source3/lib/background.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    Regular background jobs as forked helpers
   4    Copyright (C) Volker Lendecke 2012
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18 */
  19
  20 #include "includes.h"
  21 #include "lib/util/tevent_ntstatus.h"
  22 #include "lib/async_req/async_sock.h"
  23 #include "include/messages.h"
  24 #include "background.h"
  25
  26 struct background_job_state {
  27         struct tevent_context *ev;
  28         struct messaging_context *msg;
  29         uint32_t *trigger_msgs;
  30         size_t num_trigger_msgs;
  31         bool parent_longlived;
  32         int (*fn)(void *private_data);
  33         void *private_data;
  34
  35         struct tevent_req *wakeup_req;
  36         int pipe_fd;
  37 };
  38
  39 static int background_job_state_destructor(struct background_job_state *s);
  40 static void background_job_waited(struct tevent_req *subreq);
  41 static void background_job_done(struct tevent_req *subreq);
  42 static void background_job_trigger(
  43         struct messaging_context *msg, void *private_data, uint32_t msg_type,
  44         struct server_id server_id, DATA_BLOB *data);
  45
  46 struct tevent_req *background_job_send(TALLOC_CTX *mem_ctx,
  47                                        struct tevent_context *ev,
  48                                        struct messaging_context *msg,
  49                                        uint32_t *trigger_msgs,
  50                                        size_t num_trigger_msgs,
  51                                        time_t initial_wait_sec,
  52                                        int (*fn)(void *private_data),
  53                                        void *private_data)
  54 {
  55         struct tevent_req *req, *subreq;
  56         struct background_job_state *state;
  57         size_t i;
  58
  59         req = tevent_req_create(mem_ctx, &state,
  60                                 struct background_job_state);
  61         if (req == NULL) {
  62                 return NULL;
  63         }
  64
  65         state->ev = ev;
  66         state->msg = msg;
  67
  68         if (num_trigger_msgs != 0) {
  69                 state->trigger_msgs = (uint32_t *)talloc_memdup(
  70                         state, trigger_msgs,
  71                         sizeof(uint32_t) * num_trigger_msgs);
  72                 if (tevent_req_nomem(state->trigger_msgs, req)) {
  73                         return tevent_req_post(req, ev);
  74                 }
  75                 state->num_trigger_msgs = num_trigger_msgs;
  76         }
  77
  78         state->fn = fn;
  79         state->private_data = private_data;
  80
  81         state->pipe_fd = -1;
  82         talloc_set_destructor(state, background_job_state_destructor);
  83
  84         for (i=0; i<num_trigger_msgs; i++) {
  85                 NTSTATUS status;
  86                 status = messaging_register(msg, state, trigger_msgs[i],
  87                                             background_job_trigger);
  88                 if (tevent_req_nterror(req, status)) {
  89                         return tevent_req_post(req, ev);
  90                 }
  91         }
  92
  93         subreq = tevent_wakeup_send(
  94                 state, state->ev, timeval_current_ofs(initial_wait_sec, 0));
  95         if (tevent_req_nomem(subreq, req)) {
  96                 return tevent_req_post(req, ev);
  97         }
  98         tevent_req_set_callback(subreq, background_job_waited, req);
  99         state->wakeup_req = subreq;
 100         return req;
 101 }
 102
 103 static int background_job_state_destructor(struct background_job_state *state)
 104 {
 105         size_t i;
 106         if (state->pipe_fd != -1) {
 107                 close(state->pipe_fd);
 108                 state->pipe_fd = -1;
 109         }
 110         for (i=0; i<state->num_trigger_msgs; i++) {
 111                 messaging_deregister(state->msg, state->trigger_msgs[i],
 112                                      state);
 113         }
 114         return 0;
 115 }
 116
 117 static void background_job_trigger(
 118         struct messaging_context *msg, void *private_data, uint32_t msg_type,
 119         struct server_id server_id, DATA_BLOB *data)
 120 {
 121         struct background_job_state *state = talloc_get_type_abort(
 122                 private_data, struct background_job_state);
 123
 124         if (state->wakeup_req == NULL) {
 125                 return;
 126         }
 127         if (!tevent_req_set_endtime(state->wakeup_req, state->ev,
 128                                     timeval_zero())) {
 129                 DEBUG(10, ("tevent_req_set_endtime failed\n"));
 130         }
 131 }
 132
 133 static void background_job_waited(struct tevent_req *subreq)
 134 {
 135         struct tevent_req *req = tevent_req_callback_data(
 136                 subreq, struct tevent_req);
 137         struct background_job_state *state = tevent_req_data(
 138                 req, struct background_job_state);
 139         int fds[2];
 140         int res;
 141         bool ret;
 142
 143         ret = tevent_wakeup_recv(subreq);
 144         TALLOC_FREE(subreq);
 145         state->wakeup_req = NULL;
 146         if (!ret) {
 147                 tevent_req_nterror(req, NT_STATUS_INTERNAL_ERROR);
 148                 return;
 149         }
 150
 151         res = pipe(fds);
 152         if (res == -1) {
 153                 tevent_req_nterror(req, map_nt_error_from_unix(errno));
 154                 return;
 155         }
 156
 157         res = fork();
 158         if (res == -1) {
 159                 int err = errno;
 160                 close(fds[0]);
 161                 close(fds[1]);
 162                 tevent_req_nterror(req, map_nt_error_from_unix(err));
 163                 return;
 164         }
 165
 166         if (res == 0) {
 167                 /* child */
 168
 169                 NTSTATUS status;
 170                 ssize_t written;
 171
 172                 close(fds[0]);
 173
 174                 status = reinit_after_fork(state->msg, state->ev, true);
 175                 if (NT_STATUS_IS_OK(status)) {
 176                         res = state->fn(state->private_data);
 177                 } else {
 178                         res = -1;
 179                 }
 180                 written = write(fds[1], &res, sizeof(res));
 181                 if (written == -1) {
 182                         _exit(1);
 183                 }
 184
 185                 /*
 186                  * No TALLOC_FREE here, messaging_parent_dgm_cleanup_init for
 187                  * example calls background_job_send with "messaging_context"
 188                  * as talloc parent. Thus "state" will be freed with the
 189                  * following talloc_free will have removed "state" when it
 190                  * returns. TALLOC_FREE will then write a NULL into free'ed
 191                  * memory. talloc_free() is required although we immediately
 192                  * exit, the messaging_context's destructor will want to clean
 193                  * up.
 194                  */
 195                 talloc_free(state->msg);
 196                 _exit(0);
 197         }
 198
 199         /* parent */
 200
 201         close(fds[1]);
 202         state->pipe_fd = fds[0];
 203
 204         subreq = read_packet_send(state, state->ev, state->pipe_fd,
 205                                   sizeof(int), NULL, NULL);
 206         if (tevent_req_nomem(subreq, req)) {
 207                 return;
 208         }
 209         tevent_req_set_callback(subreq, background_job_done, req);
 210 }
 211
 212 static void background_job_done(struct tevent_req *subreq)
 213 {
 214         struct tevent_req *req = tevent_req_callback_data(
 215                 subreq, struct tevent_req);
 216         struct background_job_state *state = tevent_req_data(
 217                 req, struct background_job_state);
 218         ssize_t ret;
 219         uint8_t *buf;
 220         int err;
 221         int wait_secs;
 222
 223         ret = read_packet_recv(subreq, talloc_tos(), &buf, &err);
 224         TALLOC_FREE(subreq);
 225         if (ret == -1) {
 226                 tevent_req_nterror(req, map_nt_error_from_unix(err));
 227                 return;
 228         }
 229         close(state->pipe_fd);
 230         state->pipe_fd = -1;
 231         memcpy(&wait_secs, buf, sizeof(wait_secs));
 232         if (wait_secs == -1) {
 233                 tevent_req_done(req);
 234                 return;
 235         }
 236         subreq = tevent_wakeup_send(
 237                 state, state->ev, timeval_current_ofs(wait_secs, 0));
 238         if (tevent_req_nomem(subreq, req)) {
 239                 return;
 240         }
 241         tevent_req_set_callback(subreq, background_job_waited, req);
 242         state->wakeup_req = subreq;
 243 }
 244
 245 NTSTATUS background_job_recv(struct tevent_req *req)
 246 {
 247         return tevent_req_simple_recv_ntstatus(req);
 248 }