contrib/fuzz/dirstate.cc

narrow: use narrow_widen wireproto command to widen in case of ellipses

Few releases ago, we introduce narrow_widen wireproto command to be used to widen
narrow repositories. Before this patch, that was used in non-ellipses cases
only. In ellipses cases, we still do exchange.pull() which can pull more data
than required.

After this patch, the client will first check whether server supports doing
ellipses widening using wireproto command or not by checking server's wireproto
capability. If the server is upto date and support latest ellipses capability,
we call the wireproto command. Otherwise we fallback to exchange.pull() like
before.

The compat code make sure that things works even if one of the client or server
is old. The initial version of this patch does not had this compat code. It's
added to help Google release things smoothly internally. I plan to drop the
compat code before the upcoming major release.

Due to change to wireproto command, the code looks a bit dirty, next patches
will clean that up.

Differential Revision: https://phab.mercurial-scm.org/D6436

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

#include <string>

#include "pyutil.h"

extern "C" {

static PyCodeObject *code;

extern "C" int LLVMFuzzerInitialize(int *argc, char ***argv)
{
	contrib::initpy(*argv[0]);
	code = (PyCodeObject *)Py_CompileString(R"py(
from parsers import parse_dirstate
try:
    dmap = {}
    copymap = {}
    p = parse_dirstate(dmap, copymap, data)
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);
	return 0;
}

int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size)
{
	PyObject *text =
	    PyBytes_FromStringAndSize((const char *)Data, (Py_ssize_t)Size);
	PyObject *locals = PyDict_New();
	PyDict_SetItemString(locals, "data", text);
	PyObject *res = PyEval_EvalCode(code, contrib::pyglobals(), locals);
	if (!res) {
		PyErr_Print();
	}
	Py_XDECREF(res);
	Py_DECREF(locals);
	Py_DECREF(text);
	return 0; // Non-zero return values are reserved for future use.
}
}