contrib/sendmail-8.13.4/libmilter/signal.c

   1 /*
   2  *  Copyright (c) 1999-2004 Sendmail, Inc. and its suppliers.
   3  *      All rights reserved.
   4  *
   5  * By using this file, you agree to the terms and conditions set
   6  * forth in the LICENSE file which can be found at the top level of
   7  * the sendmail distribution.
   8  *
   9  */
  10
  11 #include <sm/gen.h>
  12 SM_RCSID("@(#)$Id: signal.c,v 8.42 2004/08/20 21:10:30 ca Exp $")
  13
  14 #include "libmilter.h"
  15
  16 /*
  17 **  thread to handle signals
  18 */
  19
  20 static smutex_t M_Mutex;
  21
  22 static int MilterStop = MILTER_CONT;
  23
  24 static void     *mi_signal_thread __P((void *));
  25 static int       mi_spawn_signal_thread __P((char *));
  26
  27 /*
  28 **  MI_STOP -- return value of MilterStop
  29 **
  30 **      Parameters:
  31 **              none.
  32 **
  33 **      Returns:
  34 **              value of MilterStop
  35 */
  36
  37 int
  38 mi_stop()
  39 {
  40         return MilterStop;
  41 }
  42 /*
  43 **  MI_STOP_MILTERS -- set value of MilterStop
  44 **
  45 **      Parameters:
  46 **              v -- new value for MilterStop.
  47 **
  48 **      Returns:
  49 **              none.
  50 */
  51
  52 void
  53 mi_stop_milters(v)
  54         int v;
  55 {
  56         (void) smutex_lock(&M_Mutex);
  57         if (MilterStop < v)
  58                 MilterStop = v;
  59
  60         /* close listen socket */
  61         mi_closener();
  62         (void) smutex_unlock(&M_Mutex);
  63 }
  64 /*
  65 **  MI_CLEAN_SIGNALS -- clean up signal handler thread
  66 **
  67 **      Parameters:
  68 **              none.
  69 **
  70 **      Returns:
  71 **              none.
  72 */
  73
  74 void
  75 mi_clean_signals()
  76 {
  77         (void) smutex_destroy(&M_Mutex);
  78 }
  79 /*
  80 **  MI_SIGNAL_THREAD -- thread to deal with signals
  81 **
  82 **      Parameters:
  83 **              name -- name of milter
  84 **
  85 **      Returns:
  86 **              NULL
  87 */
  88
  89 static void *
  90 mi_signal_thread(name)
  91         void *name;
  92 {
  93         int sig, errs;
  94         sigset_t set;
  95
  96         (void) sigemptyset(&set);
  97         (void) sigaddset(&set, SIGHUP);
  98         (void) sigaddset(&set, SIGTERM);
  99
 100         /* Handle Ctrl-C gracefully for debugging */
 101         (void) sigaddset(&set, SIGINT);
 102         errs = 0;
 103
 104         for (;;)
 105         {
 106                 sig = 0;
 107 #if defined(SOLARIS) || defined(__svr5__)
 108                 if ((sig = sigwait(&set)) < 0)
 109 #else /* defined(SOLARIS) || defined(__svr5__) */
 110                 if (sigwait(&set, &sig) != 0)
 111 #endif /* defined(SOLARIS) || defined(__svr5__) */
 112                 {
 113                         /* this can happen on OSF/1 (at least) */
 114                         if (errno == EINTR)
 115                                 continue;
 116                         smi_log(SMI_LOG_ERR,
 117                                 "%s: sigwait returned error: %d",
 118                                 (char *)name, errno);
 119                         if (++errs > MAX_FAILS_T)
 120                         {
 121                                 mi_stop_milters(MILTER_ABRT);
 122                                 return NULL;
 123                         }
 124                         continue;
 125                 }
 126                 errs = 0;
 127
 128                 switch (sig)
 129                 {
 130                   case SIGHUP:
 131                   case SIGTERM:
 132                         mi_stop_milters(MILTER_STOP);
 133                         return NULL;
 134                   case SIGINT:
 135                         mi_stop_milters(MILTER_ABRT);
 136                         return NULL;
 137                   default:
 138                         smi_log(SMI_LOG_ERR,
 139                                 "%s: sigwait returned unmasked signal: %d",
 140                                 (char *)name, sig);
 141                         break;
 142                 }
 143         }
 144         /* NOTREACHED */
 145 }
 146 /*
 147 **  MI_SPAWN_SIGNAL_THREAD -- spawn thread to handle signals
 148 **
 149 **      Parameters:
 150 **              name -- name of milter
 151 **
 152 **      Returns:
 153 **              MI_SUCCESS/MI_FAILURE
 154 */
 155
 156 static int
 157 mi_spawn_signal_thread(name)
 158         char *name;
 159 {
 160         sthread_t tid;
 161         int r;
 162         sigset_t set;
 163
 164         /* Mask HUP and KILL signals */
 165         (void) sigemptyset(&set);
 166         (void) sigaddset(&set, SIGHUP);
 167         (void) sigaddset(&set, SIGTERM);
 168         (void) sigaddset(&set, SIGINT);
 169
 170         if (pthread_sigmask(SIG_BLOCK, &set, NULL) != 0)
 171         {
 172                 smi_log(SMI_LOG_ERR,
 173                         "%s: Couldn't mask HUP and KILL signals", name);
 174                 return MI_FAILURE;
 175         }
 176         r = thread_create(&tid, mi_signal_thread, (void *)name);
 177         if (r != 0)
 178         {
 179                 smi_log(SMI_LOG_ERR,
 180                         "%s: Couldn't start signal thread: %d",
 181                         name, r);
 182                 return MI_FAILURE;
 183         }
 184         return MI_SUCCESS;
 185 }
 186 /*
 187 **  MI_CONTROL_STARTUP -- startup for thread to handle signals
 188 **
 189 **      Parameters:
 190 **              name -- name of milter
 191 **
 192 **      Returns:
 193 **              MI_SUCCESS/MI_FAILURE
 194 */
 195
 196 int
 197 mi_control_startup(name)
 198         char *name;
 199 {
 200
 201         if (!smutex_init(&M_Mutex))
 202         {
 203                 smi_log(SMI_LOG_ERR,
 204                         "%s: Couldn't initialize control pipe mutex", name);
 205                 return MI_FAILURE;
 206         }
 207
 208         /*
 209         **  spawn_signal_thread must happen before other threads are spawned
 210         **  off so that it can mask the right signals and other threads
 211         **  will inherit that mask.
 212         */
 213         if (mi_spawn_signal_thread(name) == MI_FAILURE)
 214         {
 215                 smi_log(SMI_LOG_ERR,
 216                         "%s: Couldn't spawn signal thread", name);
 217                 (void) smutex_destroy(&M_Mutex);
 218                 return MI_FAILURE;
 219         }
 220         return MI_SUCCESS;
 221 }