OSSL_STORE_LOADER(3SSL)

📦

version 3.5.7 · 11 versions

OSSL_STORE_LOADER(3SSL) — OpenSSL manual, bestie, and this is part 1 of the loader lore 💅

🌸 NAME 🌸

okay so this page is the whole group chat for the STORE loader universe: types and functions to manipulate, register, and unregister STORE loaders for different URI schemes. no cap, every single name is here:

first batch: OSSL_STORE_LOADER, OSSL_STORE_LOADER_fetch, OSSL_STORE_LOADER_up_ref, OSSL_STORE_LOADER_free, OSSL_STORE_LOADER_get0_provider, OSSL_STORE_LOADER_get0_properties, OSSL_STORE_LOADER_is_a, OSSL_STORE_LOADER_get0_description, OSSL_STORE_LOADER_do_all_provided, OSSL_STORE_LOADER_names_do_all
next up: OSSL_STORE_LOADER_CTX, OSSL_STORE_LOADER_new, OSSL_STORE_LOADER_get0_engine, OSSL_STORE_LOADER_get0_scheme, OSSL_STORE_LOADER_set_open, OSSL_STORE_LOADER_set_open_ex, OSSL_STORE_LOADER_set_attach, OSSL_STORE_LOADER_set_ctrl, OSSL_STORE_LOADER_set_expect, OSSL_STORE_LOADER_set_find, OSSL_STORE_LOADER_set_load, OSSL_STORE_LOADER_set_eof, OSSL_STORE_LOADER_set_error, OSSL_STORE_LOADER_set_close, OSSL_STORE_register_loader, OSSL_STORE_unregister_loader
callback typedef besties: OSSL_STORE_open_fn, OSSL_STORE_open_ex_fn, OSSL_STORE_attach_fn, OSSL_STORE_ctrl_fn, OSSL_STORE_expect_fn, OSSL_STORE_find_fn, OSSL_STORE_load_fn, OSSL_STORE_eof_fn, OSSL_STORE_error_fn, OSSL_STORE_close_fn

✨ SYNOPSIS ✨

the copy-paste ritual starts here, and yes we are keeping it literal:

#include <openssl/store.h>

typedef struct ossl_store_loader_st OSSL_STORE_LOADER;

OSSL_STORE_LOADER *OSSL_STORE_LOADER_fetch(OSSL_LIB_CTX *libctx,
                                           const char *scheme,
                                           const char *properties);
int OSSL_STORE_LOADER_up_ref(OSSL_STORE_LOADER *loader);
void OSSL_STORE_LOADER_free(OSSL_STORE_LOADER *loader);
const OSSL_PROVIDER *OSSL_STORE_LOADER_get0_provider(const OSSL_STORE_LOADER *
                                                        loader);
const char *OSSL_STORE_LOADER_get0_properties(const OSSL_STORE_LOADER *loader);
const char *OSSL_STORE_LOADER_get0_description(const OSSL_STORE_LOADER *loader);
int OSSL_STORE_LOADER_is_a(const OSSL_STORE_LOADER *loader,
                           const char *scheme);
void OSSL_STORE_LOADER_do_all_provided(OSSL_LIB_CTX *libctx,
                                       void (*user_fn)(OSSL_STORE_LOADER *loader,
                                                  void *arg),
                                       void *user_arg);
int OSSL_STORE_LOADER_names_do_all(const OSSL_STORE_LOADER *loader,
                                   void (*fn)(const char *name, void *data),
                                   void *data);

okay now the deprecated-lore warning: The following functions have been deprecated since OpenSSL 3.0, and can be hidden entirely by defining OPENSSL_API_COMPAT with a suitable version value, see openssl_user_macros(7):

OSSL_STORE_LOADER *OSSL_STORE_LOADER_new(ENGINE *e, const char *scheme);
const ENGINE *OSSL_STORE_LOADER_get0_engine(const OSSL_STORE_LOADER
                                            *store_loader);
const char *OSSL_STORE_LOADER_get0_scheme(const OSSL_STORE_LOADER
                                          *store_loader);

/* struct ossl_store_loader_ctx_st is defined differently by each loader */
typedef struct ossl_store_loader_ctx_st OSSL_STORE_LOADER_CTX;

typedef OSSL_STORE_LOADER_CTX *(*OSSL_STORE_open_fn)(
    const char *uri, const UI_METHOD *ui_method, void *ui_data);
int OSSL_STORE_LOADER_set_open(OSSL_STORE_LOADER *store_loader,
                               OSSL_STORE_open_fn store_open_function);
typedef OSSL_STORE_LOADER_CTX *(*OSSL_STORE_open_ex_fn)(
    const char *uri, const UI_METHOD *ui_method, void *ui_data);
int OSSL_STORE_LOADER_set_open_ex
    (OSSL_STORE_LOADER *store_loader,
     OSSL_STORE_open_ex_fn store_open_ex_function);
typedef OSSL_STORE_LOADER_CTX *(*OSSL_STORE_attach_fn)
    (const OSSL_STORE_LOADER *loader, BIO *bio,
     OSSL_LIB_CTX *libctx, const char *propq,
     const UI_METHOD *ui_method, void *ui_data);
int OSSL_STORE_LOADER_set_attach(OSSL_STORE_LOADER *loader,
                                 OSSL_STORE_attach_fn attach_function);
typedef int (*OSSL_STORE_ctrl_fn)(OSSL_STORE_LOADER_CTX *ctx, int cmd,
                                  va_list args);
int OSSL_STORE_LOADER_set_ctrl(OSSL_STORE_LOADER *store_loader,
                               OSSL_STORE_ctrl_fn store_ctrl_function);
typedef int (*OSSL_STORE_expect_fn)(OSSL_STORE_LOADER_CTX *ctx, int expected);
int OSSL_STORE_LOADER_set_expect(OSSL_STORE_LOADER *loader,
                                 OSSL_STORE_expect_fn expect_function);
typedef int (*OSSL_STORE_find_fn)(OSSL_STORE_LOADER_CTX *ctx,
                                  OSSL_STORE_SEARCH *criteria);
int OSSL_STORE_LOADER_set_find(OSSL_STORE_LOADER *loader,
                               OSSL_STORE_find_fn find_function);
typedef OSSL_STORE_INFO *(*OSSL_STORE_load_fn)(OSSL_STORE_LOADER_CTX *ctx,
                                               UI_METHOD *ui_method,
                                               void *ui_data);
int OSSL_STORE_LOADER_set_load(OSSL_STORE_LOADER *store_loader,
                               OSSL_STORE_load_fn store_load_function);
typedef int (*OSSL_STORE_eof_fn)(OSSL_STORE_LOADER_CTX *ctx);
int OSSL_STORE_LOADER_set_eof(OSSL_STORE_LOADER *store_loader,
                              OSSL_STORE_eof_fn store_eof_function);
typedef int (*OSSL_STORE_error_fn)(OSSL_STORE_LOADER_CTX *ctx);
int OSSL_STORE_LOADER_set_error(OSSL_STORE_LOADER *store_loader,
                                OSSL_STORE_error_fn store_error_function);
typedef int (*OSSL_STORE_close_fn)(OSSL_STORE_LOADER_CTX *ctx);
int OSSL_STORE_LOADER_set_close(OSSL_STORE_LOADER *store_loader,
                                OSSL_STORE_close_fn store_close_function);

int OSSL_STORE_register_loader(OSSL_STORE_LOADER *loader);
OSSL_STORE_LOADER *OSSL_STORE_unregister_loader(const char *scheme);

💖 DESCRIPTION 💖

okay so, boom: OSSL_STORE_LOADER is literally the method for OSSL_STORE loaders. And what do those do? They implement OSSL_STORE_open(), OSSL_STORE_open_ex(), OSSL_STORE_load(), OSSL_STORE_eof(), OSSL_STORE_error() and OSSL_STORE_close() for specific storage schemes. like, each scheme gets its own little loader bestie that handles all six of those. iconic behavior tbh ✨

OSSL_STORE_LOADER_fetch() is out here looking for an implementation for a storage scheme — it searches the providers that have been loaded into the OSSL_LIB_CTX given by libctx, and it matches against the properties given by properties. it's giving "where my people at" 🫶

OSSL_STORE_LOADER_up_ref() bumps the reference count for the given loader up by one. keep that thing alive, queen.

OSSL_STORE_LOADER_free() sends the reference count down by one, and when it hits zero it frees the loader. and if the argument is NULL? nothing happens. no drama, nothing done. 🎀

OSSL_STORE_LOADER_get0_provider() returns the provider of the given loader.

OSSL_STORE_LOADER_get0_properties() returns the property definition associated with the given loader.

OSSL_STORE_LOADER_is_a() checks if loader is an implementation of an algorithm that's identifiable with scheme. vibe check on the algorithm, basically 🌈

OSSL_STORE_LOADER_get0_description() returns a description of the loader — and this one is meant for display and human consumption, so it's whatever the loader implementation feels like saying. at the discretion of the loader, no cap.

OSSL_STORE_LOADER_do_all_provided() walks through, like, all the store implementations by all activated providers in the library context libctx, and for each one it calls user_fn with the implementation method and user_arg as arguments. a whole parade of loaders 👑

OSSL_STORE_LOADER_names_do_all() traverses all the names for the given loader and calls fn with each name and data. all the names, every single one.

🧓 Legacy Types and Functions (deprecated)

ngl bestie, this section is a nostalgia tour. These functions help applications and engines create loaders for schemes they support. They are all deprecated and discouraged in favour of provider implementations — see provider-storemgmt(7). so like, history lesson, not a recommendation 💀

OSSL_STORE_LOADER_CTX is a type template, and each loader defines it using "struct ossl_store_loader_ctx_st { ... }".

OSSL_STORE_open_fn, OSSL_STORE_open_ex_fn, OSSL_STORE_ctrl_fn, OSSL_STORE_expect_fn, OSSL_STORE_find_fn, OSSL_STORE_load_fn, OSSL_STORE_eof_fn, and OSSL_STORE_close_fn are the function pointer types used within a STORE loader. The functions pointed at define the functionality of the given loader. they are the loader's personality, fr fr.

🌸 `OSSL_STORE_open_fn` and `OSSL_STORE_open_ex_fn`

OSSL_STORE_open_ex_fn takes a URI and is expected to interpret it in the best manner possible according to the scheme the loader implements. It also takes a UI_METHOD and associated data, to be used any time something needs to be prompted for, plus a library context libctx with an associated property query propq, to be used when fetching necessary algorithms to perform the loads. Furthermore, this function is expected to initialize what needs to be initialized, to create a private data store (OSSL_STORE_LOADER_CTX, see above), and to return it. And if something goes wrong? this function is expected to return NULL. 😭

OSSL_STORE_open_fn does the same thing as OSSL_STORE_open_ex_fn but uses NULL for the library context libctx and property query propq. same energy, less context.

🦋 `OSSL_STORE_attach_fn`

This function takes a BIO, otherwise works like OSSL_STORE_open_ex_fn. that's it, that's the whole thing.

🎀 `OSSL_STORE_ctrl_fn`

This function takes a OSSL_STORE_LOADER_CTX pointer, a command number cmd and a va_list args, and is used to manipulate loader specific parameters.

Loader specific command numbers must begin at OSSL_STORE_C_CUSTOM_START. Any number below that is reserved for future globally known command numbers. so like, stay in your lane number-wise 🙈

This function is expected to return 1 on success, 0 on error.

🌟 `OSSL_STORE_expect_fn`

This function takes a OSSL_STORE_LOADER_CTX pointer and a OSSL_STORE_INFO identity expected, and is used to tell the loader what object type is expected. expected may be zero to signify that no specific object type is expected. manifesting a type, basically ✨

This function is expected to return 1 on success, 0 on error.

🔥 `OSSL_STORE_find_fn`

This function takes a OSSL_STORE_LOADER_CTX pointer and a OSSL_STORE_SEARCH search criterion, and is used to tell the loader what to search for.

When called with the loader context being NULL, this function is expected to return 1 if the loader supports the criterion, otherwise 0.

When called with the loader context being something other than NULL, this function is expected to return 1 on success, 0 on error.

💜 `OSSL_STORE_load_fn`

This function takes a OSSL_STORE_LOADER_CTX pointer and a UI_METHOD with associated data. It's expected to load the next available data, mold it into a data structure that can be wrapped in a OSSL_STORE_INFO using one of the OSSL_STORE_INFO(3) functions. If no more data is available or an error occurs, this function is expected to return NULL. And the OSSL_STORE_eof_fn and OSSL_STORE_error_fn functions must indicate if it was in fact the end of data or if an error occurred. teamwork, bestie 🫶

Note that this function retrieves one data item only. one. singular. don't get greedy.

🌈 `OSSL_STORE_eof_fn`

This function takes a OSSL_STORE_LOADER_CTX pointer and is expected to return 1 to indicate that the end of available data has been reached. It is otherwise expected to return 0. that's a wrap, folks 🎬

⭐ `OSSL_STORE_error_fn`

This function takes a OSSL_STORE_LOADER_CTX pointer and is expected to return 1 to indicate that an error occurred in a previous call to the OSSL_STORE_load_fn function. It is otherwise expected to return 0.

🍓 `OSSL_STORE_close_fn`

This function takes a OSSL_STORE_LOADER_CTX pointer and is expected to close or shut down what needs to be closed, and finally free the contents of the OSSL_STORE_LOADER_CTX pointer. It returns 1 on success and 0 on error. clean up your room, bestie 💅

OSSL_STORE_LOADER_new() creates a new OSSL_STORE_LOADER. It takes an ENGINE e and a string scheme. scheme must always be set. Both e and scheme are used as is and must therefore be alive as long as the created loader is. so like, do not let them expire on you 🙈

OSSL_STORE_LOADER_get0_engine() returns the engine of the store_loader. OSSL_STORE_LOADER_get0_scheme() returns the scheme of the store_loader.

OSSL_STORE_LOADER_set_open() sets the opener function for the store_loader.

OSSL_STORE_LOADER_set_open_ex() sets the opener with library context function for the store_loader.

OSSL_STORE_LOADER_set_attach() sets the attacher function for the store_loader.

OSSL_STORE_LOADER_set_ctrl() sets the control function for the store_loader.

OSSL_STORE_LOADER_set_expect() sets the expect function for the store_loader.

OSSL_STORE_LOADER_set_load() sets the loader function for the store_loader.

OSSL_STORE_LOADER_set_eof() sets the end of file checker function for the store_loader.

OSSL_STORE_LOADER_set_close() sets the closing function for the store_loader.

OSSL_STORE_LOADER_free() frees the given store_loader. If the argument is NULL, nothing is done. again: no drama 💀

OSSL_STORE_register_loader() registers the given store_loader and thereby makes it available for use with OSSL_STORE_open(), OSSL_STORE_open_ex(), OSSL_STORE_load(), OSSL_STORE_eof() and OSSL_STORE_close(). putting it on the map 🗺️

OSSL_STORE_unregister_loader() unregisters the store loader for the given scheme. bye bestie 👋

✨ RETURN VALUES ✨

OSSL_STORE_LOADER_fetch() returns a pointer to an OSSL_STORE_LOADER object, or NULL on error.

OSSL_STORE_LOADER_up_ref() returns 1 on success, or 0 on error.

OSSL_STORE_LOADER_names_do_all() returns 1 if the callback was called for all names. A return value of 0 means that the callback was not called for any names. 😭

OSSL_STORE_LOADER_free() doesn't return any value. it's a void king 👑

OSSL_STORE_LOADER_get0_provider() returns a pointer to a provider object, or NULL on error.

OSSL_STORE_LOADER_get0_properties() returns a pointer to a property definition string, or NULL on error.

OSSL_STORE_LOADER_is_a() returns 1 if loader was identifiable, otherwise 0.

OSSL_STORE_LOADER_get0_description() returns a pointer to a description, or NULL if there isn't one. sometimes there's just no description, and that's valid 🫶

The functions with the types OSSL_STORE_open_fn, OSSL_STORE_open_ex_fn, OSSL_STORE_ctrl_fn, OSSL_STORE_expect_fn, OSSL_STORE_load_fn, OSSL_STORE_eof_fn and OSSL_STORE_close_fn have the same return values as OSSL_STORE_open(), OSSL_STORE_open_ex(), OSSL_STORE_ctrl(), OSSL_STORE_expect(), OSSL_STORE_load(), OSSL_STORE_eof() and OSSL_STORE_close(), respectively. matching fits, iykyk 💅

OSSL_STORE_LOADER_new() returns a pointer to a OSSL_STORE_LOADER on success, or NULL on failure.

OSSL_STORE_LOADER_set_open(), OSSL_STORE_LOADER_set_open_ex(), OSSL_STORE_LOADER_set_ctrl(), OSSL_STORE_LOADER_set_load(), OSSL_STORE_LOADER_set_eof() and OSSL_STORE_LOADER_set_close() return 1 on success, or 0 on failure.

OSSL_STORE_register_loader() returns 1 on success, or 0 on failure.

OSSL_STORE_unregister_loader() returns the unregistered loader on success, or NULL on failure.

🌸 HISTORY 🌸

OSSL_STORE_LOADER_fetch(), OSSL_STORE_LOADER_up_ref(), OSSL_STORE_LOADER_get0_provider(), OSSL_STORE_LOADER_get0_properties(), OSSL_STORE_LOADER_get0_description(), OSSL_STORE_LOADER_is_a(), OSSL_STORE_LOADER_do_all_provided() and OSSL_STORE_LOADER_names_do_all() were added in OpenSSL 3.0. glow-up era ✨

OSSL_STORE_LOADER and OSSL_STORE_LOADER_free() were added in OpenSSL 1.1.1.

OSSL_STORE_LOADER_set_open_ex() and OSSL_STORE_open_ex_fn() were added in OpenSSL 3.0, and are deprecated. added and deprecated in the same era, it's giving tragic backstory 😭

OSSL_STORE_LOADER_CTX, OSSL_STORE_LOADER_new(), OSSL_STORE_LOADER_set0_scheme(), OSSL_STORE_LOADER_get0_scheme(), OSSL_STORE_LOADER_get0_engine(), OSSL_STORE_LOADER_set_expect(), OSSL_STORE_LOADER_set_find(), OSSL_STORE_LOADER_set_attach(), OSSL_STORE_LOADER_set_open_ex(), OSSL_STORE_LOADER_set_open(), OSSL_STORE_LOADER_set_ctrl(), OSSL_STORE_LOADER_set_load(), OSSL_STORE_LOADER_set_eof(), OSSL_STORE_LOADER_set_close(), OSSL_STORE_register_loader(), OSSL_STORE_LOADER_set_error(), OSSL_STORE_unregister_loader(), OSSL_STORE_open_fn(), OSSL_STORE_ctrl_fn(), OSSL_STORE_load_fn(), OSSL_STORE_eof_fn() and OSSL_STORE_close_fn() were added in OpenSSL 1.1.1, and became deprecated in OpenSSL 3.0.

👑 COPYRIGHT 👑

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>.

aaaand that's the whole page bestie, you ate that 💅 this little gem is from OpenSSL version 3.5.7, dated 2026-06-09, and it lives at OSSL_STORE_LOADER(3SSL) — go forth and load things, mwah 🎀💖🦋

📦 where this page comes from

debian trixie: libssl-doc 3.5.7-1~deb13u2 · Apache-2.0
debian trixie: libssl-doc 3.5.7-1~deb13u3 · Apache-2.0
💖 girlified by deepseek-ai/DeepSeek-V4.1-Flash-1017 on 2026-11-06: a language model's rewrite of the original, under its terms

OSSL_STORE_LOADER(3SSL)

🌸 NAME 🌸

✨ SYNOPSIS ✨

💖 DESCRIPTION 💖

🧓 Legacy Types and Functions (deprecated)

🌸 OSSL_STORE_open_fn and OSSL_STORE_open_ex_fn

🦋 OSSL_STORE_attach_fn

🎀 OSSL_STORE_ctrl_fn

🌟 OSSL_STORE_expect_fn

🔥 OSSL_STORE_find_fn

💜 OSSL_STORE_load_fn

🌈 OSSL_STORE_eof_fn

⭐ OSSL_STORE_error_fn

🍓 OSSL_STORE_close_fn