virCryptoHashBuf: return the length of the hash in bytes

virCryptoHashString also needs to know the size of the returned hash.
Return it if the hash conversion succeeded so the caller does not need
to access the hashinfo array.

This should make virCryptoHashString build without gnutls.
Also fixes the missing return value for the virCryptoHashBuf stub.
Signed-off-by: NJán Tomko <jtomko@redhat.com>
Suggested-by: NStefan Berger <stefanb@linux.vnet.ibm.com>

src/util/vircrypto.c

@@ -54,7 +54,7 @@ struct virHashInfo {
 
 verify(ARRAY_CARDINALITY(hashinfo) == VIR_CRYPTO_HASH_LAST);
 
-int
+ssize_t
 virCryptoHashBuf(virCryptoHash hash,
                  const char *input,
                  unsigned char *output)
@@ -74,16 +74,17 @@ virCryptoHashBuf(virCryptoHash hash,
         return -1;
     }
 
-    return 0;
+    return hashinfo[hash].hashlen;
 }
 #else
-int
+ssize_t
 virCryptoHashBuf(virCryptoHash hash,
                  const char *input ATTRIBUTE_UNUSED,
                  unsigned char *output ATTRIBUTE_UNUSED)
 {
     virReportError(VIR_ERR_INVALID_ARG,
                    _("algorithm=%d is not supported"), hash);
+    return -1;
 }
 #endif
 
@@ -93,18 +94,19 @@ virCryptoHashString(virCryptoHash hash,
                     char **output)
 {
     unsigned char buf[VIR_CRYPTO_LARGEST_DIGEST_SIZE];
+    ssize_t rc;
     size_t hashstrlen;
     size_t i;
 
-    if (virCryptoHashBuf(hash, input, buf) < 0)
+    if ((rc = virCryptoHashBuf(hash, input, buf)) < 0)
         return -1;
 
-    hashstrlen = (hashinfo[hash].hashlen * 2) + 1;
+    hashstrlen = (rc * 2) + 1;
 
     if (VIR_ALLOC_N(*output, hashstrlen) < 0)
         return -1;
 
-    for (i = 0; i < hashinfo[hash].hashlen; i++) {
+    for (i = 0; i < rc; i++) {
         (*output)[i * 2] = hex[(buf[i] >> 4) & 0xf];
         (*output)[(i * 2) + 1] = hex[buf[i] & 0xf];
     }

src/util/vircrypto.h

@@ -41,7 +41,7 @@ typedef enum {
     VIR_CRYPTO_CIPHER_LAST
 } virCryptoCipher;
 
-int
+ssize_t
 virCryptoHashBuf(virCryptoHash hash,
                  const char *input,
                  unsigned char *output)