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34
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1 /* oneit.c, tiny one-process init replacement.
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2 *
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3 * Copyright 2005 by Rob Landley <rob@landley.net>.
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4 */
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5
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6 #include "toys.h"
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7 #include <sys/reboot.h>
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8
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9 // The minimum amount of work necessary to get ctrl-c and such to work is:
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10 //
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11 // - Fork a child (PID 1 is special: can't exit, has various signals blocked).
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12 // - Do a setsid() (so we have our own session).
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13 // - In the child, attach stdio to /dev/tty0 (/dev/console is special)
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14 // - Exec the rest of the command line.
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15 //
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16 // PID 1 then reaps zombies until the child process it spawned exits, at which
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17 // point it calls sync() and reboot(). I could stick a kill -1 in there.
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18
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19 int oneit_main(void)
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20 {
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21 int i;
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22 pid_t pid;
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23
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24 // Create a new child process.
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25 pid = vfork();
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26 if (pid) {
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27
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28 // pid 1 just reaps zombies until it gets its child, then halts the system.
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29 while (pid!=wait(&i));
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30 sync();
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31 reboot(toys.optflags ? RB_POWER_OFF : RB_AUTOBOOT);
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32 }
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33
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34 // Redirect stdio to /dev/tty0, with new session ID, so ctrl-c works.
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35 setsid();
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36 for (i=0; i<3; i++) {
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37 close(i);
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38 open("/dev/tty0",O_RDWR);
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39 }
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40
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41 // Can't xexec() here because we vforked so we don't want to error_exit().
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42 toy_exec(toys.optargs);
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43 execvp(*toys.optargs, toys.optargs);
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44 _exit(127);
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45 }
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