blob: bd07670dba2b1aedb98257021da9eb01b6e3ccbb
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 | |
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 | |
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 | */ |
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 | */ |
143 | void FAST_FUNC update_utmp_DEAD_PROCESS(pid_t pid) |
144 | { |
145 | update_utmp(pid, DEAD_PROCESS, NULL, NULL, NULL); |
146 | } |
147 |