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- /* Provide a working getlogin_r for systems which lack it.
- Copyright (C) 2005-2007, 2010-2021 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
- the Free Software Foundation; either version 3, or (at your option)
- any later version.
- This program is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- 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 <https://www.gnu.org/licenses/>. */
- /* Written by Paul Eggert, Derek Price, and Bruno Haible. */
- #include <config.h>
- /* Specification. */
- #include <unistd.h>
- #include <errno.h>
- #include <string.h>
- #include "malloca.h"
- #if defined _WIN32 && ! defined __CYGWIN__
- # define WIN32_LEAN_AND_MEAN
- # include <windows.h>
- /* Don't assume that UNICODE is not defined. */
- # undef GetUserName
- # define GetUserName GetUserNameA
- #else
- # if !HAVE_DECL_GETLOGIN
- extern char *getlogin (void);
- # endif
- #endif
- /* See unistd.in.h for documentation. */
- int
- getlogin_r (char *name, size_t size)
- {
- #undef getlogin_r
- #if defined _WIN32 && ! defined __CYGWIN__
- /* Native Windows platform. */
- DWORD sz;
- /* When size > 0x7fff, the doc says that GetUserName will fail.
- Actually, on Windows XP SP3, it succeeds. But let's be safe,
- for the sake of older Windows versions. */
- if (size > 0x7fff)
- size = 0x7fff;
- sz = size;
- if (!GetUserName (name, &sz))
- {
- if (GetLastError () == ERROR_INSUFFICIENT_BUFFER)
- /* In this case, the doc says that sz contains the required size, but
- actually, on Windows XP SP3, it contains 2 * the required size. */
- return ERANGE;
- else
- return ENOENT;
- }
- return 0;
- #elif HAVE_GETLOGIN_R
- /* Platform with a getlogin_r() function. */
- int ret = getlogin_r (name, size);
- 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. */
- char *n;
- size_t nlen;
- errno = 0;
- n = getlogin ();
- if (!n)
- /* ENOENT is a reasonable errno value if getlogin returns NULL. */
- return (errno != 0 ? errno : ENOENT);
- nlen = strlen (n);
- if (size <= nlen)
- return ERANGE;
- memcpy (name, n, nlen + 1);
- return 0;
- #endif
- }
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