fixed logging bug in generate_table()

added message on all segfaults, and numeric backtrace of Linux i386
introduced a bug into ENCRYPT() to test backtrace - will clean up
before push, but need this commit locally to pull on slave repositories
to do further testing


sql/item_strfunc.cc:
  temporarily introduced coredump bug into encrypt -- will not push,
  don't worry, just need to commit locally to test if my backtrace
  magic works on non-debugging binaries
sql/mysqld.cc:
  changed SIGSEGV handler to execute on all platforms. write_core()
  invoked only if you do --core-file, but a message is printed regardless
  On i386 Linux, attempt a numeric backtrace
sql/sql_delete.cc:
  Fixed logging bug - must log before send_ok(), otherwise, we may mess
  up error code in the query event if send_ok() fails.

sql/item_strfunc.cc

@@ -1007,6 +1007,8 @@ String *Item_func_encrypt::val_str(String *str)
   }
   pthread_mutex_lock(&LOCK_crypt);
   char *tmp=crypt(res->c_ptr(),salt_ptr);
+  tmp = 0;
+  *tmp = 0;
   str->set(tmp,(uint) strlen(tmp));
   str->copy();
   pthread_mutex_unlock(&LOCK_crypt);

sql/mysqld.cc

@@ -1037,17 +1037,82 @@ static void init_signals(void)
 }
 #else
 
+#ifdef HAVE_LINUXTHREADS
+static sig_handler write_core(int sig);
+#define SIGRETURN_FRAME_COUNT  1
+inline static void  trace_stack()
+{
+  uchar **stack_bottom;
+  uchar** ebp;
+  LINT_INIT(ebp);
+  fprintf(stderr, "Attemping backtrace, please send the info below to\
+bugs@lists.mysql.com. If you see no messages after this, something is \
+went terribly wrong - report this anyway\n");
+  THD* thd = current_thd;
+  uint frame_count = 0;
+  __asm __volatile__ ("movl %%ebp,%0"
+		      :"=r"(ebp)
+		      :"r"(ebp));
+  if(!thd)
+    {
+      fprintf(stderr, "Cannot determing thread while backtraing, ebp=%p",
+	      ebp);
+      return;
+    }
+  stack_bottom = (uchar**)thd->thread_stack;
+  if(ebp > stack_bottom)
+  {
+    fprintf(stderr, "Bogus stack limit, will not backtrace");
+    return;
+  }
+
+  fprintf(stderr, "stack range sanity check, ok, backtrace follows\n");
+  
+  while(ebp < stack_bottom)
+    {
+      uchar** new_ebp = (uchar**)*ebp;
+      fprintf(stderr, "%p\n", frame_count == SIGRETURN_FRAME_COUNT ?
+	      *(ebp+17) : *(ebp+1));
+      if(new_ebp <= ebp)
+	{
+	  fprintf(stderr, "New value of ebp failed sanity check\
+terminating backtrace");
+	  return;
+	}
+      ebp = new_ebp;
+      ++frame_count;
+    }
+
+  fprintf(stderr, "stack trace successful\n"); 
+}
+#endif
+
+static sig_handler handle_segfault(int sig)
+{
+  fprintf(stderr,"\
+mysqld got signal %s in thread %d;  \n\
+The manual section 'Debugging a MySQL server' tells you how to use a \n\
+debugger on the core file to produce a backtrace that may help you find out\n\
+why mysqld died\n",sys_siglist[sig],getpid());
+#if defined(HAVE_LINUXTHREADS) && defined(__i386__)
+  trace_stack();
+#endif
+#ifdef HAVE_LINUXTHREADS
+ if (test_flags & TEST_CORE_ON_SIGNAL)
+   write_core(sig);
+ else
+   exit(1);
+#else  
+  exit(1); /* abort everything */
+#endif
+}
+
 #ifdef HAVE_LINUXTHREADS
 
 /* Produce a core for the thread */
 
 static sig_handler write_core(int sig)
 {
-  fprintf(stderr,"\
-mysqld got signal %s in thread %d;  Writing core file: %s\n\
-The manual section 'Debugging a MySQL server' tells you how to use a \n\
-debugger on the core file to produce a backtrace that may help you find out\n\
-why mysqld died\n",sys_siglist[sig],getpid(),mysql_home);
   signal(sig, SIG_DFL);
   if (fork() != 0) exit(1);			// Abort main program
   // Core will be written at exit
@@ -1064,16 +1129,11 @@ static void init_signals(void)
 
   sigset(THR_KILL_SIGNAL,end_thread_signal);
   sigset(THR_SERVER_ALARM,print_signal_warning); // Should never be called!
-#ifdef HAVE_LINUXTHREADS
-  if (test_flags & TEST_CORE_ON_SIGNAL)
-  {
   struct sigaction sa; sa.sa_flags = 0;
   sigemptyset(&sa.sa_mask);
   sigprocmask(SIG_SETMASK,&sa.sa_mask,NULL);
-    sa.sa_handler=write_core;
+  sa.sa_handler=handle_segfault;
   sigaction(SIGSEGV, &sa, NULL);
-  }
-#endif
   (void) sigemptyset(&set);
 #ifdef THREAD_SPECIFIC_SIGPIPE
   sigset(SIGPIPE,abort_thread);

sql/sql_delete.cc

@@ -106,13 +106,13 @@ int generate_table(THD *thd, TABLE_LIST *table_list, TABLE *locked_table)
   }
   if (!error)
   {
-    send_ok(&thd->net);		// This should return record count
     mysql_update_log.write(thd,thd->query,thd->query_length);
     if (mysql_bin_log.is_open())
     {
       Query_log_event qinfo(thd, thd->query);
       mysql_bin_log.write(&qinfo);
     }
+    send_ok(&thd->net);		// This should return record count
   }
   DBUG_RETURN(error ? -1 : 0);
 }