contrib/fuzz/fuzzutil.h

tests: use environment variable indirectly

Using environment variable directly in heredoc python code will cause
syntax error at checking module importation by import-checker.py
strictly, because "$varname" is invalid in Python syntax. "$varname"
becomes valid after environment variable substitution by shell at
writing text into file.

Current import-checker.py overlooks code fragment changed in this
patch, because of a restriction below for a line starting code
fragment.

  - filename must be specified before limit mark

    NG: cat <<EOF > FILE.py
    OK: cat > FILE.py <<EOF

import-checker.py itself is fixed in subsequent patch.

#ifndef CONTRIB_FUZZ_FUZZUTIL_H
#define CONTRIB_FUZZ_FUZZUTIL_H
#include <iostream>
#include <memory>
#include <stdint.h>

/* Try and use std::optional, but failing that assume we'll have a
 * workable https://abseil.io/ install on the include path to get
 * their backport of std::optional. */
#ifdef __has_include
#if __has_include(<optional>) && __cplusplus >= 201703L
#include <optional>
#define CONTRIB_FUZZ_HAVE_STD_OPTIONAL
#endif
#endif
#ifdef CONTRIB_FUZZ_HAVE_STD_OPTIONAL
namespace contrib
{
using std::nullopt;
using std::optional;
} /* namespace contrib */
#else
#include "third_party/absl/types/optional.h"
namespace contrib
{
using absl::nullopt;
using absl::optional;
} /* namespace contrib */
#endif

/* set DEBUG to 1 for a few debugging prints, or 2 for a lot */
#define DEBUG 0
#define LOG(level)                                                             \
	if (level <= DEBUG)                                                    \
	std::cout

struct two_inputs {
	std::unique_ptr<char[]> right;
	size_t right_size;
	std::unique_ptr<char[]> left;
	size_t left_size;
};

/* Split a non-zero-length input into two inputs. */
contrib::optional<two_inputs> SplitInputs(const uint8_t *Data, size_t Size);

#endif /* CONTRIB_FUZZ_FUZZUTIL_H */