smbd: Protect ea-reading on symlinks

[Samba.git] / source3 / lib / tevent_glib_glue.c

/*
   Unix SMB/CIFS implementation.
   Integration of a glib g_main_context into a tevent_context
   Copyright (C) Stefan Metzmacher 2016
   Copyright (C) Ralph Boehme 2016

     ** NOTE! The following LGPL license applies to the tevent
     ** library. This does NOT imply that all of Samba is released
     ** under the LGPL

   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 3 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/>.
*/

#include "replace.h"
#include "system/filesys.h"
#include "lib/util/debug.h"
#include "lib/util/select.h"
#include <tevent.h>

#undef DBGC_CLASS
#define DBGC_CLASS DBGC_TEVENT

#ifdef HAVE_GLIB
#include <glib.h>
#include "tevent_glib_glue.h"

struct fd_map {
        struct tevent_glib_glue *glue;
        int fd;
        struct tevent_fd *fd_event;
};

struct tevent_glib_glue {
        /*
         * The tevent context we're feeding.
         */
        struct tevent_context *ev;

        /*
         * The glib gmain context we're polling and whether we're currently
         * owning it by virtue of g_main_context_acquire().
         */
        GMainContext *gmain_ctx;
        bool gmain_owner;

        /*
         * Set by samba_tevent_glib_glue_quit().
         */
        bool quit;

        /*
         * tevent trace callback and data we got from tevent_get_trace_callback()
         * before installing our own trace callback.
         */
        tevent_trace_callback_t prev_tevent_trace_cb;
        void *prev_tevent_trace_data;

        /*
         * Don't call tevent_glib_prepare() in the tevent tracepoint handler if
         * explicitly told so. This is an optimisation for the case that glib
         * event sources are created from glib event callbacks.
         */
        bool skip_glib_refresh;

        /*
         * Used when acquiring the glib gmain context failed.
         */
        struct tevent_timer *acquire_retry_timer;

        /*
         * glib gmain context timeout and priority for the current event look
         * iteration. gtimeout is translated to a tevent timer event, unless it
         * is 0 which signals some event source is pending. In that case we
         * dispatch an immediate event. gpriority is ignored by us, just passed
         * to the glib relevant functions.
         */
        gint gtimeout;
        gint gpriority;
        struct tevent_timer *timer;
        struct tevent_immediate *im;
        bool scheduled_im;

        /*
         * glib gmain context fds returned from g_main_context_query(). These
         * get translated to tevent fd events.
         */
        GPollFD *gpollfds;
        gint num_gpollfds;

        /*
         * A copy of gpollfds and num_gpollfds from the previous event loop
         * iteration, used to detect changes in the set of fds.
         */
        GPollFD *prev_gpollfds;
        gint num_prev_gpollfds;

        /*
         * An array of pointers to fd_map's. The fd_map'd contain the tevent
         * event fd as well as a pointer to the corresponding glib GPollFD.
         */
        struct fd_map **fd_map;
        size_t num_maps;
};

static bool tevent_glib_prepare(struct tevent_glib_glue *glue);
static bool tevent_glib_process(struct tevent_glib_glue *glue);
static bool tevent_glib_glue_reinit(struct tevent_glib_glue *glue);
static void tevent_glib_fd_handler(struct tevent_context *ev,
                                   struct tevent_fd *fde,
                                   uint16_t flags,
                                   void *private_data);

typedef int (*gfds_cmp_cb)(const void *fd1, const void *fd2);
typedef bool (*gfds_found_cb)(struct tevent_glib_glue *glue,
                              const GPollFD *new,
                              const GPollFD *old);
typedef bool (*gfds_new_cb)(struct tevent_glib_glue *glue,
                            const GPollFD *fd);
typedef bool (*gfds_removed_cb)(struct tevent_glib_glue *glue,
                                const GPollFD *fd);

/**
 * Compare two sorted GPollFD arrays
 *
 * For every element that exists in gfds and prev_gfds found_fn() is called.
 * For every element in gfds but not in prev_gfds, new_fn() is called.
 * For every element in prev_gfds but not in gfds removed_fn() is called.
 **/
static bool cmp_gfds(struct tevent_glib_glue *glue,
                     GPollFD *gfds,
                     GPollFD *prev_gfds,
                     size_t num_gfds,
                     size_t num_prev_gfds,
                     gfds_cmp_cb cmp_cb,
                     gfds_found_cb found_cb,
                     gfds_new_cb new_cb,
                     gfds_removed_cb removed_cb)
{
        bool ok;
        size_t i = 0, j = 0;
        int cmp;

        while (i < num_gfds && j < num_prev_gfds) {
                cmp = cmp_cb(&gfds[i], &prev_gfds[j]);
                if (cmp == 0) {
                        ok = found_cb(glue, &gfds[i], &prev_gfds[j]);
                        if (!ok) {
                                return false;
                        }
                        i++;
                        j++;
                } else if (cmp < 0) {
                        ok = new_cb(glue, &gfds[i]);
                        if (!ok) {
                                return false;
                        }
                        i++;
                } else {
                        ok = removed_cb(glue, &prev_gfds[j]);
                        if (!ok) {
                                return false;
                        }
                        j++;
                }
        }

        while (i < num_gfds) {
                ok = new_cb(glue, &gfds[i++]);
                if (!ok) {
                        return false;
                }
        }

        while (j < num_prev_gfds) {
                ok = removed_cb(glue, &prev_gfds[j++]);
                if (!ok) {
                        return false;
                }
        }

        return true;
}

static int glib_fd_cmp_func(const void *p1, const void *p2)
{
        const GPollFD *lhs = p1;
        const GPollFD *rhs = p2;

        if (lhs->fd < rhs->fd) {
                return -1;
        } else if (lhs->fd > rhs->fd) {
                return 1;
        }

        return 0;
}

/*
 * We already have a tevent fd event for the glib GPollFD, but we may have to
 * update flags.
 */
static bool match_gfd_cb(struct tevent_glib_glue *glue,
                         const GPollFD *new_gfd,
                         const GPollFD *old_gfd)
{
        size_t i;
        struct fd_map *fd_map = NULL;
        struct tevent_fd *fd_event = NULL;

        if (new_gfd->events == old_gfd->events) {
                return true;
        }

        for (i = 0; i < glue->num_maps; i++) {
                if (glue->fd_map[i]->fd == new_gfd->fd) {
                        break;
                }
        }

        if (i == glue->num_maps) {
                DBG_ERR("match_gfd_cb: glib fd %d not in map\n", new_gfd->fd);
                return false;
        }

        fd_map = glue->fd_map[i];
        if (fd_map == NULL) {
                DBG_ERR("fd_map for fd %d is NULL\n", new_gfd->fd);
                return false;
        }

        fd_event = fd_map->fd_event;
        if (fd_event == NULL) {
                DBG_ERR("fd_event for fd %d is NULL\n", new_gfd->fd);
                return false;
        }

        tevent_fd_set_flags(fd_event, 0);

        if (new_gfd->events & (G_IO_IN | G_IO_HUP | G_IO_ERR)) {
                TEVENT_FD_READABLE(fd_event);
        }
        if (new_gfd->events & G_IO_OUT) {
                TEVENT_FD_WRITEABLE(fd_event);
        }

        return true;
}

static bool new_gfd_cb(struct tevent_glib_glue *glue, const GPollFD *gfd)
{
        struct tevent_fd *fd_event = NULL;
        struct fd_map *fd_map = NULL;
        uint16_t events = 0;
        bool revent;
        bool wevent;

        revent = (gfd->events & (G_IO_IN | G_IO_HUP | G_IO_ERR));
        wevent = (gfd->events & G_IO_OUT);
        if (revent) {
                events |= TEVENT_FD_READ;
        }
        if (wevent) {
                events |= TEVENT_FD_WRITE;
        }

        glue->fd_map = talloc_realloc(glue,
                                      glue->fd_map,
                                      struct fd_map *,
                                      glue->num_maps + 1);
        if (glue->fd_map == NULL) {
                DBG_ERR("talloc_realloc failed\n");
                return false;
        }
        fd_map = talloc_zero(glue->fd_map, struct fd_map);
        if (fd_map == NULL) {
                DBG_ERR("talloc_realloc failed\n");
                return false;
        }
        glue->fd_map[glue->num_maps] = fd_map;
        glue->num_maps++;

        fd_event = tevent_add_fd(glue->ev,
                                 glue->fd_map,
                                 gfd->fd,
                                 events,
                                 tevent_glib_fd_handler,
                                 fd_map);
        if (fd_event == NULL) {
                DBG_ERR("tevent_add_fd failed\n");
                return false;
        }

        *fd_map = (struct fd_map) {
                .glue = glue,
                .fd = gfd->fd,
                .fd_event = fd_event,
        };

        DBG_DEBUG("added tevent_fd for glib fd %d\n", gfd->fd);

        return true;
}

static bool remove_gfd_cb(struct tevent_glib_glue *glue, const GPollFD *gfd)
{
        size_t i;

        for (i = 0; i < glue->num_maps; i++) {
                if (glue->fd_map[i]->fd == gfd->fd) {
                        break;
                }
        }

        if (i == glue->num_maps) {
                DBG_ERR("remove_gfd_cb: glib fd %d not in map\n", gfd->fd);
                return false;
        }

        TALLOC_FREE(glue->fd_map[i]->fd_event);
        TALLOC_FREE(glue->fd_map[i]);

        if (i + 1 < glue->num_maps) {
                memmove(&glue->fd_map[i],
                        &glue->fd_map[i+1],
                        (glue->num_maps - (i + 1)) * sizeof(struct fd_map *));
        }

        glue->fd_map = talloc_realloc(glue,
                                      glue->fd_map,
                                      struct fd_map *,
                                      glue->num_maps - 1);
        if (glue->num_maps > 0 && glue->fd_map == NULL) {
                DBG_ERR("talloc_realloc failed\n");
                return false;
        }
        glue->num_maps--;

        return true;
}

static short gpoll_to_poll_event(gushort gevent)
{
        short pevent = 0;

        if (gevent & G_IO_IN) {
                pevent |= POLLIN;
        }
        if (gevent & G_IO_OUT) {
                pevent |= POLLOUT;
        }
        if (gevent & G_IO_HUP) {
                pevent |= POLLHUP;
        }
        if (gevent & G_IO_ERR) {
                pevent |= POLLERR;
        }

        return pevent;
}

static gushort poll_to_gpoll_event(short pevent)
{
        gushort gevent = 0;

        if (pevent & POLLIN) {
                gevent |= G_IO_IN;
        }
        if (pevent & POLLOUT) {
                gevent |= G_IO_OUT;
        }
        if (pevent & POLLHUP) {
                gevent |= G_IO_HUP;
        }
        if (pevent & POLLERR) {
                gevent |= G_IO_ERR;
        }

        return gevent;
}

static void tevent_glib_fd_handler(struct tevent_context *ev,
                                   struct tevent_fd *fde,
                                   uint16_t flags,
                                   void *private_data)
{
        struct fd_map *fd_map = talloc_get_type_abort(
                private_data, struct fd_map);
        struct tevent_glib_glue *glue = NULL;
        GPollFD *gpollfd = NULL;
        struct pollfd fd;
        int ret;
        int i;

        glue = fd_map->glue;

        for (i = 0; i < glue->num_gpollfds; i++) {
                if (glue->gpollfds[i].fd != fd_map->fd) {
                        continue;
                }
                gpollfd = &glue->gpollfds[i];
                break;
        }
        if (gpollfd == NULL) {
                DBG_ERR("No gpollfd for fd_map [%p] fd [%d]\n",
                        fd_map, fd_map->fd);
                return;
        }
        /*
         * We have to poll() the fd to get the correct fd event for glib. tevent
         * only tells us about readable/writable in flags, but we need the full
         * glory for glib.
         */

        fd = (struct pollfd) {
                .fd = gpollfd->fd,
                .events = gpoll_to_poll_event(gpollfd->events),
        };

        ret = sys_poll_intr(&fd, 1, 0);
        if (ret == -1) {
                DBG_ERR("poll: %s\n", strerror(errno));
                return;
        }
        if (ret == 0) {
                return;
        }

        gpollfd->revents = poll_to_gpoll_event(fd.revents);

        tevent_glib_process(glue);
        return;
}

static void tevent_glib_timer_handler(struct tevent_context *ev,
                                      struct tevent_timer *te,
                                      struct timeval current_time,
                                      void *private_data)
{
        struct tevent_glib_glue *glue = talloc_get_type_abort(
                private_data, struct tevent_glib_glue);

        glue->timer = NULL;
        tevent_glib_process(glue);
        return;
}

static void tevent_glib_im_handler(struct tevent_context *ev,
                                   struct tevent_immediate *im,
                                   void *private_data)
{
        struct tevent_glib_glue *glue = talloc_get_type_abort(
                private_data, struct tevent_glib_glue);

        glue->scheduled_im = false;
        tevent_glib_process(glue);
        return;
}

static bool save_current_fdset(struct tevent_glib_glue *glue)
{
        /*
         * Save old glib fds. We only grow the prev array.
         */

        if (glue->num_prev_gpollfds < glue->num_gpollfds) {
                glue->prev_gpollfds = talloc_realloc(glue,
                                                     glue->prev_gpollfds,
                                                     GPollFD,
                                                     glue->num_gpollfds);
                if (glue->prev_gpollfds == NULL) {
                        DBG_ERR("talloc_realloc failed\n");
                        return false;
                }
        }
        glue->num_prev_gpollfds = glue->num_gpollfds;
        if (glue->num_gpollfds > 0) {
                memcpy(glue->prev_gpollfds, glue->gpollfds,
                       sizeof(GPollFD) * glue->num_gpollfds);
                memset(glue->gpollfds, 0, sizeof(GPollFD) * glue->num_gpollfds);
        }

        return true;
}

static bool get_glib_fds_and_timeout(struct tevent_glib_glue *glue)
{
        bool ok;
        gint num_fds;

        ok = save_current_fdset(glue);
        if (!ok) {
                return false;
        }

        while (true) {
                num_fds = g_main_context_query(glue->gmain_ctx,
                                               glue->gpriority,
                                               &glue->gtimeout,
                                               glue->gpollfds,
                                               glue->num_gpollfds);
                if (num_fds == glue->num_gpollfds) {
                        break;
                }
                glue->gpollfds = talloc_realloc(glue,
                                                glue->gpollfds,
                                                GPollFD,
                                                num_fds);
                if (num_fds > 0 && glue->gpollfds == NULL) {
                        DBG_ERR("talloc_realloc failed\n");
                        return false;
                }
                glue->num_gpollfds = num_fds;
        };

        if (glue->num_gpollfds > 0) {
                qsort(glue->gpollfds,
                      num_fds,
                      sizeof(GPollFD),
                      glib_fd_cmp_func);
        }

        DBG_DEBUG("num fds: %d, timeout: %d ms\n",
                  num_fds, glue->gtimeout);

        return true;
}

static bool tevent_glib_update_events(struct tevent_glib_glue *glue)
{
        struct timeval tv;
        bool ok;

        ok = cmp_gfds(glue,
                      glue->gpollfds,
                      glue->prev_gpollfds,
                      glue->num_gpollfds,
                      glue->num_prev_gpollfds,
                      glib_fd_cmp_func,
                      match_gfd_cb,
                      new_gfd_cb,
                      remove_gfd_cb);
        if (!ok) {
                return false;
        }

        TALLOC_FREE(glue->timer);

        if (glue->gtimeout == -1) {
                return true;
        }

        if (glue->gtimeout == 0) {
                /*
                 * glue->gtimeout is 0 if g_main_context_query() returned
                 * timeout=0. That means there are pending events ready to be
                 * dispatched. We only want to run one event handler per loop
                 * iteration, so we schedule an immediate event to run it in the
                 * next iteration.
                 */
                if (glue->scheduled_im) {
                        return true;
                }
                tevent_schedule_immediate(glue->im,
                                          glue->ev,
                                          tevent_glib_im_handler,
                                          glue);
                glue->scheduled_im = true;
                return true;
        }

        tv = tevent_timeval_current_ofs(glue->gtimeout / 1000,
                                        (glue->gtimeout % 1000) * 1000);

        glue->timer = tevent_add_timer(glue->ev,
                                       glue,
                                       tv,
                                       tevent_glib_timer_handler,
                                       glue);
        if (glue->timer == NULL) {
                DBG_ERR("tevent_add_timer failed\n");
                return false;
        }

        return true;
}

static void tevent_glib_retry_timer(struct tevent_context *ev,
                                    struct tevent_timer *te,
                                    struct timeval current_time,
                                    void *private_data)
{
        struct tevent_glib_glue *glue = talloc_get_type_abort(
                private_data, struct tevent_glib_glue);

        glue->acquire_retry_timer = NULL;
        (void)tevent_glib_prepare(glue);
}

/**
 * Fetch glib event sources and add them to tevent
 *
 * Fetch glib event sources and attach corresponding tevent events to our tevent
 * context. get_glib_fds_and_timeout() gets the relevant glib event sources: the
 * set of active fds and the next timer. tevent_glib_update_events() then
 * translates those to tevent and creates tevent events.
 *
 * When called, the thread must NOT be the owner to the glib main
 * context. tevent_glib_prepare() is either the first function when the
 * tevent_glib_glue is created, or after tevent_glib_process() has been called
 * to process pending event, which will have ceased ownership.
 **/
static bool tevent_glib_prepare(struct tevent_glib_glue *glue)
{
        bool ok;
        gboolean gok;

        if (glue->quit) {
                /* Set via samba_tevent_glib_glue_quit() */
                return true;
        }

        if (glue->acquire_retry_timer != NULL) {
                /*
                 * We're still waiting on the below g_main_context_acquire() to
                 * succeed, just return.
                 */
                return true;
        }

        if (glue->gmain_owner) {
                g_main_context_release(glue->gmain_ctx);
                glue->gmain_owner = false;
        }

        gok = g_main_context_acquire(glue->gmain_ctx);
        if (!gok) {
                DBG_ERR("couldn't acquire g_main_context\n");

                /*
                 * Ensure no tevent event fires while we're not the gmain
                 * context owner. The event handler would call
                 * tevent_glib_process() and that expects being the owner of the
                 * context.
                 */
                ok = tevent_glib_glue_reinit(glue);
                if (!ok) {
                        DBG_ERR("tevent_glib_glue_reinit failed\n");
                        samba_tevent_glib_glue_quit(glue);
                        return false;
                }

                glue->acquire_retry_timer = tevent_add_timer(
                        glue->ev,
                        glue,
                        tevent_timeval_current_ofs(0, 1000),
                        tevent_glib_retry_timer,
                        glue);
                if (glue->acquire_retry_timer == NULL) {
                        DBG_ERR("tevent_add_timer failed\n");
                        samba_tevent_glib_glue_quit(glue);
                        return false;
                }
                return true;
        }
        glue->gmain_owner = true;

        /*
         * Discard "ready" return value from g_main_context_prepare(). We don't
         * want to dispatch events here, that's only done in from the tevent loop.
         */
        (void)g_main_context_prepare(glue->gmain_ctx, &glue->gpriority);

        ok = get_glib_fds_and_timeout(glue);
        if (!ok) {
                DBG_ERR("get_glib_fds_and_timeout failed\n");
                samba_tevent_glib_glue_quit(glue);
                return false;
        }

        ok = tevent_glib_update_events(glue);
        if (!ok) {
                DBG_ERR("tevent_glib_update_events failed\n");
                samba_tevent_glib_glue_quit(glue);
                return false;
        }

        return true;
}

/**
 * Process pending glib events
 *
 * tevent_glib_process() gets called to process pending glib events via
 * g_main_context_check() and then g_main_context_dispatch().
 *
 * After pending event handlers are dispatched, we rearm the glib glue event
 * handlers in tevent by calling tevent_glib_prepare().
 *
 * When tevent_glib_process() is called the thread must own the glib
 * gmain_ctx. That is achieved by tevent_glib_prepare() being the only function
 * that acquires context ownership.
 *
 * To give other threads that are blocked on g_main_context_acquire(gmain_ctx) a
 * chance to acquire context ownership (eg needed to attach event sources), we
 * release context ownership before calling tevent_glib_prepare() which will
 * acquire it again.
 */
static bool tevent_glib_process(struct tevent_glib_glue *glue)
{
        bool ok;

        DBG_DEBUG("tevent_glib_process\n");

        /*
         * Ignore the "sources_ready" return from g_main_context_check(). glib
         * itself also ignores it in g_main_context_iterate(). In theory only
         * calling g_main_context_dispatch() if g_main_context_check() returns
         * true should work, but older glib versions had a bug where
         * g_main_context_check() returns false even though events are pending.
         *
         * https://bugzilla.gnome.org/show_bug.cgi?id=11059
         */
        (void)g_main_context_check(glue->gmain_ctx,
                                   glue->gpriority,
                                   glue->gpollfds,
                                   glue->num_gpollfds);

        g_main_context_dispatch(glue->gmain_ctx);

        ok = tevent_glib_prepare(glue);
        if (!ok) {
                return false;
        }
        glue->skip_glib_refresh = true;
        return true;
}

static void tevent_glib_glue_trace_callback(enum tevent_trace_point point,
                                            void *private_data)
{
        struct tevent_glib_glue *glue = talloc_get_type_abort(
                private_data, struct tevent_glib_glue);

        if (point == TEVENT_TRACE_AFTER_LOOP_ONCE) {
                if (!glue->skip_glib_refresh) {
                        tevent_glib_prepare(glue);
                }
                glue->skip_glib_refresh = false;
        }

        /* chain previous handler */
        if (glue->prev_tevent_trace_cb != NULL) {
                glue->prev_tevent_trace_cb(point, glue->prev_tevent_trace_data);
        }
}

static void tevent_glib_glue_cleanup(struct tevent_glib_glue *glue)
{
        size_t n = talloc_array_length(glue->fd_map);
        size_t i;

        for (i = 0; i < n; i++) {
                TALLOC_FREE(glue->fd_map[i]->fd_event);
                TALLOC_FREE(glue->fd_map[i]);
        }

        tevent_set_trace_callback(glue->ev,
                                  glue->prev_tevent_trace_cb,
                                  glue->prev_tevent_trace_data);
        glue->prev_tevent_trace_cb = NULL;
        glue->prev_tevent_trace_data = NULL;

        TALLOC_FREE(glue->fd_map);
        glue->num_maps = 0;

        TALLOC_FREE(glue->gpollfds);
        glue->num_gpollfds = 0;

        TALLOC_FREE(glue->prev_gpollfds);
        glue->num_prev_gpollfds = 0;

        TALLOC_FREE(glue->timer);
        TALLOC_FREE(glue->acquire_retry_timer);
        TALLOC_FREE(glue->im);

        /*
         * These are not really needed, but let's wipe the slate clean.
         */
        glue->skip_glib_refresh = false;
        glue->gtimeout = 0;
        glue->gpriority = 0;
}

static bool tevent_glib_glue_reinit(struct tevent_glib_glue *glue)
{
        tevent_glib_glue_cleanup(glue);

        glue->im = tevent_create_immediate(glue);
        if (glue->im == NULL) {
                return false;
        }

        tevent_get_trace_callback(glue->ev,
                                  &glue->prev_tevent_trace_cb,
                                  &glue->prev_tevent_trace_data);
        tevent_set_trace_callback(glue->ev,
                                  tevent_glib_glue_trace_callback,
                                  glue);

        return true;
}

void samba_tevent_glib_glue_quit(struct tevent_glib_glue *glue)
{
        tevent_glib_glue_cleanup(glue);
        glue->quit = true;
        return;
}

struct tevent_glib_glue *samba_tevent_glib_glue_create(TALLOC_CTX *mem_ctx,
                                                       struct tevent_context *ev,
                                                       GMainContext *gmain_ctx)
{
        bool ok;
        struct tevent_glib_glue *glue = NULL;

        glue = talloc_zero(mem_ctx, struct tevent_glib_glue);
        if (glue == NULL) {
                DBG_ERR("talloc_zero failed\n");
                return NULL;
        }

        *glue = (struct tevent_glib_glue) {
                .ev = ev,
                .gmain_ctx = gmain_ctx,
        };

        glue->im = tevent_create_immediate(glue);

        tevent_get_trace_callback(glue->ev,
                                  &glue->prev_tevent_trace_cb,
                                  &glue->prev_tevent_trace_data);
        tevent_set_trace_callback(glue->ev,
                                  tevent_glib_glue_trace_callback,
                                  glue);

        ok = tevent_glib_prepare(glue);
        if (!ok) {
                TALLOC_FREE(glue);
                return NULL;
        }

        return glue;
}

#else /* HAVE_GLIB */

struct tevent_glib_glue *samba_tevent_glib_glue_create(TALLOC_CTX *mem_ctx,
                                                       struct tevent_context *ev,
                                                       GMainContext *gmain_ctx)
{
        errno = ENOSYS;
        return NULL;
}

void samba_tevent_glib_glue_quit(struct tevent_glib_glue *glue)
{
        return;
}
#endif /* HAVE_GLIB */