Pluggable libheimbase interface for DBs and misc libheimbase enhancements

[Code reviewed by Love Hörnquist Åstrand <lha@kth.se>]

    Added heim_db_*() entry points for dealing with databases, and
    make krb5_aname_to_localname() use it.

    The following enhancements to libheimbase are included:

     - Add heim_data_t and heim_string_t "reference" variants to
       avoid memory copies of potentially large data/strings.

       See heim_data_ref_create() and heim_string_ref_create().

     - Added enhancements to heim_array_t to allow their use for
       queues and stacks, and to improve performance.  See
       heim_array_insert_value().

     - Added XPath-like accessors for heim_object_t.  See
       heim_path_get(), heim_path_copy(), heim_path_create(), and
       heim_path_delete().  These are used extensively in the DB
       framework's generic composition of ACID support and in the
       test_base program

     - Made libheimbase more consistent with Core Foundation naming
       conventions.  See heim_{dict, array}_{get, copy}_value() and
       heim_path_{get, copy}().

     - Added functionality to and fixed bugs in base/json.c:
        - heim_serialize();
        - depth limit for JSON parsing (for DoS protection);
        - pretty-printing;
        - JSON compliance (see below);
        - flag options for parsing and serializing; these are needed
          because of impedance mismatches between heim_object_t and
          JSON (e.g., heim_dict_t allows non-string keys, but JSON
          does not; heimbase supports binary data, while JSON does
          not).

     - Added heim_error_enomem().

     - Enhanced the test_base program to test new functionality and
       to use heim_path*() to better test JSON encoding.  This
       includes some fuzz testing of JSON parsing, and running the
       test under valgrind.

     - Started to add doxygen documentation for libheimbase (but doc
       build for libheimbase is still incomplete).

    Note that there's still some incomplete JSON support:

     - JSON string quoting is not fully implemented;

     - libheimbase lacks support for real numbers, while JSON has
       it -- otherwise libheimbase is a superset of JSON,
       specifically in that any heim_object_t can be a key for an
       associative array.

    The following DB backends are supported natively:

     - "sorted-text", a binary search of sorted (in C locale), flat
       text files;

     - "json", a backend that stores DB contents serialized as JSON
       (this is intended for configuration-like contents).

    The DB framework supports:

     - multiple key/value tables per-DB
     - ACID transactions

    The DB framework also natively implements ACID transactions for
    any DB backends that a) do not provide transactions natively, b)
    do provide lock/unlock/sync methods (even on Windows).  This
    includes autocommit of DB updates outside transactions.

    Future DB enhancements may include:

     - add backends for various DB types (BDB, CDB, MDB, ...);

     - make libhdb use heim_db_t;

     - add a command-line tool for interfacing to databases via
       libheimbase (e.g., to get/set/delete values, create/copy/
       backup DBs, inspect history, check integrity);

     - framework-level transaction logging (with redo and undo
       logging), for generic incremental replication;

     - framework-level DB integrity checking.

       We could store a MAC of the XOR of a hash function applied to
       {key, value} for every entry in the DB, then use this to check
       DB integrity incrementally during incremental replication, as
       well as for the whole DB.

doc/Makefile.am

@@ -24,6 +24,11 @@ hdb.dxy: hdb.din Makefile
 	chmod +x hdb.dxy.tmp
 	mv hdb.dxy.tmp hdb.dxy
 
+base.dxy: base.din Makefile
+	$(dxy_subst) < $(srcdir)/base.din > base.dxy.tmp
+	chmod +x base.dxy.tmp
+	mv base.dxy.tmp base.dxy
+
 hx509.dxy: hx509.din Makefile
 	$(dxy_subst) < $(srcdir)/hx509.din > hx509.dxy.tmp
 	chmod +x hx509.dxy.tmp
@@ -57,13 +62,13 @@ vars.texi: vars.tin Makefile
 	chmod +x vars.texi.tmp
 	mv vars.texi.tmp vars.texi
 
-PROJECTS = hdb hx509 gssapi krb5 ntlm wind 
+PROJECTS = base hdb hx509 gssapi krb5 ntlm wind 
 
 if !HAVE_OPENSSL
 PROJECTS += hcrypto
 endif
 
-doxyout doxygen: hdb.dxy hx509.dxy hcrypto.dxy gssapi.dxy krb5.dxy ntlm.dxy wind.dxy
+doxyout doxygen: base.dxy hdb.dxy hx509.dxy hcrypto.dxy gssapi.dxy krb5.dxy ntlm.dxy wind.dxy
 	@find $(srcdir)/doxyout -type d ! -perm -200 -exec chmod u+w {} ';' ; \
 	rm -rf $(srcdir)/doxyout ; \
 	mkdir $(srcdir)/doxyout ; \
@@ -127,6 +132,7 @@ EXTRA_DIST = \
 	hcrypto.din \
 	header.html \
 	heimdal.css \
+	base.din \
 	hx509.din \
 	krb5.din \
 	ntlm.din \
@@ -139,6 +145,7 @@ EXTRA_DIST = \
 
 CLEANFILES = \
 	hcrypto.dxy* \
+	base.dxy* \
 	hx509.dxy* \
 	hdb.dxy* \
 	gssapi.dxy* \

doc/base.din

@@ -0,0 +1,15 @@
+# Doxyfile 1.5.3
+
+PROJECT_NAME           = Heimdal x509 library
+PROJECT_NUMBER         = @PACKAGE_VERSION@
+OUTPUT_DIRECTORY       = @srcdir@/doxyout/heimbase
+INPUT                  = @srcdir@/../base
+
+WARN_IF_UNDOCUMENTED   = YES
+
+PERL_PATH              = /usr/bin/perl
+
+HTML_HEADER = "@srcdir@/header.html"
+HTML_FOOTER = "@srcdir@/footer.html"
+
+@INCLUDE = "@srcdir@/doxytmpl.dxy"

doc/base.hhp

@@ -0,0 +1,8 @@
+[OPTIONS]
+Compatibility=1.1 or later
+Compiled file=heimbase.chm
+Contents file=toc.hhc
+Default topic=index.html
+Display compile progress=No
+Language=0x409 English (United States)
+Title=Heimdal Base