/*
   american fuzzy lop++ - a trivial program to test the build
   --------------------------------------------------------
   Originally written by Michal Zalewski
   Copyright 2014 Google Inc. All rights reserved.
   Copyright 2019-2024 AFLplusplus Project. All rights reserved.
   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at:
     http://www.apache.org/licenses/LICENSE-2.0
 */

#include <fcntl.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#define IGNORED_RETURN(x) (void)!(x)

const uint32_t crc32_tab[] = {

    0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f,
    0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
    0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2,
    0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
    0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
    0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,
    0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, 0x35b5a8fa, 0x42b2986c,
    0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
    0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423,
    0xcfba9599, 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
    0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, 0x01db7106,
    0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
    0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d,
    0x91646c97, 0xe6635c01, 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,
    0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
    0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
    0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7,
    0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,
    0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa,
    0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
    0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81,
    0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,
    0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, 0xe3630b12, 0x94643b84,
    0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
    0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
    0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,
    0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, 0xd6d6a3e8, 0xa1d1937e,
    0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
    0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55,
    0x316e8eef, 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
    0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, 0xb2bd0b28,
    0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
    0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f,
    0x72076785, 0x05005713, 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,
    0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
    0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
    0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69,
    0x616bffd3, 0x166ccf45, 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
    0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc,
    0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
    0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693,
    0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,
    0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d};

uint32_t crc32(const void *buf, size_t size) {

  const uint8_t *p = buf;
  uint32_t       crc;
  crc = ~0U;
  while (size--)
    crc = crc32_tab[(crc ^ *p++) & 0xFF] ^ (crc >> 8);
  return crc ^ ~0U;

}

/*
 * Don't you hate those contrived examples which CRC their data. We can use
 * FRIDA to patch this function out and always return success. Otherwise, we
 * could change it to actually correct the checksum.
 */
int crc32_check(char *buf, int len) {

  if (len < sizeof(uint32_t)) { return 0; }
  uint32_t expected = *(uint32_t *)&buf[len - sizeof(uint32_t)];
  uint32_t calculated = crc32(buf, len - sizeof(uint32_t));
  return expected == calculated;

}

/*
 * So you've found a really boring bug in an earlier campaign which results in
 * a NULL dereference or something like that. That bug can get in the way,
 * causing the persistent loop to exit whenever it is triggered, and can also
 * cloud your output unnecessarily. Again, we can use FRIDA to patch it out.
 */
void some_boring_bug(char c) {

  switch (c) {

    case 'A' ... 'Z':
    case 'a' ... 'z':
      __builtin_trap();
      break;

  }

}

extern void some_boring_bug2(char c);

__asm__(
    ".text                                 \n"
    "some_boring_bug2:                     \n"
    ".global some_boring_bug2              \n"
    ".type some_boring_bug2, @function     \n"
    "mov %edi, %eax                        \n"
    "cmp $0xb4, %al                        \n"
    "jne ok                                \n"
    "ud2                                   \n"
    "ok:                                   \n"
    "ret                                   \n");

void LLVMFuzzerTestOneInput(char *buf, int len) {

  if (!crc32_check(buf, len)) return;

  some_boring_bug(buf[0]);
  some_boring_bug2(buf[0]);

  if (buf[0] == '0') {

    printf("Looks like a zero to me!\n");

  } else if (buf[0] == '1') {

    printf("Pretty sure that is a one!\n");

  } else if (buf[0] == '2') {

    printf("Oh we, weren't expecting that!");
    __builtin_trap();

  } else

    printf("Neither one or zero? How quaint!\n");

}

int main(int argc, char **argv) {

  int    fd = -1;
  off_t  len;
  char  *buf = NULL;
  size_t n_read;
  int    result = -1;

  if (argc != 2) { return 1; }

  printf("Running: %s\n", argv[1]);

  fd = open(argv[1], O_RDONLY);
  if (fd < 0) { return 1; }

  len = lseek(fd, 0, SEEK_END);
  if (len < 0) { return 1; }

  if (lseek(fd, 0, SEEK_SET) != 0) { return 1; }

  buf = malloc(len);
  if (buf == NULL) { return 1; }

  n_read = read(fd, buf, len);
  if (n_read != len) { return 1; }

  printf("Running:    %s: (%zd bytes)\n", argv[1], n_read);

  LLVMFuzzerTestOneInput(buf, len);
  printf("Done:    %s: (%zd bytes)\n", argv[1], n_read);

  return 0;

}

