contrib/fuzz/standalone_fuzz_target_runner.cc

tests: convert the `root` arg of matchmod.match() to local path separators

This fixes tests that broke with 8b1a9ba375e5, complaining that "X not under
root /repo".  The vast majority of real uses are to pass `repo.root`, which is
normalized by `wdirvfs.base` being set to the result of `os.path.realpath()`.

Failure to convert looks like this:

  --- c:/Users/Matt/hg/tests/test-match.py.out
  +++ c:/Users/Matt/hg/tests/test-match.py.err
  @@ -0,0 +1,48 @@
  +ERROR: testVisitchildrensetGlob (__main__.IncludeMatcherTests)
  +
  +Traceback (most recent call last):
  +  File "c:\Users\Matt\hg\tests\test-match.py", line 180, in testVisitchildrensetGlob
  +    m = matchmod.match(b'/repo', b'', include=[b'glob:dir/z*'])
  +  File "c:\Users\Matt\hg\mercurial\match.py", line 271, in match
  +    kindpats = normalize(include, b'glob', root, cwd, auditor, warn)
  +  File "c:\Users\Matt\hg\mercurial\match.py", line 322, in _donormalize
  +    pat = pathutil.canonpath(root, cwd, pat, auditor=auditor)
  +  File "c:\Users\Matt\hg\mercurial\pathutil.py", line 251, in canonpath
  +    _(b"%s not under root '%s'") % (myname, root), hint=hint
  +Abort: dir/z* not under root '/repo'
  +ERROR: testVisitdirGlob (__main__.IncludeMatcherTests)

Differential Revision: https://phab.mercurial-scm.org/D7724

// Copyright 2017 Google Inc. All Rights Reserved.
// Licensed under the Apache License, Version 2.0 (the "License");

// Example of a standalone runner for "fuzz targets".
// It reads all files passed as parameters and feeds their contents
// one by one into the fuzz target (LLVMFuzzerTestOneInput).
// This runner does not do any fuzzing, but allows us to run the fuzz target
// on the test corpus (e.g. "do_stuff_test_data") or on a single file,
// e.g. the one that comes from a bug report.

#include <cassert>
#include <fstream>
#include <iostream>
#include <vector>

// Forward declare the "fuzz target" interface.
// We deliberately keep this inteface simple and header-free.
extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size);

extern "C" int LLVMFuzzerInitialize(int *argc, char ***argv);

int main(int argc, char **argv)
{
	LLVMFuzzerInitialize(&argc, &argv);

	for (int i = 1; i < argc; i++) {
		std::ifstream in(argv[i]);
		in.seekg(0, in.end);
		size_t length = in.tellg();
		in.seekg(0, in.beg);
		std::cout << "Reading " << length << " bytes from " << argv[i]
		          << std::endl;
		// Allocate exactly length bytes so that we reliably catch
		// buffer overflows.
		std::vector<char> bytes(length);
		in.read(bytes.data(), bytes.size());
		assert(in);
		LLVMFuzzerTestOneInput(
		    reinterpret_cast<const uint8_t *>(bytes.data()),
		    bytes.size());
		std::cout << "Execution successful" << std::endl;
	}
	return 0;
}
// no-check-code since this is from a third party