1 /* Provide a working getlogin_r for systems which lack it.
3 Copyright (C) 2005-2007, 2010-2019 Free Software Foundation, Inc.
5 This program is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 2, or (at your option)
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with this program; if not, see <https://www.gnu.org/licenses/>. */
18 /* Written by Paul Eggert, Derek Price, and Bruno Haible. */
30 #if defined _WIN32 && ! defined __CYGWIN__
31 # define WIN32_LEAN_AND_MEAN
34 # if !HAVE_DECL_GETLOGIN
35 extern char *getlogin (void);
39 /* See unistd.in.h for documentation. */
41 getlogin_r (char *name
, size_t size
)
44 #if defined _WIN32 && ! defined __CYGWIN__
45 /* Native Windows platform. */
48 /* When size > 0x7fff, the doc says that GetUserName will fail.
49 Actually, on Windows XP SP3, it succeeds. But let's be safe,
50 for the sake of older Windows versions. */
54 if (!GetUserName (name
, &sz
))
56 if (GetLastError () == ERROR_INSUFFICIENT_BUFFER
)
57 /* In this case, the doc says that sz contains the required size, but
58 actually, on Windows XP SP3, it contains 2 * the required size. */
65 /* Platform with a getlogin_r() function. */
66 int ret
= getlogin_r (name
, size
);
70 const char *nul
= memchr (name
, '\0', size
);
72 /* name contains a truncated result. */
74 if (size
> 0 && nul
== name
+ size
- 1)
76 /* strlen(name) == size-1. Determine whether the untruncated result
77 would have had length size-1 or size. */
78 char *room
= (char *) malloca (size
+ 1);
81 ret
= getlogin_r (room
, size
+ 1);
82 /* The untruncated result should be the same as in the first call. */
83 if (ret
== 0 && memcmp (name
, room
, size
) != 0)
84 /* The untruncated result would have been different. */
91 /* Platform with a getlogin() function. */
98 /* ENOENT is a reasonable errno value if getlogin returns NULL. */
99 return (errno
!= 0 ? errno
: ENOENT
);
104 memcpy (name
, n
, nlen
+ 1);