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71 lines
2.9 KiB
Plaintext
71 lines
2.9 KiB
Plaintext
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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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