From: Guilhem Bichot
Date: May 13 2008 12:43pm
Subject: removing all log files
List-Archive: http://lists.mysql.com/maria/34
Message-Id: <20080513124351.GC5049@mysql.com>
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Hello Sanja,

for http://forge.mysql.com/worklog/task.php?id=4374
"Maria - force start if Recovery fails multiple times",
in case recovery has failed many times I need to remove all logs, even
before translog_init() is called (because, if there is a log problem
or log handler bug, there could be a crash in translog_init()).
I'm going to write a simple function which will open the directory and
do "rm maria_log.[0-9]{6}".
While I was looking at ma_loghandler.c I noticed that 

/**
  @brief Check log files presence

  @retval 0 no log files.
  @retval 1 there is at least 1 log file in the directory
*/

my_bool translog_is_log_files()
{
  MY_DIR *dirp;
  uint i;
  my_bool rc= FALSE;

  /* Finds and removes transaction log files */
  if (!(dirp = my_dir(log_descriptor.directory, MYF(MY_DONT_SORT))))
    return 1;

  for (i= 0; i < dirp->number_off_files; i++)
  {
    char *file= dirp->dir_entry[i].name;
    if (strncmp(file, "maria_log.", 10) == 0 &&
        file[10] >= '0' && file[10] <= '9' &&
        file[11] >= '0' && file[11] <= '9' &&
        file[12] >= '0' && file[12] <= '9' &&
        file[13] >= '0' && file[13] <= '9' &&
        file[14] >= '0' && file[14] <= '9' &&
        file[15] >= '0' && file[15] <= '9' &&
        file[16] >= '0' && file[16] <= '9' &&
        file[17] >= '0' && file[17] <= '9' &&
        file[18] == '\0')
    {
      rc= TRUE;
      break;
    }
  }
  my_dirend(dirp);
  return FALSE;
}

has problems.
If the my_dir() fails it returns 1, which does not mean that "there is
at least 1 log file in the directory".
And, if strncmp() is true, we set rc to TRUE, but we return FALSE: rc
is never used.
So, the function always returns "no log files".

I propose that I fix this function and extend it a bit, like this:
I'll rename it to:
my_bool translog_walk_log_filenames(action)
and "action" will be a parameter: either SEARCH_FIRST or DELETE_ALL.
SEARCH_FIRST will be the equivalent of what translog_is_log_files()
does now (return TRUE at first found log), and DELETE_ALL will be what
I need (delete all found logs).

I hope this is ok with you?

-- 
   __  ___     ___ ____  __
  /  |/  /_ __/ __/ __ \/ /    Mr. Guilhem Bichot <guilhem@stripped>
 / /|_/ / // /\ \/ /_/ / /__   MySQL France, Lead Software Engineer
/_/  /_/\_, /___/\___\_\___/   Bordeaux, France
       <___/   www.mysql.com