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 | //usage:#define openvt_trivial_usage
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12 | //usage: "[-c N] [-sw] [PROG ARGS]"
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13 | //usage:#define openvt_full_usage "\n\n"
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14 | //usage: "Start PROG on a new virtual terminal\n"
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15 | //usage: "\n -c N Use specified VT"
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16 | //usage: "\n -s Switch to the VT"
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17 | /* //usage: "\n -l Run PROG as login shell (by prepending '-')" */
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18 | //usage: "\n -w Wait for PROG to exit"
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19 | //usage:
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20 | //usage:#define openvt_example_usage
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21 | //usage: "openvt 2 /bin/ash\n"
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22 |
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23 | #include <linux/vt.h>
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24 | #include "libbb.h"
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25 |
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26 | /* "Standard" openvt's man page (we do not support all of this):
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27 |
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28 | openvt [-c NUM] [-fsulv] [--] [command [args]]
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29 |
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30 | Find the first available VT, and run command on it. Stdio is directed
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31 | to that VT. If no command is specified then $SHELL is used.
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32 |
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33 | -c NUM
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34 | Use the given VT number, not the first free one.
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35 | -f
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36 | Force opening a VT: don't try to check if VT is already in use.
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37 | -s
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38 | Switch to the new VT when starting the command.
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39 | The VT of the new command will be made the new current VT.
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40 | -u
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41 | Figure out the owner of the current VT, and run login as that user.
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42 | Suitable to be called by init. Shouldn't be used with -c or -l.
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43 | -l
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44 | Make the command a login shell: a "-" is prepended to the argv[0]
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45 | when command is executed.
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46 | -v
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47 | Verbose.
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48 | -w
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49 | Wait for command to complete. If -w and -s are used together,
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50 | switch back to the controlling terminal when the command completes.
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51 |
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52 | bbox:
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53 | -u: not implemented
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54 | -f: always in effect
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55 | -l: not implemented, ignored
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56 | -v: ignored
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57 | -ws: does NOT switch back
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58 | */
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59 |
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60 | /* Helper: does this fd understand VT_xxx? */
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61 | static int not_vt_fd(int fd)
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62 | {
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63 | struct vt_stat vtstat;
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64 | return ioctl(fd, VT_GETSTATE, &vtstat); /* !0: error, it's not VT fd */
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65 | }
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66 |
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67 | /* Helper: get a fd suitable for VT_xxx */
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68 | static int get_vt_fd(void)
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69 | {
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70 | int fd;
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71 |
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72 | /* Do we, by chance, already have it? */
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73 | for (fd = 0; fd < 3; fd++)
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74 | if (!not_vt_fd(fd))
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75 | return fd;
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76 | fd = open(DEV_CONSOLE, O_RDONLY | O_NONBLOCK);
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77 | if (fd >= 0 && !not_vt_fd(fd))
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78 | return fd;
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79 | bb_error_msg_and_die("can't find open VT");
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80 | }
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81 |
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82 | static int find_free_vtno(void)
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83 | {
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84 | int vtno;
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85 | int fd = get_vt_fd();
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86 |
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87 | errno = 0;
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88 | /*xfunc_error_retval = 3; - do we need compat? */
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89 | if (ioctl(fd, VT_OPENQRY, &vtno) != 0 || vtno <= 0)
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90 | bb_perror_msg_and_die("can't find open VT");
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91 | // Not really needed, grep for DAEMON_ONLY_SANITIZE
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92 | // if (fd > 2)
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93 | // close(fd);
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94 | return vtno;
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95 | }
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96 |
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97 | /* vfork scares gcc, it generates bigger code.
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98 | * Keep it away from main program.
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99 | * TODO: move to libbb; or adapt existing libbb's spawn().
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100 | */
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101 | static NOINLINE void vfork_child(char **argv)
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102 | {
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103 | if (vfork() == 0) {
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104 | /* CHILD */
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105 | /* Try to make this VT our controlling tty */
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106 | setsid(); /* lose old ctty */
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107 | ioctl(STDIN_FILENO, TIOCSCTTY, 0 /* 0: don't forcibly steal */);
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108 | //bb_error_msg("our sid %d", getsid(0));
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109 | //bb_error_msg("our pgrp %d", getpgrp());
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110 | //bb_error_msg("VT's sid %d", tcgetsid(0));
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111 | //bb_error_msg("VT's pgrp %d", tcgetpgrp(0));
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112 | BB_EXECVP_or_die(argv);
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113 | }
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114 | }
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115 |
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116 | int openvt_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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117 | int openvt_main(int argc UNUSED_PARAM, char **argv)
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118 | {
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119 | char vtname[sizeof(VC_FORMAT) + sizeof(int)*3];
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120 | struct vt_stat vtstat;
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121 | char *str_c;
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122 | int vtno;
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123 | int flags;
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124 | enum {
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125 | OPT_c = (1 << 0),
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126 | OPT_w = (1 << 1),
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127 | OPT_s = (1 << 2),
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128 | OPT_l = (1 << 3),
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129 | OPT_f = (1 << 4),
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130 | OPT_v = (1 << 5),
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131 | };
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132 |
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133 | /* "+" - stop on first non-option */
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134 | flags = getopt32(argv, "+c:wslfv", &str_c);
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135 | argv += optind;
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136 |
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137 | if (flags & OPT_c) {
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138 | /* Check for illegal vt number: < 1 or > 63 */
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139 | vtno = xatou_range(str_c, 1, 63);
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140 | } else {
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141 | vtno = find_free_vtno();
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142 | }
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143 |
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144 | /* Grab new VT */
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145 | sprintf(vtname, VC_FORMAT, vtno);
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146 | /* (Try to) clean up stray open fds above fd 2 */
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147 | bb_daemonize_or_rexec(DAEMON_CLOSE_EXTRA_FDS | DAEMON_ONLY_SANITIZE, NULL);
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148 | close(STDIN_FILENO);
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149 | /*setsid(); - BAD IDEA: after we exit, child is SIGHUPed... */
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150 | xopen(vtname, O_RDWR);
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151 | xioctl(STDIN_FILENO, VT_GETSTATE, &vtstat);
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152 |
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153 | if (flags & OPT_s) {
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154 | console_make_active(STDIN_FILENO, vtno);
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155 | }
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156 |
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157 | if (!argv[0]) {
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158 | argv--;
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159 | argv[0] = (char *) get_shell_name();
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160 | /*argv[1] = NULL; - already is */
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161 | }
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162 |
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163 | xdup2(STDIN_FILENO, STDOUT_FILENO);
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164 | xdup2(STDIN_FILENO, STDERR_FILENO);
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165 |
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166 | #ifdef BLOAT
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167 | {
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168 | /* Handle -l (login shell) option */
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169 | const char *prog = argv[0];
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170 | if (flags & OPT_l)
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171 | argv[0] = xasprintf("-%s", argv[0]);
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172 | }
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173 | #endif
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174 |
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175 | vfork_child(argv);
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176 | if (flags & OPT_w) {
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177 | /* We have only one child, wait for it */
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178 | safe_waitpid(-1, NULL, 0); /* loops on EINTR */
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179 | if (flags & OPT_s) {
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180 | console_make_active(STDIN_FILENO, vtstat.v_active);
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181 | // Compat: even with -c N (try to) disallocate:
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182 | // # /usr/app/kbd-1.12/bin/openvt -f -c 9 -ws sleep 5
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183 | // openvt: could not deallocate console 9
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184 | xioctl(STDIN_FILENO, VT_DISALLOCATE, (void*)(ptrdiff_t)vtno);
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185 | }
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186 | }
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187 | return EXIT_SUCCESS;
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188 | }
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