfo *qmp_add_fd(bool has_fdset_id, int64_t fdset_id,
	const char opaque, Error *errp)
	{
	int fd;
	Monitor *mon = monitor_cur();
	AddfdInfo *fdinfo;

	fd = qemu_chr_fe_get_msgfd(&mon->chr);
	if (fd == -1) {
	error_setg(errp, "No file descriptor supplied via SCM_RIGHTS");
	goto error;
	}

	fdinfo = monitor_fdset_add_fd(fd, has_fdset_id, fdset_id, opaque, errp);
	if (fdinfo) {
	return fdinfo;
	}

	error:
	if (fd != -1) {
	close(fd);
	}
	return NULL;
	}

	void qmp_remove_fd(int64_t fdset_id, bool has_fd, int64_t fd, Error **errp)
	{
	MonFdset *mon_fdset;
	MonFdsetFd *mon_fdset_fd;
	char fd_str[60];

	QEMU_LOCK_GUARD(&mon_fdsets_lock);
	QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
	if (mon_fdset->id != fdset_id) {
	continue;
	}
	QLIST_FOREACH(mon_fdset_fd, &mon_fdset->fds, next) {
	if (has_fd) {
	if (mon_fdset_fd->fd != fd) {
	continue;
	}
	mon_fdset_fd->removed = true;
	break;
	} else {
	mon_fdset_fd->removed = true;
	}
	}
	if (has_fd && !mon_fdset_fd) {
	goto error;
	}
	monitor_fdset_cleanup(mon_fdset);
	return;
	}

	error:
	if (has_fd) {
	snprintf(fd_str, sizeof(fd_str), "fdset-id:%" PRId64 ", fd:%" PRId64,
	fdset_id, fd);
	} else {
	snprintf(fd_str, sizeof(fd_str), "fdset-id:%" PRId64, fdset_id);
	}
	error_setg(errp, "File descriptor named '%s' not found", fd_str);
	}

	FdsetInfoList qmp_query_fdsets(Error *errp)
	{
	MonFdset *mon_fdset;
	MonFdsetFd *mon_fdset_fd;
	FdsetInfoList *fdset_list = NULL;

	QEMU_LOCK_GUARD(&mon_fdsets_lock);
	QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
	FdsetInfo fdset_info = g_malloc0(sizeof(fdset_info));

	fdset_info->fdset_id = mon_fdset->id;

	QLIST_FOREACH(mon_fdset_fd, &mon_fdset->fds, next) {
	FdsetFdInfo *fdsetfd_info;

	fdsetfd_info = g_malloc0(sizeof(*fdsetfd_info));
	fdsetfd_info->fd = mon_fdset_fd->fd;
	fdsetfd_info->opaque = g_strdup(mon_fdset_fd->opaque);

	QAPI_LIST_PREPEND(fdset_info->fds, fdsetfd_info);
	}

	QAPI_LIST_PREPEND(fdset_list, fdset_info);
	}

	return fdset_list;
	}

	AddfdInfo *monitor_fdset_add_fd(int fd, bool has_fdset_id, int64_t fdset_id,
	const char opaque, Error *errp)
	{
	MonFdset *mon_fdset = NULL;
	MonFdsetFd *mon_fdset_fd;
	AddfdInfo *fdinfo;

	QEMU_LOCK_GUARD(&mon_fdsets_lock);
	if (has_fdset_id) {
	QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
	/* Break if match found or match impossible due to ordering by ID */
	if (fdset_id <= mon_fdset->id) {
	if (fdset_id < mon_fdset->id) {
	mon_fdset = NULL;
	}
	break;
	}
	}
	}

	if (mon_fdset == NULL) {
	int64_t fdset_id_prev = -1;
	MonFdset *mon_fdset_cur = QLIST_FIRST(&mon_fdsets);

	if (has_fdset_id) {
	if (fdset_id < 0) {
	error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "fdset-id",
	"a non-negative value");
	return NULL;
	}
	/* Use specified fdset ID */
	QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
	mon_fdset_cur = mon_fdset;
	if (fdset_id < mon_fdset_cur->id) {
	break;
	}
	}
	} else {
	/* Use first available fdset ID */
	QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
	mon_fdset_cur = mon_fdset;
	if (fdset_id_prev == mon_fdset_cur->id - 1) {
	fdset_id_prev = mon_fdset_cur->id;
	continue;
	}
	break;
	}
	}

	mon_fdset = g_malloc0(sizeof(*mon_fdset));
	if (has_fdset_id) {
	mon_fdset->id = fdset_id;
	} else {
	mon_fdset->id = fdset_id_prev + 1;
	}

	/* The fdset list is ordered by fdset ID */
	if (!mon_fdset_cur) {
	QLIST_INSERT_HEAD(&mon_fdsets, mon_fdset, next);
	} else if (mon_fdset->id < mon_fdset_cur->id) {
	QLIST_INSERT_BEFORE(mon_fdset_cur, mon_fdset, next);
	} else {
	QLIST_INSERT_AFTER(mon_fdset_cur, mon_fdset, next);
	}
	}

	mon_fdset_fd = g_malloc0(sizeof(*mon_fdset_fd));
	mon_fdset_fd->fd = fd;
	mon_fdset_fd->removed = false;
	mon_fdset_fd->opaque = g_strdup(opaque);
	QLIST_INSERT_HEAD(&mon_fdset->fds, mon_fdset_fd, next);

	fdinfo = g_malloc0(sizeof(*fdinfo));
	fdinfo->fdset_id = mon_fdset->id;
	fdinfo->fd = mon_fdset_fd->fd;

	return fdinfo;
	}

	int monitor_fdset_dup_fd_add(int64_t fdset_id, int flags)
	{
	#ifdef _WIN32
	return -ENOENT;
	#else
	MonFdset *mon_fdset;

	QEMU_LOCK_GUARD(&mon_fdsets_lock);
	QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
	MonFdsetFd *mon_fdset_fd;
	MonFdsetFd *mon_fdset_fd_dup;
	int fd = -1;
	int dup_fd;
	int mon_fd_flags;

	if (mon_fdset->id != fdset_id) {
	continue;
	}

	QLIST_FOREACH(mon_fdset_fd, &mon_fdset->fds, next) {
	mon_fd_flags = fcntl(mon_fdset_fd->fd, F_GETFL);
	if (mon_fd_flags == -1) {
	return -1;
	}

	if ((flags & O_ACCMODE) == (mon_fd_flags & O_ACCMODE)) {
	fd = mon_fdset_fd->fd;
	break;
	}
	}

	if (fd == -1) {
	errno = EACCES;
	return -1;
	}

	dup_fd = qemu_dup_flags(fd, flags);
	if (dup_fd == -1) {
	return -1;
	}

	mon_fdset_fd_dup = g_malloc0(sizeof(*mon_fdset_fd_dup));
	mon_fdset_fd_dup->fd = dup_fd;
	QLIST_INSERT_HEAD(&mon_fdset->dup_fds, mon_fdset_fd_dup, next);
	return dup_fd;
	}

	errno = ENOENT;
	return -1;
	#endif
	}

	static int64_t monitor_fdset_dup_fd_find_remove(int dup_fd, bool remove)
	{
	MonFdset *mon_fdset;
	MonFdsetFd *mon_fdset_fd_dup;

	QEMU_LOCK_GUARD(&mon_fdsets_lock);
	QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
	QLIST_FOREACH(mon_fdset_fd_dup, &mon_fdset->dup_fds, next) {
	if (mon_fdset_fd_dup->fd == dup_fd) {
	if (remove) {
	QLIST_REMOVE(mon_fdset_fd_dup, next);
	g_free(mon_fdset_fd_dup);
	if (QLIST_EMPTY(&mon_fdset->dup_fds)) {
	monitor_fdset_cleanup(mon_fdset);
	}
	return -1;
	} else {
	return mon_fdset->id;
	}
	}
	}
	}

	return -1;
	}

	int64_t monitor_fdset_dup_fd_find(int dup_fd)
	{
	return monitor_fdset_dup_fd_find_remove(dup_fd, false);
	}

	void monitor_fdset_dup_fd_remove(int dup_fd)
	{
	monitor_fdset_dup_fd_find_remove(dup_fd, true);
	}

	int monitor_fd_param(Monitor mon, const char fdname, Error **errp)
	{
	int fd;

	if (!qemu_isdigit(fdname[0]) && mon) {
	fd = monitor_get_fd(mon, fdname, errp);
	} else {
	fd = qemu_parse_fd(fdname);
	if (fd < 0) {
	error_setg(errp, "Invalid file descriptor number '%s'",
	fdname);
	}
	}

	return fd;
	}

	static void __attribute__((__constructor__)) monitor_fds_init(void)
	{
	qemu_mutex_init(&mon_fdsets_lock);
	}