pkcs11: leverage sc_wait_for_event to avoid unneccesary queries to card

card_detect_all() is now used as global entry point even to reader
specific card detection (card_detect() is removed). This enforces
a constant update of reader_states so that no events are silently
dropped. This removes the need for having a timer in C_GetSlotInfo() for
avoiding too many queries. If the reader implementation (i.e.
reader-*.c) does not implement wait_for_event, then all slots will be
queried on request just like it used to be.

fixes OpenSC#3107

src/pkcs11/pkcs11-global.c

@@ -53,6 +53,7 @@ sc_context_t *context = NULL;
 struct sc_pkcs11_config sc_pkcs11_conf;
 list_t sessions;
 list_t virtual_slots;
+void *reader_states = NULL;
 #if !defined(_WIN32)
 pid_t initialized_pid = (pid_t)-1;
 #endif
@@ -432,6 +433,9 @@ CK_RV C_Finalize(CK_VOID_PTR pReserved)
 	}
 	list_destroy(&virtual_slots);
 
+	sc_wait_for_event(context, 0, NULL, NULL, 0, &reader_states);
+	reader_states = NULL;
+
 	sc_release_context(context);
 	context = NULL;
 
@@ -585,37 +589,9 @@ CK_RV C_GetSlotList(CK_BBOOL       tokenPresent,  /* only slots with token prese
 	return rv;
 }
 
-static sc_timestamp_t get_current_time(void)
-{
-#if HAVE_GETTIMEOFDAY
-	struct timeval tv;
-	struct timezone tz;
-	sc_timestamp_t curr;
-
-	if (gettimeofday(&tv, &tz) != 0)
-		return 0;
-
-	curr = tv.tv_sec;
-	curr *= 1000;
-	curr += tv.tv_usec / 1000;
-#else
-	struct _timeb time_buf;
-	sc_timestamp_t curr;
-
-	_ftime(&time_buf);
-
-	curr = time_buf.time;
-	curr *= 1000;
-	curr += time_buf.millitm;
-#endif
-
-	return curr;
-}
-
 CK_RV C_GetSlotInfo(CK_SLOT_ID slotID, CK_SLOT_INFO_PTR pInfo)
 {
 	struct sc_pkcs11_slot *slot = NULL;
-	sc_timestamp_t now;
 	const char *name;
 	CK_RV rv;
 
@@ -644,18 +620,11 @@ CK_RV C_GetSlotInfo(CK_SLOT_ID slotID, CK_SLOT_INFO_PTR pInfo)
 		if (slot->reader == NULL) {
 			rv = CKR_TOKEN_NOT_PRESENT;
 		} else {
-			now = get_current_time();
-			if (now >= slot->slot_state_expires || now == 0) {
-				/* Update slot status */
-				rv = card_detect(slot->reader);
-				sc_log(context, "C_GetSlotInfo() card detect rv 0x%lX", rv);
-
-				if (rv == CKR_TOKEN_NOT_RECOGNIZED || rv == CKR_OK)
-					slot->slot_info.flags |= CKF_TOKEN_PRESENT;
-
-				/* Don't ask again within the next second */
-				slot->slot_state_expires = now + 1000;
-			}
+			/* Update slot status */
+			card_detect_all();
+
+			if (slot->p11card && slot->p11card->card)
+				slot->slot_info.flags |= CKF_TOKEN_PRESENT;
 		}
 	}
 

src/pkcs11/sc-pkcs11.h

@@ -220,7 +220,6 @@ struct sc_pkcs11_slot {
 	void *fw_data;			/* Framework specific data */  /* TODO: get know how it used */
 	list_t objects;			/* Objects in this slot */
 	unsigned int nsessions;		/* Number of sessions using this slot */
-	sc_timestamp_t slot_state_expires;
 
 	int fw_data_idx;		/* Index of framework data */
 	struct sc_app_info *app_info;	/* Application associated to slot */
@@ -393,6 +392,7 @@ extern struct sc_pkcs11_config sc_pkcs11_conf;
 extern list_t sessions;
 extern list_t virtual_slots;
 extern list_t cards;
+extern void *reader_states;
 
 /* Framework definitions */
 extern struct sc_pkcs11_framework_ops framework_pkcs15;
@@ -412,7 +412,6 @@ CK_RV card_removed(sc_reader_t *reader);
 CK_RV card_detect_all(void);
 CK_RV create_slot(sc_reader_t *reader);
 void init_slot_info(CK_SLOT_INFO_PTR pInfo, sc_reader_t *reader);
-CK_RV card_detect(sc_reader_t *reader);
 CK_RV slot_get_slot(CK_SLOT_ID id, struct sc_pkcs11_slot **);
 CK_RV slot_get_token(CK_SLOT_ID id, struct sc_pkcs11_slot **);
 CK_RV slot_token_removed(CK_SLOT_ID id);

src/pkcs11/slot.c

@@ -389,8 +389,18 @@ CK_RV
 card_detect_all(void)
 {
 	unsigned int i, j;
+	const unsigned int event_mask = SC_EVENT_CARD_EVENTS|SC_EVENT_READER_EVENTS;
+	unsigned int events = 0;
+	sc_reader_t *event_reader = NULL;
+	int r;
 
 	sc_log(context, "Detect all cards");
+	r = sc_wait_for_event(context, event_mask, &event_reader, &events, 1, &reader_states);
+	if ((SC_SUCCESS == r && events == 0) || SC_ERROR_EVENT_TIMEOUT == r) {
+		sc_log(context, "No state change since last call, skipping card detection");
+		return CKR_OK;
+	}
+
 	/* Detect cards in all initialized readers */
 	for (i=0; i< sc_ctx_get_reader_count(context); i++) {
 		sc_reader_t *reader = sc_ctx_get_reader(context, i);
@@ -474,15 +484,7 @@ CK_RV slot_get_token(CK_SLOT_ID id, struct sc_pkcs11_slot ** slot)
 	if (rv != CKR_OK)
 		return rv;
 
-	if (!((*slot)->slot_info.flags & CKF_TOKEN_PRESENT)) {
-		if ((*slot)->reader == NULL)
-			return CKR_TOKEN_NOT_PRESENT;
-		sc_log(context, "Slot(id=0x%lX): get token: now detect card", id);
-		rv = card_detect((*slot)->reader);
-		if (rv != CKR_OK)
-			return rv;
-	}
-
+	card_detect_all();
 	if (!((*slot)->slot_info.flags & CKF_TOKEN_PRESENT)) {
 		sc_log(context, "card detected, but slot not presenting token");
 		return CKR_TOKEN_NOT_PRESENT;