fuzz: fix an unused result on getcwd() in pyutil

clang was rightly complaining about this, so let's just fix it.

Differential Revision: https://phab.mercurial-scm.org/D7558

contrib/fuzz/pyutil.cc

@@ -1,49 +1,54 b''
 #include "pyutil.h"
 
+#include <iostream>
 #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);
+		if (!getcwd(wd, 8192)) {
+			std::cerr << "Failed to call getcwd: errno " << errno
+			          << std::endl;
+			exit(1);
+		}
 		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