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 static bool is_child = false;
  27
  28 void ctdb_set_child_info(TALLOC_CTX *mem_ctx, const char *child_name_fmt, ...)
  29 {
  30         is_child = true;
  31         if (child_name_fmt != NULL) {
  32                 va_list ap;
  33                 char *t;
  34
  35                 va_start(ap, child_name_fmt);
  36                 t = talloc_vasprintf(mem_ctx, child_name_fmt, ap);
  37                 debug_extra = talloc_asprintf(mem_ctx, "%s:", t);
  38                 talloc_free(t);
  39                 va_end(ap);
  40         }
  41 }
  42
  43 bool ctdb_is_child_process(void)
  44 {
  45         return is_child;
  46 }
  47
  48 void ctdb_track_child(struct ctdb_context *ctdb, pid_t pid)
  49 {
  50         char *process;
  51
  52         /* Only CTDB main daemon should track child processes */
  53         if (getpid() != ctdb->ctdbd_pid) {
  54                 return;
  55         }
  56
  57         process = talloc_asprintf(ctdb->child_processes, "process:%d", (int)pid);
  58         trbt_insert32(ctdb->child_processes, pid, process);
  59 }
  60
  61 /*
  62  * This function forks a child process and drops the realtime
  63  * scheduler for the child process.
  64  */
  65 pid_t ctdb_fork_no_free_ringbuffer(struct ctdb_context *ctdb)
  66 {
  67         pid_t pid;
  68
  69         pid = fork();
  70         if (pid == -1) {
  71                 return -1;
  72         }
  73         if (pid == 0) {
  74                 ctdb_set_child_info(ctdb, NULL);
  75
  76                 /* Close the Unix Domain socket and the TCP socket.
  77                  * This ensures that none of the child processes will
  78                  * look like the main daemon when it is not running.
  79                  * tevent needs to be stopped before closing sockets.
  80                  */
  81                 if (ctdb->ev != NULL) {
  82                         talloc_free(ctdb->ev);
  83                         ctdb->ev = NULL;
  84                 }
  85                 if (ctdb->daemon.sd != -1) {
  86                         close(ctdb->daemon.sd);
  87                         ctdb->daemon.sd = -1;
  88                 }
  89                 if (ctdb->methods != NULL) {
  90                         ctdb->methods->shutdown(ctdb);
  91                 }
  92
  93                 /* The child does not need to be realtime */
  94                 if (ctdb->do_setsched) {
  95                         reset_scheduler();
  96                 }
  97                 ctdb->can_send_controls = false;
  98
  99                 return 0;
 100         }
 101
 102         ctdb_track_child(ctdb, pid);
 103         return pid;
 104 }
 105
 106 pid_t ctdb_fork(struct ctdb_context *ctdb)
 107 {
 108         pid_t pid;
 109
 110         pid = ctdb_fork_no_free_ringbuffer(ctdb);
 111         if (pid == 0) {
 112                 ctdb_log_ringbuffer_free();
 113         }
 114
 115         return pid;
 116 }
 117
 118
 119 static void ctdb_sigchld_handler(struct tevent_context *ev,
 120         struct tevent_signal *te, int signum, int count,
 121         void *dont_care,
 122         void *private_data)
 123 {
 124         struct ctdb_context *ctdb = talloc_get_type(private_data, struct ctdb_context);
 125         int status;
 126         pid_t pid = -1;
 127
 128         while (pid != 0) {
 129                 pid = waitpid(-1, &status, WNOHANG);
 130                 if (pid == -1) {
 131                         DEBUG(DEBUG_ERR, (__location__ " waitpid() returned error. errno:%d\n", errno));
 132                         return;
 133                 }
 134                 if (pid > 0) {
 135                         char *process;
 136
 137                         if (getpid() != ctdb->ctdbd_pid) {
 138                                 continue;
 139                         }
 140
 141                         process = trbt_lookup32(ctdb->child_processes, pid);
 142                         if (process == NULL) {
 143                                 DEBUG(DEBUG_ERR,("Got SIGCHLD from pid:%d we didn not spawn with ctdb_fork\n", pid));
 144                         }
 145
 146                         DEBUG(DEBUG_DEBUG, ("SIGCHLD from %d %s\n", (int)pid, process));
 147                         talloc_free(process);
 148                 }
 149         }
 150 }
 151
 152
 153 struct tevent_signal *
 154 ctdb_init_sigchld(struct ctdb_context *ctdb)
 155 {
 156         struct tevent_signal *se;
 157
 158         ctdb->child_processes = trbt_create(ctdb, 0);
 159
 160         se = tevent_add_signal(ctdb->ev, ctdb, SIGCHLD, 0, ctdb_sigchld_handler, ctdb);
 161         return se;
 162 }
 163
 164 int
 165 ctdb_kill(struct ctdb_context *ctdb, pid_t pid, int signum)
 166 {
 167         char *process;
 168
 169         if (signum == 0) {
 170                 return kill(pid, signum);
 171         }
 172
 173         if (getpid() != ctdb->ctdbd_pid) {
 174                 return kill(pid, signum);
 175         }
 176
 177         process = trbt_lookup32(ctdb->child_processes, pid);
 178         if (process == NULL) {
 179                 DEBUG(DEBUG_ERR,("ctdb_kill: trying to kill(%d, %d) a process that does not exist\n", pid, signum));
 180                 return 0;
 181         }
 182
 183         return kill(pid, signum);
 184 }