tpm-backend: Made few interface methods optional

This allows backend implementations left optional interface methods.
For mandatory methods assertion checks added.

Took the opportunity to remove unused methods:
 - tpm_backend_get_desc()
 - TPMDriverOps->handle_startup_error

Signed-off-by: Amarnath Valluri <amarnath.valluri@intel.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Stefan Berger<stefanb@linux.vnet.ibm.com>
Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>

1 files changed, 24 insertions, 15 deletions

diff --git a/backends/tpm.c b/backends/tpm.c
index cf5abf1582..8911597fab 100644
--- a/backends/tpm.c
+++ b/backends/tpm.c
@@ -44,13 +44,6 @@ enum TpmType tpm_backend_get_type(TPMBackend *s)
     return k->ops->type;
 }
 
-const char *tpm_backend_get_desc(TPMBackend *s)
-{
-    TPMBackendClass *k = TPM_BACKEND_GET_CLASS(s);
-
-    return k->ops->desc();
-}
-
 int tpm_backend_init(TPMBackend *s, TPMState *state,
                      TPMRecvDataCB *datacb)
 {
@@ -58,12 +51,14 @@ int tpm_backend_init(TPMBackend *s, TPMState *state,
 
     s->tpm_state = state;
     s->recv_data_callback = datacb;
+    s->had_startup_error = false;
 
-    return k->ops->init(s);
+    return k->ops->init ? k->ops->init(s) : 0;
 }
 
 int tpm_backend_startup_tpm(TPMBackend *s)
 {
+    int res = 0;
     TPMBackendClass *k = TPM_BACKEND_GET_CLASS(s);
 
     /* terminate a running TPM */
@@ -73,20 +68,24 @@ int tpm_backend_startup_tpm(TPMBackend *s)
                                        NULL);
     g_thread_pool_push(s->thread_pool, (gpointer)TPM_BACKEND_CMD_INIT, NULL);
 
-    return k->ops->startup_tpm(s);
+    res = k->ops->startup_tpm ? k->ops->startup_tpm(s) : 0;
+
+    s->had_startup_error = (res != 0);
+
+    return res;
 }
 
 bool tpm_backend_had_startup_error(TPMBackend *s)
 {
-    TPMBackendClass *k = TPM_BACKEND_GET_CLASS(s);
-
-    return k->ops->had_startup_error(s);
+    return s->had_startup_error;
 }
 
 size_t tpm_backend_realloc_buffer(TPMBackend *s, TPMSizedBuffer *sb)
 {
     TPMBackendClass *k = TPM_BACKEND_GET_CLASS(s);
 
+    assert(k->ops->realloc_buffer);
+
     return k->ops->realloc_buffer(sb);
 }
 
@@ -100,15 +99,21 @@ void tpm_backend_reset(TPMBackend *s)
 {
     TPMBackendClass *k = TPM_BACKEND_GET_CLASS(s);
 
-    k->ops->reset(s);
+    if (k->ops->reset) {
+        k->ops->reset(s);
+    }
 
     tpm_backend_thread_end(s);
+
+    s->had_startup_error = false;
 }
 
 void tpm_backend_cancel_cmd(TPMBackend *s)
 {
     TPMBackendClass *k = TPM_BACKEND_GET_CLASS(s);
 
+    assert(k->ops->cancel_cmd);
+
     k->ops->cancel_cmd(s);
 }
 
@@ -116,20 +121,24 @@ bool tpm_backend_get_tpm_established_flag(TPMBackend *s)
 {
     TPMBackendClass *k = TPM_BACKEND_GET_CLASS(s);
 
-    return k->ops->get_tpm_established_flag(s);
+    return k->ops->get_tpm_established_flag ?
+           k->ops->get_tpm_established_flag(s) : false;
 }
 
 int tpm_backend_reset_tpm_established_flag(TPMBackend *s, uint8_t locty)
 {
     TPMBackendClass *k = TPM_BACKEND_GET_CLASS(s);
 
-    return k->ops->reset_tpm_established_flag(s, locty);
+    return k->ops->reset_tpm_established_flag ?
+           k->ops->reset_tpm_established_flag(s, locty) : 0;
 }
 
 TPMVersion tpm_backend_get_tpm_version(TPMBackend *s)
 {
     TPMBackendClass *k = TPM_BACKEND_GET_CLASS(s);
 
+    assert(k->ops->get_tpm_version);
+
     return k->ops->get_tpm_version(s);
 }