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✏️ Editing: OSSL_STORE_open.3

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.\" ========================================================================
.\"
.IX Title "OSSL_STORE_OPEN 3"
.TH OSSL_STORE_OPEN 3 "2023-09-11" "1.1.1w" "OpenSSL"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "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
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #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);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
These functions help the application to fetch supported objects (see
\&\*(L"\s-1SUPPORTED OBJECTS\*(R"\s0 in \s-1\fBOSSL_STORE_INFO\s0\fR\|(3) for information on which those are)
from a given \s-1URI\s0 (see \*(L"\s-1SUPPORTED SCHEMES\*(R"\s0 for more information on
the supported \s-1URI\s0 schemes).
The general method to do so is to \*(L"open\*(R" the \s-1URI\s0 using \fBOSSL_STORE_open()\fR,
read each available and supported object using \fBOSSL_STORE_load()\fR as long as
\&\fBOSSL_STORE_eof()\fR hasn't been reached, and finish it off with \fBOSSL_STORE_close()\fR.
.PP
The retrieved information is stored in a \fB\s-1OSSL_STORE_INFO\s0\fR, which is further
described in \s-1\fBOSSL_STORE_INFO\s0\fR\|(3).
.SS "Types"
.IX Subsection "Types"
\&\fB\s-1OSSL_STORE_CTX\s0\fR is a context variable that holds all the internal
information for \fBOSSL_STORE_open()\fR, \fBOSSL_STORE_load()\fR, \fBOSSL_STORE_eof()\fR and
\&\fBOSSL_STORE_close()\fR to work together.
.SS "Functions"
.IX Subsection "Functions"
\&\fBOSSL_STORE_open()\fR takes a uri or path \fIuri\fR, password \s-1UI\s0 method
\&\fIui_method\fR with associated data \fIui_data\fR, and post processing
callback \fIpost_process\fR with associated data \fIpost_process_data\fR,
opens a channel to the data located at that \s-1URI\s0 and returns a
\&\fB\s-1OSSL_STORE_CTX\s0\fR with all necessary internal information.
The given \fIui_method\fR and \fIui_data\fR will be reused by all
functions that use \fB\s-1OSSL_STORE_CTX\s0\fR when interaction is needed,
for instance to provide a password.
The given \fIpost_process\fR and \fIpost_process_data\fR will be reused by
\&\fBOSSL_STORE_load()\fR to manipulate or drop the value to be returned.
The \fIpost_process\fR function drops values by returning \s-1NULL,\s0 which
will cause \fBOSSL_STORE_load()\fR to start its process over with loading
the next object, until \fIpost_process\fR returns something other than
\&\s-1NULL,\s0 or the end of data is reached as indicated by \fBOSSL_STORE_eof()\fR.
.PP
\&\fBOSSL_STORE_ctrl()\fR takes a \fB\s-1OSSL_STORE_CTX\s0\fR, and command number \fIcmd\fR 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.
.PP
There are also global controls available:
.IP "\fB\s-1OSSL_STORE_C_USE_SECMEM\s0\fR" 4
.IX Item "OSSL_STORE_C_USE_SECMEM"
Controls if the loader should attempt to use secure memory for any
allocated \fB\s-1OSSL_STORE_INFO\s0\fR and its contents.
This control expects one argument, a pointer to an \fBint\fR that is expected to
have the value 1 (yes) or 0 (no).
Any other value is an error.
.PP
\&\fBOSSL_STORE_load()\fR takes a \fB\s-1OSSL_STORE_CTX\s0\fR, tries to load the next available
object and return it wrapped with  \fB\s-1OSSL_STORE_INFO\s0\fR.
.PP
\&\fBOSSL_STORE_eof()\fR takes a \fB\s-1OSSL_STORE_CTX\s0\fR and checks if we've reached the end
of data.
.PP
\&\fBOSSL_STORE_error()\fR takes a \fB\s-1OSSL_STORE_CTX\s0\fR and checks if an error occurred in
the last \fBOSSL_STORE_load()\fR call.
Note that it may still be meaningful to try and load more objects, unless
\&\fBOSSL_STORE_eof()\fR shows that the end of data has been reached.
.PP
\&\fBOSSL_STORE_close()\fR takes a \fB\s-1OSSL_STORE_CTX\s0\fR, closes the channel that was opened
by \fBOSSL_STORE_open()\fR and frees all other information that was stored in the
\&\fB\s-1OSSL_STORE_CTX\s0\fR, as well as the \fB\s-1OSSL_STORE_CTX\s0\fR itself.
If \fIctx\fR is \s-1NULL\s0 it does nothing.
.SH "SUPPORTED SCHEMES"
.IX Header "SUPPORTED SCHEMES"
The basic supported scheme is \fBfile:\fR.
Any other scheme can be added dynamically, using
\&\fBOSSL_STORE_register_loader()\fR.
.SH "NOTES"
.IX Header "NOTES"
A string without a scheme prefix (that is, a non-URI string) is
implicitly interpreted as using the \fIfile:\fR scheme.
.PP
There are some tools that can be used together with
\&\fBOSSL_STORE_open()\fR to determine if any failure is caused by an unparsable
\&\s-1URI,\s0 or if it's a different error (such as memory allocation
failures); if the \s-1URI\s0 was parsable but the scheme unregistered, the
top error will have the reason \f(CW\*(C`OSSL_STORE_R_UNREGISTERED_SCHEME\*(C'\fR.
.PP
These functions make no direct assumption regarding the pass phrase received
from the password callback.
The loaders may make assumptions, however.
For example, the \fBfile:\fR scheme loader inherits the assumptions made by
OpenSSL functionality that handles the different file types; this is mostly
relevant for PKCS#12 objects.
See \fBpassphrase\-encoding\fR\|(7) for further information.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
\&\fBOSSL_STORE_open()\fR returns a pointer to a \fB\s-1OSSL_STORE_CTX\s0\fR on success, or
\&\s-1NULL\s0 on failure.
.PP
\&\fBOSSL_STORE_load()\fR returns a pointer to a \fB\s-1OSSL_STORE_INFO\s0\fR on success, or
\&\s-1NULL\s0 on error or when end of data is reached.
Use \fBOSSL_STORE_error()\fR and \fBOSSL_STORE_eof()\fR to determine the meaning of a
returned \s-1NULL.\s0
.PP
\&\fBOSSL_STORE_eof()\fR returns 1 if the end of data has been reached, otherwise
0.
.PP
\&\fBOSSL_STORE_error()\fR returns 1 if an error occurred in an \fBOSSL_STORE_load()\fR call,
otherwise 0.
.PP
\&\fBOSSL_STORE_ctrl()\fR and \fBOSSL_STORE_close()\fR returns 1 on success, or 0 on failure.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBossl_store\fR\|(7), \s-1\fBOSSL_STORE_INFO\s0\fR\|(3), \fBOSSL_STORE_register_loader\fR\|(3),
\&\fBpassphrase\-encoding\fR\|(7)
.SH "HISTORY"
.IX Header "HISTORY"
\&\s-1\fBOSSL_STORE_CTX\s0()\fR, \fBOSSL_STORE_post_process_info_fn()\fR, \fBOSSL_STORE_open()\fR,
\&\fBOSSL_STORE_ctrl()\fR, \fBOSSL_STORE_load()\fR, \fBOSSL_STORE_eof()\fR and \fBOSSL_STORE_close()\fR
were added in OpenSSL 1.1.1.
.PP
Handling of \s-1NULL\s0 \fIctx\fR argument for \fBOSSL_STORE_close()\fR
was introduced in OpenSSL 1.1.1h.
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright 2016\-2020 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>.

MR SKB