1 | /* Copyright (C) 1996-2022 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 <assert.h> |
19 | #include <errno.h> |
20 | #include <limits.h> |
21 | #include <string.h> |
22 | #include <unistd.h> |
23 | #include <stdlib.h> |
24 | #include <utmp.h> |
25 | #include <shlib-compat.h> |
26 | |
27 | /* Return the result of ttyname in the buffer pointed to by TTY, which should |
28 | be of length BUF_LEN. If it is too long to fit in this buffer, a |
29 | sufficiently long buffer is allocated using malloc, and returned in TTY. |
30 | 0 is returned upon success, -1 otherwise. */ |
31 | static int |
32 | tty_name (int fd, char **tty, size_t buf_len) |
33 | { |
34 | int rv; /* Return value. 0 = success. */ |
35 | char *buf = *tty; /* Buffer for ttyname, initially the user's. */ |
36 | |
37 | for (;;) |
38 | { |
39 | char *new_buf; |
40 | |
41 | if (buf_len) |
42 | { |
43 | rv = __ttyname_r (fd, buf, buf_len); |
44 | |
45 | if (rv != 0 || memchr (buf, '\0', buf_len)) |
46 | /* We either got an error, or we succeeded and the |
47 | returned name fit in the buffer. */ |
48 | break; |
49 | |
50 | /* Try again with a longer buffer. */ |
51 | buf_len += buf_len; /* Double it */ |
52 | } |
53 | else |
54 | /* No initial buffer; start out by mallocing one. */ |
55 | buf_len = 128; /* First time guess. */ |
56 | |
57 | if (buf != *tty) |
58 | /* We've already malloced another buffer at least once. */ |
59 | new_buf = realloc (ptr: buf, size: buf_len); |
60 | else |
61 | new_buf = malloc (size: buf_len); |
62 | if (! new_buf) |
63 | { |
64 | rv = -1; |
65 | __set_errno (ENOMEM); |
66 | break; |
67 | } |
68 | buf = new_buf; |
69 | } |
70 | |
71 | if (rv == 0) |
72 | *tty = buf; /* Return buffer to the user. */ |
73 | else if (buf != *tty) |
74 | free (ptr: buf); /* Free what we malloced when returning an error. */ |
75 | |
76 | return rv; |
77 | } |
78 | |
79 | void |
80 | __login (const struct utmp *ut) |
81 | { |
82 | #ifdef PATH_MAX |
83 | char _tty[PATH_MAX + UT_LINESIZE]; |
84 | #else |
85 | char _tty[512 + UT_LINESIZE]; |
86 | #endif |
87 | char *tty = _tty; |
88 | int found_tty; |
89 | const char *ttyp; |
90 | struct utmp copy = *ut; |
91 | |
92 | /* Fill in those fields we supply. */ |
93 | copy.ut_type = USER_PROCESS; |
94 | copy.ut_pid = getpid (); |
95 | |
96 | /* Seek tty. */ |
97 | found_tty = tty_name (STDIN_FILENO, tty: &tty, buf_len: sizeof (_tty)); |
98 | if (found_tty < 0) |
99 | found_tty = tty_name (STDOUT_FILENO, tty: &tty, buf_len: sizeof (_tty)); |
100 | if (found_tty < 0) |
101 | found_tty = tty_name (STDERR_FILENO, tty: &tty, buf_len: sizeof (_tty)); |
102 | |
103 | if (found_tty >= 0) |
104 | { |
105 | /* We only want to insert the name of the tty without path. |
106 | But take care of name like /dev/pts/3. */ |
107 | if (strncmp (tty, "/dev/" , 5) == 0) |
108 | ttyp = tty + 5; /* Skip the "/dev/". */ |
109 | else |
110 | ttyp = basename (tty); |
111 | |
112 | /* Position to record for this tty. */ |
113 | strncpy (copy.ut_line, ttyp, UT_LINESIZE); |
114 | |
115 | /* Tell that we want to use the UTMP file. */ |
116 | if (__utmpname (_PATH_UTMP) == 0) |
117 | { |
118 | /* Open UTMP file. */ |
119 | __setutent (); |
120 | |
121 | /* Write the entry. */ |
122 | __pututline (©); |
123 | |
124 | /* Close UTMP file. */ |
125 | __endutent (); |
126 | } |
127 | |
128 | if (tty != _tty) |
129 | free (ptr: tty); /* Free buffer malloced by tty_name. */ |
130 | } |
131 | else |
132 | /* We provide a default value so that the output does not contain |
133 | an random bytes in this field. */ |
134 | strncpy (copy.ut_line, "???" , UT_LINESIZE); |
135 | |
136 | /* Update the WTMP file. Here we have to add a new entry. */ |
137 | __updwtmp (_PATH_WTMP, ©); |
138 | } |
139 | versioned_symbol (libc, __login, login, GLIBC_2_34); |
140 | libc_hidden_ver (__login, login) |
141 | |
142 | #if OTHER_SHLIB_COMPAT (libutil, GLIBC_2_0, GLIBC_2_34) |
143 | compat_symbol (libutil, __login, login, GLIBC_2_0); |
144 | #endif |
145 | |