build: Make TPM2 support conditionaltpm-work

* configure.ac (HAVE_LIBTSS): New acdefine and am_conditional.
* agent/Makefile.am: (gpg_agent_SOURCES): Move tpm files to ...
(gpg_agent_SOURCES) [HAVE_LIBTSS]: ... here.
* agent/agent.h (divert_tpm2_pksign, divert_tpm2_pkdecrypt)
(divert_tpm2_writekey) [!HAVE_LIBTSS]: Add stub functions.

--
This adds a configure stanza to check for the necessary libtss to
support TPM functions.  If found, the library functions will be
dynamically loaded, meaning that a system built with TPM2 support will
still execute correctly (obviously minus TPM2 support) if installed
without libtss being present.

Signed-off-by: James Bottomley <[email protected]>

1 files changed, 11 insertions, 0 deletions

diff --git a/configure.ac b/configure.ac
index 9dd9230c0..fe1078a00 100644
--- a/configure.ac
+++ b/configure.ac
@@ -100,6 +100,7 @@ have_gnutls=no
 have_sqlite=no
 have_npth=no
 have_libusb=no
+have_libtss=no
 have_system_resolver=no
 gnupg_have_ldap="n/a"
 
@@ -1590,6 +1591,15 @@ AC_SUBST(NETLIBS)
 AC_SUBST(W32SOCKLIBS)
 
 #
+# TPM libtss library .. don't compile TPM support if we don't have it
+#
+AC_CHECK_LIB(tss, TSS_Create, [have_libtss=yes])
+if test "$have_libtss" = yes; then
+   AC_DEFINE(HAVE_LIBTSS, 1, [Defined if we have TPM2 support library])
+fi
+AM_CONDITIONAL(HAVE_LIBTSS, test "$have_libtss" = yes)
+
+#
 # Setup gcc specific options
 #
 USE_C99_CFLAGS=
@@ -2072,6 +2082,7 @@ echo "
         TLS support:         $use_tls_library
         TOFU support:        $use_tofu
         Tor support:         $show_tor_support
+        TPM support:         $have_libtss
 "
 if test x"$use_regex" != xyes ; then
 echo "