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