EVP_Digest*Update, EVP_DigestFinal, and HMAC_Update can never fail.

Enough code fails to check their return codes anyway. We ought to make
it official.

Change-Id: Ie646360fd7073ea943036f5e21bed13df7e1b77a
Reviewed-on: https://boringssl-review.googlesource.com/4954
Reviewed-by: Adam Langley <agl@google.com>

include/openssl/digest.h

diff --git a/include/openssl/digest.h b/include/openssl/digest.h
index 8285dce..a7123cc 100644
--- a/include/openssl/digest.h
+++ b/include/openssl/digest.h
@@ -134,7 +134,7 @@
 OPENSSL_EXPORT int EVP_DigestInit(EVP_MD_CTX *ctx, const EVP_MD *type);
 
 /* EVP_DigestUpdate hashes |len| bytes from |data| into the hashing operation
- * in |ctx|. It returns one on success and zero otherwise. */
+ * in |ctx|. It returns one. */
 OPENSSL_EXPORT int EVP_DigestUpdate(EVP_MD_CTX *ctx, const void *data,
                                     size_t len);
 
@@ -144,10 +144,9 @@
 
 /* EVP_DigestFinal_ex finishes the digest in |ctx| and writes the output to
  * |md_out|. At most |EVP_MAX_MD_SIZE| bytes are written. If |out_size| is not
- * NULL then |*out_size| is set to the number of bytes written. It returns one
- * on success and zero otherwise. After this call, the hash cannot be updated
- * or finished again until |EVP_DigestInit_ex| is called to start another
- * hashing operation. */
+ * NULL then |*out_size| is set to the number of bytes written. It returns one.
+ * After this call, the hash cannot be updated or finished again until
+ * |EVP_DigestInit_ex| is called to start another hashing operation. */
 OPENSSL_EXPORT int EVP_DigestFinal_ex(EVP_MD_CTX *ctx, uint8_t *md_out,
                                       unsigned int *out_size);
 
@@ -251,7 +250,7 @@
   /* update is usually copied from |digest->update| but can differ in some
    * cases, i.e. HMAC.
    * TODO(davidben): Remove this hook once |EVP_PKEY_HMAC| is gone. */
-  int (*update)(EVP_MD_CTX *ctx, const void *data, size_t count);
+  void (*update)(EVP_MD_CTX *ctx, const void *data, size_t count);
 
   /* pctx is an opaque (at this layer) pointer to additional context that
    * EVP_PKEY functions may store in this object. */

include/openssl/evp.h

diff --git a/include/openssl/evp.h b/include/openssl/evp.h
index 28ae987..490a951 100644
--- a/include/openssl/evp.h
+++ b/include/openssl/evp.h
@@ -241,8 +241,7 @@
                                       EVP_PKEY *pkey);
 
 /* EVP_DigestSignUpdate appends |len| bytes from |data| to the data which will
- * be signed in |EVP_DigestSignFinal|. It returns one on success and zero
- * otherwise. */
+ * be signed in |EVP_DigestSignFinal|. It returns one. */
 OPENSSL_EXPORT int EVP_DigestSignUpdate(EVP_MD_CTX *ctx, const void *data,
                                         size_t len);
 
@@ -293,8 +292,7 @@
                                                      EVP_PKEY *pkey);
 
 /* EVP_DigestVerifyUpdate appends |len| bytes from |data| to the data which
- * will be verified by |EVP_DigestVerifyFinal|. It returns one on success and
- * zero otherwise. */
+ * will be verified by |EVP_DigestVerifyFinal|. It returns one. */
 OPENSSL_EXPORT int EVP_DigestVerifyUpdate(EVP_MD_CTX *ctx, const void *data,
                                           size_t len);
 

include/openssl/hmac.h

diff --git a/include/openssl/hmac.h b/include/openssl/hmac.h
index 89cdf8f..b8cf4af 100644
--- a/include/openssl/hmac.h
+++ b/include/openssl/hmac.h
@@ -106,7 +106,7 @@
                                 const EVP_MD *md, ENGINE *impl);
 
 /* HMAC_Update hashes |data_len| bytes from |data| into the current HMAC
- * operation in |ctx|. It returns one on success and zero on error. */
+ * operation in |ctx|. It returns one. */
 OPENSSL_EXPORT int HMAC_Update(HMAC_CTX *ctx, const uint8_t *data,
                                size_t data_len);