MDEV-16825 SIGSEGV after SIGINT in bootstrap mode

* Fixes segmentation fault on SIGINT;
* Interrupt blocked fgets() while daemon is in the shutting down progress.

[fixes #527]

mysql-test/main/bootstrap.result

@@ -26,3 +26,7 @@ select * from mysql.plugin;
 name	dl
 EXAMPLE	ha_example.so
 truncate table mysql.plugin;
+#
+# MDEV-16825 SIGSEGV after SIGINT in bootstrap mode
+#
+Success!

mysql-test/main/bootstrap.test

@@ -106,3 +106,22 @@ use test;
 EOF
 --exec $MYSQLD_BOOTSTRAP_CMD --ignore-db-dirs='some_dir' --ignore-db-dirs='some_dir' < $MYSQLTEST_VARDIR/tmp/bootstrap_9969.sql >> $MYSQLTEST_VARDIR/tmp/bootstrap.log 2>&1
 --remove_file $MYSQLTEST_VARDIR/tmp/bootstrap_9969.sql
+
+--echo #
+--echo # MDEV-16825 SIGSEGV after SIGINT in bootstrap mode
+--echo #
+--perl
+use POSIX qw(WNOHANG);
+my $wait= 5; # seconds to wait process shutdown
+$|= 1;
+my $pid= open(BOOTSTRAP, '|-',  $ENV{'MYSQLD_BOOTSTRAP_CMD'})
+  or die $ENV{'MYSQLD_BOOTSTRAP_CMD'}. ": $!";
+print BOOTSTRAP "select 1;\n"; # make sure process accepts input
+kill INT => $pid;
+my $status;
+while ($wait-- && ($status= waitpid($pid, WNOHANG)) < 1)
+{
+  sleep 1;
+}
+print $status != $pid ? "Failed!\n" : "Success!\n";
+EOF

scripts/comp_sql.c

@@ -40,6 +40,8 @@
 
 FILE *in, *out;
 
+volatile sig_atomic_t kill_in_progress= 0;
+
 static void die(const char *fmt, ...)
 {
   va_list args;

sql/mysqld.cc

@@ -784,12 +784,14 @@ mysql_rwlock_t LOCK_grant, LOCK_sys_init_connect, LOCK_sys_init_slave;
 mysql_prlock_t LOCK_system_variables_hash;
 mysql_cond_t COND_thread_count, COND_start_thread;
 pthread_t signal_thread;
+pthread_t *bootstrap_thread= NULL;
 pthread_attr_t connection_attrib;
 mysql_mutex_t LOCK_server_started;
 mysql_cond_t COND_server_started;
 
 int mysqld_server_started=0, mysqld_server_initialized= 0;
 File_parser_dummy_hook file_parser_dummy_hook;
+volatile sig_atomic_t kill_in_progress= 0;
 
 /* replication parameters, if master_host is not NULL, we are a slave */
 uint report_port= 0;
@@ -801,7 +803,6 @@ char *opt_logname, *opt_slow_logname, *opt_bin_logname;
 
 /* Static variables */
 
-static volatile sig_atomic_t kill_in_progress;
 my_bool opt_stack_trace;
 my_bool opt_expect_abort= 0, opt_bootstrap= 0;
 static my_bool opt_myisam_log;
@@ -1651,6 +1652,10 @@ static void close_connections(void)
 #endif
     close_server_sock();
   }
+#ifndef DONT_USE_THR_ALARM
+  if (bootstrap_thread)
+    pthread_kill(*bootstrap_thread, thr_client_alarm);
+#endif
   mysql_mutex_unlock(&LOCK_start_thread);
 #endif /* __WIN__ */
 
@@ -1761,7 +1766,8 @@ static void close_connections(void)
   mysql_mutex_unlock(&LOCK_thread_count); // For unlink from list
 
   Events::deinit();
-  slave_prepare_for_shutdown();
+  if (!opt_bootstrap)
+    slave_prepare_for_shutdown();
   mysql_bin_log.stop_background_thread();
   ack_receiver.stop();
 
@@ -6468,6 +6474,7 @@ static void bootstrap(MYSQL_FILE *file)
     delete thd;
     DBUG_VOID_RETURN;
   }
+  bootstrap_thread= &thd->real_id;
   /* Wait for thread to die */
   mysql_mutex_lock(&LOCK_thread_count);
   while (in_bootstrap)

sql/mysqld.h

@@ -29,6 +29,7 @@
 #include <my_rnd.h>
 #include "my_pthread.h"
 #include "my_rdtsc.h"
+#include <signal.h>
 
 class THD;
 class CONNECT;
@@ -178,6 +179,7 @@ extern char *opt_backup_history_logname, *opt_backup_progress_logname,
             *opt_backup_settings_name;
 extern const char *log_output_str;
 extern const char *log_backup_output_str;
+extern volatile sig_atomic_t kill_in_progress;
 
 /* System Versioning begin */
 enum vers_system_time_t

sql/sql_bootstrap.cc

@@ -17,8 +17,11 @@
 #include "mariadb.h"
 #include <ctype.h>
 #include <string.h>
+#include <signal.h>
 #include "sql_bootstrap.h"
 
+extern volatile sig_atomic_t kill_in_progress;
+
 int read_bootstrap_query(char *query, int *query_length,
                          fgets_input_t input, fgets_fn_t fgets_fn, int *error)
 {
@@ -37,7 +40,7 @@ int read_bootstrap_query(char *query, int *query_length,
       *error= fgets_error;
 
     if (fgets_error != 0)
-      return READ_BOOTSTRAP_ERROR;
+      return kill_in_progress ? READ_BOOTSTRAP_EOF : READ_BOOTSTRAP_ERROR;
 
     if (line == NULL)
       return (query_len == 0) ? READ_BOOTSTRAP_EOF : READ_BOOTSTRAP_ERROR;