Replumbing: give the possibility for the provider to create a context

OSSL_provider_init() gets another output parameter, holding a pointer
to a provider side context.  It's entirely up to the provider to
define the context and what it's being used for.  This pointer is
passed back to other provider functions, typically the provider global
get_params and set_params functions, and also the diverse algorithm
context creators, and of course, the teardown function.

With this, a provider can be instantiated more than once, or be
re-loaded as the case may be, while maintaining instance state.

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/8848)

1 files changed, 12 insertions, 3 deletions

diff --git a/test/p_test.c b/test/p_test.c
index bf13a0a070..93196f74c4 100644
--- a/test/p_test.c
+++ b/test/p_test.c
@@ -38,13 +38,18 @@ static const OSSL_ITEM p_param_types[] = {
     { 0, NULL }
 };
 
-static const OSSL_ITEM *p_get_param_types(const OSSL_PROVIDER *_)
+/* This is a trick to ensure we define the provider functions correctly */
+static OSSL_provider_get_param_types_fn p_get_param_types;
+static OSSL_provider_get_params_fn p_get_params;
+
+static const OSSL_ITEM *p_get_param_types(void *_)
 {
     return p_param_types;
 }
 
-static int p_get_params(const OSSL_PROVIDER *prov, OSSL_PARAM params[])
+static int p_get_params(void *vprov, const OSSL_PARAM params[])
 {
+    const OSSL_PROVIDER *prov = vprov;
     const OSSL_PARAM *p = params;
     int ok = 1;
 
@@ -101,7 +106,8 @@ static const OSSL_DISPATCH p_test_table[] = {
 
 int OSSL_provider_init(const OSSL_PROVIDER *provider,
                        const OSSL_DISPATCH *in,
-                       const OSSL_DISPATCH **out)
+                       const OSSL_DISPATCH **out,
+                       void **provctx)
 {
     for (; in->function_id != 0; in++) {
         switch (in->function_id) {
@@ -117,6 +123,9 @@ int OSSL_provider_init(const OSSL_PROVIDER *provider,
         }
     }
 
+    /* Because we use this in get_params, we need to pass it back */
+    *provctx = (void *)provider;
+
     *out = p_test_table;
     return 1;
 }