Add EVP_MD_CTX_ctrl function.

Reviewed-by: NTim Hudson <tjh@openssl.org>

crypto/evp/digest.c

@@ -364,3 +364,14 @@ int EVP_MD_CTX_cleanup(EVP_MD_CTX *ctx)
 
     return 1;
 }
+
+int EVP_MD_CTX_ctrl(EVP_MD_CTX *ctx, int cmd, int p1, void *p2)
+{
+    if (ctx->digest && ctx->digest->md_ctrl) {
+        int ret = ctx->digest->md_ctrl(ctx, cmd, p1, p2);
+        if (ret <= 0)
+            return 0;
+        return 1;
+    }
+    return 0;
+}

include/openssl/evp.h

@@ -626,6 +626,7 @@ void BIO_set_md(BIO *, const EVP_MD *md);
 
 void EVP_MD_CTX_init(EVP_MD_CTX *ctx);
 int EVP_MD_CTX_cleanup(EVP_MD_CTX *ctx);
+int EVP_MD_CTX_ctrl(EVP_MD_CTX *ctx, int cmd, int p1, void *p2);
 EVP_MD_CTX *EVP_MD_CTX_create(void);
 void EVP_MD_CTX_destroy(EVP_MD_CTX *ctx);
 /*__owur*/ int EVP_MD_CTX_copy_ex(EVP_MD_CTX *out, const EVP_MD_CTX *in);