X-Git-Url: http://git.ozlabs.org/?p=ccan;a=blobdiff_plain;f=ccan%2Fcrypto%2Fshachain%2Fshachain.h;h=d95b97363f7d8e0bb243b6ebba9f35c8db3b5364;hp=ba4ba11cd64c02d1d66a362d35bac98e39a2f0bc;hb=e6abb93d50ba9f1e90163d7db53be70b8ef81a96;hpb=d23fb57c8e276090325162966b094ebf71e73e68

diff --git a/ccan/crypto/shachain/shachain.h b/ccan/crypto/shachain/shachain.h
index ba4ba11c..d95b9736 100644
--- a/ccan/crypto/shachain/shachain.h
+++ b/ccan/crypto/shachain/shachain.h
@@ -6,9 +6,8 @@
 #include <stdbool.h>
 #include <stdint.h>
 
-/* Useful for testing. */
-#ifndef shachain_index_t
-#define shachain_index_t uint64_t
+#ifndef SHACHAIN_BITS
+#define SHACHAIN_BITS (sizeof(uint64_t) * 8)
 #endif
 
 /**
@@ -38,7 +37,7 @@
  *	shachain_from_seed(&seed, index--, hash);
  * }
  */
-void shachain_from_seed(const struct sha256 *seed, shachain_index_t index,
+void shachain_from_seed(const struct sha256 *seed, uint64_t index,
 			struct sha256 *hash);
 
 /**
@@ -51,12 +50,12 @@ void shachain_from_seed(const struct sha256 *seed, shachain_index_t index,
  * added.
  */
 struct shachain {
-	shachain_index_t min_index;
+	uint64_t min_index;
 	unsigned int num_valid;
 	struct {
-		shachain_index_t index;
+		uint64_t index;
 		struct sha256 hash;
-	} known[sizeof(shachain_index_t) * 8 + 1];
+	} known[SHACHAIN_BITS + 1];
 };
 
 /**
@@ -67,20 +66,28 @@ struct shachain {
  */
 void shachain_init(struct shachain *chain);
 
+/**
+ * shachain_next_index - what's the next index I can add to the shachain?
+ * @chain: the chain
+ *
+ * This returns 0xFFFFFFFFFFFFFFFF (for a freshly
+ * initialized chain), or one less than the previously successfully
+ * added value.
+ */
+uint64_t shachain_next_index(const struct shachain *chain);
+
 /**
  * shachain_add_hash - record the hash for the next index.
  * @chain: the chain to add to
  * @index: the index of the hash
  * @hash: the hash value.
  *
- * You can only add index 0xFFFFFFFFFFFFFFFF (for a freshly
- * initialized chain), or one less than the previously successfully
- * added value.
+ * You can only add shachain_next_index(@chain).
  *
  * This can fail (return false without altering @chain) if the hash
  * for this index isn't consistent with previous hashes (ie. wasn't
  * generated from the same seed), though it can't always detect that.
- * If the hash is inconsistent yet undetected, the next addition will
+ * If the hash is inconsistent yet undetected, a future addition will
  * fail.
  *
  * Example:
@@ -94,7 +101,7 @@ void shachain_init(struct shachain *chain);
  * }
  */
 bool shachain_add_hash(struct shachain *chain,
-		       shachain_index_t index, const struct sha256 *hash);
+		       uint64_t index, const struct sha256 *hash);
 
 /**
  * shachain_get_hash - get the hash for a given index.
@@ -125,5 +132,5 @@ bool shachain_add_hash(struct shachain *chain,
  * }
  */
 bool shachain_get_hash(const struct shachain *chain,
-		       shachain_index_t index, struct sha256 *hash);
+		       uint64_t index, struct sha256 *hash);
 #endif /* CCAN_CRYPTO_SHACHAIN_H */