contrib/fuzz/pyutil.cc

copies: move comment about implementation of mergecopies() to end

When you start reading about mergecopies(), you want to know what it
is, not that there are different implementations depending on config,
so this patch moves that comment to the end.

By the way, we don't seem to define what "copytracing" is. I'm just
leaving it that way because I don't know what it is myself. It seems
to be referred to only on mergecopies() (and not in pathcopies(), for
example), so maybe "copytracing" is supposed to be exactly what
mergecopies() does?

Differential Revision: https://phab.mercurial-scm.org/D6235

#include "pyutil.h"

#include <string>

namespace contrib
{

static char cpypath[8192] = "\0";

static PyObject *mainmod;
static PyObject *globals;

/* TODO: use Python 3 for this fuzzing? */
PyMODINIT_FUNC initparsers(void);

void initpy(const char *cselfpath)
{
	const std::string subdir = "/sanpy/lib/python2.7";
	/* HACK ALERT: we need a full Python installation built without
	   pymalloc and with ASAN, so we dump one in
	   $OUT/sanpy/lib/python2.7. This helps us wire that up. */
	std::string selfpath(cselfpath);
	std::string pypath;
	auto pos = selfpath.rfind("/");
	if (pos == std::string::npos) {
		char wd[8192];
		getcwd(wd, 8192);
		pypath = std::string(wd) + subdir;
	} else {
		pypath = selfpath.substr(0, pos) + subdir;
	}
	strncpy(cpypath, pypath.c_str(), pypath.size());
	setenv("PYTHONPATH", cpypath, 1);
	setenv("PYTHONNOUSERSITE", "1", 1);
	/* prevent Python from looking up users in the fuzz environment */
	setenv("PYTHONUSERBASE", cpypath, 1);
	Py_SetPythonHome(cpypath);
	Py_InitializeEx(0);
	mainmod = PyImport_AddModule("__main__");
	globals = PyModule_GetDict(mainmod);
	initparsers();
}

PyObject *pyglobals()
{
	return globals;
}

} // namespace contrib