Fix for BUG#2045 "Sending SIGHUP to mysqld crashes it if running with --log-bin".

The constructor of Rotate_log_event used when we are rotating our binlog or
relay log, should not assume that there is a nonzero THD available.
For example, when we are reacting to SIGHUP, the THD is 0.
In fact we don't need to use the THD in this constructor;
we can do like for Stop_log_event, and use the minimal Log_event
constructor.
If we were allowed to put Unix-specific commands in the testsuite,
I'd add a test for this (<sigh>).


sql/log.cc:
  A comment to warn that thd can be 0.
  The part about LOG_EVENT_FORCED_ROTATE_F is just to avoid segfault;
  this flag is already removed in 4.1 anyway.
sql/log_event.cc:
  A comment.
sql/log_event.h:
  The constructor of Rotate_log_event used when we are rotating our binlog or
  relay log, should not assume that there is a nonzero THD available.
  For example, when we are reacting to SIGHUP, the THD is 0.
  In fact we don't need to use the THD in this constructor;
  we can do like for Stop_log_event, and use the minimal Log_event
  constructor.
  This fixes BUG#2045 
  "Sending SIGHUP to mysqld crashes it if running with --log-bin"

1 files changed, 2 insertions, 2 deletions

diff --git a/sql/log.cc b/sql/log.cc
index e6eaa3b802c..8bd42d28e59 100644
--- a/sql/log.cc
+++ b/sql/log.cc
@@ -843,7 +843,7 @@ void MYSQL_LOG::new_file(bool need_lock)
         We log the whole file name for log file as the user may decide
         to change base names at some point.
       */
-      THD* thd = current_thd;
+      THD* thd = current_thd; /* may be 0 if we are reacting to SIGHUP */
       Rotate_log_event r(thd,new_name+dirname_length(new_name));
       r.set_log_pos(this);
       
@@ -852,7 +852,7 @@ void MYSQL_LOG::new_file(bool need_lock)
         the slave running with log-bin, we set the flag on rotate
         event to prevent infinite log rotation loop
       */
-      if (thd->slave_thread)
+      if (thd && thd->slave_thread)
         r.flags|= LOG_EVENT_FORCED_ROTATE_F;
       r.write(&log_file);
       bytes_written += r.get_event_len();