=pod =head1 NAME OSSL_STORE_CTX, OSSL_STORE_post_process_info_fn, OSSL_STORE_open, OSSL_STORE_ctrl, OSSL_STORE_load, OSSL_STORE_eof, OSSL_STORE_error, OSSL_STORE_close - Types and functions to read objects from a URI =head1 SYNOPSIS #include typedef struct ossl_store_ctx_st OSSL_STORE_CTX; typedef OSSL_STORE_INFO *(*OSSL_STORE_post_process_info_fn)(OSSL_STORE_INFO *, void *); OSSL_STORE_CTX *OSSL_STORE_open(const char *uri, const UI_METHOD *ui_method, void *ui_data, OSSL_STORE_post_process_info_fn post_process, void *post_process_data); int OSSL_STORE_ctrl(OSSL_STORE_CTX *ctx, int cmd, ... /* args */); OSSL_STORE_INFO *OSSL_STORE_load(OSSL_STORE_CTX *ctx); int OSSL_STORE_eof(OSSL_STORE_CTX *ctx); int OSSL_STORE_error(OSSL_STORE_CTX *ctx); int OSSL_STORE_close(OSSL_STORE_CTX *ctx); =head1 DESCRIPTION These functions help the application to fetch supported objects (see L for information on which those are) from a given URI (see L for more information on the supported URI schemes). The general method to do so is to "open" the URI using OSSL_STORE_open(), read each available and supported object using OSSL_STORE_load() as long as OSSL_STORE_eof() hasn't been reached, and finish it off with OSSL_STORE_close(). The retrieved information is stored in a B, which is further described in L. =head2 Types B is a context variable that holds all the internal information for OSSL_STORE_open(), OSSL_STORE_load(), OSSL_STORE_eof() and OSSL_STORE_close() to work together. =head2 Functions OSSL_STORE_open() takes a uri or path B, password UI method B with associated data B, and post processing callback B with associated data B, opens a channel to the data located at that URI and returns a B with all necessary internal information. The given B and B will be reused by all functions that use B when interaction is needed. The given B and B will be reused by OSSL_STORE_load() to manipulate or drop the value to be returned. OSSL_STORE_ctrl() takes a B, and command number B and more arguments not specified here. The available loader specific command numbers and arguments they each take depends on the loader that's used and is documented together with that loader. There are also global controls available: =over 4 =item B Controls if the loader should attempt to use secure memory for any allocated B and its contents. This control expects one argument, a pointer to an B that is expected to have the value 1 (yes) or 0 (no). Any other value is an error. =back OSSL_STORE_load() takes a B, tries to load the next available object and return it wrapped with B. OSSL_STORE_eof() takes a B and checks if we've reached the end of data. OSSL_STORE_error() takes a B and checks if an error occured in the last OSSL_STORE_load() call. Note that it may still be meaningful to try and load more objects, unless OSSL_STORE_eof() shows that the end of data has been reached. OSSL_STORE_close() takes a B, closes the channel that was opened by OSSL_STORE_open() and frees all other information that was stored in the B, as well as the B itself. =head1 SUPPORTED SCHEMES The basic supported scheme is B. Any other scheme can be added dynamically, using OSSL_STORE_register_loader(). =head1 NOTES When unsure whether a given string contains a simple file or directory reference, or if it's a full blown URI, the question is how to figure that out. One way is to try OSSL_STORE_open_file() and if that fails, try OSSL_STORE_open(). The other way is the other way around. Either way you choose, there are corner cases, F might very will be a simple file reference on a system that supports the notion of volumes. This manual won't tell you which way is better, that's up to each application developer to decide on their own. However, there are some tools that can be used together with OSSL_STORE_open() to determine if any failure is caused by an unparsable URI, or if it's a different error (such as memory allocation failures); if the URI was parsable but the scheme unregistered, the top error will have the reason C. If you decide to use OSSL_STORE_open() with OSSL_STORE_open_file() as a fallback, those reasons can be good tools to decide if the fallback should be taken or not. =head1 RETURN VALUES OSSL_STORE_open() returns a pointer to a B on success, or B on failure. OSSL_STORE_load() returns a pointer to a B on success, or B on error or when end of data is reached. Use OSSL_STORE_error() and OSSL_STORE_eof() to determine the meaning of a returned B. OSSL_STORE_eof() returns 1 if the end of data has been reached, otherwise 0. OSSL_STORE_error() returns 1 if an error occured in a OSSL_STORE_load() call, otherwise 0. OSSL_STORE_ctrl() and OSSL_STORE_close() returns 1 on success, or 0 on failure. =head1 SEE ALSO L, L, L =head1 HISTORY OSSL_STORE_CTX(), OSSL_STORE_post_process_info_fn(), OSSL_STORE_open(), OSSL_STORE_ctrl(), OSSL_STORE_load(), OSSL_STORE_eof() and OSSL_STORE_close() were added to OpenSSL 1.1.1. =head1 COPYRIGHT Copyright 2016-2017 The OpenSSL Project Authors. All Rights Reserved. Licensed under the OpenSSL license (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 L. =cut