source3/printing/samba-bgqd.c

   1 /*
   2  *  Printing background queue helper
   3  *
   4  *  This program is free software; you can redistribute it and/or modify
   5  *  it under the terms of the GNU General Public License as published by
   6  *  the Free Software Foundation; either version 3 of the License, or
   7  *  (at your option) any later version.
   8  *
   9  *  This program is distributed in the hope that it will be useful,
  10  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  *  GNU General Public License for more details.
  13  *
  14  *  You should have received a copy of the GNU General Public License
  15  *  along with this program; if not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 #include "replace.h"
  19 #include "system/filesys.h"
  20 #include "lib/util/server_id.h"
  21 #include "source3/locking/share_mode_lock.h"
  22 #include "source3/param/loadparm.h"
  23 #include "source3/param/param_proto.h"
  24 #include "lib/cmdline/cmdline.h"
  25 #include "lib/cmdline/closefrom_except.h"
  26 #include "lib/util/talloc_stack.h"
  27 #include "lib/util/debug.h"
  28 #include "lib/util/signal.h"
  29 #include "lib/util/fault.h"
  30 #include "lib/util/become_daemon.h"
  31 #include "lib/util/charset/charset.h"
  32 #include "lib/util/samba_util.h"
  33 #include "lib/util/sys_rw.h"
  34 #include "lib/util/pidfile.h"
  35 #include "lib/async_req/async_sock.h"
  36 #include "dynconfig/dynconfig.h"
  37 #include "source3/lib/global_contexts.h"
  38 #include "messages.h"
  39 #include "nsswitch/winbind_client.h"
  40 #include "source3/include/auth.h"
  41 #include "source3/lib/util_procid.h"
  42 #include "source3/auth/proto.h"
  43 #include "source3/printing/queue_process.h"
  44 #include "source3/lib/substitute.h"
  45
  46 static void watch_handler(struct tevent_req *req)
  47 {
  48         bool *pdone = tevent_req_callback_data_void(req);
  49         *pdone = true;
  50 }
  51
  52 static void bgqd_sig_term_handler(
  53         struct tevent_context *ev,
  54         struct tevent_signal *se,
  55         int signum,
  56         int count,
  57         void *siginfo,
  58         void *private_data)
  59 {
  60         bool *pdone = private_data;
  61         *pdone = true;
  62 }
  63
  64 static bool ready_signal_filter(
  65         struct messaging_rec *rec, void *private_data)
  66 {
  67         pid_t pid = getpid();
  68         ssize_t written;
  69
  70         if (rec->msg_type != MSG_DAEMON_READY_FD) {
  71                 return false;
  72         }
  73         if (rec->num_fds != 1) {
  74                 return false;
  75         }
  76
  77         written = sys_write(rec->fds[0], &pid, sizeof(pid));
  78         if (written != sizeof(pid)) {
  79                 DBG_ERR("Could not write pid: %s\n", strerror(errno));
  80         }
  81
  82         return false;
  83 }
  84
  85 static int samba_bgqd_pidfile_create(
  86         struct messaging_context *msg_ctx,
  87         const char *progname,
  88         int ready_signal_fd)
  89 {
  90         const char *piddir = lp_pid_directory();
  91         size_t len = strlen(piddir) + strlen(progname) + 6;
  92         char pidFile[len];
  93         pid_t existing_pid;
  94         int fd, ret;
  95
  96         snprintf(pidFile,
  97                  sizeof(pidFile),
  98                  "%s/%s.pid",
  99                  piddir, progname);
 100
 101         ret = pidfile_path_create(pidFile, &fd, &existing_pid);
 102         if (ret == 0) {
 103                 struct tevent_req *ready_signal_req = NULL;
 104
 105                 /*
 106                  * Listen for fd's sent via MSG_DAEMON_READY_FD:
 107                  * Multiple instances of this process might have raced
 108                  * for creating the pidfile. Make sure the parent does
 109                  * not suffer from this race, reply on behalf of the
 110                  * loser of this race.
 111                  */
 112
 113                 ready_signal_req = messaging_filtered_read_send(
 114                         msg_ctx,
 115                         messaging_tevent_context(msg_ctx),
 116                         msg_ctx,
 117                         ready_signal_filter,
 118                         NULL);
 119                 if (ready_signal_req == NULL) {
 120                         DBG_DEBUG("messaging_filtered_read_send failed\n");
 121                         pidfile_unlink(piddir, progname);
 122                         pidfile_fd_close(fd);
 123                         return ENOMEM;
 124                 }
 125
 126                 /* leak fd */
 127                 return 0;
 128         }
 129
 130         if (ret != EAGAIN) {
 131                 DBG_DEBUG("pidfile_path_create() failed: %s\n",
 132                           strerror(ret));
 133                 return ret;
 134         }
 135
 136         DBG_DEBUG("%s pid %d exists\n", progname, (int)existing_pid);
 137
 138         if (ready_signal_fd != -1) {
 139                 /*
 140                  * We lost the race for the pidfile, but someone else
 141                  * can report readiness on our behalf.
 142                  */
 143                 NTSTATUS status = messaging_send_iov(
 144                         msg_ctx,
 145                         pid_to_procid(existing_pid),
 146                         MSG_DAEMON_READY_FD,
 147                         NULL,
 148                         0,
 149                         &ready_signal_fd,
 150                         1);
 151                 if (!NT_STATUS_IS_OK(status)) {
 152                         DBG_DEBUG("Could not send ready_signal_fd: %s\n",
 153                                   nt_errstr(status));
 154                 }
 155         }
 156
 157         return EAGAIN;
 158 }
 159
 160 int main(int argc, const char *argv[])
 161 {
 162         struct samba_cmdline_daemon_cfg *cmdline_daemon_cfg = NULL;
 163         const struct loadparm_substitution *lp_sub =
 164                 loadparm_s3_global_substitution();
 165         const char *progname = getprogname();
 166         TALLOC_CTX *frame = NULL;
 167         poptContext pc;
 168         struct messaging_context *msg_ctx = NULL;
 169         struct tevent_context *ev = NULL;
 170         struct tevent_req *watch_req = NULL;
 171         struct tevent_signal *sigterm_handler = NULL;
 172         struct bq_state *bq = NULL;
 173         int log_stdout = 0;
 174         int ready_signal_fd = -1;
 175         int watch_fd = -1;
 176         NTSTATUS status;
 177         int ret;
 178         bool ok;
 179         bool done = false;
 180         int exitcode = 1;
 181
 182         struct poptOption long_options[] = {
 183                 POPT_AUTOHELP
 184                 POPT_COMMON_SAMBA
 185                 POPT_COMMON_DAEMON
 186
 187                 /*
 188                  * File descriptor to write the PID of the helper
 189                  * process to
 190                  */
 191                 {
 192                         .longName   = "ready-signal-fd",
 193                         .argInfo    = POPT_ARG_INT,
 194                         .arg        = &ready_signal_fd,
 195                         .descrip    = "Fd to signal readiness to" ,
 196                 },
 197
 198                 /*
 199                  * Read end of a pipe held open by the parent
 200                  * smbd. Exit this process when it becomes readable.
 201                  */
 202                 {
 203                         .longName   = "parent-watch-fd",
 204                         .argInfo    = POPT_ARG_INT,
 205                         .arg        = &watch_fd,
 206                         .descrip    = "Fd to watch for exiting",
 207                 },
 208                 POPT_TABLEEND
 209         };
 210
 211         {
 212                 const char *fd_params[] = {
 213                         "ready-signal-fd", "parent-watch-fd",
 214                 };
 215
 216                 closefrom_except_fd_params(
 217                         3, ARRAY_SIZE(fd_params), fd_params, argc, argv);
 218         }
 219
 220         talloc_enable_null_tracking();
 221         frame = talloc_stackframe();
 222         umask(0);
 223         set_remote_machine_name("smbd-bgqd", true);
 224
 225         ok = samba_cmdline_init(frame,
 226                                 SAMBA_CMDLINE_CONFIG_SERVER,
 227                                 true /* require_smbconf */);
 228         if (!ok) {
 229                 DBG_ERR("Failed to setup cmdline parser!\n");
 230                 exit(ENOMEM);
 231         }
 232
 233         cmdline_daemon_cfg = samba_cmdline_get_daemon_cfg();
 234
 235         pc = samba_popt_get_context(progname,
 236                                     argc,
 237                                     argv,
 238                                     long_options,
 239                                     0);
 240         if (pc == NULL) {
 241                 DBG_ERR("Failed to get popt context!\n");
 242                 exit(ENOMEM);
 243         }
 244
 245         ret = poptGetNextOpt(pc);
 246         if (ret < -1) {
 247                 fprintf(stderr, "invalid options: %s\n", poptStrerror(ret));
 248                 goto done;
 249         }
 250
 251         poptFreeContext(pc);
 252
 253         log_stdout = (debug_get_log_type() == DEBUG_STDOUT);
 254
 255         /* main process will notify systemd */
 256         daemon_sd_notifications(false);
 257
 258         if (!cmdline_daemon_cfg->fork) {
 259                 daemon_status(progname, "Starting process ... ");
 260         } else {
 261                 become_daemon(true,
 262                               cmdline_daemon_cfg->no_process_group,
 263                               log_stdout);
 264         }
 265
 266         BlockSignals(true, SIGPIPE);
 267
 268         smb_init_locale();
 269         dump_core_setup(progname, lp_logfile(frame, lp_sub));
 270
 271         msg_ctx = global_messaging_context();
 272         if (msg_ctx == NULL) {
 273                 DBG_ERR("messaging_init() failed\n");
 274                 goto done;
 275         }
 276         ev = messaging_tevent_context(msg_ctx);
 277
 278         ret = samba_bgqd_pidfile_create(msg_ctx, progname, ready_signal_fd);
 279         if (ret != 0) {
 280                 goto done;
 281         }
 282
 283         if (watch_fd != -1) {
 284                 watch_req = wait_for_read_send(ev, ev, watch_fd, true);
 285                 if (watch_req == NULL) {
 286                         fprintf(stderr, "tevent_add_fd failed\n");
 287                         goto done;
 288                 }
 289                 tevent_req_set_callback(watch_req, watch_handler, &done);
 290         }
 291
 292         (void)winbind_off();
 293         ok = init_guest_session_info(frame);
 294         (void)winbind_on();
 295         if (!ok) {
 296                 DBG_ERR("init_guest_session_info failed\n");
 297                 goto done;
 298         }
 299
 300         (void)winbind_off();
 301         status = init_system_session_info(frame);
 302         (void)winbind_on();
 303         if (!NT_STATUS_IS_OK(status)) {
 304                 DBG_ERR("init_system_session_info failed: %s\n",
 305                         nt_errstr(status));
 306                 goto done;
 307         }
 308
 309         sigterm_handler = tevent_add_signal(
 310                 ev, frame, SIGTERM, 0, bgqd_sig_term_handler, &done);
 311         if (sigterm_handler == NULL) {
 312                 DBG_ERR("Could not install SIGTERM handler\n");
 313                 goto done;
 314         }
 315
 316         bq = register_printing_bq_handlers(frame, msg_ctx);
 317         if (bq == NULL) {
 318                 DBG_ERR("Could not register bq handlers\n");
 319                 goto done;
 320         }
 321
 322         ok = locking_init();
 323         if (!ok) {
 324                 DBG_ERR("locking_init failed\n");
 325                 goto done;
 326         }
 327
 328         if (ready_signal_fd != -1) {
 329                 pid_t pid = getpid();
 330                 ssize_t written;
 331
 332                 written = sys_write(ready_signal_fd, &pid, sizeof(pid));
 333                 if (written != sizeof(pid)) {
 334                         DBG_ERR("Reporting readiness failed\n");
 335                         goto done;
 336                 }
 337                 close(ready_signal_fd);
 338                 ready_signal_fd = -1;
 339         }
 340
 341         while (!done) {
 342                 TALLOC_CTX *tmp = talloc_stackframe();
 343                 ret = tevent_loop_once(ev);
 344                 TALLOC_FREE(tmp);
 345                 if (ret != 0) {
 346                         DBG_ERR("tevent_loop_once failed\n");
 347                         break;
 348                 }
 349         }
 350
 351         exitcode = 0;
 352 done:
 353         TALLOC_FREE(watch_req);
 354         TALLOC_FREE(bq);
 355         TALLOC_FREE(sigterm_handler);
 356         global_messaging_context_free();
 357         TALLOC_FREE(frame);
 358         return exitcode;
 359 }