[PATCH BlueZ] shared/crypto: Transform bt_cryto in a singleton

[Luiz Augusto von Dentz <luiz.dentz@gmail.com>]

From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

This makes bt_crypto always return the same instance thus avoiding the
problem of having multiple PF sockets opened which may hit the file
descriptor limit.
---
 src/shared/crypto.c | 37 ++++++++++++++++++++++---------------
 1 file changed, 22 insertions(+), 15 deletions(-)

diff --git a/src/shared/crypto.c b/src/shared/crypto.c
index 6d14903e4..d5efa416d 100644
--- a/src/shared/crypto.c
+++ b/src/shared/crypto.c
@@ -126,34 +126,40 @@ static int cmac_aes_setup(void)
 	return fd;
 }
 
+static struct bt_crypto *singleton;
+
 struct bt_crypto *bt_crypto_new(void)
 {
-	struct bt_crypto *crypto;
+	if (singleton)
+		return bt_crypto_ref(singleton);
 
-	crypto = new0(struct bt_crypto, 1);
+	singleton = new0(struct bt_crypto, 1);
 
-	crypto->ecb_aes = ecb_aes_setup();
-	if (crypto->ecb_aes < 0) {
-		free(crypto);
+	singleton->ecb_aes = ecb_aes_setup();
+	if (singleton->ecb_aes < 0) {
+		free(singleton);
+		singleton = NULL;
 		return NULL;
 	}
 
-	crypto->urandom = urandom_setup();
-	if (crypto->urandom < 0) {
-		close(crypto->ecb_aes);
-		free(crypto);
+	singleton->urandom = urandom_setup();
+	if (singleton->urandom < 0) {
+		close(singleton->ecb_aes);
+		free(singleton);
+		singleton = NULL;
 		return NULL;
 	}
 
-	crypto->cmac_aes = cmac_aes_setup();
-	if (crypto->cmac_aes < 0) {
-		close(crypto->urandom);
-		close(crypto->ecb_aes);
-		free(crypto);
+	singleton->cmac_aes = cmac_aes_setup();
+	if (singleton->cmac_aes < 0) {
+		close(singleton->urandom);
+		close(singleton->ecb_aes);
+		free(singleton);
+		singleton = NULL;
 		return NULL;
 	}
 
-	return bt_crypto_ref(crypto);
+	return bt_crypto_ref(singleton);
 }
 
 struct bt_crypto *bt_crypto_ref(struct bt_crypto *crypto)
@@ -179,6 +185,7 @@ void bt_crypto_unref(struct bt_crypto *crypto)
 	close(crypto->cmac_aes);
 
 	free(crypto);
+	singleton = NULL;
 }
 
 bool bt_crypto_random_bytes(struct bt_crypto *crypto,
-- 
2.26.2