ctdb/common/ctdb_fork.c

   1 /*
   2    functions to track and manage processes
   3
   4    Copyright (C) Ronnie Sahlberg 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 "system/wait.h"
  22 #include "../include/ctdb_client.h"
  23 #include "../include/ctdb_private.h"
  24 #include "../common/rb_tree.h"
  25
  26 void ctdb_set_child_info(TALLOC_CTX *mem_ctx, const char *child_name_fmt, ...)
  27 {
  28         if (child_name_fmt != NULL) {
  29                 va_list ap;
  30                 char *t;
  31
  32                 va_start(ap, child_name_fmt);
  33                 t = talloc_vasprintf(mem_ctx, child_name_fmt, ap);
  34                 debug_extra = talloc_asprintf(mem_ctx, "%s:", t);
  35                 talloc_free(t);
  36                 va_end(ap);
  37         }
  38 }
  39
  40 void ctdb_track_child(struct ctdb_context *ctdb, pid_t pid)
  41 {
  42         char *process;
  43
  44         /* Only CTDB main daemon should track child processes */
  45         if (getpid() != ctdb->ctdbd_pid) {
  46                 return;
  47         }
  48
  49         process = talloc_asprintf(ctdb->child_processes, "process:%d", (int)pid);
  50         trbt_insert32(ctdb->child_processes, pid, process);
  51 }
  52
  53 /*
  54  * This function forks a child process and drops the realtime
  55  * scheduler for the child process.
  56  */
  57 pid_t ctdb_fork_no_free_ringbuffer(struct ctdb_context *ctdb)
  58 {
  59         pid_t pid;
  60
  61         pid = fork();
  62         if (pid == -1) {
  63                 return -1;
  64         }
  65         if (pid == 0) {
  66                 ctdb_set_child_info(ctdb, NULL);
  67
  68                 /* Close the Unix Domain socket and the TCP socket.
  69                  * This ensures that none of the child processes will
  70                  * look like the main daemon when it is not running.
  71                  * tevent needs to be stopped before closing sockets.
  72                  */
  73                 if (ctdb->ev != NULL) {
  74                         talloc_free(ctdb->ev);
  75                         ctdb->ev = NULL;
  76                 }
  77                 if (ctdb->daemon.sd != -1) {
  78                         close(ctdb->daemon.sd);
  79                         ctdb->daemon.sd = -1;
  80                 }
  81                 if (ctdb->methods != NULL) {
  82                         ctdb->methods->shutdown(ctdb);
  83                 }
  84
  85                 /* The child does not need to be realtime */
  86                 if (ctdb->do_setsched) {
  87                         reset_scheduler();
  88                 }
  89                 ctdb->can_send_controls = false;
  90
  91                 return 0;
  92         }
  93
  94         ctdb_track_child(ctdb, pid);
  95         return pid;
  96 }
  97
  98 pid_t ctdb_fork(struct ctdb_context *ctdb)
  99 {
 100         pid_t pid;
 101
 102         pid = ctdb_fork_no_free_ringbuffer(ctdb);
 103         if (pid == 0) {
 104                 ctdb_log_ringbuffer_free();
 105         }
 106
 107         return pid;
 108 }
 109
 110
 111 static void ctdb_sigchld_handler(struct tevent_context *ev,
 112         struct tevent_signal *te, int signum, int count,
 113         void *dont_care,
 114         void *private_data)
 115 {
 116         struct ctdb_context *ctdb = talloc_get_type(private_data, struct ctdb_context);
 117         int status;
 118         pid_t pid = -1;
 119
 120         while (pid != 0) {
 121                 pid = waitpid(-1, &status, WNOHANG);
 122                 if (pid == -1) {
 123                         DEBUG(DEBUG_ERR, (__location__ " waitpid() returned error. errno:%d\n", errno));
 124                         return;
 125                 }
 126                 if (pid > 0) {
 127                         char *process;
 128
 129                         if (getpid() != ctdb->ctdbd_pid) {
 130                                 continue;
 131                         }
 132
 133                         process = trbt_lookup32(ctdb->child_processes, pid);
 134                         if (process == NULL) {
 135                                 DEBUG(DEBUG_ERR,("Got SIGCHLD from pid:%d we didn not spawn with ctdb_fork\n", pid));
 136                         }
 137
 138                         DEBUG(DEBUG_DEBUG, ("SIGCHLD from %d %s\n", (int)pid, process));
 139                         talloc_free(process);
 140                 }
 141         }
 142 }
 143
 144
 145 struct tevent_signal *
 146 ctdb_init_sigchld(struct ctdb_context *ctdb)
 147 {
 148         struct tevent_signal *se;
 149
 150         ctdb->child_processes = trbt_create(ctdb, 0);
 151
 152         se = tevent_add_signal(ctdb->ev, ctdb, SIGCHLD, 0, ctdb_sigchld_handler, ctdb);
 153         return se;
 154 }
 155
 156 int
 157 ctdb_kill(struct ctdb_context *ctdb, pid_t pid, int signum)
 158 {
 159         char *process;
 160
 161         if (signum == 0) {
 162                 return kill(pid, signum);
 163         }
 164
 165         if (getpid() != ctdb->ctdbd_pid) {
 166                 return kill(pid, signum);
 167         }
 168
 169         process = trbt_lookup32(ctdb->child_processes, pid);
 170         if (process == NULL) {
 171                 DEBUG(DEBUG_ERR,("ctdb_kill: trying to kill(%d, %d) a process that does not exist\n", pid, signum));
 172                 return 0;
 173         }
 174
 175         return kill(pid, signum);
 176 }