fuzzer-api.cpp

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#include <tesseract/baseapi.h>
#include "leptonica/allheaders.h"
 
#include <libgen.h>     // for dirname
#include <cstdio>       // for printf
#include <cstdlib>      // for std::getenv, std::setenv
#include <string>       // for std::string
 
#ifndef TESSERACT_FUZZER_WIDTH
#define TESSERACT_FUZZER_WIDTH 100
#endif
 
#ifndef TESSERACT_FUZZER_HEIGHT
#define TESSERACT_FUZZER_HEIGHT 100
#endif
 
class BitReader {
 private:
  uint8_t const* data;
  size_t size;
  size_t shift;
 
 public:
  BitReader(const uint8_t* data, size_t size)
      : data(data), size(size), shift(0) {}
 
  int Read(void) {
    if (size == 0) {
      return 0;
    }
 
    const int ret = ((*data) >> shift) & 1;
 
    shift++;
    if (shift >= 8) {
      shift = 0;
      data++;
      size--;
    }
 
    return ret;
  }
};
 
static tesseract::TessBaseAPI* api = nullptr;
 
extern "C" int LLVMFuzzerInitialize(int* /*pArgc*/, char*** pArgv) {
  if (std::getenv("TESSDATA_PREFIX") == nullptr) {
    std::string binary_path = *pArgv[0];
    const std::string filepath = dirname(&binary_path[0]);
 
    const std::string tessdata_path = filepath + "/" + "tessdata";
    if (setenv("TESSDATA_PREFIX", tessdata_path.c_str(), 1) != 0) {
      printf("Setenv failed\n");
      std::abort();
    }
  }
 
  api = new tesseract::TessBaseAPI();
  if (api->Init(nullptr, "eng") != 0) {
    printf("Cannot initialize API\n");
    abort();
  }
 
  /* Silence output */
  api->SetVariable("debug_file", "/dev/null");
 
  return 0;
}
 
static PIX* createPix(BitReader& BR, const size_t width, const size_t height) {
  Pix* pix = pixCreate(width, height, 1);
 
  if (pix == nullptr) {
    printf("pix creation failed\n");
    abort();
  }
 
  for (size_t i = 0; i < width; i++) {
    for (size_t j = 0; j < height; j++) {
      pixSetPixel(pix, i, j, BR.Read());
    }
  }
 
  return pix;
}
 
extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
  BitReader BR(data, size);
 
  auto pix = createPix(BR, TESSERACT_FUZZER_WIDTH, TESSERACT_FUZZER_HEIGHT);
 
  api->SetImage(pix);
 
  char* outText = api->GetUTF8Text();
 
  pixDestroy(&pix);
  delete[] outText;
 
  return 0;
}