getty: fix a minor problem of Ctrl-D not printing '\n'
Also removed defines for control chars which are never changed, and added login/getty README. Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko
parent
ee320c6d9c
commit
e9dc354df8
70
loginutils/README
Normal file
70
loginutils/README
Normal file
@ -0,0 +1,70 @@
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Getty
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??? Should getty open tty with or without O_NONBLOCK?
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For serial lines, it means "should getty wait for Carrier Detect pin?"
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I checked other getties:
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- agetty always uses O_NONBLOCK
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- mgetty uses O_NONBLOCK unless run with -b, or as "getty"
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??? If we decided to use O_NONBLOCK (perhaps optionally with -b),
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when getty should send -I INITSTR data to tty? After open succeeds?
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What if we also want to initialize *modem* with some AT commands?
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??? Should we check/create /var/lock/LCK..ttyPFX lockfiles?
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??? mgetty opens tty but does NOT lock it, then waits for input via
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select/poll, and when input is available, it checks lock file.
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If it exists, mgetty exits (it assumes someone else uses the line).
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If no, it creates the file (lock the tty). Sounds like a good algorithm
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to use if we are called with -w...
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Getty should establish a new session and process group, and ensure
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that tty is a ctty.
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??? Should getty ensure that other processes which might have opened
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fds to this tty be dusconnected? agetty has a -R option which makes
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agetty call vhangup() after tty is opened. (Then agetty opens it again,
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since it probably vhangup'ed its own fd too).
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Getty should leave the tty in approximately the same state as "stty sane"
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before it execs login program. Minor things we do conditionally are:
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c_iflag |= ICRNL; // if '\r' was used to end username
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??? mgetty uses per-tty file to ignore connects, /etc/nologin.ttyxx -
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is it useful?
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It should be possible to run "getty 0 -" from a shell prompt.
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[This currently doesn't work from interactive shell since setsid()
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fails in process group leader. The workaround is to run it as a child
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of something. sh -c 'getty - 0; true' usually works. Should we fix this?]
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It should leave tty in a sane state when it exits (Ctrl-D, -t SEC timeout):
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echo should be on, speed, control chars properly set, etc.
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(However, it can't restore ctty. The symptom is that "</dev/tty"
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fails in the parent shell after getty exits: /dev/tty can't be opened).
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Getty should write LOGIN_PROCESS utmp record before it starts waiting
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for username to be entered.
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Login
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Login should not try to set up tty parameters - apart from switching echo
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off while entering password, and switching it back on after.
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Login should not leave "echo off" state when it times out reading password
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or otherwise terminates (Ctrl-C, Ctrl-D etc).
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??? Should login establish a new session and/or process group, and ensure
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that tty is a ctty? Without this, running login directly (not via getty)
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from e.g. initscript will usually result with a login session without
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ctty and without session/pgrp properly created...
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It should be possible to run "login [USER]" from a shell prompt,
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and it should work (not block/die/error out).
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Similarly to getty, it should leave tty in the sane state when it exits.
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??? Should login write LOGIN_PROCESS utmp record before it starts waiting
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for username/password to be entered?
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Login should write USER_PROCESS utmp record just before it is about
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to exec user's shell.
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@ -63,18 +63,8 @@ static FILE *dbf;
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*/
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#define ISSUE "/etc/issue"
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/* Some shorthands for control characters */
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#define CTL(x) ((x) ^ 0100) /* Assumes ASCII dialect */
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#define BS CTL('H') /* back space */
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#define DEL CTL('?') /* delete */
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/* Defaults for line-editing etc. characters; you may want to change this */
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#define DEF_INTR CTL('C') /* default interrupt character */
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#define DEF_QUIT CTL('\\') /* default quit char */
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#define DEF_KILL CTL('U') /* default kill char */
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#define DEF_EOF CTL('D') /* default EOF char */
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#define DEF_EOL '\n'
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#define DEF_SWITCH 0 /* default switch char (none) */
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/* Macro to build Ctrl-LETTER. Assumes ASCII dialect */
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#define CTL(x) ((x) ^ 0100)
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/*
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* When multiple baud rates are specified on the command line,
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@ -365,17 +355,17 @@ static void finalize_tty_attrs(void)
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* (why "stty sane" unsets this bit?)
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*/
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G.tty_attrs.c_cc[VINTR] = DEF_INTR;
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G.tty_attrs.c_cc[VQUIT] = DEF_QUIT;
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G.tty_attrs.c_cc[VEOF] = DEF_EOF;
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G.tty_attrs.c_cc[VEOL] = DEF_EOL;
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G.tty_attrs.c_cc[VINTR] = CTL('C');
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G.tty_attrs.c_cc[VQUIT] = CTL('\\');
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G.tty_attrs.c_cc[VEOF] = CTL('D');
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G.tty_attrs.c_cc[VEOL] = '\n';
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#ifdef VSWTC
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G.tty_attrs.c_cc[VSWTC] = DEF_SWITCH;
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G.tty_attrs.c_cc[VSWTC] = 0;
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#endif
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#ifdef VSWTCH
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G.tty_attrs.c_cc[VSWTCH] = DEF_SWITCH;
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G.tty_attrs.c_cc[VSWTCH] = 0;
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#endif
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G.tty_attrs.c_cc[VKILL] = DEF_KILL;
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G.tty_attrs.c_cc[VKILL] = CTL('U');
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/* Other control chars:
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* VEOL2
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* VERASE, VWERASE - (word) erase. we may set VERASE in get_logname
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@ -386,6 +376,9 @@ static void finalize_tty_attrs(void)
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*/
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set_tty_attrs();
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/* Now the newline character should be properly written */
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full_write(STDOUT_FILENO, "\n", 1);
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}
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/* extract baud rate from modem status message */
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@ -449,8 +442,7 @@ static char *get_logname(void)
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tcflush(STDIN_FILENO, TCIFLUSH);
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/* Prompt for and read a login name */
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G.line_buf[0] = '\0';
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while (!G.line_buf[0]) {
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do {
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/* Write issue file and prompt */
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#ifdef ISSUE
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if (!(option_mask32 & F_NOISSUE))
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@ -458,9 +450,8 @@ static char *get_logname(void)
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#endif
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print_login_prompt();
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/* Read name, watch for break, parity, erase, kill, end-of-line */
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/* Read name, watch for break, erase, kill, end-of-line */
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bp = G.line_buf;
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G.eol = '\0';
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while (1) {
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/* Do not report trivial EINTR/EIO errors */
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errno = EINTR; /* make read of 0 bytes be silent too */
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@ -471,20 +462,14 @@ static char *get_logname(void)
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bb_perror_msg_and_die(bb_msg_read_error);
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}
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/* BREAK. If we have speeds to try,
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* return NULL (will switch speeds and return here) */
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if (c == '\0' && G.numspeed > 1)
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return NULL;
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/* Do erase, kill and end-of-line processing */
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switch (c) {
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case '\r':
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case '\n':
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*bp = '\0';
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G.eol = c;
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goto got_logname;
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case BS:
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case DEL:
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case CTL('H'):
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case 0x7f:
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G.tty_attrs.c_cc[VERASE] = c;
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if (bp > G.line_buf) {
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full_write(STDOUT_FILENO, "\010 \010", 3);
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@ -497,9 +482,16 @@ static char *get_logname(void)
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bp--;
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}
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break;
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case CTL('C'):
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case CTL('D'):
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finalize_tty_attrs();
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exit(EXIT_SUCCESS);
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case '\0':
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/* BREAK. If we have speeds to try,
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* return NULL (will switch speeds and return here) */
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if (G.numspeed > 1)
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return NULL;
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/* fall through and ignore it */
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default:
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if ((unsigned char)c < ' ') {
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/* ignore garbage characters */
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@ -512,7 +504,7 @@ static char *get_logname(void)
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}
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} /* end of get char loop */
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got_logname: ;
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} /* while logname is empty */
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} while (G.line_buf[0] == '\0'); /* while logname is empty */
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return G.line_buf;
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}
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@ -682,9 +674,6 @@ int getty_main(int argc UNUSED_PARAM, char **argv)
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finalize_tty_attrs();
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/* Now the newline character should be properly written */
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full_write(STDOUT_FILENO, "\n", 1);
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/* Let the login program take care of password validation */
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/* We use PATH because we trust that root doesn't set "bad" PATH,
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* and getty is not suid-root applet */
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@ -443,7 +443,6 @@ int login_main(int argc UNUSED_PARAM, char **argv)
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if (pw->pw_uid != 0)
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die_if_nologin();
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#if ENABLE_LOGIN_SESSION_AS_CHILD
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child_pid = vfork();
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if (child_pid != 0) {
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