path: root/secure/lib/libcrypto/man/man3/OSSL_STORE_LOADER.3

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.\" ========================================================================
.\"
.IX Title "OSSL_STORE_LOADER 3"
.TH OSSL_STORE_LOADER 3 "2022-05-03" "1.1.1o" "OpenSSL"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
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.nh
.SH "NAME"
OSSL_STORE_LOADER, 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_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_LOADER_free, OSSL_STORE_register_loader, OSSL_STORE_unregister_loader, OSSL_STORE_open_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
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #include <openssl/store.h>
\&
\& typedef struct ossl_store_loader_st OSSL_STORE_LOADER;
\&
\& 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 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);
\& void OSSL_STORE_LOADER_free(OSSL_STORE_LOADER *store_loader);
\&
\& int OSSL_STORE_register_loader(OSSL_STORE_LOADER *loader);
\& OSSL_STORE_LOADER *OSSL_STORE_unregister_loader(const char *scheme);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
These functions help applications and engines to create loaders for
schemes they support.
.SS "Types"
.IX Subsection "Types"
\&\fB\s-1OSSL_STORE_LOADER\s0\fR is the type to hold a loader.
It contains a scheme and the functions needed to implement
\&\fBOSSL_STORE_open()\fR, \fBOSSL_STORE_load()\fR, \fBOSSL_STORE_eof()\fR, \fBOSSL_STORE_error()\fR and
\&\fBOSSL_STORE_close()\fR for this scheme.
.PP
\&\fB\s-1OSSL_STORE_LOADER_CTX\s0\fR is a type template, to be defined by each loader
using \fBstruct ossl_store_loader_ctx_st { ... }\fR.
.PP
\&\fBOSSL_STORE_open_fn\fR, \fBOSSL_STORE_ctrl_fn\fR, \fBOSSL_STORE_expect_fn\fR,
\&\fBOSSL_STORE_find_fn\fR, \fBOSSL_STORE_load_fn\fR, \fBOSSL_STORE_eof_fn\fR,
and \fBOSSL_STORE_close_fn\fR
are the function pointer types used within a \s-1STORE\s0 loader.
The functions pointed at define the functionality of the given loader.
.IP "\fBOSSL_STORE_open_fn\fR" 4
.IX Item "OSSL_STORE_open_fn"
This function takes a \s-1URI\s0 and is expected to interpret it in the best
manner possible according to the scheme the loader implements, it also
takes a \fB\s-1UI_METHOD\s0\fR and associated data, to be used any time
something needs to be prompted for.
Furthermore, this function is expected to initialize what needs to be
initialized, to create a private data store (\fB\s-1OSSL_STORE_LOADER_CTX\s0\fR, see
above), and to return it.
If something goes wrong, this function is expected to return \s-1NULL.\s0
.IP "\fBOSSL_STORE_ctrl_fn\fR" 4
.IX Item "OSSL_STORE_ctrl_fn"
This function takes a \fB\s-1OSSL_STORE_LOADER_CTX\s0\fR pointer, a command number
\&\fBcmd\fR and a \fBva_list\fR \fBargs\fR and is used to manipulate loader
specific parameters.
.Sp
Loader specific command numbers must begin at \fB\s-1OSSL_STORE_C_CUSTOM_START\s0\fR.
Any number below that is reserved for future globally known command
numbers.
.Sp
This function is expected to return 1 on success, 0 on error.
.IP "\fBOSSL_STORE_expect_fn\fR" 4
.IX Item "OSSL_STORE_expect_fn"
This function takes a \fB\s-1OSSL_STORE_LOADER_CTX\s0\fR pointer and a \fB\s-1OSSL_STORE_INFO\s0\fR
identity \fBexpected\fR, and is used to tell the loader what object type is
expected.
\&\fBexpected\fR may be zero to signify that no specific object type is expected.
.Sp
This function is expected to return 1 on success, 0 on error.
.IP "\fBOSSL_STORE_find_fn\fR" 4
.IX Item "OSSL_STORE_find_fn"
This function takes a \fB\s-1OSSL_STORE_LOADER_CTX\s0\fR pointer and a
\&\fB\s-1OSSL_STORE_SEARCH\s0\fR search criterion, and is used to tell the loader what
to search for.
.Sp
When called with the loader context being \fB\s-1NULL\s0\fR, this function is expected
to return 1 if the loader supports the criterion, otherwise 0.
.Sp
When called with the loader context being something other than \fB\s-1NULL\s0\fR, this
function is expected to return 1 on success, 0 on error.
.IP "\fBOSSL_STORE_load_fn\fR" 4
.IX Item "OSSL_STORE_load_fn"
This function takes a \fB\s-1OSSL_STORE_LOADER_CTX\s0\fR pointer and a \fB\s-1UI_METHOD\s0\fR
with associated data.
It's expected to load the next available data, mold it into a data
structure that can be wrapped in a \fB\s-1OSSL_STORE_INFO\s0\fR using one of the
\&\s-1\fBOSSL_STORE_INFO\s0\fR\|(3) functions.
If no more data is available or an error occurs, this function is
expected to return \s-1NULL.\s0
The \fBOSSL_STORE_eof_fn\fR and \fBOSSL_STORE_error_fn\fR functions must indicate if
it was in fact the end of data or if an error occurred.
.Sp
Note that this function retrieves \fIone\fR data item only.
.IP "\fBOSSL_STORE_eof_fn\fR" 4
.IX Item "OSSL_STORE_eof_fn"
This function takes a \fB\s-1OSSL_STORE_LOADER_CTX\s0\fR 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.
.IP "\fBOSSL_STORE_error_fn\fR" 4
.IX Item "OSSL_STORE_error_fn"
This function takes a \fB\s-1OSSL_STORE_LOADER_CTX\s0\fR pointer and is expected to
return 1 to indicate that an error occurred in a previous call to the
\&\fBOSSL_STORE_load_fn\fR function.
It is otherwise expected to return 0.
.IP "\fBOSSL_STORE_close_fn\fR" 4
.IX Item "OSSL_STORE_close_fn"
This function takes a \fB\s-1OSSL_STORE_LOADER_CTX\s0\fR pointer and is expected to
close or shut down what needs to be closed, and finally free the
contents of the \fB\s-1OSSL_STORE_LOADER_CTX\s0\fR pointer.
It returns 1 on success and 0 on error.
.SS "Functions"
.IX Subsection "Functions"
\&\fBOSSL_STORE_LOADER_new()\fR creates a new \fB\s-1OSSL_STORE_LOADER\s0\fR.
It takes an \fB\s-1ENGINE\s0\fR \fBe\fR and a string \fBscheme\fR.
\&\fBscheme\fR must \fIalways\fR be set.
Both \fBe\fR and \fBscheme\fR are used as is and must therefore be alive as
long as the created loader is.
.PP
\&\fBOSSL_STORE_LOADER_get0_engine()\fR returns the engine of the \fBstore_loader\fR.
\&\fBOSSL_STORE_LOADER_get0_scheme()\fR returns the scheme of the \fBstore_loader\fR.
.PP
\&\fBOSSL_STORE_LOADER_set_open()\fR sets the opener function for the
\&\fBstore_loader\fR.
.PP
\&\fBOSSL_STORE_LOADER_set_ctrl()\fR sets the control function for the
\&\fBstore_loader\fR.
.PP
\&\fBOSSL_STORE_LOADER_set_expect()\fR sets the expect function for the
\&\fBstore_loader\fR.
.PP
\&\fBOSSL_STORE_LOADER_set_load()\fR sets the loader function for the
\&\fBstore_loader\fR.
.PP
\&\fBOSSL_STORE_LOADER_set_eof()\fR sets the end of file checker function for the
\&\fBstore_loader\fR.
.PP
\&\fBOSSL_STORE_LOADER_set_close()\fR sets the closing function for the
\&\fBstore_loader\fR.
.PP
\&\fBOSSL_STORE_LOADER_free()\fR frees the given \fBstore_loader\fR.
.PP
\&\fBOSSL_STORE_register_loader()\fR register the given \fBstore_loader\fR and thereby
makes it available for use with \fBOSSL_STORE_open()\fR, \fBOSSL_STORE_load()\fR,
\&\fBOSSL_STORE_eof()\fR and \fBOSSL_STORE_close()\fR.
.PP
\&\fBOSSL_STORE_unregister_loader()\fR unregister the store loader for the given
\&\fBscheme\fR.
.SH "NOTES"
.IX Header "NOTES"
The \fBfile:\fR scheme has built in support.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
The functions with the types \fBOSSL_STORE_open_fn\fR, \fBOSSL_STORE_ctrl_fn\fR,
\&\fBOSSL_STORE_expect_fn\fR,
\&\fBOSSL_STORE_load_fn\fR, \fBOSSL_STORE_eof_fn\fR and \fBOSSL_STORE_close_fn\fR have the
same return values as \fBOSSL_STORE_open()\fR, \fBOSSL_STORE_ctrl()\fR, \fBOSSL_STORE_expect()\fR,
\&\fBOSSL_STORE_load()\fR, \fBOSSL_STORE_eof()\fR and \fBOSSL_STORE_close()\fR, respectively.
.PP
\&\fBOSSL_STORE_LOADER_new()\fR returns a pointer to a \fB\s-1OSSL_STORE_LOADER\s0\fR on success,
or \fB\s-1NULL\s0\fR on failure.
.PP
\&\fBOSSL_STORE_LOADER_set_open()\fR, \fBOSSL_STORE_LOADER_set_ctrl()\fR,
\&\fBOSSL_STORE_LOADER_set_load()\fR, \fBOSSL_STORE_LOADER_set_eof()\fR and
\&\fBOSSL_STORE_LOADER_set_close()\fR return 1 on success, or 0 on failure.
.PP
\&\fBOSSL_STORE_register_loader()\fR returns 1 on success, or 0 on failure.
.PP
\&\fBOSSL_STORE_unregister_loader()\fR returns the unregistered loader on success,
or \fB\s-1NULL\s0\fR on failure.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBossl_store\fR\|(7), \fBOSSL_STORE_open\fR\|(3)
.SH "HISTORY"
.IX Header "HISTORY"
\&\s-1\fBOSSL_STORE_LOADER\s0()\fR, \s-1\fBOSSL_STORE_LOADER_CTX\s0()\fR, \fBOSSL_STORE_LOADER_new()\fR,
\&\fBOSSL_STORE_LOADER_set0_scheme()\fR, \fBOSSL_STORE_LOADER_set_open()\fR,
\&\fBOSSL_STORE_LOADER_set_ctrl()\fR, \fBOSSL_STORE_LOADER_set_load()\fR,
\&\fBOSSL_STORE_LOADER_set_eof()\fR, \fBOSSL_STORE_LOADER_set_close()\fR,
\&\fBOSSL_STORE_LOADER_free()\fR, \fBOSSL_STORE_register_loader()\fR,
\&\fBOSSL_STORE_unregister_loader()\fR, \fBOSSL_STORE_open_fn()\fR, \fBOSSL_STORE_ctrl_fn()\fR,
\&\fBOSSL_STORE_load_fn()\fR, \fBOSSL_STORE_eof_fn()\fR and \fBOSSL_STORE_close_fn()\fR
were added in OpenSSL 1.1.1.
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright 2016\-2019 The OpenSSL Project Authors. All Rights Reserved.
.PP
Licensed under the OpenSSL license (the \*(L"License\*(R").  You may not use
this file except in compliance with the License.  You can obtain a copy
in the file \s-1LICENSE\s0 in the source distribution or at
<https://www.openssl.org/source/license.html>.