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6ec2e0f5 SDJ |
1 | /* Provide a working getlogin_r for systems which lack it. |
2 | ||
5df4cba6 | 3 | Copyright (C) 2005-2007, 2010-2020 Free Software Foundation, Inc. |
6ec2e0f5 SDJ |
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 | |
c0c3707f | 16 | along with this program; if not, see <https://www.gnu.org/licenses/>. */ |
6ec2e0f5 SDJ |
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 | ||
c0c3707f CB |
28 | #include "malloca.h" |
29 | ||
30 | #if defined _WIN32 && ! defined __CYGWIN__ | |
6ec2e0f5 SDJ |
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 | |
c0c3707f | 44 | #if defined _WIN32 && ! defined __CYGWIN__ |
6ec2e0f5 SDJ |
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 | ||
c0c3707f CB |
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 | } | |
6ec2e0f5 SDJ |
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 | } |