contrib/fuzz/jsonescapeu8fast.cc

setup: drop legacy osx compiler tuning to enable universal builds

This was triggering deprecation warnings about migrating to `packaging.version`
from `distutils` Version classes with `make local`.  But rather than migrate
that code, let's just get rid of some ~10-12 year old workarounds.  As a bonus,
the cext libraries that are built are now universal binaries containing x86_64
and arm64 images (at least when built on macOS 11.4 with Xcode 12.5 and the
universal version of Python 3.9.13).

Several things to note here:

   - Apple dropped support for 10.15 in Nov 2022, and OS X Lion that is
     referenced is 10.7 (unsupported since late 2014)
   - `xcode4` was basically always True because of the `>=` check (10.8 used
     Xcode 5, and I have Xcode 10.2 on 10.14)
   - `xcode51` was always False for modern-ish Xcode, because of the exact
     version string matching
   - Python 3.8 only supports OS X 10.9+; the Python 3.9.1+ universal installer
     is macOS 11+ only, and Python 3.10 drops the x86_64 installer to deliver
     only the universal installer.

All of this is to say, the only thing lost by dropping this code on modern Xcode
is that `os.environ['ARCHFLAGS'] = ''` is no longer set.  But we probably
shouldn't be setting that anymore, as shown by the universal libraries now being
generated.  I was able to `make local` and `python3 run-tests.py --local` with
python 3.9.9, Xcode 10.2, and macOS 10.14.6, and didn't incur any more than the
usual few test errors, so this should still work on some older versions of
macOS.

#include <Python.h>
#include <assert.h>
#include <stdlib.h>
#include <unistd.h>

#include "pyutil.h"

#include <iostream>
#include <string>
#include "FuzzedDataProvider.h"

extern "C" {

static PYCODETYPE *code;

extern "C" int LLVMFuzzerInitialize(int *argc, char ***argv)
{
	contrib::initpy(*argv[0]);
	code = (PYCODETYPE *)Py_CompileString(R"py(
try:
    parsers.jsonescapeu8fast(data, paranoid)
except Exception as e:
    pass
    # uncomment this print if you're editing this Python code
    # to debug failures.
    # print(e)
)py",
	                                      "fuzzer", Py_file_input);
	if (!code) {
		std::cerr << "failed to compile Python code!" << std::endl;
	}
	return 0;
}

int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size)
{
	FuzzedDataProvider provider(Data, Size);
	bool paranoid = provider.ConsumeBool();
	std::string remainder = provider.ConsumeRemainingBytesAsString();

	PyObject *mtext = PyBytes_FromStringAndSize(
	    (const char *)remainder.c_str(), remainder.size());
	PyObject *locals = PyDict_New();
	PyDict_SetItemString(locals, "data", mtext);
	PyDict_SetItemString(locals, "paranoid", paranoid ? Py_True : Py_False);
	PyObject *res = PyEval_EvalCode(code, contrib::pyglobals(), locals);
	if (!res) {
		PyErr_Print();
	}
	Py_XDECREF(res);
	Py_DECREF(locals);
	Py_DECREF(mtext);
	return 0; // Non-zero return values are reserved for future use.
}
}