X-Git-Url: http://git.tuebingen.mpg.de/?a=blobdiff_plain;f=command.c;fp=command.c;h=a72a524fa179e605e152adc32b6a37305162b70f;hb=0ce0301d8184fcebb1aafda396d6a9ae71bf1301;hp=84b7d9438fa21a3fd491ab4a0ee0918f6ff9c086;hpb=42c6dc96316660fe476a6baadd87a2c79da07c83;p=paraslash.git

diff --git a/command.c b/command.c
index 84b7d943..a72a524f 100644
--- a/command.c
+++ b/command.c
@@ -49,9 +49,14 @@ static const char * const server_command_perms_txt[] = {LSG_SERVER_CMD_AUX_INFOS
 extern int mmd_mutex;
 extern struct misc_meta_data *mmd;
 int send_afs_status(struct command_context *cc, int parser_friendly);
+static bool subcmd_should_die;
 
-static void dummy(__a_unused int s)
+static void command_handler_sighandler(int s)
 {
+	if (s != SIGTERM)
+		return;
+	PARA_EMERG_LOG("terminating on signal %d\n", SIGTERM);
+	subcmd_should_die = true;
 }
 
 /*
@@ -492,9 +497,21 @@ static int com_stat(struct command_context *cc, struct lls_parse_result *lpr)
 	bool parser_friendly = SERVER_CMD_OPT_GIVEN(STAT, PARSER_FRIENDLY,
 		lpr) > 0;
 	uint32_t num = SERVER_CMD_UINT32_VAL(STAT, NUM, lpr);
+	const struct timespec ts = {.tv_sec = 50, .tv_nsec = 0};
 
-	para_sigaction(SIGUSR1, dummy);
+	para_sigaction(SIGINT, SIG_IGN);
+	para_sigaction(SIGUSR1, command_handler_sighandler);
+	para_sigaction(SIGTERM, command_handler_sighandler);
+	/*
+	 * Simply checking subcmd_should_die is racy because a signal may
+	 * arrive after the check but before the subsequent call to sleep(3).
+	 * If this happens, sleep(3) would not be interrupted by the signal.
+	 * To avoid this we block SIGTERM here and allow it to arrive only
+	 * while we sleep.
+	 */
+	para_block_signal(SIGTERM);
 	for (;;) {
+		sigset_t set;
 		/*
 		 * Copy the mmd structure to minimize the time we hold the mmd
 		 * lock.
@@ -517,7 +534,15 @@ static int com_stat(struct command_context *cc, struct lls_parse_result *lpr)
 		ret = 1;
 		if (num > 0 && !--num)
 			goto out;
-		sleep(50);
+		sigemptyset(&set); /* empty set means: unblock all signals */
+		/*
+		 * pselect(2) allows to atomically unblock signals, then go to
+		 * sleep. Calling sigprocmask(2) followed by sleep(3) would
+		 * open a race window similar to the one described above.
+		 */
+		pselect(1, NULL, NULL, NULL, &ts, &set);
+		if (subcmd_should_die)
+			goto out;
 		ret = -E_SERVER_CRASH;
 		if (getppid() == 1)
 			goto out;