Use __attribute__((fallthrough)) rather than magic GCC comments.

GCC added an implicit-fallthrough warning a while back, where it
would complain if you had a nontrivial "case:" block that didn't end
with break, return, or something like that.  Clang recently added
the same thing.

GCC, however, would let you annotate a fall-through as intended by
any of various magic "/* fall through */" comments.  Clang, however,
only seems to like "__attribute__((fallthrough))".  Fortunately, GCC
accepts that too.

A previous commit in this branch defined a FALLTHROUGH macro to do
the right thing if GNUC is defined; here we replace all of our "fall
through" comments with uses of that macro.

This is an automated commit, made with the following perl one-liner:

  #!/usr/bin/perl -i -p
  s#/\* *falls? ?thr.*?\*/#FALLTHROUGH;#i;

(In order to avoid conflicts, I'm applying this script separately to
each maint branch. This is the 0.4.2 version.)

2 files changed, 18 insertions, 18 deletions

diff --git a/src/lib/crypt_ops/crypto_digest_nss.c b/src/lib/crypt_ops/crypto_digest_nss.c
index bc7a0fab16..afa8f6d5ef 100644
--- a/src/lib/crypt_ops/crypto_digest_nss.c
+++ b/src/lib/crypt_ops/crypto_digest_nss.c
@@ -37,8 +37,8 @@ digest_alg_to_nss_oid(digest_algorithm_t alg)
     case DIGEST_SHA1: return SEC_OID_SHA1;
     case DIGEST_SHA256: return SEC_OID_SHA256;
     case DIGEST_SHA512: return SEC_OID_SHA512;
-    case DIGEST_SHA3_256: /* Fall through */
-    case DIGEST_SHA3_512: /* Fall through */
+    case DIGEST_SHA3_256: FALLTHROUGH;
+    case DIGEST_SHA3_512: FALLTHROUGH;
     default:
       return SEC_OID_UNKNOWN;
   }
@@ -85,12 +85,12 @@ static bool
 library_supports_digest(digest_algorithm_t alg)
 {
   switch (alg) {
-    case DIGEST_SHA1: /* Fall through */
-    case DIGEST_SHA256: /* Fall through */
+    case DIGEST_SHA1: FALLTHROUGH;
+    case DIGEST_SHA256: FALLTHROUGH;
     case DIGEST_SHA512:
       return true;
-    case DIGEST_SHA3_256: /* Fall through */
-    case DIGEST_SHA3_512: /* Fall through */
+    case DIGEST_SHA3_256: FALLTHROUGH;
+    case DIGEST_SHA3_512: FALLTHROUGH;
     default:
       return false;
   }
@@ -197,8 +197,8 @@ crypto_digest_alloc_bytes(digest_algorithm_t alg)
 #define END_OF_FIELD(f) (offsetof(crypto_digest_t, f) + \
                          STRUCT_FIELD_SIZE(crypto_digest_t, f))
   switch (alg) {
-    case DIGEST_SHA1: /* Fall through */
-    case DIGEST_SHA256: /* Fall through */
+    case DIGEST_SHA1: FALLTHROUGH;
+    case DIGEST_SHA256: FALLTHROUGH;
     case DIGEST_SHA512:
       return END_OF_FIELD(d.ctx);
     case DIGEST_SHA3_256:
@@ -224,8 +224,8 @@ crypto_digest_new_internal(digest_algorithm_t algorithm)
 
   switch (algorithm)
     {
-    case DIGEST_SHA1: /* fall through */
-    case DIGEST_SHA256: /* fall through */
+    case DIGEST_SHA1: FALLTHROUGH;
+    case DIGEST_SHA256: FALLTHROUGH;
     case DIGEST_SHA512:
       r->d.ctx = PK11_CreateDigestContext(digest_alg_to_nss_oid(algorithm));
       if (BUG(!r->d.ctx)) {
@@ -312,8 +312,8 @@ crypto_digest_add_bytes(crypto_digest_t *digest, const char *data,
    * just doing it ourselves. Hashes are fast.
    */
   switch (digest->algorithm) {
-    case DIGEST_SHA1: /* fall through */
-    case DIGEST_SHA256: /* fall through */
+    case DIGEST_SHA1: FALLTHROUGH;
+    case DIGEST_SHA256: FALLTHROUGH;
     case DIGEST_SHA512:
       tor_assert(len <= UINT_MAX);
       SECStatus s = PK11_DigestOp(digest->d.ctx,
@@ -321,7 +321,7 @@ crypto_digest_add_bytes(crypto_digest_t *digest, const char *data,
                                   (unsigned int)len);
       tor_assert(s == SECSuccess);
       break;
-    case DIGEST_SHA3_256: /* FALLSTHROUGH */
+    case DIGEST_SHA3_256: FALLTHROUGH;
     case DIGEST_SHA3_512:
       keccak_digest_update(&digest->d.sha3, (const uint8_t *)data, len);
       break;
diff --git a/src/lib/crypt_ops/crypto_digest_openssl.c b/src/lib/crypt_ops/crypto_digest_openssl.c
index b0d8b6aee9..50a8ff4d27 100644
--- a/src/lib/crypt_ops/crypto_digest_openssl.c
+++ b/src/lib/crypt_ops/crypto_digest_openssl.c
@@ -160,11 +160,11 @@ crypto_digest_alloc_bytes(digest_algorithm_t alg)
     case DIGEST_SHA512:
       return END_OF_FIELD(d.sha512);
 #ifdef OPENSSL_HAS_SHA3
-    case DIGEST_SHA3_256: /* Fall through */
+    case DIGEST_SHA3_256: FALLTHROUGH;
     case DIGEST_SHA3_512:
       return END_OF_FIELD(d.md);
 #else
-    case DIGEST_SHA3_256: /* Fall through */
+    case DIGEST_SHA3_256: FALLTHROUGH;
     case DIGEST_SHA3_512:
       return END_OF_FIELD(d.sha3);
 #endif /* defined(OPENSSL_HAS_SHA3) */
@@ -304,14 +304,14 @@ crypto_digest_add_bytes(crypto_digest_t *digest, const char *data,
       SHA512_Update(&digest->d.sha512, (void*)data, len);
       break;
 #ifdef OPENSSL_HAS_SHA3
-    case DIGEST_SHA3_256: /* FALLSTHROUGH */
+    case DIGEST_SHA3_256: FALLTHROUGH;
     case DIGEST_SHA3_512: {
       int r = EVP_DigestUpdate(digest->d.md, data, len);
       tor_assert(r);
   }
       break;
 #else /* !defined(OPENSSL_HAS_SHA3) */
-    case DIGEST_SHA3_256: /* FALLSTHROUGH */
+    case DIGEST_SHA3_256: FALLTHROUGH;
     case DIGEST_SHA3_512:
       keccak_digest_update(&digest->d.sha3, (const uint8_t *)data, len);
       break;
@@ -377,7 +377,7 @@ crypto_digest_get_digest(crypto_digest_t *digest,
       SHA512_Final(r, &tmpenv.d.sha512);
       break;
 //LCOV_EXCL_START
-    case DIGEST_SHA3_256: /* FALLSTHROUGH */
+    case DIGEST_SHA3_256: FALLTHROUGH;
     case DIGEST_SHA3_512:
     default:
       log_warn(LD_BUG, "Handling unexpected algorithm %d", digest->algorithm);