Bug #20748: Configuration files should not be read more than once

A user could not override system-wide settings in their ~/.my.cnf,
because the DEFAULT_SYSCONFDIR was being searched last.  Also, in
some configurations (especially when the --sysconfdir compile-time
option is set to /etc or /etc/mysql), the system-wide my.cnf file
was read multiple times, causing confusion and potential problems.

Rearrange default directories to conform to the manual and logic.
Move --sysconfdir=<path> (DEFAULT_SYSCONFDIR) from the last default
directory to the middle of the list.  $HOME/.my.cnf should be last,
so the user is able to override the system-wide settings.

Change init_default_directories() to remove duplicates from the
list.


include/my_sys.h:
  Add array_append_string_unique(), from mf_arr_appstr.c
libmysql/Makefile.shared:
  Add new mf_arr_appstr.lo object
mysys/CMakeLists.txt:
  Add new mf_arr_appstr.c source.
mysys/Makefile.am:
  Add new mf_arr_appstr.c source.
mysys/default.c:
  Change order in which defaults files are added to default_directories,
  in order to conform to the manual (and to common sense).  This fixes
  a particularly bad problem on Unix, where ~/.my.cnf was read before
  /usr/local/etc/my.cnf.
  
  Also, don't add duplicate entries; move the existing entry to the
  end of the list instead.
  
  
  Here is a comparison of the order of defaults files, BEFORE and AFTER
  this patch.
  
  On Windows:
  
  BEFORE:  C:\, GetWindowsDirectory(), GetSystemWindowsDirectory(),
           $MYSQL_HOME, defaults-extra-file, INSTALLDIR
  
  AFTER:  GetSystemWindowsDirectory(), GetWindowsDirectory(), C:\,
          INSTALLDIR, $MYSQL_HOME, defaults-extra-file
  
  GetSystemWindowsDirectory() is moved before GetWindowsDirectory() because
  the former is shared by all Terminal Services users, while the latter is
  private for each user.
  
  
  On Netware (no change):
  
  BEFORE:  sys:/etc/, $MYSQL_HOME, defaults-extra-file
  
  AFTER:  sys:/etc, $MYSQL_HOME, defaults-extra-file
  
  
  On OS/2:
  
  BEFORE:  $ETC, /etc, $MYSQL_HOME, defaults-extra-file
  
  AFTER:  /etc, $ETC, $MYSQL_HOME, defaults-extra-file
  
  
  On everything else (general Unix):
  
  BEFORE:  /etc, $MYSQL_HOME, defaults-extra-file, ~/, --sysconfdir
  
  AFTER:  /etc/, --sysconfdir, $MYSQL_HOME, defaults-extra-file, ~/
  
  The BEFORE code added --sysconfdir on all systems, but only the
  Unix build system actually defined a value for it.
mysys/mf_arr_appstr.c:
  BitKeeper file /home/tsmith/m/bk/build/50-b20748/mysys/mf_arr_appstr.c

1 files changed, 61 insertions, 0 deletions

diff --git a/mysys/mf_arr_appstr.c b/mysys/mf_arr_appstr.c
new file mode 100644
index 00000000000..1edbea9df4a
--- /dev/null
+++ b/mysys/mf_arr_appstr.c
@@ -0,0 +1,61 @@
+/* Copyright (C) 2007 MySQL AB
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; version 2 of the License.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */
+
+#include "mysys_priv.h"
+#include <m_string.h>                           /* strcmp() */
+
+
+/**
+  Append str to array, or move to the end if it already exists
+
+  @param str    String to be appended
+  @param array  The array, terminated by a NULL element, all unused elements
+                pre-initialized to NULL
+  @param size   Size of the array; array must be terminated by a NULL
+                pointer, so can hold size - 1 elements
+
+  @retval FALSE  Success
+  @retval TRUE   Failure, array is full
+*/
+
+my_bool array_append_string_unique(const char *str,
+                                   const char **array, size_t size)
+{
+  const char **p;
+  /* end points at the terminating NULL element */
+  const char **end= array + size - 1;
+  DBUG_ASSERT(*end == NULL);
+
+  for (p= array; *p; ++p)
+  {
+    if (strcmp(*p, str) == 0)
+      break;
+  }
+  if (p >= end)
+    return TRUE;                               /* Array is full */
+
+  DBUG_ASSERT(*p == NULL || strcmp(*p, str) == 0);
+
+  while (*(p + 1))
+  {
+    *p= *(p + 1);
+    ++p;
+  }
+
+  DBUG_ASSERT(p < end);
+  *p= str;
+
+  return FALSE;                                 /* Success */
+}