[thirdparty/openssl.git] / doc / man3 / OSSL_STORE_open.pod

=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 <openssl/store.h>

 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<OSSL_STORE_INFO(3)/SUPPORTED OBJECTS> for information on which those are)
from a given URI (see L</SUPPORTED SCHEMES> 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<OSSL_STORE_INFO>, which is further
described in L<OSSL_STORE_INFO(3)>.

=head2 Types

B<OSSL_STORE_CTX> 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<uri>, password UI method
B<ui_method> with associated data B<ui_data>, and post processing
callback B<post_process> with associated data B<post_process_data>,
opens a channel to the data located at that URI and returns a
B<OSSL_STORE_CTX> with all necessary internal information.
The given B<ui_method> and B<ui_data_data> will be reused by all
functions that use B<OSSL_STORE_CTX> when interaction is needed.
The given B<post_process> and B<post_process_data> will be reused by
OSSL_STORE_load() to manipulate or drop the value to be returned.
The B<post_process> function drops values by returning B<NULL>, which
will cause OSSL_STORE_load() to start its process over with loading
the next object, until B<post_process> returns something other than
B<NULL>, or the end of data is reached as indicated by OSSL_STORE_eof().

OSSL_STORE_ctrl() takes a B<OSSL_STORE_CTX>, and command number B<cmd> 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<OSSL_STORE_C_USE_SECMEM>

Controls if the loader should attempt to use secure memory for any
allocated B<OSSL_STORE_INFO> and its contents.
This control expects one argument, a pointer to an B<int> 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<OSSL_STORE_CTX>, tries to load the next available
object and return it wrapped with  B<OSSL_STORE_INFO>.

OSSL_STORE_eof() takes a B<OSSL_STORE_CTX> and checks if we've reached the end
of data.

OSSL_STORE_error() takes a B<OSSL_STORE_CTX> and checks if an error occurred 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<OSSL_STORE_CTX>, closes the channel that was opened
by OSSL_STORE_open() and frees all other information that was stored in the
B<OSSL_STORE_CTX>, as well as the B<OSSL_STORE_CTX> itself.

=head1 SUPPORTED SCHEMES

The basic supported scheme is B<file:>.
Any other scheme can be added dynamically, using
OSSL_STORE_register_loader().

=head1 NOTES

A string without a scheme prefix (that is, a non-URI string) is
implicitly interpreted as using the F<file:> scheme.

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<OSSL_STORE_R_UNREGISTERED_SCHEME>.

These functions make no direct assumption regarding the pass phrase received
from the password callback.
The loaders may make assumptions, however.
For example, the B<file:> scheme loader inherits the assumptions made by
OpenSSL functionality that handles the different file types; this is mostly
relevant for PKCS#12 objects.
See L<passphrase-encoding(7)> for further information.

=head1 RETURN VALUES

OSSL_STORE_open() returns a pointer to a B<OSSL_STORE_CTX> on success, or
B<NULL> on failure.

OSSL_STORE_load() returns a pointer to a B<OSSL_STORE_INFO> on success, or
B<NULL> 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<NULL>.

OSSL_STORE_eof() returns 1 if the end of data has been reached, otherwise
0.

OSSL_STORE_error() returns 1 if an error occurred in an 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<ossl_store(7)>, L<OSSL_STORE_INFO(3)>, L<OSSL_STORE_register_loader(3)>,
L<passphrase-encoding(7)>

=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 in OpenSSL 1.1.1.

=head1 COPYRIGHT

Copyright 2016-2018 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
L<https://www.openssl.org/source/license.html>.

=cut
Commit	Line	Data
e2e603fe RL	1	=pod
	2
	3	=head1 NAME
	4
	5	OSSL_STORE_CTX, OSSL_STORE_post_process_info_fn, OSSL_STORE_open,
	6	OSSL_STORE_ctrl, OSSL_STORE_load, OSSL_STORE_eof, OSSL_STORE_error,
	7	OSSL_STORE_close - Types and functions to read objects from a URI
	8
	9	=head1 SYNOPSIS
	10
	11	#include <openssl/store.h>
dae2218d	12
e2e603fe RL	13	typedef struct ossl_store_ctx_st OSSL_STORE_CTX;
	14
	15	typedef OSSL_STORE_INFO (OSSL_STORE_post_process_info_fn)(OSSL_STORE_INFO *,
	16	void *);
	17
	18	OSSL_STORE_CTX OSSL_STORE_open(const char uri, const UI_METHOD *ui_method,
	19	void *ui_data,
	20	OSSL_STORE_post_process_info_fn post_process,
	21	void *post_process_data);
	22	int OSSL_STORE_ctrl(OSSL_STORE_CTX ctx, int cmd, ... / args */);
	23	OSSL_STORE_INFO OSSL_STORE_load(OSSL_STORE_CTX ctx);
	24	int OSSL_STORE_eof(OSSL_STORE_CTX *ctx);
	25	int OSSL_STORE_error(OSSL_STORE_CTX *ctx);
	26	int OSSL_STORE_close(OSSL_STORE_CTX *ctx);
	27
	28	=head1 DESCRIPTION
	29
	30	These functions help the application to fetch supported objects (see
	31	L<OSSL_STORE_INFO(3)/SUPPORTED OBJECTS> for information on which those are)
	32	from a given URI (see L</SUPPORTED SCHEMES> for more information on
	33	the supported URI schemes).
	34	The general method to do so is to "open" the URI using OSSL_STORE_open(),
	35	read each available and supported object using OSSL_STORE_load() as long as
	36	OSSL_STORE_eof() hasn't been reached, and finish it off with OSSL_STORE_close().
	37
	38	The retrieved information is stored in a B<OSSL_STORE_INFO>, which is further
	39	described in L<OSSL_STORE_INFO(3)>.
	40
	41	=head2 Types
	42
	43	B<OSSL_STORE_CTX> is a context variable that holds all the internal
	44	information for OSSL_STORE_open(), OSSL_STORE_load(), OSSL_STORE_eof() and
	45	OSSL_STORE_close() to work together.
	46
	47	=head2 Functions
	48
	49	OSSL_STORE_open() takes a uri or path B<uri>, password UI method
	50	B<ui_method> with associated data B<ui_data>, and post processing
	51	callback B<post_process> with associated data B<post_process_data>,
	52	opens a channel to the data located at that URI and returns a
	53	B<OSSL_STORE_CTX> with all necessary internal information.
	54	The given B<ui_method> and B<ui_data_data> will be reused by all
	55	functions that use B<OSSL_STORE_CTX> when interaction is needed.
	56	The given B<post_process> and B<post_process_data> will be reused by
	57	OSSL_STORE_load() to manipulate or drop the value to be returned.
33024295 RL	58	The B<post_process> function drops values by returning B<NULL>, which
	59	will cause OSSL_STORE_load() to start its process over with loading
	60	the next object, until B<post_process> returns something other than
	61	B<NULL>, or the end of data is reached as indicated by OSSL_STORE_eof().
e2e603fe RL	62
	63	OSSL_STORE_ctrl() takes a B<OSSL_STORE_CTX>, and command number B<cmd> and
	64	more arguments not specified here.
7852f588 RL	65	The available loader specific command numbers and arguments they each
	66	take depends on the loader that's used and is documented together with
	67	that loader.
	68
	69	There are also global controls available:
	70
	71	=over 4
	72
	73	=item B<OSSL_STORE_C_USE_SECMEM>
	74
	75	Controls if the loader should attempt to use secure memory for any
	76	allocated B<OSSL_STORE_INFO> and its contents.
	77	This control expects one argument, a pointer to an B<int> that is expected to
	78	have the value 1 (yes) or 0 (no).
	79	Any other value is an error.
	80
	81	=back
e2e603fe RL	82
	83	OSSL_STORE_load() takes a B<OSSL_STORE_CTX>, tries to load the next available
	84	object and return it wrapped with B<OSSL_STORE_INFO>.
	85
	86	OSSL_STORE_eof() takes a B<OSSL_STORE_CTX> and checks if we've reached the end
	87	of data.
	88
3266cf58	89	OSSL_STORE_error() takes a B<OSSL_STORE_CTX> and checks if an error occurred in
e2e603fe	90	the last OSSL_STORE_load() call.
6fc1d33c RL	91	Note that it may still be meaningful to try and load more objects, unless
6fc1d33c RL	92	OSSL_STORE_eof() shows that the end of data has been reached.
e2e603fe RL	93
	94	OSSL_STORE_close() takes a B<OSSL_STORE_CTX>, closes the channel that was opened
	95	by OSSL_STORE_open() and frees all other information that was stored in the
	96	B<OSSL_STORE_CTX>, as well as the B<OSSL_STORE_CTX> itself.
	97
	98	=head1 SUPPORTED SCHEMES
	99
	100	The basic supported scheme is B<file:>.
	101	Any other scheme can be added dynamically, using
	102	OSSL_STORE_register_loader().
	103
	104	=head1 NOTES
	105
1fb2993d BK	106	A string without a scheme prefix (that is, a non-URI string) is
	107	implicitly interpreted as using the F<file:> scheme.
	108
	109	There are some tools that can be used together with
e2e603fe RL	110	OSSL_STORE_open() to determine if any failure is caused by an unparsable
	111	URI, or if it's a different error (such as memory allocation
	112	failures); if the URI was parsable but the scheme unregistered, the
	113	top error will have the reason C<OSSL_STORE_R_UNREGISTERED_SCHEME>.
e2e603fe	114
84814344 RL	115	These functions make no direct assumption regarding the pass phrase received
	116	from the password callback.
	117	The loaders may make assumptions, however.
	118	For example, the B<file:> scheme loader inherits the assumptions made by
	119	OpenSSL functionality that handles the different file types; this is mostly
	120	relevant for PKCS#12 objects.
	121	See L<passphrase-encoding(7)> for further information.
	122
e2e603fe RL	123	=head1 RETURN VALUES
e2e603fe RL	124
6fc1d33c RL	125	OSSL_STORE_open() returns a pointer to a B<OSSL_STORE_CTX> on success, or
	126	B<NULL> on failure.
	127
	128	OSSL_STORE_load() returns a pointer to a B<OSSL_STORE_INFO> on success, or
	129	B<NULL> on error or when end of data is reached.
	130	Use OSSL_STORE_error() and OSSL_STORE_eof() to determine the meaning of a
	131	returned B<NULL>.
e2e603fe RL	132
	133	OSSL_STORE_eof() returns 1 if the end of data has been reached, otherwise
	134	0.
	135
3266cf58	136	OSSL_STORE_error() returns 1 if an error occurred in an OSSL_STORE_load() call,
e2e603fe RL	137	otherwise 0.
	138
	139	OSSL_STORE_ctrl() and OSSL_STORE_close() returns 1 on success, or 0 on failure.
	140
	141	=head1 SEE ALSO
	142
84814344 RL	143	L<ossl_store(7)>, L<OSSL_STORE_INFO(3)>, L<OSSL_STORE_register_loader(3)>,
84814344 RL	144	L<passphrase-encoding(7)>
e2e603fe RL	145
	146	=head1 HISTORY
	147
	148	OSSL_STORE_CTX(), OSSL_STORE_post_process_info_fn(), OSSL_STORE_open(),
	149	OSSL_STORE_ctrl(), OSSL_STORE_load(), OSSL_STORE_eof() and OSSL_STORE_close()
fc5ecadd	150	were added in OpenSSL 1.1.1.
e2e603fe RL	151
	152	=head1 COPYRIGHT
	153
b0edda11	154	Copyright 2016-2018 The OpenSSL Project Authors. All Rights Reserved.
e2e603fe	155
4746f25a	156	Licensed under the Apache License 2.0 (the "License"). You may not use
e2e603fe RL	157	this file except in compliance with the License. You can obtain a copy
	158	in the file LICENSE in the source distribution or at
	159	L<https://www.openssl.org/source/license.html>.
	160
	161	=cut