1 | /* vi: set sw=4 ts=4: */
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2 | /*
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3 | * openvt.c - open a vt to run a command.
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4 | *
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5 | * busyboxed by Quy Tonthat <quy@signal3.com>
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6 | * hacked by Tito <farmatito@tiscali.it>
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7 | *
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8 | * Licensed under GPLv2 or later, see file LICENSE in this source tree.
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9 | */
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10 |
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11 | #include <linux/vt.h>
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12 | #include "libbb.h"
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13 |
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14 | /* "Standard" openvt's man page (we do not support all of this):
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15 |
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16 | openvt [-c NUM] [-fsulv] [--] [command [args]]
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17 |
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18 | Find the first available VT, and run command on it. Stdio is directed
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19 | to that VT. If no command is specified then $SHELL is used.
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20 |
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21 | -c NUM
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22 | Use the given VT number, not the first free one.
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23 | -f
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24 | Force opening a VT: don't try to check if VT is already in use.
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25 | -s
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26 | Switch to the new VT when starting the command.
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27 | The VT of the new command will be made the new current VT.
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28 | -u
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29 | Figure out the owner of the current VT, and run login as that user.
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30 | Suitable to be called by init. Shouldn't be used with -c or -l.
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31 | -l
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32 | Make the command a login shell: a "-" is prepended to the argv[0]
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33 | when command is executed.
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34 | -v
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35 | Verbose.
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36 | -w
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37 | Wait for command to complete. If -w and -s are used together,
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38 | switch back to the controlling terminal when the command completes.
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39 |
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40 | bbox:
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41 | -u: not implemented
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42 | -f: always in effect
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43 | -l: not implemented, ignored
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44 | -v: ignored
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45 | -ws: does NOT switch back
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46 | */
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47 |
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48 | /* Helper: does this fd understand VT_xxx? */
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49 | static int not_vt_fd(int fd)
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50 | {
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51 | struct vt_stat vtstat;
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52 | return ioctl(fd, VT_GETSTATE, &vtstat); /* !0: error, it's not VT fd */
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53 | }
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54 |
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55 | /* Helper: get a fd suitable for VT_xxx */
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56 | static int get_vt_fd(void)
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57 | {
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58 | int fd;
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59 |
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60 | /* Do we, by chance, already have it? */
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61 | for (fd = 0; fd < 3; fd++)
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62 | if (!not_vt_fd(fd))
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63 | return fd;
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64 | fd = open(DEV_CONSOLE, O_RDONLY | O_NONBLOCK);
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65 | if (fd >= 0 && !not_vt_fd(fd))
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66 | return fd;
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67 | bb_error_msg_and_die("can't find open VT");
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68 | }
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69 |
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70 | static int find_free_vtno(void)
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71 | {
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72 | int vtno;
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73 | int fd = get_vt_fd();
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74 |
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75 | errno = 0;
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76 | /*xfunc_error_retval = 3; - do we need compat? */
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77 | if (ioctl(fd, VT_OPENQRY, &vtno) != 0 || vtno <= 0)
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78 | bb_perror_msg_and_die("can't find open VT");
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79 | // Not really needed, grep for DAEMON_ONLY_SANITIZE
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80 | // if (fd > 2)
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81 | // close(fd);
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82 | return vtno;
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83 | }
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84 |
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85 | /* vfork scares gcc, it generates bigger code.
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86 | * Keep it away from main program.
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87 | * TODO: move to libbb; or adapt existing libbb's spawn().
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88 | */
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89 | static NOINLINE void vfork_child(char **argv)
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90 | {
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91 | if (vfork() == 0) {
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92 | /* CHILD */
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93 | /* Try to make this VT our controlling tty */
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94 | setsid(); /* lose old ctty */
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95 | ioctl(STDIN_FILENO, TIOCSCTTY, 0 /* 0: don't forcibly steal */);
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96 | //bb_error_msg("our sid %d", getsid(0));
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97 | //bb_error_msg("our pgrp %d", getpgrp());
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98 | //bb_error_msg("VT's sid %d", tcgetsid(0));
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99 | //bb_error_msg("VT's pgrp %d", tcgetpgrp(0));
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100 | BB_EXECVP_or_die(argv);
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101 | }
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102 | }
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103 |
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104 | int openvt_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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105 | int openvt_main(int argc UNUSED_PARAM, char **argv)
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106 | {
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107 | char vtname[sizeof(VC_FORMAT) + sizeof(int)*3];
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108 | struct vt_stat vtstat;
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109 | char *str_c;
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110 | int vtno;
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111 | int flags;
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112 | enum {
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113 | OPT_c = (1 << 0),
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114 | OPT_w = (1 << 1),
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115 | OPT_s = (1 << 2),
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116 | OPT_l = (1 << 3),
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117 | OPT_f = (1 << 4),
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118 | OPT_v = (1 << 5),
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119 | };
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120 |
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121 | /* "+" - stop on first non-option */
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122 | flags = getopt32(argv, "+c:wslfv", &str_c);
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123 | argv += optind;
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124 |
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125 | if (flags & OPT_c) {
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126 | /* Check for illegal vt number: < 1 or > 63 */
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127 | vtno = xatou_range(str_c, 1, 63);
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128 | } else {
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129 | vtno = find_free_vtno();
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130 | }
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131 |
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132 | /* Grab new VT */
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133 | sprintf(vtname, VC_FORMAT, vtno);
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134 | /* (Try to) clean up stray open fds above fd 2 */
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135 | bb_daemonize_or_rexec(DAEMON_CLOSE_EXTRA_FDS | DAEMON_ONLY_SANITIZE, NULL);
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136 | close(STDIN_FILENO);
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137 | /*setsid(); - BAD IDEA: after we exit, child is SIGHUPed... */
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138 | xopen(vtname, O_RDWR);
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139 | xioctl(STDIN_FILENO, VT_GETSTATE, &vtstat);
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140 |
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141 | if (flags & OPT_s) {
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142 | console_make_active(STDIN_FILENO, vtno);
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143 | }
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144 |
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145 | if (!argv[0]) {
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146 | argv--;
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147 | argv[0] = getenv("SHELL");
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148 | if (!argv[0])
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149 | argv[0] = (char *) DEFAULT_SHELL;
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150 | /*argv[1] = NULL; - already is */
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151 | }
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152 |
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153 | xdup2(STDIN_FILENO, STDOUT_FILENO);
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154 | xdup2(STDIN_FILENO, STDERR_FILENO);
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155 |
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156 | #ifdef BLOAT
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157 | {
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158 | /* Handle -l (login shell) option */
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159 | const char *prog = argv[0];
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160 | if (flags & OPT_l)
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161 | argv[0] = xasprintf("-%s", argv[0]);
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162 | }
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163 | #endif
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164 |
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165 | vfork_child(argv);
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166 | if (flags & OPT_w) {
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167 | /* We have only one child, wait for it */
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168 | safe_waitpid(-1, NULL, 0); /* loops on EINTR */
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169 | if (flags & OPT_s) {
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170 | console_make_active(STDIN_FILENO, vtstat.v_active);
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171 | // Compat: even with -c N (try to) disallocate:
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172 | // # /usr/app/kbd-1.12/bin/openvt -f -c 9 -ws sleep 5
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173 | // openvt: could not deallocate console 9
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174 | xioctl(STDIN_FILENO, VT_DISALLOCATE, (void*)(ptrdiff_t)vtno);
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175 | }
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176 | }
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177 | return EXIT_SUCCESS;
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178 | }
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