mirror of
https://github.com/openssl/openssl.git
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222 lines
7.9 KiB
Plaintext
222 lines
7.9 KiB
Plaintext
=pod
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=head1 NAME
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OSSL_ENCODER_CTX,
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OSSL_ENCODER_CTX_new,
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OSSL_ENCODER_settable_ctx_params,
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OSSL_ENCODER_CTX_set_params,
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OSSL_ENCODER_CTX_free,
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OSSL_ENCODER_CTX_set_selection,
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OSSL_ENCODER_CTX_set_output_type,
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OSSL_ENCODER_CTX_set_output_structure,
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OSSL_ENCODER_CTX_add_encoder,
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OSSL_ENCODER_CTX_add_extra,
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OSSL_ENCODER_CTX_get_num_encoders,
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OSSL_ENCODER_INSTANCE,
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OSSL_ENCODER_INSTANCE_get_encoder,
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OSSL_ENCODER_INSTANCE_get_encoder_ctx,
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OSSL_ENCODER_INSTANCE_get_output_type,
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OSSL_ENCODER_INSTANCE_get_output_structure,
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OSSL_ENCODER_CONSTRUCT,
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OSSL_ENCODER_CLEANUP,
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OSSL_ENCODER_CTX_set_construct,
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OSSL_ENCODER_CTX_set_construct_data,
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OSSL_ENCODER_CTX_set_cleanup
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- Encoder context routines
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=head1 SYNOPSIS
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#include <openssl/encoder.h>
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typedef struct ossl_encoder_ctx_st OSSL_ENCODER_CTX;
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OSSL_ENCODER_CTX *OSSL_ENCODER_CTX_new();
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const OSSL_PARAM *OSSL_ENCODER_settable_ctx_params(OSSL_ENCODER *encoder);
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int OSSL_ENCODER_CTX_set_params(OSSL_ENCODER_CTX *ctx,
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const OSSL_PARAM params[]);
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void OSSL_ENCODER_CTX_free(OSSL_ENCODER_CTX *ctx);
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int OSSL_ENCODER_CTX_set_selection(OSSL_ENCODER_CTX *ctx, int selection);
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int OSSL_ENCODER_CTX_set_output_type(OSSL_ENCODER_CTX *ctx,
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const char *output_type);
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int OSSL_ENCODER_CTX_set_output_structure(OSSL_ENCODER_CTX *ctx,
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const char *output_structure);
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int OSSL_ENCODER_CTX_add_encoder(OSSL_ENCODER_CTX *ctx, OSSL_ENCODER *encoder);
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int OSSL_ENCODER_CTX_add_extra(OSSL_ENCODER_CTX *ctx,
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OSSL_LIB_CTX *libctx, const char *propq);
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int OSSL_ENCODER_CTX_get_num_encoders(OSSL_ENCODER_CTX *ctx);
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typedef struct ossl_encoder_instance_st OSSL_ENCODER_INSTANCE;
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OSSL_ENCODER *
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OSSL_ENCODER_INSTANCE_get_encoder(OSSL_ENCODER_INSTANCE *encoder_inst);
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void *
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OSSL_ENCODER_INSTANCE_get_encoder_ctx(OSSL_ENCODER_INSTANCE *encoder_inst);
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const char *
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OSSL_ENCODER_INSTANCE_get_output_type(OSSL_ENCODER_INSTANCE *encoder_inst);
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const char *
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OSSL_ENCODER_INSTANCE_get_output_structure(OSSL_ENCODER_INSTANCE *encoder_inst);
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typedef const void *OSSL_ENCODER_CONSTRUCT(OSSL_ENCODER_INSTANCE *encoder_inst,
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void *construct_data);
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typedef void OSSL_ENCODER_CLEANUP(void *construct_data);
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int OSSL_ENCODER_CTX_set_construct(OSSL_ENCODER_CTX *ctx,
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OSSL_ENCODER_CONSTRUCT *construct);
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int OSSL_ENCODER_CTX_set_construct_data(OSSL_ENCODER_CTX *ctx,
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void *construct_data);
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int OSSL_ENCODER_CTX_set_cleanup(OSSL_ENCODER_CTX *ctx,
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OSSL_ENCODER_CLEANUP *cleanup);
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=head1 DESCRIPTION
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Encoding an input object to the desired encoding may be done with a chain of
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encoder implementations, which means that the output from one encoder may be
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the input for the next in the chain. The B<OSSL_ENCODER_CTX> holds all the
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data about these encoders. This allows having generic format encoders such
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as DER to PEM, as well as more specialized encoders like RSA to DER.
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The final output type must be given, and a chain of encoders must end with
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an implementation that produces that output type.
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At the beginning of the encoding process, a constructor provided by the
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caller is called to ensure that there is an appropriate provider-side object
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to start with.
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The constructor is set with OSSL_ENCODER_CTX_set_construct().
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B<OSSL_ENCODER_INSTANCE> is an opaque structure that contains data about the
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encoder that is going to be used, and that may be useful for the
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constructor. There are some functions to extract data from this type,
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described in L</Constructor> below.
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=head2 Functions
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OSSL_ENCODER_CTX_new() creates a B<OSSL_ENCODER_CTX>.
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OSSL_ENCODER_settable_ctx_params() returns an L<OSSL_PARAM(3)>
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array of parameter descriptors.
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OSSL_ENCODER_CTX_set_params() attempts to set parameters specified
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with an L<OSSL_PARAM(3)> array I<params>. Parameters that the
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implementation doesn't recognise should be ignored.
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OSSL_ENCODER_CTX_free() frees the given context I<ctx>.
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OSSL_ENCODER_CTX_add_encoder() populates the B<OSSL_ENCODER_CTX>
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I<ctx> with a encoder, to be used to encode an input object.
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OSSL_ENCODER_CTX_add_extra() finds encoders that further encodes output
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from already added encoders, and adds them as well. This is used to build
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encoder chains.
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OSSL_ENCODER_CTX_set_output_type() sets the ending output type. This must
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be specified, and determines if a complete encoder chain is available.
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OSSL_ENCODER_CTX_set_output_structure() sets the desired output structure.
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This may be used to determines what encoder implementations may be used.
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Depending on the type of object being encoded, the output structure may
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not be relevant.
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OSSL_ENCODER_CTX_get_num_encoders() gets the number of encoders currently
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added to the context I<ctx>.
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OSSL_ENCODER_CTX_set_construct() sets the constructor I<construct>.
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OSSL_ENCODER_CTX_set_construct_data() sets the constructor data that is
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passed to the constructor every time it's called.
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OSSL_ENCODER_CTX_set_cleanup() sets the constructor data I<cleanup>
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function. This is called by L<OSSL_ENCODER_CTX_free(3)>.
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=head2 Constructor
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A B<OSSL_ENCODER_CONSTRUCT> gets the following arguments:
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=over 4
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=item I<encoder_inst>
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The B<OSSL_ENCODER_INSTANCE> for the encoder from which the constructor gets
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its data.
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=item I<construct_data>
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The pointer that was set with OSSL_ENCODE_CTX_set_construct_data().
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=back
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The constructor is expected to return a valid (non-NULL) pointer to a
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provider-native object that can be used as first input of an encoding chain,
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or NULL to indicate that an error has occurred.
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These utility functions may be used by a constructor:
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OSSL_ENCODER_INSTANCE_get_encoder() can be used to get the encoder
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implementation of the encoder instance I<encoder_inst>.
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OSSL_ENCODER_INSTANCE_get_encoder_ctx() can be used to get the encoder
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implementation's provider context of the encoder instance I<encoder_inst>.
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OSSL_ENCODER_INSTANCE_get_output_type() can be used to get the output type
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for the encoder implementation of the encoder instance I<encoder_inst>.
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This will never be NULL.
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OSSL_ENCODER_INSTANCE_get_output_structure() can be used to get the output
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structure for the encoder implementation of the encoder instance
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I<encoder_inst>.
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This may be NULL.
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=head1 RETURN VALUES
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OSSL_ENCODER_CTX_new() returns a pointer to a B<OSSL_ENCODER_CTX>, or NULL
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if the context structure couldn't be allocated.
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OSSL_ENCODER_settable_ctx_params() returns an L<OSSL_PARAM(3)> array, or
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NULL if none is available.
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OSSL_ENCODER_CTX_set_params() returns 1 if all recognised parameters were
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valid, or 0 if one of them was invalid or caused some other failure in the
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implementation.
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OSSL_ENCODER_CTX_add_encoder(), OSSL_ENCODER_CTX_add_extra(),
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OSSL_ENCODER_CTX_set_construct(), OSSL_ENCODER_CTX_set_construct_data() and
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OSSL_ENCODER_CTX_set_cleanup() return 1 on success, or 0 on failure.
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OSSL_ENCODER_CTX_get_num_encoders() returns the current number of encoders.
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It returns 0 if I<ctx> is NULL.
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OSSL_ENCODER_INSTANCE_get_encoder() returns an B<OSSL_ENCODER> pointer on
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success, or NULL on failure.
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OSSL_ENCODER_INSTANCE_get_encoder_ctx() returns a provider context pointer on
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success, or NULL on failure.
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OSSL_ENCODER_INSTANCE_get_output_type() returns a string with the name of the
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input type, if relevant. NULL is a valid returned value.
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OSSL_ENCODER_INSTANCE_get_output_type() returns a string with the name of the
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output type.
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OSSL_ENCODER_INSTANCE_get_output_structure() returns a string with the name
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of the output structure.
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=head1 SEE ALSO
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L<provider(7)>, L<OSSL_ENCODER(3)>
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=head1 HISTORY
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The functions described here were added in OpenSSL 3.0.
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=head1 COPYRIGHT
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Copyright 2019-2022 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the Apache License 2.0 (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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