From dba12258b9e60ece0917b6907c5e07a2a1b62727 Mon Sep 17 00:00:00 2001
From: "guilhem@mysql.com" <>
Date: Mon, 8 Dec 2003 16:18:25 +0100
Subject: [PATCH] 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       | 4 ++--
 sql/log_event.cc | 7 ++++++-
 sql/log_event.h  | 2 +-
 3 files changed, 9 insertions(+), 4 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();
diff --git a/sql/log_event.cc b/sql/log_event.cc
index d17c94a2b44..9779b7401dd 100644
--- a/sql/log_event.cc
+++ b/sql/log_event.cc
@@ -128,7 +128,12 @@ Log_event::Log_event(THD* thd_arg, uint16 flags_arg, bool using_trans)
 	       (thd->options & (OPTION_NOT_AUTOCOMMIT | OPTION_BEGIN)));
 }
 
-
+/*
+  This minimal constructor is for when you are not even sure that there is a
+  valid THD. For example in the server when we are shutting down or flushing
+  logs after receiving a SIGHUP (then we must write a Rotate to the binlog but
+  we have no THD, so we need this minimal constructor).
+*/
 Log_event::Log_event()
   :temp_buf(0), exec_time(0), cached_event_len(0), flags(0), cache_stmt(0),
    thd(0)
diff --git a/sql/log_event.h b/sql/log_event.h
index 929d550951e..a1a7798be34 100644
--- a/sql/log_event.h
+++ b/sql/log_event.h
@@ -607,7 +607,7 @@ public:
   Rotate_log_event(THD* thd_arg, const char* new_log_ident_arg,
 		   uint ident_len_arg = 0,
 		   ulonglong pos_arg = LOG_EVENT_OFFSET)
-    :Log_event(thd_arg,0,0), new_log_ident(new_log_ident_arg),
+    :Log_event(), new_log_ident(new_log_ident_arg),
     pos(pos_arg),ident_len(ident_len_arg ? ident_len_arg :
 			   (uint) strlen(new_log_ident_arg)), alloced(0)
   {}