Introduce HMAC_CTX_copy_ex and deprecate HMAC_CTX_copy.

HMAC_CTX_copy's documentation is off. It actually follows the old copy
functions which call FOO_init on dest first. Notably this means that they leak
memory if dest is currently in use.

Add HMAC_CTX_copy_ex as an analog of EVP_MD_CTX_copy and deprecate
HMAC_CTX_copy. (EVP_CIPHER_CTX_copy, in contrast, was correct from the start.)

Change-Id: I48566c858663d3f659bd356200cf862e196576c9
Reviewed-on: https://boringssl-review.googlesource.com/2694
Reviewed-by: Adam Langley <agl@google.com>

1 files changed, 9 insertions, 4 deletions

diff --git a/crypto/hmac/hmac.c b/crypto/hmac/hmac.c
index bb96606c..9c1e77ae 100644
--- a/crypto/hmac/hmac.c
+++ b/crypto/hmac/hmac.c
@@ -188,10 +188,10 @@ size_t HMAC_size(const HMAC_CTX *ctx) {
   return EVP_MD_size(ctx->md);
 }
 
-int HMAC_CTX_copy(HMAC_CTX *dest, const HMAC_CTX *src) {
-  if (!EVP_MD_CTX_copy(&dest->i_ctx, &src->i_ctx) ||
-      !EVP_MD_CTX_copy(&dest->o_ctx, &src->o_ctx) ||
-      !EVP_MD_CTX_copy(&dest->md_ctx, &src->md_ctx)) {
+int HMAC_CTX_copy_ex(HMAC_CTX *dest, const HMAC_CTX *src) {
+  if (!EVP_MD_CTX_copy_ex(&dest->i_ctx, &src->i_ctx) ||
+      !EVP_MD_CTX_copy_ex(&dest->o_ctx, &src->o_ctx) ||
+      !EVP_MD_CTX_copy_ex(&dest->md_ctx, &src->md_ctx)) {
     return 0;
   }
 
@@ -213,3 +213,8 @@ int HMAC_Init(HMAC_CTX *ctx, const void *key, int key_len, const EVP_MD *md) {
   }
   return HMAC_Init_ex(ctx, key, key_len, md, NULL);
 }
+
+int HMAC_CTX_copy(HMAC_CTX *dest, const HMAC_CTX *src) {
+  HMAC_CTX_init(dest);
+  return HMAC_CTX_copy_ex(dest, src);
+}