=pod

=head1 NAME

ossl_namemap_new, ossl_namemap_free, ossl_namemap_stored,
ossl_namemap_add, ossl_namemap_name2num, ossl_namemap_doall_names
- internal number E<lt>-E<gt> name map

=head1 SYNOPSIS

 #include "internal/cryptlib.h"

 OSSL_NAMEMAP *ossl_namemap_stored(OPENSSL_CTX *libctx);

 OSSL_NAMEMAP *ossl_namemap_new(void);
 void ossl_namemap_free(OSSL_NAMEMAP *namemap);

 int ossl_namemap_add(OSSL_NAMEMAP *namemap, int number, const char *name);

 int ossl_namemap_name2num(const OSSL_NAMEMAP *namemap, const char *name);
 void ossl_namemap_doall_names(const OSSL_NAMEMAP *namemap, int number,
                               void (*fn)(const char *name, void *data),
                               void *data);

=head1 DESCRIPTION

A B<OSSL_NAMEMAP> is a one-to-many number E<lt>-E<gt> names map, which
can be used to give any arbitrary set of names (any string) a unique
dynamic identity that is valid throughout the lifetime of the associated
library context.

ossl_namemap_new() and ossl_namemap_free() construct and destruct a
new B<OSSL_NAMEMAP>.
This is suitable to use when the B<OSSL_NAMEMAP> is embedded in other
structures, or should be independent for any reason.

ossl_namemap_stored() finds or auto-creates the default namemap in the
given library context.
The returned B<OSSL_NAMEMAP> can't be destructed using
ossl_namemap_free().

ossl_namemap_add() adds a new name to the namemap if it's not already
present.
If the given I<number> is zero, a new number will be allocated to
identify this I<name>.
If the given I<number> is non-zero, the I<name> is added to the set of
names already associated with that number.

ossl_namemap_name2num() finds the number corresponding to the given
I<name>.

ossl_namemap_doall_names() walks through all names associated with
I<number> in the given I<namemap> and calls the function I<fn> for
each of them.
I<fn> is also passed the I<data> argument, which allows any caller to
pass extra data for that function to use.

=head1 RETURN VALUES

ossl_namemap_new() and ossl_namemap_stored() return the pointer to a
B<OSSL_NAMEMAP>, or NULL on error.

ossl_namemap_add() returns the number associated with the added
string, or zero on error.

ossl_namemap_num2names() returns a pointer to a NULL-terminated list of
pointers to the names corresponding to the given number, or NULL if
it's undefined in the given B<OSSL_NAMEMAP>.

ossl_namemap_name2num() returns the number corresponding to the given
name, or 0 if it's undefined in the given B<OSSL_NAMEMAP>.

=head1 NOTES

The result from ossl_namemap_num2names() isn't thread safe, other threads
dealing with the same namemap may cause the list of names to change
location.
It is therefore strongly recommended to only use the result in code
guarded by a thread lock.

=head1 HISTORY

The functions described here were all added in OpenSSL 3.0.

=head1 COPYRIGHT

Copyright 2019 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>.

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