MPMs unix: Place signals handlers and helpers out of DSOs to avoid

a possible crash if a signal is caught during (graceful) restart.
PR 60487.



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1783849 13f79535-47bb-0310-9956-ffa450edef68

2 files changed, 174 insertions, 0 deletions

diff --git a/os/unix/unixd.c b/os/unix/unixd.c
index d7042bf686..07a9bef754 100644
--- a/os/unix/unixd.c
+++ b/os/unix/unixd.c
@@ -434,6 +434,155 @@ 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;
+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));
+        retained_data->mpm_state = AP_MPMQ_STARTING;
+    }
+    return retained_data;
+}
+
+static void sig_term(int sig)
+{
+    retained_data->mpm_state = AP_MPMQ_STOPPING;
+    if (retained_data->shutdown_pending
+            && (retained_data->is_ungraceful
+                || sig == AP_SIG_GRACEFUL_STOP)) {
+        /* Already handled */
+        return;
+    }
+
+    retained_data->shutdown_pending = 1;
+    if (sig != AP_SIG_GRACEFUL_STOP) {
+        retained_data->is_ungraceful = 1;
+    }
+}
+
+static void sig_restart(int sig)
+{
+    retained_data->mpm_state = AP_MPMQ_STOPPING;
+    if (retained_data->restart_pending
+            && (retained_data->is_ungraceful
+                || sig == AP_SIG_GRACEFUL)) {
+        /* Already handled */
+        return;
+    }
+
+    retained_data->restart_pending = 1;
+    if (sig != AP_SIG_GRACEFUL) {
+        retained_data->is_ungraceful = 1;
+    }
+}
+
+static apr_status_t unset_signals(void *unused)
+{
+    retained_data->shutdown_pending = retained_data->restart_pending = 0;
+    retained_data->was_graceful = !retained_data->is_ungraceful;
+    retained_data->is_ungraceful = 0;
+
+    return APR_SUCCESS;
+}
+
+AP_DECLARE(void) ap_unixd_mpm_set_signals(apr_pool_t *pconf, int one_process)
+{
+#ifndef NO_USE_SIGACTION
+    struct sigaction sa;
+#endif
+
+    /* Signals' handlers depend on retained data */
+    (void)ap_unixd_mpm_get_retained_data();
+
+#ifndef NO_USE_SIGACTION
+    memset(&sa, 0, sizeof sa);
+    sigemptyset(&sa.sa_mask);
+
+#ifdef SIGPIPE
+    sa.sa_handler = SIG_IGN;
+    if (sigaction(SIGPIPE, &sa, NULL) < 0)
+        ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf, APLOGNO(00269)
+                     "sigaction(SIGPIPE)");
+#endif
+#ifdef SIGXCPU
+    sa.sa_handler = SIG_DFL;
+    if (sigaction(SIGXCPU, &sa, NULL) < 0)
+        ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf, APLOGNO(00267)
+                     "sigaction(SIGXCPU)");
+#endif
+#ifdef SIGXFSZ
+    /* For systems following the LFS standard, ignoring SIGXFSZ allows
+     * a write() beyond the 2GB limit to fail gracefully with E2BIG
+     * rather than terminate the process. */
+    sa.sa_handler = SIG_IGN;
+    if (sigaction(SIGXFSZ, &sa, NULL) < 0)
+        ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf, APLOGNO(00268)
+                     "sigaction(SIGXFSZ)");
+#endif
+
+    sa.sa_handler = sig_term;
+    if (sigaction(SIGTERM, &sa, NULL) < 0)
+        ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf, APLOGNO(00264)
+                     "sigaction(SIGTERM)");
+#ifdef SIGINT
+    if (sigaction(SIGINT, &sa, NULL) < 0)
+        ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf, APLOGNO(00266)
+                     "sigaction(SIGINT)");
+#endif
+#ifdef AP_SIG_GRACEFUL_STOP
+    if (sigaction(AP_SIG_GRACEFUL_STOP, &sa, NULL) < 0)
+        ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf, APLOGNO(00265)
+                     "sigaction(" AP_SIG_GRACEFUL_STOP_STRING ")");
+#endif
+
+    /* Don't catch restart signals in ONE_PROCESS mode :) */
+    if (!one_process) {
+        sa.sa_handler = sig_restart;
+        if (sigaction(SIGHUP, &sa, NULL) < 0)
+            ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf, APLOGNO(00270)
+                         "sigaction(SIGHUP)");
+        if (sigaction(AP_SIG_GRACEFUL, &sa, NULL) < 0)
+            ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf, APLOGNO(00271)
+                         "sigaction(" AP_SIG_GRACEFUL_STRING ")");
+    }
+
+#else  /* NO_USE_SIGACTION */
+
+#ifdef SIGPIPE
+    apr_signal(SIGPIPE, SIG_IGN);
+#endif /* SIGPIPE */
+#ifdef SIGXCPU
+    apr_signal(SIGXCPU, SIG_DFL);
+#endif /* SIGXCPU */
+#ifdef SIGXFSZ
+    apr_signal(SIGXFSZ, SIG_IGN);
+#endif /* SIGXFSZ */
+
+    apr_signal(SIGTERM, sig_term);
+#ifdef AP_SIG_GRACEFUL_STOP
+    apr_signal(AP_SIG_GRACEFUL_STOP, sig_term);
+#endif /* AP_SIG_GRACEFUL_STOP */
+
+    if (!one_process) {
+        /* Don't restart in ONE_PROCESS mode :) */
+#ifdef SIGHUP
+        apr_signal(SIGHUP, sig_restart);
+#endif /* SIGHUP */
+#ifdef AP_SIG_GRACEFUL
+        apr_signal(AP_SIG_GRACEFUL, sig_restart);
+#endif /* AP_SIG_GRACEFUL */
+    }
+
+#endif /* NO_USE_SIGACTION */
+
+    apr_pool_cleanup_register(pconf, NULL, unset_signals,
+                              apr_pool_cleanup_null);
+}
+
+
 #ifdef _OSD_POSIX
 
 #include "apr_lib.h"
diff --git a/os/unix/unixd.h b/os/unix/unixd.h
index 74961c348e..ed977c6fde 100644
--- a/os/unix/unixd.h
+++ b/os/unix/unixd.h
@@ -27,6 +27,7 @@
 
 #include "httpd.h"
 #include "http_config.h"
+#include "scoreboard.h"
 #include "ap_listen.h"
 #ifdef HAVE_SYS_TIME_H
 #include <sys/time.h>
@@ -109,6 +110,30 @@ AP_DECLARE(apr_status_t) ap_unixd_accept(void **accepted, ap_listen_rec *lr, apr
 #define ap_os_killpg(x, y)      (kill (-(x), (y)))
 #endif /* HAVE_KILLPG */
 
+typedef struct {
+    void            *baton;  /* MPM's */
+
+    /* volatile because they're updated from signals' handlers */
+    int volatile    mpm_state;
+    int volatile    shutdown_pending;
+    int volatile    restart_pending;
+    int volatile    is_ungraceful;
+
+    ap_generation_t my_generation;
+    int             module_loads;
+    int             was_graceful;
+
+    /*
+     * Current number of listeners buckets and maximum reached across
+     * restarts (to size retained data according to dynamic num_buckets,
+     * eg. idle_spawn_rate).
+     */
+    int num_buckets, max_buckets;
+} ap_unixd_mpm_retained_data;
+
+AP_DECLARE(ap_unixd_mpm_retained_data *) ap_unixd_mpm_get_retained_data(void);
+AP_DECLARE(void) ap_unixd_mpm_set_signals(apr_pool_t *pconf, int once_process);
+
 #ifdef __cplusplus
 }
 #endif