for further mucking with data.  This can be of use in ill situations
where not all the required massaging can be done on data with SQL
by means of stored procedures, but overlays are called too early
and cannot be used to make data non LDAP compliant.
- only support for bidirectional DN mucking is provided right now
- support for other values mucking is planned
- write is not completely tested yet
- the API could change quite often; don't rely too much on it

other cleanup has been added.

- There might be special cases that require the unique key to be a string
  (just ran into one); since this is not a generally useful change, it's
  hidden behind #defines.
- Added essential support for telephoneNumber match; the same infrastructure
  might be useful for other specialized matches (also regular matches should
  use it to handle multiple spaces and so!).
- Fixed dynamic backend initialization.
- Cleaned up search base DN normalization (works also if no uppercase function
  is available, using case exact matches).

make file names more slapd-ish; add attribute inheritance to search attributes; precompile uppercased search

don't search if the filter is invalid; search also if an attribute is undefined for that objectclass, the filter may succeed anyway

use syntax and matching rules knowledge when preparing SQL filters (to reduce pseudo-normalization efforts and search candidate number)

improve limits handling and consistency; return "Admin limit exceeded" instead of "Unwilling to perform"

fix extendedMatch and approx hfilter andling; get rid of subtree_cond (argh, need to trim it from config and docs ...)

  to back-bdb, back-ldbm and back-sql (the latter with limitations);
- added handling of ":dn" attributes to extended rfc2254 filters
  and to matched value filter
- altered the behavior of get_mra() when a matching rule is given:
  now it checks whether it is compatible with the attribute syntax
  and, in case it is, the given mr is used.  In case of no type,
  the check is delayed when filtering

Now related ITSes need be audited and possibly closed.

Enhancements:
  - re-styled code for better readability
  - upgraded backend API to reflect recent changes
  - LDAP schema is checked when loading SQL/LDAP mapping
  - AttributeDescription/ObjectClass pointers used for more efficient
    mapping lookup
  - bervals used where string length is required often
  - atomized write operations by committing at the end of each operation
    and defaulting connection closure to rollback
  - added LDAP access control to write operations
  - fully implemented modrdn (with rdn attrs change, deleteoldrdn,
    access check, parent/children check and more)
  - added parent access control, children control to delete operation
  - added structuralObjectClass operational attribute check and
    value return on search
  - added hasSubordinate operational attribute on demand
  - search limits are appropriately enforced
  - function backsql_strcat() has been made more efficient
  - concat function has been made configurable by means of a pattern
  - added config switches:
      - fail_if_no_mapping	write operations fail if there is no mapping
      - has_ldapinfo_dn_ru	overrides autodetect
      - concat_pattern		a string containing two '?' is used
				(note that "?||?" should be more portable
				than builtin function "CONCAT(?,?)")
      - strcast_func		cast of string constants in "SELECT DISTINCT					statements (needed by PostgreSQL)
      - upper_needs_cast	cast the argument of upper when required
				(basically when building dn substring queries)

Todo:
  - add security checks for SQL statements that can be injected (?)
  - re-test with previously supported RDBMs
  - replace dn_ru and so with normalized dn (no need for upper() and so
    in dn match)
  - implement a backsql_normalize() function to replace the upper()
    conversion routines
  - note that subtree deletion, subtree renaming and so could be easily
    implemented (rollback and consistency checks are available :)
  - implement "lastmod" and other operational stuff (ldap_entries table ?)

- now all write operations appear to work correctly with PostgeSQL 7.0
- all write operations have been made transactional (atomic writes to
  entries are committed separately only in case of complete^1 success
  while all other operations are rolled-back by default)
- more cleanup and handling of exceptional conditions

TODO:
- deen to check with different databases and more up to date versions
  of both unixODBC and PostgreSQL.

^1: attribute add/modify/delete operations silently succeed if the
    appropriate add/delete proc does not exist for each attribute;
    this may be correct to hide undesired/unimplemented correspondence
    between LDAP and SQL databases; however, a more appropriate
    LDAP behavior would be a failure with LDAP_UNAVAILABLE if a
    single write operation cannot be executed for such reason

- re-style according to the style giudelines for better readability
- updated to recent frontend/backend API changes
- fixed a few quirks about normalization
- "optimized" a few memory allocation/string handling functions
- fixed a few quirks about add/modify (still have to look ad modrdn)

todo:
- there is still something broken (at least with PostgreSQL and IBM db2,
  the two RDBMS O have at hand) when adding
- move everything to struct bervals and try to save a few strlen
- try some LDAP/SQL syntax relation to use appropriate value bind if possible
- ...