sbus: Add meta data structures and code generator

These metadata structures hold the information about all the
details of a DBus interface. They are typically generated from
the canonical XML form of the DBus interface, although they
may also be hand crafted.

Add some handy functions for looking up methods, props, signals,
in the metadata of an interface. Currently lookups are just done
by looking through an array. If performance becomes an issue (ie:
very large interfaces) it would be really easy to sort things
and use bsearch().

Later commits will include some definitions using this metadata
and related functions.

DBus interfaces are defined here:

http://dbus.freedesktop.org/doc/dbus-specification.html#introspection-format

The introspection data format has become the standard way to represent a
DBus interface. For many examples see /usr/share/dbus-1/interfaces/ on a
typical linux machine.

A word about annotations. These are extra flags or values that can be
assigned to anything. So far, the codegen supports this annotation:

org.freedesktop.DBus.GLib.CSymbol
 - An annotation specified in the specification that tells us what C symbol
   to generate for a given interface or method. By default the codegen will
   build up a symbol name from the DBus name.

It is possible to confuse the code generator into producing invalid
C code (with strange method names, for example), but the C compiler
catches such silliness right away.

Add tests testing basic features of the codegen and poking through
the metadata it creates. Also test the metadata lookup functions.

Generated code is checked in for easy discovery.

An example of the XML interface definitions can be found at:

  src/tests/sbus_codegen_tests.xml

And an example of the generated header can be found here:

  src/tests/sbus_codegen_tests_generated.h

Reviewed-by: Jakub Hrozek <jhrozek@redhat.com>
Reviewed-by: Sumit Bose <sbose@redhat.com>
Reviewed-by: Lukáš Slebodník <lslebodn@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>

(cherry picked from commit b699c4d7f85a5404be1d1ee9450331aea869b886)

Conflicts:
    Makefile.am

1 files changed, 46 insertions, 1 deletions

diff --git a/Makefile.am b/Makefile.am
index 8d92326de..de916d3ac 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -133,7 +133,8 @@ if HAVE_CHECK
         debug-tests \
         ipa_hbac-tests \
         sss_idmap-tests \
-        responder_socket_access-tests
+        responder_socket_access-tests \
+        sbus_codegen_tests
 
 if BUILD_SSH
     non_interactive_check_based_tests += sysdb_ssh-tests
@@ -437,6 +438,7 @@ dist_noinst_HEADERS = \
     src/responder/ssh/sshsrv_private.h \
     src/sbus/sbus_client.h \
     src/sbus/sssd_dbus.h \
+    src/sbus/sssd_dbus_meta.h \
     src/sbus/sssd_dbus_private.h \
     src/db/sysdb.h \
     src/db/sysdb_sudo.h \
@@ -561,6 +563,7 @@ libsss_util_la_SOURCES = \
     src/sbus/sbus_client.c \
     src/sbus/sssd_dbus_common.c \
     src/sbus/sssd_dbus_connection.c \
+    src/sbus/sssd_dbus_meta.c \
     src/sbus/sssd_dbus_server.c \
     src/util/util.c \
     src/util/memory.c \
@@ -637,6 +640,37 @@ include_HEADERS = \
     src/sss_client/idmap/sss_nss_idmap.h
 
 ####################
+# Sbus Codegen     #
+####################
+
+# Yes, the goal here is that the generated files end up in $(srcdir)
+# not $(builddir). Always use $(srcdir) here.
+CODEGEN_XML = \
+    $(srcdir)/src/tests/sbus_codegen_tests.xml
+
+SBUS_CODEGEN = src/sbus/sbus_codegen
+
+EXTRA_DIST += \
+    $(SBUS_CODEGEN) \
+    $(CODEGEN_XML)
+
+SUFFIXES = .xml _generated.h _generated.c
+
+.xml_generated.h:
+	$(srcdir)/$(SBUS_CODEGEN) --mode=header --output=$@ $<
+.xml_generated.c:
+	$(srcdir)/$(SBUS_CODEGEN) --mode=source --output=$@ $<
+
+# Regenerate when codegen changes
+CODEGEN_CODE = \
+    $(CODEGEN_XML:.xml=_generated.c) \
+    $(CODEGEN_XML:.xml=_generated.h)
+
+$(CODEGEN_CODE): $(SBUS_CODEGEN)
+
+BUILT_SOURCES = $(CODEGEN_CODE)
+
+####################
 # Program Binaries #
 ####################
 sssd_SOURCES = \
@@ -1257,6 +1291,17 @@ krb5_child_test_LDADD = \
     $(SSSD_INTERNAL_LTLIBS) \
     libsss_test_common.la
 
+sbus_codegen_tests_SOURCES = \
+   src/tests/sbus_codegen_tests.c \
+   src/tests/sbus_codegen_tests_generated.c \
+   src/tests/sbus_codegen_tests_generated.h
+sbus_codegen_tests_CFLAGS = \
+    $(CHECK_CFLAGS)
+sbus_codegen_tests_LDADD = \
+    $(SSSD_INTERNAL_LTLIBS) \
+    $(SSSD_LIBS) \
+    $(CHECK_LIBS)
+
 if HAVE_CMOCKA
 
 TEST_MOCK_RESP_OBJ = \