crypto/store/store_meth.c - third_party/openssl - Git at Google

 /*
  * Copyright 2020-2021 The OpenSSL Project Authors. All Rights Reserved.
  *
  * Licensed under the Apache License 2.0 (the "License").  You may not use
  * this file except in compliance with the License.  You can obtain a copy
  * in the file LICENSE in the source distribution or at
  * https://www.openssl.org/source/license.html
  */

 #include <openssl/crypto.h>
 #include "crypto/store.h"
 #include "internal/core.h"
 #include "internal/namemap.h"
 #include "internal/property.h"
 #include "internal/provider.h"
 #include "store_local.h"

 int OSSL_STORE_LOADER_up_ref(OSSL_STORE_LOADER *loader)
 {
     int ref = 0;

     if (loader->prov != NULL)
         CRYPTO_UP_REF(&loader->refcnt, &ref, loader->lock);
     return 1;
 }

 void OSSL_STORE_LOADER_free(OSSL_STORE_LOADER *loader)
 {
     if (loader != NULL && loader->prov != NULL) {
         int i;

         CRYPTO_DOWN_REF(&loader->refcnt, &i, loader->lock);
         if (i > 0)
             return;
         ossl_provider_free(loader->prov);
         CRYPTO_THREAD_lock_free(loader->lock);
     }
     OPENSSL_free(loader);
 }

 /*
  * OSSL_STORE_LOADER_new() expects the scheme as a constant string,
  * which we currently don't have, so we need an alternative allocator.
  */
 static OSSL_STORE_LOADER *new_loader(OSSL_PROVIDER *prov)
 {
     OSSL_STORE_LOADER *loader;

     if ((loader = OPENSSL_zalloc(sizeof(*loader))) == NULL
         || (loader->lock = CRYPTO_THREAD_lock_new()) == NULL) {
         OPENSSL_free(loader);
         return NULL;
     }
     loader->prov = prov;
     ossl_provider_up_ref(prov);
     loader->refcnt = 1;

     return loader;
 }

 static int up_ref_loader(void *method)
 {
     return OSSL_STORE_LOADER_up_ref(method);
 }

 static void free_loader(void *method)
 {
     OSSL_STORE_LOADER_free(method);
 }

 /* Permanent loader method store, constructor and destructor */
 static void loader_store_free(void *vstore)
 {
     ossl_method_store_free(vstore);
 }

 static void *loader_store_new(OSSL_LIB_CTX *ctx)
 {
     return ossl_method_store_new(ctx);
 }


 static const OSSL_LIB_CTX_METHOD loader_store_method = {
     /* We want loader_store to be cleaned up before the provider store */
     OSSL_LIB_CTX_METHOD_PRIORITY_2,
     loader_store_new,
     loader_store_free,
 };

 /* Data to be passed through ossl_method_construct() */
 struct loader_data_st {
     OSSL_LIB_CTX *libctx;
     int scheme_id;               /* For get_loader_from_store() */
     const char *scheme;          /* For get_loader_from_store() */
     const char *propquery;       /* For get_loader_from_store() */

     OSSL_METHOD_STORE *tmp_store; /* For get_tmp_loader_store() */

     unsigned int flag_construct_error_occurred : 1;
 };

 /*
  * Generic routines to fetch / create OSSL_STORE methods with
  * ossl_method_construct()
  */

 /* Temporary loader method store, constructor and destructor */
 static void *get_tmp_loader_store(void *data)
 {
     struct loader_data_st *methdata = data;

     if (methdata->tmp_store == NULL)
         methdata->tmp_store = ossl_method_store_new(methdata->libctx);
     return methdata->tmp_store;
 }

  static void dealloc_tmp_loader_store(void *store)
 {
     if (store != NULL)
         ossl_method_store_free(store);
 }

 /* Get the permanent loader store */
 static OSSL_METHOD_STORE *get_loader_store(OSSL_LIB_CTX *libctx)
 {
     return ossl_lib_ctx_get_data(libctx, OSSL_LIB_CTX_STORE_LOADER_STORE_INDEX,
                                 &loader_store_method);
 }

 /* Get loader methods from a store, or put one in */
 static void *get_loader_from_store(void *store, const OSSL_PROVIDER **prov,
                                    void *data)
 {
     struct loader_data_st *methdata = data;
     void *method = NULL;
     int id;

     if ((id = methdata->scheme_id) == 0) {
         OSSL_NAMEMAP *namemap = ossl_namemap_stored(methdata->libctx);

         id = ossl_namemap_name2num(namemap, methdata->scheme);
     }

     if (store == NULL
         && (store = get_loader_store(methdata->libctx)) == NULL)
         return NULL;

     if (!ossl_method_store_fetch(store, id, methdata->propquery, prov, &method))
         return NULL;
     return method;
 }

 static int put_loader_in_store(void *store, void *method,
                                const OSSL_PROVIDER *prov,
                                const char *scheme, const char *propdef,
                                void *data)
 {
     struct loader_data_st *methdata = data;
     OSSL_NAMEMAP *namemap;
     int id;

     if ((namemap = ossl_namemap_stored(methdata->libctx)) == NULL
         || (id = ossl_namemap_name2num(namemap, scheme)) == 0)
         return 0;

     if (store == NULL && (store = get_loader_store(methdata->libctx)) == NULL)
         return 0;

     return ossl_method_store_add(store, prov, id, propdef, method,
                                  up_ref_loader, free_loader);
 }

 static void *loader_from_algorithm(int scheme_id, const OSSL_ALGORITHM *algodef,
                                    OSSL_PROVIDER *prov)
 {
     OSSL_STORE_LOADER *loader = NULL;
     const OSSL_DISPATCH *fns = algodef->implementation;

     if ((loader = new_loader(prov)) == NULL)
         return NULL;
     loader->scheme_id = scheme_id;
     loader->propdef = algodef->property_definition;
     loader->description = algodef->algorithm_description;

     for (; fns->function_id != 0; fns++) {
         switch (fns->function_id) {
         case OSSL_FUNC_STORE_OPEN:
             if (loader->p_open == NULL)
                 loader->p_open = OSSL_FUNC_store_open(fns);
             break;
         case OSSL_FUNC_STORE_ATTACH:
             if (loader->p_attach == NULL)
                 loader->p_attach = OSSL_FUNC_store_attach(fns);
             break;
         case OSSL_FUNC_STORE_SETTABLE_CTX_PARAMS:
             if (loader->p_settable_ctx_params == NULL)
                 loader->p_settable_ctx_params =
                     OSSL_FUNC_store_settable_ctx_params(fns);
             break;
         case OSSL_FUNC_STORE_SET_CTX_PARAMS:
             if (loader->p_set_ctx_params == NULL)
                 loader->p_set_ctx_params = OSSL_FUNC_store_set_ctx_params(fns);
             break;
         case OSSL_FUNC_STORE_LOAD:
             if (loader->p_load == NULL)
                 loader->p_load = OSSL_FUNC_store_load(fns);
             break;
         case OSSL_FUNC_STORE_EOF:
             if (loader->p_eof == NULL)
                 loader->p_eof = OSSL_FUNC_store_eof(fns);
             break;
         case OSSL_FUNC_STORE_CLOSE:
             if (loader->p_close == NULL)
                 loader->p_close = OSSL_FUNC_store_close(fns);
             break;
         case OSSL_FUNC_STORE_EXPORT_OBJECT:
             if (loader->p_export_object == NULL)
                 loader->p_export_object = OSSL_FUNC_store_export_object(fns);
             break;
         }
     }

     if ((loader->p_open == NULL && loader->p_attach == NULL)
         || loader->p_load == NULL
         || loader->p_eof == NULL
         || loader->p_close == NULL) {
         /* Only set_ctx_params is optionaal */
         OSSL_STORE_LOADER_free(loader);
         ERR_raise(ERR_LIB_OSSL_STORE, OSSL_STORE_R_LOADER_INCOMPLETE);
         return NULL;
     }
     return loader;
 }

 /*
  * The core fetching functionality passes the scheme of the implementation.
  * This function is responsible to getting an identity number for them,
  * then call loader_from_algorithm() with that identity number.
  */
 static void *construct_loader(const OSSL_ALGORITHM *algodef,
                               OSSL_PROVIDER *prov, void *data)
 {
     /*
      * This function is only called if get_loader_from_store() returned
      * NULL, so it's safe to say that of all the spots to create a new
      * namemap entry, this is it.  Should the scheme already exist there, we
      * know that ossl_namemap_add() will return its corresponding number.
      */
     struct loader_data_st *methdata = data;
     OSSL_LIB_CTX *libctx = ossl_provider_libctx(prov);
     OSSL_NAMEMAP *namemap = ossl_namemap_stored(libctx);
     const char *scheme = algodef->algorithm_names;
     int id = ossl_namemap_add_name(namemap, 0, scheme);
     void *method = NULL;

     if (id != 0)
         method = loader_from_algorithm(id, algodef, prov);

     /*
      * Flag to indicate that there was actual construction errors.  This
      * helps inner_loader_fetch() determine what error it should
      * record on inaccessible algorithms.
      */
     if (method == NULL)
         methdata->flag_construct_error_occurred = 1;

     return method;
 }

 /* Intermediary function to avoid ugly casts, used below */
 static void destruct_loader(void *method, void *data)
 {
     OSSL_STORE_LOADER_free(method);
 }

 /* Fetching support.  Can fetch by numeric identity or by scheme */
 static OSSL_STORE_LOADER *
 inner_loader_fetch(struct loader_data_st *methdata, int id,
                    const char *scheme, const char *properties)
 {
     OSSL_METHOD_STORE *store = get_loader_store(methdata->libctx);
     OSSL_NAMEMAP *namemap = ossl_namemap_stored(methdata->libctx);
     const char *const propq = properties != NULL ? properties : "";
     void *method = NULL;
     int unsupported = 0;

     if (store == NULL || namemap == NULL) {
         ERR_raise(ERR_LIB_OSSL_STORE, ERR_R_PASSED_INVALID_ARGUMENT);
         return NULL;
     }

     /*
      * If we have been passed both an id and a scheme, we have an
      * internal programming error.
      */
     if (!ossl_assert(id == 0 || scheme == NULL)) {
         ERR_raise(ERR_LIB_OSSL_STORE, ERR_R_INTERNAL_ERROR);
         return NULL;
     }

     /* If we haven't received a name id yet, try to get one for the name */
     if (id == 0 && scheme != NULL)
         id = ossl_namemap_name2num(namemap, scheme);

     /*
      * If we haven't found the name yet, chances are that the algorithm to
      * be fetched is unsupported.
      */
     if (id == 0)
         unsupported = 1;

     if (id == 0
         || !ossl_method_store_cache_get(store, NULL, id, propq, &method)) {
         OSSL_METHOD_CONSTRUCT_METHOD mcm = {
             get_tmp_loader_store,
             get_loader_from_store,
             put_loader_in_store,
             construct_loader,
             destruct_loader
         };
         OSSL_PROVIDER *prov = NULL;

         methdata->scheme_id = id;
         methdata->scheme = scheme;
         methdata->propquery = propq;
         methdata->flag_construct_error_occurred = 0;
         if ((method = ossl_method_construct(methdata->libctx, OSSL_OP_STORE,
                                             &prov, 0 /* !force_cache */,
                                             &mcm, methdata)) != NULL) {
             /*
              * If construction did create a method for us, we know that there
              * is a correct scheme_id, since those have already been calculated
              * in get_loader_from_store() and put_loader_in_store() above.
              */
             if (id == 0)
                 id = ossl_namemap_name2num(namemap, scheme);
             ossl_method_store_cache_set(store, prov, id, propq, method,
                                         up_ref_loader, free_loader);
         }

         /*
          * If we never were in the constructor, the algorithm to be fetched
          * is unsupported.
          */
         unsupported = !methdata->flag_construct_error_occurred;
     }

     if ((id != 0 || scheme != NULL) && method == NULL) {
         int code = unsupported ? ERR_R_UNSUPPORTED : ERR_R_FETCH_FAILED;
         const char *helpful_msg =
             unsupported
             ? ( "No store loader found. For standard store loaders you need "
                 "at least one of the default or base providers available. "
                 "Did you forget to load them? Info: " )
             : "";

         if (scheme == NULL)
             scheme = ossl_namemap_num2name(namemap, id, 0);
         ERR_raise_data(ERR_LIB_OSSL_STORE, code,
                        "%s%s, Scheme (%s : %d), Properties (%s)",
                        helpful_msg,
                        ossl_lib_ctx_get_descriptor(methdata->libctx),
                        scheme = NULL ? "<null>" : scheme, id,
                        properties == NULL ? "<null>" : properties);
     }

     return method;
 }

 OSSL_STORE_LOADER *OSSL_STORE_LOADER_fetch(OSSL_LIB_CTX *libctx,
                                            const char *scheme,
                                            const char *properties)
 {
     struct loader_data_st methdata;
     void *method;

     methdata.libctx = libctx;
     methdata.tmp_store = NULL;
     method = inner_loader_fetch(&methdata, 0, scheme, properties);
     dealloc_tmp_loader_store(methdata.tmp_store);
     return method;
 }

 OSSL_STORE_LOADER *ossl_store_loader_fetch_by_number(OSSL_LIB_CTX *libctx,
                                                      int scheme_id,
                                                      const char *properties)
 {
     struct loader_data_st methdata;
     void *method;

     methdata.libctx = libctx;
     methdata.tmp_store = NULL;
     method = inner_loader_fetch(&methdata, scheme_id, NULL, properties);
     dealloc_tmp_loader_store(methdata.tmp_store);
     return method;
 }

 /*
  * Library of basic method functions
  */

 const OSSL_PROVIDER *OSSL_STORE_LOADER_get0_provider(const OSSL_STORE_LOADER *loader)
 {
     if (!ossl_assert(loader != NULL)) {
         ERR_raise(ERR_LIB_OSSL_STORE, ERR_R_PASSED_NULL_PARAMETER);
         return 0;
     }

     return loader->prov;
 }

 const char *OSSL_STORE_LOADER_get0_properties(const OSSL_STORE_LOADER *loader)
 {
     if (!ossl_assert(loader != NULL)) {
         ERR_raise(ERR_LIB_OSSL_STORE, ERR_R_PASSED_NULL_PARAMETER);
         return 0;
     }

     return loader->propdef;
 }

 int ossl_store_loader_get_number(const OSSL_STORE_LOADER *loader)
 {
     if (!ossl_assert(loader != NULL)) {
         ERR_raise(ERR_LIB_OSSL_STORE, ERR_R_PASSED_NULL_PARAMETER);
         return 0;
     }

     return loader->scheme_id;
 }

 const char *OSSL_STORE_LOADER_get0_description(const OSSL_STORE_LOADER *loader)
 {
     return loader->description;
 }

 int OSSL_STORE_LOADER_is_a(const OSSL_STORE_LOADER *loader, const char *name)
 {
     if (loader->prov != NULL) {
         OSSL_LIB_CTX *libctx = ossl_provider_libctx(loader->prov);
         OSSL_NAMEMAP *namemap = ossl_namemap_stored(libctx);

         return ossl_namemap_name2num(namemap, name) == loader->scheme_id;
     }
     return 0;
 }

 struct do_one_data_st {
     void (*user_fn)(OSSL_STORE_LOADER *loader, void *arg);
     void *user_arg;
 };

 static void do_one(ossl_unused int id, void *method, void *arg)
 {
     struct do_one_data_st *data = arg;

     data->user_fn(method, data->user_arg);
 }

 void OSSL_STORE_LOADER_do_all_provided(OSSL_LIB_CTX *libctx,
                                        void (*user_fn)(OSSL_STORE_LOADER *loader,
                                                        void *arg),
                                        void *user_arg)
 {
     struct loader_data_st methdata;
     struct do_one_data_st data;

     methdata.libctx = libctx;
     methdata.tmp_store = NULL;
     (void)inner_loader_fetch(&methdata, 0, NULL, NULL /* properties */);

     data.user_fn = user_fn;
     data.user_arg = user_arg;
     if (methdata.tmp_store != NULL)
         ossl_method_store_do_all(methdata.tmp_store, &do_one, &data);
     ossl_method_store_do_all(get_loader_store(libctx), &do_one, &data);
     dealloc_tmp_loader_store(methdata.tmp_store);
 }

 int OSSL_STORE_LOADER_names_do_all(const OSSL_STORE_LOADER *loader,
                                    void (*fn)(const char *name, void *data),
                                    void *data)
 {
     if (loader == NULL)
         return 0;

     if (loader->prov != NULL) {
         OSSL_LIB_CTX *libctx = ossl_provider_libctx(loader->prov);
         OSSL_NAMEMAP *namemap = ossl_namemap_stored(libctx);

         return ossl_namemap_doall_names(namemap, loader->scheme_id, fn, data);
     }

     return 1;
 }
	/*
	* Copyright 2020-2021 The OpenSSL Project Authors. All Rights Reserved.
	*
	* Licensed under the Apache License 2.0 (the "License"). You may not use
	* this file except in compliance with the License. You can obtain a copy
	* in the file LICENSE in the source distribution or at
	* https://www.openssl.org/source/license.html
	*/

	#include <openssl/crypto.h>
	#include "crypto/store.h"
	#include "internal/core.h"
	#include "internal/namemap.h"
	#include "internal/property.h"
	#include "internal/provider.h"
	#include "store_local.h"

	int OSSL_STORE_LOADER_up_ref(OSSL_STORE_LOADER *loader)
	{
	int ref = 0;

	if (loader->prov != NULL)
	CRYPTO_UP_REF(&loader->refcnt, &ref, loader->lock);
	return 1;
	}

	void OSSL_STORE_LOADER_free(OSSL_STORE_LOADER *loader)
	{
	if (loader != NULL && loader->prov != NULL) {
	int i;

	CRYPTO_DOWN_REF(&loader->refcnt, &i, loader->lock);
	if (i > 0)
	return;
	ossl_provider_free(loader->prov);
	CRYPTO_THREAD_lock_free(loader->lock);
	}
	OPENSSL_free(loader);
	}

	/*
	* OSSL_STORE_LOADER_new() expects the scheme as a constant string,
	* which we currently don't have, so we need an alternative allocator.
	*/
	static OSSL_STORE_LOADER new_loader(OSSL_PROVIDER prov)
	{
	OSSL_STORE_LOADER *loader;

	if ((loader = OPENSSL_zalloc(sizeof(*loader))) == NULL
	\|\| (loader->lock = CRYPTO_THREAD_lock_new()) == NULL) {
	OPENSSL_free(loader);
	return NULL;
	}
	loader->prov = prov;
	ossl_provider_up_ref(prov);
	loader->refcnt = 1;

	return loader;
	}

	static int up_ref_loader(void *method)
	{
	return OSSL_STORE_LOADER_up_ref(method);
	}

	static void free_loader(void *method)
	{
	OSSL_STORE_LOADER_free(method);
	}

	/* Permanent loader method store, constructor and destructor */
	static void loader_store_free(void *vstore)
	{
	ossl_method_store_free(vstore);
	}

	static void loader_store_new(OSSL_LIB_CTX ctx)
	{
	return ossl_method_store_new(ctx);
	}


	static const OSSL_LIB_CTX_METHOD loader_store_method = {
	/* We want loader_store to be cleaned up before the provider store */
	OSSL_LIB_CTX_METHOD_PRIORITY_2,
	loader_store_new,
	loader_store_free,
	};

	/* Data to be passed through ossl_method_construct() */
	struct loader_data_st {
	OSSL_LIB_CTX *libctx;
	int scheme_id; /* For get_loader_from_store() */
	const char scheme; / For get_loader_from_store() */
	const char propquery; / For get_loader_from_store() */

	OSSL_METHOD_STORE tmp_store; / For get_tmp_loader_store() */

	unsigned int flag_construct_error_occurred : 1;
	};

	/*
	* Generic routines to fetch / create OSSL_STORE methods with
	* ossl_method_construct()
	*/

	/* Temporary loader method store, constructor and destructor */
	static void get_tmp_loader_store(void data)
	{
	struct loader_data_st *methdata = data;

	if (methdata->tmp_store == NULL)
	methdata->tmp_store = ossl_method_store_new(methdata->libctx);
	return methdata->tmp_store;
	}

	static void dealloc_tmp_loader_store(void *store)
	{
	if (store != NULL)
	ossl_method_store_free(store);
	}

	/* Get the permanent loader store */
	static OSSL_METHOD_STORE get_loader_store(OSSL_LIB_CTX libctx)
	{
	return ossl_lib_ctx_get_data(libctx, OSSL_LIB_CTX_STORE_LOADER_STORE_INDEX,
	&loader_store_method);
	}

	/* Get loader methods from a store, or put one in */
	static void get_loader_from_store(void store, const OSSL_PROVIDER **prov,
	void *data)
	{
	struct loader_data_st *methdata = data;
	void *method = NULL;
	int id;

	if ((id = methdata->scheme_id) == 0) {
	OSSL_NAMEMAP *namemap = ossl_namemap_stored(methdata->libctx);

	id = ossl_namemap_name2num(namemap, methdata->scheme);
	}

	if (store == NULL
	&& (store = get_loader_store(methdata->libctx)) == NULL)
	return NULL;

	if (!ossl_method_store_fetch(store, id, methdata->propquery, prov, &method))
	return NULL;
	return method;
	}

	static int put_loader_in_store(void store, void method,
	const OSSL_PROVIDER *prov,
	const char scheme, const char propdef,
	void *data)
	{
	struct loader_data_st *methdata = data;
	OSSL_NAMEMAP *namemap;
	int id;

	if ((namemap = ossl_namemap_stored(methdata->libctx)) == NULL
	\|\| (id = ossl_namemap_name2num(namemap, scheme)) == 0)
	return 0;

	if (store == NULL && (store = get_loader_store(methdata->libctx)) == NULL)
	return 0;

	return ossl_method_store_add(store, prov, id, propdef, method,
	up_ref_loader, free_loader);
	}

	static void loader_from_algorithm(int scheme_id, const OSSL_ALGORITHM algodef,
	OSSL_PROVIDER *prov)
	{
	OSSL_STORE_LOADER *loader = NULL;
	const OSSL_DISPATCH *fns = algodef->implementation;

	if ((loader = new_loader(prov)) == NULL)
	return NULL;
	loader->scheme_id = scheme_id;
	loader->propdef = algodef->property_definition;
	loader->description = algodef->algorithm_description;

	for (; fns->function_id != 0; fns++) {
	switch (fns->function_id) {
	case OSSL_FUNC_STORE_OPEN:
	if (loader->p_open == NULL)
	loader->p_open = OSSL_FUNC_store_open(fns);
	break;
	case OSSL_FUNC_STORE_ATTACH:
	if (loader->p_attach == NULL)
	loader->p_attach = OSSL_FUNC_store_attach(fns);
	break;
	case OSSL_FUNC_STORE_SETTABLE_CTX_PARAMS:
	if (loader->p_settable_ctx_params == NULL)
	loader->p_settable_ctx_params =
	OSSL_FUNC_store_settable_ctx_params(fns);
	break;
	case OSSL_FUNC_STORE_SET_CTX_PARAMS:
	if (loader->p_set_ctx_params == NULL)
	loader->p_set_ctx_params = OSSL_FUNC_store_set_ctx_params(fns);
	break;
	case OSSL_FUNC_STORE_LOAD:
	if (loader->p_load == NULL)
	loader->p_load = OSSL_FUNC_store_load(fns);
	break;
	case OSSL_FUNC_STORE_EOF:
	if (loader->p_eof == NULL)
	loader->p_eof = OSSL_FUNC_store_eof(fns);
	break;
	case OSSL_FUNC_STORE_CLOSE:
	if (loader->p_close == NULL)
	loader->p_close = OSSL_FUNC_store_close(fns);
	break;
	case OSSL_FUNC_STORE_EXPORT_OBJECT:
	if (loader->p_export_object == NULL)
	loader->p_export_object = OSSL_FUNC_store_export_object(fns);
	break;
	}
	}

	if ((loader->p_open == NULL && loader->p_attach == NULL)
	\|\| loader->p_load == NULL
	\|\| loader->p_eof == NULL
	\|\| loader->p_close == NULL) {
	/* Only set_ctx_params is optionaal */
	OSSL_STORE_LOADER_free(loader);
	ERR_raise(ERR_LIB_OSSL_STORE, OSSL_STORE_R_LOADER_INCOMPLETE);
	return NULL;
	}
	return loader;
	}

	/*
	* The core fetching functionality passes the scheme of the implementation.
	* This function is responsible to getting an identity number for them,
	* then call loader_from_algorithm() with that identity number.
	*/
	static void construct_loader(const OSSL_ALGORITHM algodef,
	OSSL_PROVIDER prov, void data)
	{
	/*
	* This function is only called if get_loader_from_store() returned
	* NULL, so it's safe to say that of all the spots to create a new
	* namemap entry, this is it. Should the scheme already exist there, we
	* know that ossl_namemap_add() will return its corresponding number.
	*/
	struct loader_data_st *methdata = data;
	OSSL_LIB_CTX *libctx = ossl_provider_libctx(prov);
	OSSL_NAMEMAP *namemap = ossl_namemap_stored(libctx);
	const char *scheme = algodef->algorithm_names;
	int id = ossl_namemap_add_name(namemap, 0, scheme);
	void *method = NULL;

	if (id != 0)
	method = loader_from_algorithm(id, algodef, prov);

	/*
	* Flag to indicate that there was actual construction errors. This
	* helps inner_loader_fetch() determine what error it should
	* record on inaccessible algorithms.
	*/
	if (method == NULL)
	methdata->flag_construct_error_occurred = 1;

	return method;
	}

	/* Intermediary function to avoid ugly casts, used below */
	static void destruct_loader(void method, void data)
	{
	OSSL_STORE_LOADER_free(method);
	}

	/* Fetching support. Can fetch by numeric identity or by scheme */
	static OSSL_STORE_LOADER *
	inner_loader_fetch(struct loader_data_st *methdata, int id,
	const char scheme, const char properties)
	{
	OSSL_METHOD_STORE *store = get_loader_store(methdata->libctx);
	OSSL_NAMEMAP *namemap = ossl_namemap_stored(methdata->libctx);
	const char *const propq = properties != NULL ? properties : "";
	void *method = NULL;
	int unsupported = 0;

	if (store == NULL \|\| namemap == NULL) {
	ERR_raise(ERR_LIB_OSSL_STORE, ERR_R_PASSED_INVALID_ARGUMENT);
	return NULL;
	}

	/*
	* If we have been passed both an id and a scheme, we have an
	* internal programming error.
	*/
	if (!ossl_assert(id == 0 \|\| scheme == NULL)) {
	ERR_raise(ERR_LIB_OSSL_STORE, ERR_R_INTERNAL_ERROR);
	return NULL;
	}

	/* If we haven't received a name id yet, try to get one for the name */
	if (id == 0 && scheme != NULL)
	id = ossl_namemap_name2num(namemap, scheme);

	/*
	* If we haven't found the name yet, chances are that the algorithm to
	* be fetched is unsupported.
	*/
	if (id == 0)
	unsupported = 1;

	if (id == 0
	\|\| !ossl_method_store_cache_get(store, NULL, id, propq, &method)) {
	OSSL_METHOD_CONSTRUCT_METHOD mcm = {
	get_tmp_loader_store,
	get_loader_from_store,
	put_loader_in_store,
	construct_loader,
	destruct_loader
	};
	OSSL_PROVIDER *prov = NULL;

	methdata->scheme_id = id;
	methdata->scheme = scheme;
	methdata->propquery = propq;
	methdata->flag_construct_error_occurred = 0;
	if ((method = ossl_method_construct(methdata->libctx, OSSL_OP_STORE,
	&prov, 0 /* !force_cache */,
	&mcm, methdata)) != NULL) {
	/*
	* If construction did create a method for us, we know that there
	* is a correct scheme_id, since those have already been calculated
	* in get_loader_from_store() and put_loader_in_store() above.
	*/
	if (id == 0)
	id = ossl_namemap_name2num(namemap, scheme);
	ossl_method_store_cache_set(store, prov, id, propq, method,
	up_ref_loader, free_loader);
	}

	/*
	* If we never were in the constructor, the algorithm to be fetched
	* is unsupported.
	*/
	unsupported = !methdata->flag_construct_error_occurred;
	}

	if ((id != 0 \|\| scheme != NULL) && method == NULL) {
	int code = unsupported ? ERR_R_UNSUPPORTED : ERR_R_FETCH_FAILED;
	const char *helpful_msg =
	unsupported
	? ( "No store loader found. For standard store loaders you need "
	"at least one of the default or base providers available. "
	"Did you forget to load them? Info: " )
	: "";

	if (scheme == NULL)
	scheme = ossl_namemap_num2name(namemap, id, 0);
	ERR_raise_data(ERR_LIB_OSSL_STORE, code,
	"%s%s, Scheme (%s : %d), Properties (%s)",
	helpful_msg,
	ossl_lib_ctx_get_descriptor(methdata->libctx),
	scheme = NULL ? "<null>" : scheme, id,
	properties == NULL ? "<null>" : properties);
	}

	return method;
	}

	OSSL_STORE_LOADER OSSL_STORE_LOADER_fetch(OSSL_LIB_CTX libctx,
	const char *scheme,
	const char *properties)
	{
	struct loader_data_st methdata;
	void *method;

	methdata.libctx = libctx;
	methdata.tmp_store = NULL;
	method = inner_loader_fetch(&methdata, 0, scheme, properties);
	dealloc_tmp_loader_store(methdata.tmp_store);
	return method;
	}

	OSSL_STORE_LOADER ossl_store_loader_fetch_by_number(OSSL_LIB_CTX libctx,
	int scheme_id,
	const char *properties)
	{
	struct loader_data_st methdata;
	void *method;

	methdata.libctx = libctx;
	methdata.tmp_store = NULL;
	method = inner_loader_fetch(&methdata, scheme_id, NULL, properties);
	dealloc_tmp_loader_store(methdata.tmp_store);
	return method;
	}

	/*
	* Library of basic method functions
	*/

	const OSSL_PROVIDER OSSL_STORE_LOADER_get0_provider(const OSSL_STORE_LOADER loader)
	{
	if (!ossl_assert(loader != NULL)) {
	ERR_raise(ERR_LIB_OSSL_STORE, ERR_R_PASSED_NULL_PARAMETER);
	return 0;
	}

	return loader->prov;
	}

	const char OSSL_STORE_LOADER_get0_properties(const OSSL_STORE_LOADER loader)
	{
	if (!ossl_assert(loader != NULL)) {
	ERR_raise(ERR_LIB_OSSL_STORE, ERR_R_PASSED_NULL_PARAMETER);
	return 0;
	}

	return loader->propdef;
	}

	int ossl_store_loader_get_number(const OSSL_STORE_LOADER *loader)
	{
	if (!ossl_assert(loader != NULL)) {
	ERR_raise(ERR_LIB_OSSL_STORE, ERR_R_PASSED_NULL_PARAMETER);
	return 0;
	}

	return loader->scheme_id;
	}

	const char OSSL_STORE_LOADER_get0_description(const OSSL_STORE_LOADER loader)
	{
	return loader->description;
	}

	int OSSL_STORE_LOADER_is_a(const OSSL_STORE_LOADER loader, const char name)
	{
	if (loader->prov != NULL) {
	OSSL_LIB_CTX *libctx = ossl_provider_libctx(loader->prov);
	OSSL_NAMEMAP *namemap = ossl_namemap_stored(libctx);

	return ossl_namemap_name2num(namemap, name) == loader->scheme_id;
	}
	return 0;
	}

	struct do_one_data_st {
	void (user_fn)(OSSL_STORE_LOADER loader, void *arg);
	void *user_arg;
	};

	static void do_one(ossl_unused int id, void method, void arg)
	{
	struct do_one_data_st *data = arg;

	data->user_fn(method, data->user_arg);
	}

	void OSSL_STORE_LOADER_do_all_provided(OSSL_LIB_CTX *libctx,
	void (user_fn)(OSSL_STORE_LOADER loader,
	void *arg),
	void *user_arg)
	{
	struct loader_data_st methdata;
	struct do_one_data_st data;

	methdata.libctx = libctx;
	methdata.tmp_store = NULL;
	(void)inner_loader_fetch(&methdata, 0, NULL, NULL /* properties */);

	data.user_fn = user_fn;
	data.user_arg = user_arg;
	if (methdata.tmp_store != NULL)
	ossl_method_store_do_all(methdata.tmp_store, &do_one, &data);
	ossl_method_store_do_all(get_loader_store(libctx), &do_one, &data);
	dealloc_tmp_loader_store(methdata.tmp_store);
	}

	int OSSL_STORE_LOADER_names_do_all(const OSSL_STORE_LOADER *loader,
	void (fn)(const char name, void *data),
	void *data)
	{
	if (loader == NULL)
	return 0;

	if (loader->prov != NULL) {
	OSSL_LIB_CTX *libctx = ossl_provider_libctx(loader->prov);
	OSSL_NAMEMAP *namemap = ossl_namemap_stored(libctx);

	return ossl_namemap_doall_names(namemap, loader->scheme_id, fn, data);
	}

	return 1;
	}