1/* Copyright (C) 1996-2019 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library 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 GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <http://www.gnu.org/licenses/>. */
18
19#include <assert.h>
20#include <errno.h>
21#include <limits.h>
22#include <string.h>
23#include <unistd.h>
24#include <stdlib.h>
25#include <utmp.h>
26
27
28/* Return the result of ttyname in the buffer pointed to by TTY, which should
29 be of length BUF_LEN. If it is too long to fit in this buffer, a
30 sufficiently long buffer is allocated using malloc, and returned in TTY.
31 0 is returned upon success, -1 otherwise. */
32static int
33tty_name (int fd, char **tty, size_t buf_len)
34{
35 int rv; /* Return value. 0 = success. */
36 char *buf = *tty; /* Buffer for ttyname, initially the user's. */
37
38 for (;;)
39 {
40 char *new_buf;
41
42 if (buf_len)
43 {
44 rv = ttyname_r (fd, buf, buf_len);
45
46 if (rv != 0 || memchr (buf, '\0', buf_len))
47 /* We either got an error, or we succeeded and the
48 returned name fit in the buffer. */
49 break;
50
51 /* Try again with a longer buffer. */
52 buf_len += buf_len; /* Double it */
53 }
54 else
55 /* No initial buffer; start out by mallocing one. */
56 buf_len = 128; /* First time guess. */
57
58 if (buf != *tty)
59 /* We've already malloced another buffer at least once. */
60 new_buf = realloc (buf, buf_len);
61 else
62 new_buf = malloc (buf_len);
63 if (! new_buf)
64 {
65 rv = -1;
66 __set_errno (ENOMEM);
67 break;
68 }
69 buf = new_buf;
70 }
71
72 if (rv == 0)
73 *tty = buf; /* Return buffer to the user. */
74 else if (buf != *tty)
75 free (buf); /* Free what we malloced when returning an error. */
76
77 return rv;
78}
79
80void
81login (const struct utmp *ut)
82{
83#ifdef PATH_MAX
84 char _tty[PATH_MAX + UT_LINESIZE];
85#else
86 char _tty[512 + UT_LINESIZE];
87#endif
88 char *tty = _tty;
89 int found_tty;
90 const char *ttyp;
91 struct utmp copy = *ut;
92
93 /* Fill in those fields we supply. */
94#if _HAVE_UT_TYPE - 0
95 copy.ut_type = USER_PROCESS;
96#endif
97#if _HAVE_UT_PID - 0
98 copy.ut_pid = getpid ();
99#endif
100
101 /* Seek tty. */
102 found_tty = tty_name (STDIN_FILENO, &tty, sizeof (_tty));
103 if (found_tty < 0)
104 found_tty = tty_name (STDOUT_FILENO, &tty, sizeof (_tty));
105 if (found_tty < 0)
106 found_tty = tty_name (STDERR_FILENO, &tty, sizeof (_tty));
107
108 if (found_tty >= 0)
109 {
110 /* We only want to insert the name of the tty without path.
111 But take care of name like /dev/pts/3. */
112 if (strncmp (tty, "/dev/", 5) == 0)
113 ttyp = tty + 5; /* Skip the "/dev/". */
114 else
115 ttyp = basename (tty);
116
117 /* Position to record for this tty. */
118 strncpy (copy.ut_line, ttyp, UT_LINESIZE);
119
120 /* Tell that we want to use the UTMP file. */
121 if (utmpname (_PATH_UTMP) == 0)
122 {
123 /* Open UTMP file. */
124 setutent ();
125
126 /* Write the entry. */
127 pututline (&copy);
128
129 /* Close UTMP file. */
130 endutent ();
131 }
132
133 if (tty != _tty)
134 free (tty); /* Free buffer malloced by tty_name. */
135 }
136 else
137 /* We provide a default value so that the output does not contain
138 an random bytes in this field. */
139 strncpy (copy.ut_line, "???", UT_LINESIZE);
140
141 /* Update the WTMP file. Here we have to add a new entry. */
142 updwtmp (_PATH_WTMP, &copy);
143}
144