110 lines
3.2 KiB
C
110 lines
3.2 KiB
C
/* Provide a working getlogin_r for systems which lack it.
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Copyright (C) 2005-2007, 2010-2022 Free Software Foundation, Inc.
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This file is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation; either version 2.1 of the
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License, or (at your option) any later version.
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This file is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>. */
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/* Written by Paul Eggert, Derek Price, and Bruno Haible. */
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#include <config.h>
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/* Specification. */
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#include <unistd.h>
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#include <errno.h>
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#include <string.h>
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#include "malloca.h"
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#if defined _WIN32 && ! defined __CYGWIN__
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# define WIN32_LEAN_AND_MEAN
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# include <windows.h>
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/* Don't assume that UNICODE is not defined. */
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# undef GetUserName
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# define GetUserName GetUserNameA
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#else
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# if !HAVE_DECL_GETLOGIN
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extern char *getlogin (void);
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# endif
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#endif
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/* See unistd.in.h for documentation. */
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int
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getlogin_r (char *name, size_t size)
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{
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#undef getlogin_r
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#if defined _WIN32 && ! defined __CYGWIN__
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/* Native Windows platform. */
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DWORD sz;
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/* When size > 0x7fff, the doc says that GetUserName will fail.
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Actually, on Windows XP SP3, it succeeds. But let's be safe,
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for the sake of older Windows versions. */
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if (size > 0x7fff)
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size = 0x7fff;
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sz = size;
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if (!GetUserName (name, &sz))
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{
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if (GetLastError () == ERROR_INSUFFICIENT_BUFFER)
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/* In this case, the doc says that sz contains the required size, but
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actually, on Windows XP SP3, it contains 2 * the required size. */
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return ERANGE;
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else
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return ENOENT;
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}
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return 0;
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#elif HAVE_GETLOGIN_R
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/* Platform with a getlogin_r() function. */
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int ret = getlogin_r (name, size);
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if (ret == 0)
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{
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const char *nul = memchr (name, '\0', size);
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if (nul == NULL)
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/* name contains a truncated result. */
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return ERANGE;
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if (size > 0 && nul == name + size - 1)
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{
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/* strlen(name) == size-1. Determine whether the untruncated result
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would have had length size-1 or size. */
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char *room = (char *) malloca (size + 1);
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if (room == NULL)
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return ENOMEM;
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ret = getlogin_r (room, size + 1);
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/* The untruncated result should be the same as in the first call. */
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if (ret == 0 && memcmp (name, room, size) != 0)
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/* The untruncated result would have been different. */
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ret = ERANGE;
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freea (room);
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}
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}
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return ret;
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#else
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/* Platform with a getlogin() function. */
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char *n;
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size_t nlen;
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errno = 0;
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n = getlogin ();
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if (!n)
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/* ENOENT is a reasonable errno value if getlogin returns NULL. */
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return (errno != 0 ? errno : ENOENT);
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nlen = strlen (n);
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if (size <= nlen)
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return ERANGE;
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memcpy (name, n, nlen + 1);
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return 0;
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#endif
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}
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