src/test_utils.cpp

#include <zlib.h>
#include <test_utils.hpp>
#include <cstring>

bool gzipInflate(const std::string& compressedBytes,
                 std::string& uncompressedBytes) {
  if (compressedBytes.size() == 0) {
    uncompressedBytes = compressedBytes;
    return true;
  }

  uncompressedBytes.clear();

  unsigned full_length = compressedBytes.size();
  unsigned half_length = compressedBytes.size() / 2;

  unsigned uncompLength = full_length;
  char* uncomp = (char*)calloc(sizeof(char), uncompLength);

  z_stream strm;
  strm.next_in = (Bytef*)compressedBytes.c_str();
  strm.avail_in = compressedBytes.size();
  strm.total_out = 0;
  strm.zalloc = Z_NULL;
  strm.zfree = Z_NULL;

  bool done = false;

  if (inflateInit2(&strm, (16 + MAX_WBITS)) != Z_OK) {
    free(uncomp);
    return false;
  }

  while (!done) {
    // If our output buffer is too small
    if (strm.total_out >= uncompLength) {
      // Increase size of output buffer
      char* uncomp2 = (char*)calloc(sizeof(char), uncompLength + half_length);
      std::memcpy(uncomp2, uncomp, uncompLength);
      uncompLength += half_length;
      free(uncomp);
      uncomp = uncomp2;
    }

    strm.next_out = (Bytef*)(uncomp + strm.total_out);
    strm.avail_out = uncompLength - strm.total_out;

    // Inflate another chunk.
    int err = inflate(&strm, Z_SYNC_FLUSH);
    if (err == Z_STREAM_END)
      done = true;
    else if (err != Z_OK) {
      break;
    }
  }

  if (inflateEnd(&strm) != Z_OK) {
    free(uncomp);
    return false;
  }

  for (size_t i = 0; i < strm.total_out; ++i) {
    uncompressedBytes += uncomp[i];
  }
  free(uncomp);
  return true;
}