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OSSL_STORE_LOADER(3SSL)             OpenSSL             OSSL_STORE_LOADER(3SSL)

NAME
       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, 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, 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 - Types and functions to
       manipulate, register and unregister STORE loaders for different URI
       schemes

SYNOPSIS
        #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);

       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
       OSSL_STORE_LOADER is a method for OSSL_STORE loaders, which 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.

       OSSL_STORE_LOADER_fetch() looks for an implementation for a storage
       scheme within the providers that has been loaded into the OSSL_LIB_CTX
       given by libctx, and with the properties given by properties.

       OSSL_STORE_LOADER_up_ref() increments the reference count for the given
       loader.

       OSSL_STORE_LOADER_free() decrements the reference count for the given
       loader, and when the count reaches zero, frees it.  If the argument is
       NULL, nothing is 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.

       OSSL_STORE_LOADER_get0_description() returns a description of the
       loader, meant for display and human consumption.  The description is at
       the discretion of the loader implementation.

       OSSL_STORE_LOADER_do_all_provided() traverses all store implementations
       by all activated providers in the library context libctx, and for each
       of the implementations, calls user_fn with the implementation method and
       user_arg as arguments.

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

   Legacy Types and Functions (deprecated)
       These functions help applications and engines to create loaders for
       schemes they support.  These are all deprecated and discouraged in
       favour of provider implementations, see provider-storemgmt(7).

       OSSL_STORE_LOADER_CTX is a type template, to be defined by each loader
       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.

       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, as well as 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.  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.

       OSSL_STORE_attach_fn
           This    function    takes    a    BIO,    otherwise    works    like
           OSSL_STORE_open_ex_fn.

       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.

           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.

           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.     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.

           Note that this function retrieves one data item only.

       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.

       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.

       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.

       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.

       OSSL_STORE_register_loader() register 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().

       OSSL_STORE_unregister_loader() unregister the store loader for the given
       scheme.

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.

       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.

       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.

       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.

SEE ALSO
       ossl_store(7),           OSSL_STORE_open(3),            OSSL_LIB_CTX(3),
       provider-storemgmt(7)

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.

       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.

       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
       Copyright 2016-2024 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>.

3.5.7                              2026-06-09           OSSL_STORE_LOADER(3SSL)

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