core, MPMs unix: follow up to r1809881.

Deregister all hooks first (in pre_cleanup), by doing it last we could still
have had them run when DSOs were unloaded.

Likewise, avoid double faults when handling fatal signals by restoring the
default handler before pconf is cleared (we can't ap_log_error there).

Finally, we need to ignore sig_term/restart (do nothing) when the main
process is exiting (i.e. ap_pglobal is destroyed), since retained_data are
freed.

Aimed to fix all faults in PR 61558.



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1809973 13f79535-47bb-0310-9956-ffa450edef68

os/unix/unixd.c

@@ -437,11 +437,19 @@ AP_DECLARE(apr_status_t) ap_unixd_accept(void **accepted, ap_listen_rec *lr,
 /* Unixes MPMs' */
 
 static ap_unixd_mpm_retained_data *retained_data = NULL;
+static apr_status_t retained_data_cleanup(void *unused)
+{
+    (void)unused;
+    retained_data = NULL;
+    return APR_SUCCESS;
+}
+
 AP_DECLARE(ap_unixd_mpm_retained_data *) ap_unixd_mpm_get_retained_data()
 {
     if (!retained_data) {
         retained_data = ap_retained_data_create("ap_unixd_mpm_retained_data",
                                                 sizeof(*retained_data));
+        apr_pool_pre_cleanup_register(ap_pglobal, NULL, retained_data_cleanup);
         retained_data->mpm_state = AP_MPMQ_STARTING;
     }
     return retained_data;
@@ -449,6 +457,10 @@ AP_DECLARE(ap_unixd_mpm_retained_data *) ap_unixd_mpm_get_retained_data()
 
 static void sig_term(int sig)
 {
+    if (!retained_data) {
+        /* Main process (ap_pglobal) is dying */
+        return;
+    }
     retained_data->mpm_state = AP_MPMQ_STOPPING;
     if (retained_data->shutdown_pending
             && (retained_data->is_ungraceful
@@ -465,6 +477,10 @@ static void sig_term(int sig)
 
 static void sig_restart(int sig)
 {
+    if (!retained_data) {
+        /* Main process (ap_pglobal) is dying */
+        return;
+    }
     retained_data->mpm_state = AP_MPMQ_STOPPING;
     if (retained_data->restart_pending
             && (retained_data->is_ungraceful
@@ -494,6 +510,10 @@ AP_DECLARE(void) ap_unixd_mpm_set_signals(apr_pool_t *pconf, int one_process)
     struct sigaction sa;
 #endif
 
+    if (!one_process) {
+        ap_fatal_signal_setup(ap_server_conf, pconf);
+    }
+
     /* Signals' handlers depend on retained data */
     (void)ap_unixd_mpm_get_retained_data();
 

server/main.c

@@ -295,13 +295,30 @@ static int abort_on_oom(int retcode)
     return retcode; /* unreachable, hopefully. */
 }
 
+/* Deregister all hooks when clearing pconf (pre_cleanup).
+ * TODO: have a hook to deregister and run them from here?
+ *       ap_clear_auth_internal() is already a candidate.
+ */
 static apr_status_t deregister_all_hooks(void *unused)
 {
     (void)unused;
+    ap_clear_auth_internal();
     apr_hook_deregister_all();
     return APR_SUCCESS;
 }
 
+static void reset_process_pconf(process_rec *process)
+{
+    if (process->pconf) {
+        apr_pool_clear(process->pconf);
+    }
+    else {
+        apr_pool_create(&process->pconf, process->pool);
+        apr_pool_tag(process->pconf, "pconf");
+    }
+    apr_pool_pre_cleanup_register(process->pconf, NULL, deregister_all_hooks);
+}
+
 static process_rec *init_process(int *argc, const char * const * *argv)
 {
     process_rec *process;
@@ -346,8 +363,9 @@ static process_rec *init_process(int *argc, const char * const * *argv)
     process = apr_palloc(cntx, sizeof(process_rec));
     process->pool = cntx;
 
-    apr_pool_create(&process->pconf, process->pool);
-    apr_pool_tag(process->pconf, "pconf");
+    process->pconf = NULL;
+    reset_process_pconf(process);
+
     process->argc = *argc;
     process->argv = *argv;
     process->short_name = apr_filepath_name_get((*argv)[0]);
@@ -504,10 +522,6 @@ int main(int argc, const char * const argv[])
     }
 #endif
 
-    /* Deregister all hooks (lastly) when done with pconf */
-    apr_pool_cleanup_register(pconf, NULL, deregister_all_hooks,
-                              apr_pool_cleanup_null);
-
     apr_pool_create(&pcommands, ap_pglobal);
     apr_pool_tag(pcommands, "pcommands");
     ap_server_pre_read_config  = apr_array_make(pcommands, 1,
@@ -754,12 +768,7 @@ int main(int argc, const char * const argv[])
 
     do {
         ap_main_state = AP_SQ_MS_DESTROY_CONFIG;
-        apr_pool_clear(pconf);
-        ap_clear_auth_internal();
-
-        /* Deregister all hooks (lastly) when done with pconf */
-        apr_pool_cleanup_register(pconf, NULL, deregister_all_hooks,
-                                  apr_pool_cleanup_null);
+        reset_process_pconf(process);
 
         ap_main_state = AP_SQ_MS_CREATE_CONFIG;
         ap_config_generation++;

server/mpm/event/event.c

@@ -3149,9 +3149,6 @@ static int event_run(apr_pool_t * _pconf, apr_pool_t * plog, server_rec * s)
         ap_scoreboard_image->global->running_generation = retained->mpm->my_generation;
     }
 
-    if (!one_process) {
-        ap_fatal_signal_setup(ap_server_conf, pconf);
-    }
     ap_unixd_mpm_set_signals(pconf, one_process);
 
     /* Don't thrash since num_buckets depends on the

server/mpm/motorz/motorz.c

@@ -1104,9 +1104,6 @@ static int motorz_run(apr_pool_t *_pconf, apr_pool_t *plog, server_rec *s)
         ap_scoreboard_image->global->running_generation = mz->mpm->my_generation;
     }
 
-    if (!one_process) {
-        ap_fatal_signal_setup(ap_server_conf, pconf);
-    }
     ap_unixd_mpm_set_signals(pconf, one_process);
 
     if (one_process) {

server/mpm/prefork/prefork.c

@@ -864,9 +864,6 @@ static int prefork_run(apr_pool_t *_pconf, apr_pool_t *plog, server_rec *s)
         ap_scoreboard_image->global->running_generation = retained->mpm->my_generation;
     }
 
-    if (!one_process) {
-        ap_fatal_signal_setup(ap_server_conf, pconf);
-    }
     ap_unixd_mpm_set_signals(pconf, one_process);
 
     if (one_process) {

server/mpm/worker/worker.c

@@ -1672,9 +1672,6 @@ static int worker_run(apr_pool_t *_pconf, apr_pool_t *plog, server_rec *s)
         ap_scoreboard_image->global->running_generation = retained->mpm->my_generation;
     }
 
-    if (!one_process) {
-        ap_fatal_signal_setup(ap_server_conf, pconf);
-    }
     ap_unixd_mpm_set_signals(pconf, one_process);
 
     /* Don't thrash since num_buckets depends on the

server/mpm_unix.c

@@ -1009,6 +1009,33 @@ AP_DECLARE(apr_status_t) ap_fatal_signal_child_setup(server_rec *s)
     return APR_SUCCESS;
 }
 
+/* We can't call sig_coredump (ap_log_error) once pconf is destroyed, so
+ * avoid double faults by restoring each default signal handler on cleanup.
+ */
+static apr_status_t fatal_signal_cleanup(void *unused)
+{
+    (void)unused;
+
+    apr_signal(SIGSEGV, SIG_DFL);
+#ifdef SIGBUS
+    apr_signal(SIGBUS, SIG_DFL);
+#endif /* SIGBUS */
+#ifdef SIGABORT
+    apr_signal(SIGABORT, SIG_DFL);
+#endif /* SIGABORT */
+#ifdef SIGABRT
+    apr_signal(SIGABRT, SIG_DFL);
+#endif /* SIGABRT */
+#ifdef SIGILL
+    apr_signal(SIGILL, SIG_DFL);
+#endif /* SIGILL */
+#ifdef SIGFPE
+    apr_signal(SIGFPE, SIG_DFL);
+#endif /* SIGFPE */
+
+    return APR_SUCCESS;
+}
+
 AP_DECLARE(apr_status_t) ap_fatal_signal_setup(server_rec *s,
                                                apr_pool_t *in_pconf)
 {
@@ -1071,6 +1098,8 @@ AP_DECLARE(apr_status_t) ap_fatal_signal_setup(server_rec *s,
 
     pconf = in_pconf;
     parent_pid = my_pid = getpid();
+    apr_pool_cleanup_register(pconf, NULL, fatal_signal_cleanup,
+                              fatal_signal_cleanup);
 
     return APR_SUCCESS;
 }