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         struct tevent_req *pipe_req;
  38 };
  39
  40 static int background_job_state_destructor(struct background_job_state *s);
  41 static void background_job_waited(struct tevent_req *subreq);
  42 static void background_job_done(struct tevent_req *subreq);
  43 static void background_job_trigger(
  44         struct messaging_context *msg, void *private_data, uint32_t msg_type,
  45         struct server_id server_id, DATA_BLOB *data);
  46
  47 struct tevent_req *background_job_send(TALLOC_CTX *mem_ctx,
  48                                        struct tevent_context *ev,
  49                                        struct messaging_context *msg,
  50                                        uint32_t *trigger_msgs,
  51                                        size_t num_trigger_msgs,
  52                                        time_t initial_wait_sec,
  53                                        int (*fn)(void *private_data),
  54                                        void *private_data)
  55 {
  56         struct tevent_req *req, *subreq;
  57         struct background_job_state *state;
  58         size_t i;
  59
  60         req = tevent_req_create(mem_ctx, &state,
  61                                 struct background_job_state);
  62         if (req == NULL) {
  63                 return NULL;
  64         }
  65
  66         state->ev = ev;
  67         state->msg = msg;
  68
  69         if (num_trigger_msgs != 0) {
  70                 state->trigger_msgs = (uint32_t *)talloc_memdup(
  71                         state, trigger_msgs,
  72                         sizeof(uint32_t) * num_trigger_msgs);
  73                 if (tevent_req_nomem(state->trigger_msgs, req)) {
  74                         return tevent_req_post(req, ev);
  75                 }
  76                 state->num_trigger_msgs = num_trigger_msgs;
  77         }
  78
  79         state->fn = fn;
  80         state->private_data = private_data;
  81
  82         state->pipe_fd = -1;
  83         talloc_set_destructor(state, background_job_state_destructor);
  84
  85         for (i=0; i<num_trigger_msgs; i++) {
  86                 NTSTATUS status;
  87                 status = messaging_register(msg, state, trigger_msgs[i],
  88                                             background_job_trigger);
  89                 if (tevent_req_nterror(req, status)) {
  90                         return tevent_req_post(req, ev);
  91                 }
  92         }
  93
  94         subreq = tevent_wakeup_send(
  95                 state, state->ev, timeval_current_ofs(initial_wait_sec, 0));
  96         if (tevent_req_nomem(subreq, req)) {
  97                 return tevent_req_post(req, ev);
  98         }
  99         tevent_req_set_callback(subreq, background_job_waited, req);
 100         state->wakeup_req = subreq;
 101         return req;
 102 }
 103
 104 static int background_job_state_destructor(struct background_job_state *state)
 105 {
 106         size_t i;
 107
 108         TALLOC_FREE(state->pipe_req);
 109         if (state->pipe_fd != -1) {
 110                 close(state->pipe_fd);
 111                 state->pipe_fd = -1;
 112         }
 113
 114         for (i=0; i<state->num_trigger_msgs; i++) {
 115                 messaging_deregister(state->msg, state->trigger_msgs[i],
 116                                      state);
 117         }
 118
 119         return 0;
 120 }
 121
 122 static void background_job_trigger(
 123         struct messaging_context *msg, void *private_data, uint32_t msg_type,
 124         struct server_id server_id, DATA_BLOB *data)
 125 {
 126         struct background_job_state *state = talloc_get_type_abort(
 127                 private_data, struct background_job_state);
 128
 129         if (state->wakeup_req == NULL) {
 130                 return;
 131         }
 132         if (!tevent_req_set_endtime(state->wakeup_req, state->ev,
 133                                     timeval_zero())) {
 134                 DEBUG(10, ("tevent_req_set_endtime failed\n"));
 135         }
 136 }
 137
 138 static void background_job_waited(struct tevent_req *subreq)
 139 {
 140         struct tevent_req *req = tevent_req_callback_data(
 141                 subreq, struct tevent_req);
 142         struct background_job_state *state = tevent_req_data(
 143                 req, struct background_job_state);
 144         int fds[2];
 145         int res;
 146         bool ret;
 147
 148         ret = tevent_wakeup_recv(subreq);
 149         TALLOC_FREE(subreq);
 150         state->wakeup_req = NULL;
 151         if (!ret) {
 152                 tevent_req_nterror(req, NT_STATUS_INTERNAL_ERROR);
 153                 return;
 154         }
 155
 156         res = pipe(fds);
 157         if (res == -1) {
 158                 tevent_req_nterror(req, map_nt_error_from_unix(errno));
 159                 return;
 160         }
 161
 162         res = fork();
 163         if (res == -1) {
 164                 int err = errno;
 165                 close(fds[0]);
 166                 close(fds[1]);
 167                 tevent_req_nterror(req, map_nt_error_from_unix(err));
 168                 return;
 169         }
 170
 171         if (res == 0) {
 172                 /* child */
 173
 174                 NTSTATUS status;
 175                 ssize_t written;
 176
 177                 close(fds[0]);
 178
 179                 status = reinit_after_fork(state->msg, state->ev, true, NULL);
 180                 if (NT_STATUS_IS_OK(status)) {
 181                         res = state->fn(state->private_data);
 182                 } else {
 183                         res = -1;
 184                 }
 185                 written = write(fds[1], &res, sizeof(res));
 186                 if (written == -1) {
 187                         _exit(1);
 188                 }
 189
 190                 /*
 191                  * No TALLOC_FREE here, messaging_parent_dgm_cleanup_init for
 192                  * example calls background_job_send with "messaging_context"
 193                  * as talloc parent. Thus "state" will be freed with the
 194                  * following talloc_free will have removed "state" when it
 195                  * returns. TALLOC_FREE will then write a NULL into free'ed
 196                  * memory. talloc_free() is required although we immediately
 197                  * exit, the messaging_context's destructor will want to clean
 198                  * up.
 199                  */
 200                 talloc_free(state->msg);
 201                 _exit(0);
 202         }
 203
 204         /* parent */
 205
 206         close(fds[1]);
 207         state->pipe_fd = fds[0];
 208
 209         subreq = read_packet_send(state, state->ev, state->pipe_fd,
 210                                   sizeof(int), NULL, NULL);
 211         if (tevent_req_nomem(subreq, req)) {
 212                 return;
 213         }
 214         tevent_req_set_callback(subreq, background_job_done, req);
 215         state->pipe_req = subreq;
 216 }
 217
 218 static void background_job_done(struct tevent_req *subreq)
 219 {
 220         struct tevent_req *req = tevent_req_callback_data(
 221                 subreq, struct tevent_req);
 222         struct background_job_state *state = tevent_req_data(
 223                 req, struct background_job_state);
 224         ssize_t ret;
 225         uint8_t *buf;
 226         int err;
 227         int wait_secs;
 228
 229         state->pipe_req = NULL;
 230
 231         ret = read_packet_recv(subreq, talloc_tos(), &buf, &err);
 232         TALLOC_FREE(subreq);
 233         if (ret == -1) {
 234                 tevent_req_nterror(req, map_nt_error_from_unix(err));
 235                 return;
 236         }
 237         close(state->pipe_fd);
 238         state->pipe_fd = -1;
 239         memcpy(&wait_secs, buf, sizeof(wait_secs));
 240         if (wait_secs == -1) {
 241                 tevent_req_done(req);
 242                 return;
 243         }
 244         subreq = tevent_wakeup_send(
 245                 state, state->ev, timeval_current_ofs(wait_secs, 0));
 246         if (tevent_req_nomem(subreq, req)) {
 247                 return;
 248         }
 249         tevent_req_set_callback(subreq, background_job_waited, req);
 250         state->wakeup_req = subreq;
 251 }
 252
 253 NTSTATUS background_job_recv(struct tevent_req *req)
 254 {
 255         return tevent_req_simple_recv_ntstatus(req);
 256 }