1 /* vi: set sw=4 ts=4: */
2 /*
3 * utmp/wtmp support routines.
4 *
5 * Copyright (C) 2010 Denys Vlasenko
6 *
7 * Licensed under GPLv2, see file LICENSE in this source tree.
8 */
9 #include "libbb.h"
10
touch(const char * filename)11 static void touch(const char *filename)
12 {
13 if (access(filename, R_OK | W_OK) == -1)
14 close(open(filename, O_WRONLY | O_CREAT, 0664));
15 }
16
write_new_utmp(pid_t pid,int new_type,const char * tty_name,const char * username,const char * hostname)17 void FAST_FUNC write_new_utmp(pid_t pid, int new_type, const char *tty_name, const char *username, const char *hostname)
18 {
19 struct utmpx utent;
20 char *id;
21 unsigned width;
22
23 memset(&utent, 0, sizeof(utent));
24 utent.ut_pid = pid;
25 utent.ut_type = new_type;
26 tty_name = skip_dev_pfx(tty_name);
27 safe_strncpy(utent.ut_line, tty_name, sizeof(utent.ut_line));
28 if (username)
29 safe_strncpy(utent.ut_user, username, sizeof(utent.ut_user));
30 if (hostname)
31 safe_strncpy(utent.ut_host, hostname, sizeof(utent.ut_host));
32 utent.ut_tv.tv_sec = time(NULL);
33
34 /* Invent our own ut_id. ut_id is only 4 chars wide.
35 * Try to fit something remotely meaningful... */
36 id = utent.ut_id;
37 width = sizeof(utent.ut_id);
38 if (tty_name[0] == 'p') {
39 /* if "ptyXXX", map to "pXXX" */
40 /* if "pts/XX", map to "p/XX" */
41 *id++ = 'p';
42 width--;
43 } /* else: usually it's "ttyXXXX", map to "XXXX" */
44 if (strlen(tty_name) > 3)
45 tty_name += 3;
46 strncpy(id, tty_name, width);
47
48 touch(_PATH_UTMPX);
49 //utmpxname(_PATH_UTMPX);
50 setutxent();
51 /* Append new one (hopefully, unless we collide on ut_id) */
52 pututxline(&utent);
53 endutxent();
54
55 #if ENABLE_FEATURE_WTMP
56 /* "man utmp" says wtmp file should *not* be created automagically */
57 /*touch(bb_path_wtmp_file);*/
58 updwtmpx(bb_path_wtmp_file, &utent);
59 #endif
60 }
61
62 /*
63 * Read "man utmp" to make sense out of it.
64 */
update_utmp(pid_t pid,int new_type,const char * tty_name,const char * username,const char * hostname)65 void FAST_FUNC update_utmp(pid_t pid, int new_type, const char *tty_name, const char *username, const char *hostname)
66 {
67 struct utmpx utent;
68 struct utmpx *utp;
69
70 touch(_PATH_UTMPX);
71 //utmpxname(_PATH_UTMPX);
72 setutxent();
73
74 /* Did init/getty/telnetd/sshd/... create an entry for us?
75 * It should be (new_type-1), but we'd also reuse
76 * any other potentially stale xxx_PROCESS entry */
77 while ((utp = getutxent()) != NULL) {
78 if (utp->ut_pid == pid
79 // && ut->ut_line[0]
80 && utp->ut_id[0] /* must have nonzero id */
81 && ( utp->ut_type == INIT_PROCESS
82 || utp->ut_type == LOGIN_PROCESS
83 || utp->ut_type == USER_PROCESS
84 || utp->ut_type == DEAD_PROCESS
85 )
86 ) {
87 if (utp->ut_type >= new_type) {
88 /* Stale record. Nuke hostname */
89 memset(utp->ut_host, 0, sizeof(utp->ut_host));
90 }
91 /* NB: pututxline (see later) searches for matching utxent
92 * using getutxid(utent) - we must not change ut_id
93 * if we want *exactly this* record to be overwritten!
94 */
95 break;
96 }
97 }
98 //endutxent(); - no need, pututxline can deal with (and actually likes)
99 //the situation when utmp file is positioned on found record
100
101 if (!utp) {
102 if (new_type != DEAD_PROCESS)
103 write_new_utmp(pid, new_type, tty_name, username, hostname);
104 else
105 endutxent();
106 return;
107 }
108
109 /* Make a copy. We can't use *utp, pututxline's internal getutxid
110 * will overwrite it before it is used! */
111 utent = *utp;
112
113 utent.ut_type = new_type;
114 if (tty_name)
115 safe_strncpy(utent.ut_line, skip_dev_pfx(tty_name), sizeof(utent.ut_line));
116 if (username)
117 safe_strncpy(utent.ut_user, username, sizeof(utent.ut_user));
118 if (hostname)
119 safe_strncpy(utent.ut_host, hostname, sizeof(utent.ut_host));
120 utent.ut_tv.tv_sec = time(NULL);
121
122 /* Update, or append new one */
123 //setutxent();
124 pututxline(&utent);
125 endutxent();
126
127 #if ENABLE_FEATURE_WTMP
128 /* "man utmp" says wtmp file should *not* be created automagically */
129 /*touch(bb_path_wtmp_file);*/
130 updwtmpx(bb_path_wtmp_file, &utent);
131 #endif
132 }
133
134 /* man utmp:
135 * When init(8) finds that a process has exited, it locates its utmp entry
136 * by ut_pid, sets ut_type to DEAD_PROCESS, and clears ut_user, ut_host
137 * and ut_time with null bytes.
138 * [same applies to other processes which maintain utmp entries, like telnetd]
139 *
140 * We do not bother actually clearing fields:
141 * it might be interesting to know who was logged in and from where
142 */
update_utmp_DEAD_PROCESS(pid_t pid)143 void FAST_FUNC update_utmp_DEAD_PROCESS(pid_t pid)
144 {
145 update_utmp(pid, DEAD_PROCESS, NULL, NULL, NULL);
146 }
147