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      1 /*
      2  * Copyright (c) Meta Platforms, Inc. and affiliates.
      3  * All rights reserved.
      4  *
      5  * This source code is licensed under both the BSD-style license (found in the
      6  * LICENSE file in the root directory of this source tree) and the GPLv2 (found
      7  * in the COPYING file in the root directory of this source tree).
      8  * You may select, at your option, one of the above-listed licenses.
      9  */
     10 
     11 /**
     12  * Helper APIs for generating random data from input data stream.
     13  The producer reads bytes from the end of the input and appends them together
     14  to generate  a random number in the requested range. If it runs out of input
     15  data, it will keep returning the same value (min) over and over again.
     16 
     17  */
     18 
     19 #ifndef FUZZ_DATA_PRODUCER_H
     20 #define FUZZ_DATA_PRODUCER_H
     21 
     22 #include <stddef.h>
     23 #include <stdint.h>
     24 #include <stdio.h>
     25 #include <stdlib.h>
     26 
     27 
     28 /* Struct used for maintaining the state of the data */
     29 typedef struct FUZZ_dataProducer_s FUZZ_dataProducer_t;
     30 
     31 /* Returns a data producer state struct. Use for producer initialization. */
     32 FUZZ_dataProducer_t *FUZZ_dataProducer_create(const uint8_t *data, size_t size);
     33 
     34 /* Frees the data producer */
     35 void FUZZ_dataProducer_free(FUZZ_dataProducer_t *producer);
     36 
     37 /* Returns value between [min, max] */
     38 uint32_t FUZZ_dataProducer_uint32Range(FUZZ_dataProducer_t *producer, uint32_t min,
     39                                   uint32_t max);
     40 
     41 /* Returns a uint32 value */
     42 uint32_t FUZZ_dataProducer_uint32(FUZZ_dataProducer_t *producer);
     43 
     44 /* Returns a signed value between [min, max] */
     45 int32_t FUZZ_dataProducer_int32Range(FUZZ_dataProducer_t *producer,
     46                                     int32_t min, int32_t max);
     47 
     48 /* Returns the size of the remaining bytes of data in the producer */
     49 size_t FUZZ_dataProducer_remainingBytes(FUZZ_dataProducer_t *producer);
     50 
     51 /* Rolls back the data producer state to have remainingBytes remaining */
     52 void FUZZ_dataProducer_rollBack(FUZZ_dataProducer_t *producer, size_t remainingBytes);
     53 
     54 /* Returns true if the data producer is out of bytes */
     55 int FUZZ_dataProducer_empty(FUZZ_dataProducer_t *producer);
     56 
     57 /* Restricts the producer to only the last newSize bytes of data.
     58 If newSize > current data size, nothing happens. Returns the number of bytes
     59 the producer won't use anymore, after contracting. */
     60 size_t FUZZ_dataProducer_contract(FUZZ_dataProducer_t *producer, size_t newSize);
     61 
     62 /* Restricts the producer to use only the last X bytes of data, where X is
     63  a random number in the interval [0, data_size]. Returns the size of the
     64  remaining data the producer won't use anymore (the prefix). */
     65 size_t FUZZ_dataProducer_reserveDataPrefix(FUZZ_dataProducer_t *producer);
     66 #endif // FUZZ_DATA_PRODUCER_H
     67