doc/man3/OSSL_DECODER.pod - third_party/openssl - Git at Google

 =pod

 =head1 NAME

 OSSL_DECODER,
 OSSL_DECODER_fetch,
 OSSL_DECODER_up_ref,
 OSSL_DECODER_free,
 OSSL_DECODER_get0_provider,
 OSSL_DECODER_get0_properties,
 OSSL_DECODER_is_a,
 OSSL_DECODER_get0_name,
 OSSL_DECODER_get0_description,
 OSSL_DECODER_do_all_provided,
 OSSL_DECODER_names_do_all,
 OSSL_DECODER_gettable_params,
 OSSL_DECODER_get_params
 - Decoder method routines

 =head1 SYNOPSIS

  #include <openssl/decoder.h>

  typedef struct ossl_decoder_st OSSL_DECODER;

  OSSL_DECODER *OSSL_DECODER_fetch(OSSL_LIB_CTX *ctx, const char *name,
                                   const char *properties);
  int OSSL_DECODER_up_ref(OSSL_DECODER *decoder);
  void OSSL_DECODER_free(OSSL_DECODER *decoder);
  const OSSL_PROVIDER *OSSL_DECODER_get0_provider(const OSSL_DECODER *decoder);
  const char *OSSL_DECODER_get0_properties(const OSSL_DECODER *decoder);
  int OSSL_DECODER_is_a(const OSSL_DECODER *decoder, const char *name);
  const char *OSSL_DECODER_get0_name(const OSSL_DECODER *decoder);
  const char *OSSL_DECODER_get0_description(const OSSL_DECODER *decoder);
  void OSSL_DECODER_do_all_provided(OSSL_LIB_CTX *libctx,
                                    void (*fn)(OSSL_DECODER *decoder, void *arg),
                                    void *arg);
  int OSSL_DECODER_names_do_all(const OSSL_DECODER *decoder,
                                void (*fn)(const char *name, void *data),
                                void *data);
  const OSSL_PARAM *OSSL_DECODER_gettable_params(OSSL_DECODER *decoder);
  int OSSL_DECODER_get_params(OSSL_DECODER_CTX *ctx, const OSSL_PARAM params[]);

 =head1 DESCRIPTION

 B<OSSL_DECODER> is a method for decoders, which know how to
 decode encoded data into an object of some type that the rest
 of OpenSSL knows how to handle.

 OSSL_DECODER_fetch() looks for an algorithm within the provider that
 has been loaded into the B<OSSL_LIB_CTX> given by I<ctx>, having the
 name given by I<name> and the properties given by I<properties>.
 The I<name> determines what type of object the fetched decoder
 method is expected to be able to decode, and the properties are
 used to determine the expected output type.
 For known properties and the values they may have, please have a look
 in L<provider-encoder(7)/Names and properties>.

 OSSL_DECODER_up_ref() increments the reference count for the given
 I<decoder>.

 OSSL_DECODER_free() decrements the reference count for the given
 I<decoder>, and when the count reaches zero, frees it.

 OSSL_DECODER_get0_provider() returns the provider of the given
 I<decoder>.

 OSSL_DECODER_get0_properties() returns the property definition associated
 with the given I<decoder>.

 OSSL_DECODER_is_a() checks if I<decoder> is an implementation
 of an algorithm that's identifiable with I<name>.

 OSSL_DECODER_get0_name() returns the name used to fetch the given I<decoder>.

 OSSL_DECODER_get0_description() returns a description of the I<decoder>, meant
 for display and human consumption.  The description is at the discretion
 of the I<decoder> implementation.

 OSSL_DECODER_names_do_all() traverses all names for the given
 I<decoder>, and calls I<fn> with each name and I<data> as arguments.

 OSSL_DECODER_do_all_provided() traverses all decoder
 implementations by all activated providers in the library context
 I<libctx>, and for each of the implementations, calls I<fn> with the
 implementation method and I<arg> as arguments.

 OSSL_DECODER_gettable_params() returns an L<OSSL_PARAM(3)>
 array of parameter descriptors.

 OSSL_DECODER_get_params() attempts to get parameters specified
 with an L<OSSL_PARAM(3)> array I<params>.  Parameters that the
 implementation doesn't recognise should be ignored.

 =head1 RETURN VALUES

 OSSL_DECODER_fetch() returns a pointer to an OSSL_DECODER object,
 or NULL on error.

 OSSL_DECODER_up_ref() returns 1 on success, or 0 on error.

 OSSL_DECODER_free() doesn't return any value.

 OSSL_DECODER_get0_provider() returns a pointer to a provider object, or
 NULL on error.

 OSSL_DECODER_get0_properties() returns a pointer to a property
 definition string, or NULL on error.

 OSSL_DECODER_is_a() returns 1 if I<decoder> was identifiable,
 otherwise 0.

 OSSL_DECODER_get0_name() returns the algorithm name from the provided
 implementation for the given I<decoder>. Note that the I<decoder> may have
 multiple synonyms associated with it. In this case the first name from the
 algorithm definition is returned. Ownership of the returned string is retained
 by the I<decoder> object and should not be freed by the caller.

 OSSL_DECODER_get0_description() returns a pointer to a description, or NULL if
 there isn't one.

 OSSL_DECODER_names_do_all() returns 1 if the callback was called for all
 names. A return value of 0 means that the callback was not called for any names.

 =head1 NOTES

 OSSL_DECODER_fetch() may be called implicitly by other fetching
 functions, using the same library context and properties.
 Any other API that uses keys will typically do this.

 =head1 EXAMPLES

 To list all decoders in a provider to a bio_out:

  static void collect_decoders(OSSL_DECODER *decoder, void *stack)
  {
      STACK_OF(OSSL_DECODER) *decoder_stack = stack;

      sk_OSSL_DECODER_push(decoder_stack, decoder);
      OSSL_DECODER_up_ref(decoder);
  }

  void print_name(const char *name, void *vdata)
  {
      BIO *bio = vdata;

      BIO_printf(bio, "%s ", name);
  }


  STACK_OF(OSSL_DECODER) *decoders;
  int i;

  decoders = sk_OSSL_DECODER_new_null();

  BIO_printf(bio_out, "DECODERs provided by %s:\n", provider);
  OSSL_DECODER_do_all_provided(NULL, collect_decoders,
                               decoders);

  for (i = 0; i < sk_OSSL_DECODER_num(decoders); i++) {
      OSSL_DECODER *decoder = sk_OSSL_DECODER_value(decoders, i);

      if (strcmp(OSSL_PROVIDER_get0_name(OSSL_DECODER_get0_provider(decoder)),
                 provider) != 0)
          continue;

      if (OSSL_DECODER_names_do_all(decoder, print_name, bio_out))
             BIO_printf(bio_out, "\n");
  }
  sk_OSSL_DECODER_pop_free(decoders, OSSL_DECODER_free);

 =head1 SEE ALSO

 L<provider(7)>, L<OSSL_DECODER_CTX(3)>, L<OSSL_DECODER_from_bio(3)>,
 L<OSSL_DECODER_CTX_new_for_pkey(3)>, L<OSSL_LIB_CTX(3)>

 =head1 HISTORY

 The functions described here were added in OpenSSL 3.0.

 =head1 COPYRIGHT

 Copyright 2020-2021 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
	=pod

	=head1 NAME

	OSSL_DECODER,
	OSSL_DECODER_fetch,
	OSSL_DECODER_up_ref,
	OSSL_DECODER_free,
	OSSL_DECODER_get0_provider,
	OSSL_DECODER_get0_properties,
	OSSL_DECODER_is_a,
	OSSL_DECODER_get0_name,
	OSSL_DECODER_get0_description,
	OSSL_DECODER_do_all_provided,
	OSSL_DECODER_names_do_all,
	OSSL_DECODER_gettable_params,
	OSSL_DECODER_get_params
	- Decoder method routines

	=head1 SYNOPSIS

	#include <openssl/decoder.h>

	typedef struct ossl_decoder_st OSSL_DECODER;

	OSSL_DECODER OSSL_DECODER_fetch(OSSL_LIB_CTX ctx, const char *name,
	const char *properties);
	int OSSL_DECODER_up_ref(OSSL_DECODER *decoder);
	void OSSL_DECODER_free(OSSL_DECODER *decoder);
	const OSSL_PROVIDER OSSL_DECODER_get0_provider(const OSSL_DECODER decoder);
	const char OSSL_DECODER_get0_properties(const OSSL_DECODER decoder);
	int OSSL_DECODER_is_a(const OSSL_DECODER decoder, const char name);
	const char OSSL_DECODER_get0_name(const OSSL_DECODER decoder);
	const char OSSL_DECODER_get0_description(const OSSL_DECODER decoder);
	void OSSL_DECODER_do_all_provided(OSSL_LIB_CTX *libctx,
	void (fn)(OSSL_DECODER decoder, void *arg),
	void *arg);
	int OSSL_DECODER_names_do_all(const OSSL_DECODER *decoder,
	void (fn)(const char name, void *data),
	void *data);
	const OSSL_PARAM OSSL_DECODER_gettable_params(OSSL_DECODER decoder);
	int OSSL_DECODER_get_params(OSSL_DECODER_CTX *ctx, const OSSL_PARAM params[]);

	=head1 DESCRIPTION

	B<OSSL_DECODER> is a method for decoders, which know how to
	decode encoded data into an object of some type that the rest
	of OpenSSL knows how to handle.

	OSSL_DECODER_fetch() looks for an algorithm within the provider that
	has been loaded into the B<OSSL_LIB_CTX> given by I<ctx>, having the
	name given by I<name> and the properties given by I<properties>.
	The I<name> determines what type of object the fetched decoder
	method is expected to be able to decode, and the properties are
	used to determine the expected output type.
	For known properties and the values they may have, please have a look
	in L<provider-encoder(7)/Names and properties>.

	OSSL_DECODER_up_ref() increments the reference count for the given
	I<decoder>.

	OSSL_DECODER_free() decrements the reference count for the given
	I<decoder>, and when the count reaches zero, frees it.

	OSSL_DECODER_get0_provider() returns the provider of the given
	I<decoder>.

	OSSL_DECODER_get0_properties() returns the property definition associated
	with the given I<decoder>.

	OSSL_DECODER_is_a() checks if I<decoder> is an implementation
	of an algorithm that's identifiable with I<name>.

	OSSL_DECODER_get0_name() returns the name used to fetch the given I<decoder>.

	OSSL_DECODER_get0_description() returns a description of the I<decoder>, meant
	for display and human consumption. The description is at the discretion
	of the I<decoder> implementation.

	OSSL_DECODER_names_do_all() traverses all names for the given
	I<decoder>, and calls I<fn> with each name and I<data> as arguments.

	OSSL_DECODER_do_all_provided() traverses all decoder
	implementations by all activated providers in the library context
	I<libctx>, and for each of the implementations, calls I<fn> with the
	implementation method and I<arg> as arguments.

	OSSL_DECODER_gettable_params() returns an L<OSSL_PARAM(3)>
	array of parameter descriptors.

	OSSL_DECODER_get_params() attempts to get parameters specified
	with an L<OSSL_PARAM(3)> array I<params>. Parameters that the
	implementation doesn't recognise should be ignored.

	=head1 RETURN VALUES

	OSSL_DECODER_fetch() returns a pointer to an OSSL_DECODER object,
	or NULL on error.

	OSSL_DECODER_up_ref() returns 1 on success, or 0 on error.

	OSSL_DECODER_free() doesn't return any value.

	OSSL_DECODER_get0_provider() returns a pointer to a provider object, or
	NULL on error.

	OSSL_DECODER_get0_properties() returns a pointer to a property
	definition string, or NULL on error.

	OSSL_DECODER_is_a() returns 1 if I<decoder> was identifiable,
	otherwise 0.

	OSSL_DECODER_get0_name() returns the algorithm name from the provided
	implementation for the given I<decoder>. Note that the I<decoder> may have
	multiple synonyms associated with it. In this case the first name from the
	algorithm definition is returned. Ownership of the returned string is retained
	by the I<decoder> object and should not be freed by the caller.

	OSSL_DECODER_get0_description() returns a pointer to a description, or NULL if
	there isn't one.

	OSSL_DECODER_names_do_all() returns 1 if the callback was called for all
	names. A return value of 0 means that the callback was not called for any names.

	=head1 NOTES

	OSSL_DECODER_fetch() may be called implicitly by other fetching
	functions, using the same library context and properties.
	Any other API that uses keys will typically do this.

	=head1 EXAMPLES

	To list all decoders in a provider to a bio_out:

	static void collect_decoders(OSSL_DECODER decoder, void stack)
	{
	STACK_OF(OSSL_DECODER) *decoder_stack = stack;

	sk_OSSL_DECODER_push(decoder_stack, decoder);
	OSSL_DECODER_up_ref(decoder);
	}

	void print_name(const char name, void vdata)
	{
	BIO *bio = vdata;

	BIO_printf(bio, "%s ", name);
	}


	STACK_OF(OSSL_DECODER) *decoders;
	int i;

	decoders = sk_OSSL_DECODER_new_null();

	BIO_printf(bio_out, "DECODERs provided by %s:\n", provider);
	OSSL_DECODER_do_all_provided(NULL, collect_decoders,
	decoders);

	for (i = 0; i < sk_OSSL_DECODER_num(decoders); i++) {
	OSSL_DECODER *decoder = sk_OSSL_DECODER_value(decoders, i);

	if (strcmp(OSSL_PROVIDER_get0_name(OSSL_DECODER_get0_provider(decoder)),
	provider) != 0)
	continue;

	if (OSSL_DECODER_names_do_all(decoder, print_name, bio_out))
	BIO_printf(bio_out, "\n");
	}
	sk_OSSL_DECODER_pop_free(decoders, OSSL_DECODER_free);

	=head1 SEE ALSO

	L<provider(7)>, L<OSSL_DECODER_CTX(3)>, L<OSSL_DECODER_from_bio(3)>,
	L<OSSL_DECODER_CTX_new_for_pkey(3)>, L<OSSL_LIB_CTX(3)>

	=head1 HISTORY

	The functions described here were added in OpenSSL 3.0.

	=head1 COPYRIGHT

	Copyright 2020-2021 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