mps_reader.h

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/*
 *  Copyright The Mbed TLS Contributors
 *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
 */
 
#ifndef MBEDTLS_READER_H
#define MBEDTLS_READER_H
 
#include <stdio.h>
 
#include "mps_common.h"
#include "mps_error.h"
 
struct mbedtls_mps_reader;
typedef struct mbedtls_mps_reader mbedtls_mps_reader;
 
/*
 * Structure definitions
 */
 
struct mbedtls_mps_reader {
    unsigned char *frag;  
    mbedtls_mps_stored_size_t frag_len;
    mbedtls_mps_stored_size_t commit;
    mbedtls_mps_stored_size_t end;
    mbedtls_mps_stored_size_t pending;
    /* The accumulator is only needed if we need to be able to pause
     * the reader. A few bytes could be saved by moving this to a
     * separate struct and using a pointer here. */
 
    unsigned char *acc;   
    mbedtls_mps_stored_size_t acc_len;
    mbedtls_mps_stored_size_t acc_available;
    union {
        mbedtls_mps_stored_size_t acc_remaining;
        mbedtls_mps_stored_size_t frag_offset;
    } acc_share;
};
 
/*
 * API organization:
 * A reader object is usually prepared and maintained
 * by some lower layer and passed for usage to an upper
 * layer, and the API naturally splits according to which
 * layer is supposed to use the respective functions.
 */
 
/*
 * Maintenance API (Lower layer)
 */
 
int mbedtls_mps_reader_init(mbedtls_mps_reader *reader,
                            unsigned char *acc,
                            mbedtls_mps_size_t acc_len);
 
int mbedtls_mps_reader_free(mbedtls_mps_reader *reader);
 
int mbedtls_mps_reader_feed(mbedtls_mps_reader *reader,
                            unsigned char *buf,
                            mbedtls_mps_size_t buflen);
 
int mbedtls_mps_reader_reclaim(mbedtls_mps_reader *reader,
                               int *paused);
 
/*
 * Usage API (Upper layer)
 */
 
int mbedtls_mps_reader_get(mbedtls_mps_reader *reader,
                           mbedtls_mps_size_t desired,
                           unsigned char **buffer,
                           mbedtls_mps_size_t *buflen);
 
int mbedtls_mps_reader_commit(mbedtls_mps_reader *reader);
 
#endif /* MBEDTLS_READER_H */