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, 26 insertions, 0 deletions

diff --git a/agent/agent.h b/agent/agent.h
index 7a77eb629..67e82b763 100644
--- a/agent/agent.h
+++ b/agent/agent.h
@@ -535,6 +535,7 @@ gpg_error_t agent_marktrusted (ctrl_t ctrl, const char *name,
 void agent_reload_trustlist (void);
 
 /*-- divert-tpm2.c --*/
+#ifdef HAVE_LIBTSS
 int divert_tpm2_pksign (ctrl_t ctrl, const char *desc_text,
                         const unsigned char *digest, size_t digestlen, int algo,
                         const unsigned char *shadow_info, unsigned char **r_sig,
@@ -545,6 +546,31 @@ int divert_tpm2_pkdecrypt (ctrl_t ctrl, const char *desc_text,
                            char **r_buf, size_t *r_len, int *r_padding);
 int divert_tpm2_writekey (ctrl_t ctrl, const unsigned char *grip,
                           gcry_sexp_t s_skey);
+#else
+static inline int divert_tpm2_pksign (ctrl_t ctrl, const char *desc_text,
+				      const unsigned char *digest,
+				      size_t digestlen, int algo,
+				      const unsigned char *shadow_info,
+				      unsigned char **r_sig,
+				      size_t *r_siglen)
+{
+  return -EINVAL;
+}
+static inline int divert_tpm2_pkdecrypt (ctrl_t ctrl, const char *desc_text,
+					 const unsigned char *cipher,
+					 const unsigned char *shadow_info,
+					 char **r_buf, size_t *r_len,
+					 int *r_padding)
+{
+  return -EINVAL;
+}
+static inline int divert_tpm2_writekey (ctrl_t ctrl, const unsigned char *grip,
+					gcry_sexp_t s_skey)
+{
+  return -EINVAL;
+}
+#endif
+
 
 
 /*-- divert-scd.c --*/