1 | /* Copyright (C) 2010-2020 Free Software Foundation, Inc. |
2 | This file is part of the GNU C Library. |
3 | |
4 | The GNU C Library is free software; you can redistribute it and/or |
5 | modify it under the terms of the GNU Lesser General Public |
6 | License as published by the Free Software Foundation; either |
7 | version 2.1 of the License, or (at your option) any later version. |
8 | |
9 | The GNU C Library is distributed in the hope that it will be useful, |
10 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
12 | Lesser General Public License for more details. |
13 | |
14 | You should have received a copy of the GNU Lesser General Public |
15 | License along with the GNU C Library; if not, see |
16 | <https://www.gnu.org/licenses/>. */ |
17 | |
18 | #include <pwd.h> |
19 | #include <unistd.h> |
20 | #include <not-cancel.h> |
21 | #include <scratch_buffer.h> |
22 | |
23 | #define STATIC static |
24 | static int getlogin_r_fd0 (char *name, size_t namesize); |
25 | #define __getlogin_r getlogin_r_fd0 |
26 | #include <sysdeps/unix/getlogin_r.c> |
27 | #undef __getlogin_r |
28 | |
29 | |
30 | /* Try to determine login name from /proc/self/loginuid and return 0 |
31 | if successful. If /proc/self/loginuid cannot be read return -1. |
32 | Otherwise return the error number. */ |
33 | |
34 | int |
35 | attribute_hidden |
36 | __getlogin_r_loginuid (char *name, size_t namesize) |
37 | { |
38 | int fd = __open_nocancel ("/proc/self/loginuid" , O_RDONLY); |
39 | if (fd == -1) |
40 | return -1; |
41 | |
42 | /* We are reading a 32-bit number. 12 bytes are enough for the text |
43 | representation. If not, something is wrong. */ |
44 | char uidbuf[12]; |
45 | ssize_t n = TEMP_FAILURE_RETRY (__read_nocancel (fd, uidbuf, |
46 | sizeof (uidbuf))); |
47 | __close_nocancel_nostatus (fd); |
48 | |
49 | uid_t uid; |
50 | char *endp; |
51 | if (n <= 0 |
52 | || n == sizeof (uidbuf) |
53 | || (uidbuf[n] = '\0', |
54 | uid = strtoul (uidbuf, &endp, 10), |
55 | endp == uidbuf || *endp != '\0')) |
56 | return -1; |
57 | |
58 | /* If there is no login uid, linux sets /proc/self/loginid to the sentinel |
59 | value of, (uid_t) -1, so check if that value is set and return early to |
60 | avoid making unneeded nss lookups. */ |
61 | if (uid == (uid_t) -1) |
62 | { |
63 | __set_errno (ENXIO); |
64 | return ENXIO; |
65 | } |
66 | |
67 | struct passwd pwd; |
68 | struct passwd *tpwd; |
69 | int result = 0; |
70 | int res; |
71 | struct scratch_buffer tmpbuf; |
72 | scratch_buffer_init (&tmpbuf); |
73 | |
74 | while ((res = __getpwuid_r (uid, &pwd, |
75 | tmpbuf.data, tmpbuf.length, &tpwd)) == ERANGE) |
76 | { |
77 | if (!scratch_buffer_grow (&tmpbuf)) |
78 | { |
79 | result = ENOMEM; |
80 | goto out; |
81 | } |
82 | } |
83 | |
84 | if (res != 0 || tpwd == NULL) |
85 | { |
86 | result = -1; |
87 | goto out; |
88 | } |
89 | |
90 | size_t needed = strlen (pwd.pw_name) + 1; |
91 | if (needed > namesize) |
92 | { |
93 | __set_errno (ERANGE); |
94 | result = ERANGE; |
95 | goto out; |
96 | } |
97 | |
98 | memcpy (name, pwd.pw_name, needed); |
99 | |
100 | out: |
101 | scratch_buffer_free (&tmpbuf); |
102 | return result; |
103 | } |
104 | |
105 | |
106 | /* Return at most NAME_LEN characters of the login name of the user in NAME. |
107 | If it cannot be determined or some other error occurred, return the error |
108 | code. Otherwise return 0. */ |
109 | |
110 | int |
111 | __getlogin_r (char *name, size_t namesize) |
112 | { |
113 | int res = __getlogin_r_loginuid (name, namesize); |
114 | if (res >= 0) |
115 | return res; |
116 | |
117 | return getlogin_r_fd0 (name, namesize); |
118 | } |
119 | libc_hidden_def (__getlogin_r) |
120 | weak_alias (__getlogin_r, getlogin_r) |
121 | libc_hidden_weak (getlogin_r) |
122 | |