#include <stdio.h>

#include <stddef.h>

#include <stdint.h>

#include <string.h>

#include <assert.h>

#include <stdlib.h>

#include <inttypes.h>

#include "zlib.h"

#define CHECK_ERR(err, msg) { \

    if (err != Z_OK) { \

        fprintf(stderr, "%s error: %d\n", msg, err); \

        return 0; \

    } \

}

static const uint8_t *data;

static size_t dataLen;

static alloc_func zalloc = NULL;

static free_func zfree = NULL;

/* ===========================================================================

 * Test deflate() with small buffers

 */

int test_deflate(unsigned char *compr, size_t comprLen) {

  z_stream c_stream; /* compression stream */

  int err;

  unsigned long len = dataLen;

  c_stream.zalloc = zalloc;

  c_stream.zfree = zfree;

  c_stream.opaque = (void *)0;

  err = deflateInit(&c_stream, Z_DEFAULT_COMPRESSION);

  CHECK_ERR(err, "deflateInit");

  c_stream.next_in = (Bytef *)data;

  c_stream.next_out = compr;

  while (c_stream.total_in != len && c_stream.total_out < comprLen) {

    c_stream.avail_in = c_stream.avail_out = 1; /* force small buffers */

    err = deflate(&c_stream, Z_NO_FLUSH);

    CHECK_ERR(err, "deflate small 1");

  }

  /* Finish the stream, still forcing small buffers: */

  for (;;) {

    c_stream.avail_out = 1;

    err = deflate(&c_stream, Z_FINISH);

    if (err == Z_STREAM_END)

      break;

    CHECK_ERR(err, "deflate small 2");

  }

  err = deflateEnd(&c_stream);

  CHECK_ERR(err, "deflateEnd");

  return 0;

}

/* ===========================================================================

 * Test inflate() with small buffers

 */

int test_inflate(unsigned char *compr, size_t comprLen, unsigned char *uncompr,

                  size_t uncomprLen) {

  int err;

  z_stream d_stream; /* decompression stream */

  d_stream.zalloc = zalloc;

  d_stream.zfree = zfree;

  d_stream.opaque = (void *)0;

  d_stream.next_in = compr;

  d_stream.avail_in = 0;

  d_stream.next_out = uncompr;

  err = inflateInit(&d_stream);

  CHECK_ERR(err, "inflateInit");

  while (d_stream.total_out < uncomprLen && d_stream.total_in < comprLen) {

    d_stream.avail_in = d_stream.avail_out = 1; /* force small buffers */

    err = inflate(&d_stream, Z_NO_FLUSH);

    if (err == Z_STREAM_END)

      break;

    CHECK_ERR(err, "inflate");

  }

  err = inflateEnd(&d_stream);

  CHECK_ERR(err, "inflateEnd");

  if (memcmp(uncompr, data, dataLen)) {

    fprintf(stderr, "bad inflate\n");

    return 0;

  }

  return 0;

}

int LLVMFuzzerTestOneInput(const uint8_t *d, size_t size) {

  size_t comprLen = compressBound(size);

  size_t uncomprLen = size;

  uint8_t *compr, *uncompr;

  /* Discard inputs larger than 1Mb. */

  static size_t kMaxSize = 1024 * 1024;

  if (size < 1 || size > kMaxSize)

    return 0;

  data = d;

  dataLen = size;

  compr = (uint8_t *)calloc(1, comprLen);

  uncompr = (uint8_t *)calloc(1, uncomprLen);

  test_deflate(compr, comprLen);

  test_inflate(compr, comprLen, uncompr, uncomprLen);

  free(compr);

  free(uncompr);

  /* This function must return 0. */

  return 0;

}