/* Provide a working getlogin_r for systems which lack it.
- Copyright (C) 2005-2007, 2010-2016 Free Software Foundation, Inc.
+ Copyright (C) 2005-2007, 2010-2020 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
- along with this program; if not, see <http://www.gnu.org/licenses/>. */
+ along with this program; if not, see <https://www.gnu.org/licenses/>. */
/* Written by Paul Eggert, Derek Price, and Bruno Haible. */
#include <errno.h>
#include <string.h>
-#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
+#include "malloca.h"
+
+#if defined _WIN32 && ! defined __CYGWIN__
# define WIN32_LEAN_AND_MEAN
# include <windows.h>
#else
getlogin_r (char *name, size_t size)
{
#undef getlogin_r
-#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
+#if defined _WIN32 && ! defined __CYGWIN__
/* Native Windows platform. */
DWORD sz;
/* Platform with a getlogin_r() function. */
int ret = getlogin_r (name, size);
- if (ret == 0 && memchr (name, '\0', size) == NULL)
- /* name contains a truncated result. */
- return ERANGE;
+ if (ret == 0)
+ {
+ const char *nul = memchr (name, '\0', size);
+ if (nul == NULL)
+ /* name contains a truncated result. */
+ return ERANGE;
+ if (size > 0 && nul == name + size - 1)
+ {
+ /* strlen(name) == size-1. Determine whether the untruncated result
+ would have had length size-1 or size. */
+ char *room = (char *) malloca (size + 1);
+ if (room == NULL)
+ return ENOMEM;
+ ret = getlogin_r (room, size + 1);
+ /* The untruncated result should be the same as in the first call. */
+ if (ret == 0 && memcmp (name, room, size) != 0)
+ /* The untruncated result would have been different. */
+ ret = ERANGE;
+ freea (room);
+ }
+ }
return ret;
#else
/* Platform with a getlogin() function. */