| 1 | /* Provide a working getlogin_r for systems which lack it. |
| 2 | |
| 3 | Copyright (C) 2005-2007, 2010-2018 Free Software Foundation, Inc. |
| 4 | |
| 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 3, or (at your option) |
| 8 | any later version. |
| 9 | |
| 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. |
| 14 | |
| 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/>. */ |
| 17 | |
| 18 | /* Written by Paul Eggert, Derek Price, and Bruno Haible. */ |
| 19 | |
| 20 | #include <config.h> |
| 21 | |
| 22 | /* Specification. */ |
| 23 | #include <unistd.h> |
| 24 | |
| 25 | #include <errno.h> |
| 26 | #include <string.h> |
| 27 | |
| 28 | #include "malloca.h" |
| 29 | |
| 30 | #if defined _WIN32 && ! defined __CYGWIN__ |
| 31 | # define WIN32_LEAN_AND_MEAN |
| 32 | # include <windows.h> |
| 33 | #else |
| 34 | # if !HAVE_DECL_GETLOGIN |
| 35 | extern char *getlogin (void); |
| 36 | # endif |
| 37 | #endif |
| 38 | |
| 39 | /* See unistd.in.h for documentation. */ |
| 40 | int |
| 41 | getlogin_r (char *name, size_t size) |
| 42 | { |
| 43 | #undef getlogin_r |
| 44 | #if defined _WIN32 && ! defined __CYGWIN__ |
| 45 | /* Native Windows platform. */ |
| 46 | DWORD sz; |
| 47 | |
| 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. */ |
| 51 | if (size > 0x7fff) |
| 52 | size = 0x7fff; |
| 53 | sz = size; |
| 54 | if (!GetUserName (name, &sz)) |
| 55 | { |
| 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. */ |
| 59 | return ERANGE; |
| 60 | else |
| 61 | return ENOENT; |
| 62 | } |
| 63 | return 0; |
| 64 | #elif HAVE_GETLOGIN_R |
| 65 | /* Platform with a getlogin_r() function. */ |
| 66 | int ret = getlogin_r (name, size); |
| 67 | |
| 68 | if (ret == 0) |
| 69 | { |
| 70 | const char *nul = memchr (name, '\0', size); |
| 71 | if (nul == NULL) |
| 72 | /* name contains a truncated result. */ |
| 73 | return ERANGE; |
| 74 | if (size > 0 && nul == name + size - 1) |
| 75 | { |
| 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); |
| 79 | if (room == NULL) |
| 80 | return ENOMEM; |
| 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. */ |
| 85 | ret = ERANGE; |
| 86 | freea (room); |
| 87 | } |
| 88 | } |
| 89 | return ret; |
| 90 | #else |
| 91 | /* Platform with a getlogin() function. */ |
| 92 | char *n; |
| 93 | size_t nlen; |
| 94 | |
| 95 | errno = 0; |
| 96 | n = getlogin (); |
| 97 | if (!n) |
| 98 | /* ENOENT is a reasonable errno value if getlogin returns NULL. */ |
| 99 | return (errno != 0 ? errno : ENOENT); |
| 100 | |
| 101 | nlen = strlen (n); |
| 102 | if (size <= nlen) |
| 103 | return ERANGE; |
| 104 | memcpy (name, n, nlen + 1); |
| 105 | return 0; |
| 106 | #endif |
| 107 | } |