--- /dev/null
+ Getty
+
+??? Should getty open tty with or without O_NONBLOCK?
+For serial lines, it means "should getty wait for Carrier Detect pin?"
+I checked other getties:
+
+- agetty always uses O_NONBLOCK
+- mgetty uses O_NONBLOCK unless run with -b, or as "getty"
+
+??? If we decided to use O_NONBLOCK (perhaps optionally with -b),
+when getty should send -I INITSTR data to tty? After open succeeds?
+What if we also want to initialize *modem* with some AT commands?
+
+??? Should we check/create /var/lock/LCK..ttyPFX lockfiles?
+
+??? mgetty opens tty but does NOT lock it, then waits for input via
+select/poll, and when input is available, it checks lock file.
+If it exists, mgetty exits (it assumes someone else uses the line).
+If no, it creates the file (lock the tty). Sounds like a good algorithm
+to use if we are called with -w...
+
+Getty should establish a new session and process group, and ensure
+that tty is a ctty.
+
+??? Should getty ensure that other processes which might have opened
+fds to this tty be dusconnected? agetty has a -R option which makes
+agetty call vhangup() after tty is opened. (Then agetty opens it again,
+since it probably vhangup'ed its own fd too).
+
+Getty should leave the tty in approximately the same state as "stty sane"
+before it execs login program. Minor things we do conditionally are:
+ c_iflag |= ICRNL; // if '\r' was used to end username
+
+??? mgetty uses per-tty file to ignore connects, /etc/nologin.ttyxx -
+is it useful?
+
+It should be possible to run "getty 0 -" from a shell prompt.
+[This currently doesn't work from interactive shell since setsid()
+fails in process group leader. The workaround is to run it as a child
+of something. sh -c 'getty - 0; true' usually works. Should we fix this?]
+It should leave tty in a sane state when it exits (Ctrl-D, -t SEC timeout):
+echo should be on, speed, control chars properly set, etc.
+(However, it can't restore ctty. The symptom is that "</dev/tty"
+fails in the parent shell after getty exits: /dev/tty can't be opened).
+
+Getty should write LOGIN_PROCESS utmp record before it starts waiting
+for username to be entered.
+
+ Login
+
+Login should not try to set up tty parameters - apart from switching echo
+off while entering password, and switching it back on after.
+
+Login should not leave "echo off" state when it times out reading password
+or otherwise terminates (Ctrl-C, Ctrl-D etc).
+
+??? Should login establish a new session and/or process group, and ensure
+that tty is a ctty? Without this, running login directly (not via getty)
+from e.g. initscript will usually result with a login session without
+ctty and without session/pgrp properly created...
+
+It should be possible to run "login [USER]" from a shell prompt,
+and it should work (not block/die/error out).
+Similarly to getty, it should leave tty in the sane state when it exits.
+
+??? Should login write LOGIN_PROCESS utmp record before it starts waiting
+for username/password to be entered?
+
+Login should write USER_PROCESS utmp record just before it is about
+to exec user's shell.
*/
#define ISSUE "/etc/issue"
-/* Some shorthands for control characters */
-#define CTL(x) ((x) ^ 0100) /* Assumes ASCII dialect */
-#define BS CTL('H') /* back space */
-#define DEL CTL('?') /* delete */
-
-/* Defaults for line-editing etc. characters; you may want to change this */
-#define DEF_INTR CTL('C') /* default interrupt character */
-#define DEF_QUIT CTL('\\') /* default quit char */
-#define DEF_KILL CTL('U') /* default kill char */
-#define DEF_EOF CTL('D') /* default EOF char */
-#define DEF_EOL '\n'
-#define DEF_SWITCH 0 /* default switch char (none) */
+/* Macro to build Ctrl-LETTER. Assumes ASCII dialect */
+#define CTL(x) ((x) ^ 0100)
/*
* When multiple baud rates are specified on the command line,
* (why "stty sane" unsets this bit?)
*/
- G.tty_attrs.c_cc[VINTR] = DEF_INTR;
- G.tty_attrs.c_cc[VQUIT] = DEF_QUIT;
- G.tty_attrs.c_cc[VEOF] = DEF_EOF;
- G.tty_attrs.c_cc[VEOL] = DEF_EOL;
+ G.tty_attrs.c_cc[VINTR] = CTL('C');
+ G.tty_attrs.c_cc[VQUIT] = CTL('\\');
+ G.tty_attrs.c_cc[VEOF] = CTL('D');
+ G.tty_attrs.c_cc[VEOL] = '\n';
#ifdef VSWTC
- G.tty_attrs.c_cc[VSWTC] = DEF_SWITCH;
+ G.tty_attrs.c_cc[VSWTC] = 0;
#endif
#ifdef VSWTCH
- G.tty_attrs.c_cc[VSWTCH] = DEF_SWITCH;
+ G.tty_attrs.c_cc[VSWTCH] = 0;
#endif
- G.tty_attrs.c_cc[VKILL] = DEF_KILL;
+ G.tty_attrs.c_cc[VKILL] = CTL('U');
/* Other control chars:
* VEOL2
* VERASE, VWERASE - (word) erase. we may set VERASE in get_logname
*/
set_tty_attrs();
+
+ /* Now the newline character should be properly written */
+ full_write(STDOUT_FILENO, "\n", 1);
}
/* extract baud rate from modem status message */
tcflush(STDIN_FILENO, TCIFLUSH);
/* Prompt for and read a login name */
- G.line_buf[0] = '\0';
- while (!G.line_buf[0]) {
+ do {
/* Write issue file and prompt */
#ifdef ISSUE
if (!(option_mask32 & F_NOISSUE))
#endif
print_login_prompt();
- /* Read name, watch for break, parity, erase, kill, end-of-line */
+ /* Read name, watch for break, erase, kill, end-of-line */
bp = G.line_buf;
- G.eol = '\0';
while (1) {
/* Do not report trivial EINTR/EIO errors */
errno = EINTR; /* make read of 0 bytes be silent too */
bb_perror_msg_and_die(bb_msg_read_error);
}
- /* BREAK. If we have speeds to try,
- * return NULL (will switch speeds and return here) */
- if (c == '\0' && G.numspeed > 1)
- return NULL;
-
- /* Do erase, kill and end-of-line processing */
switch (c) {
case '\r':
case '\n':
*bp = '\0';
G.eol = c;
goto got_logname;
- case BS:
- case DEL:
+ case CTL('H'):
+ case 0x7f:
G.tty_attrs.c_cc[VERASE] = c;
if (bp > G.line_buf) {
full_write(STDOUT_FILENO, "\010 \010", 3);
bp--;
}
break;
+ case CTL('C'):
case CTL('D'):
finalize_tty_attrs();
exit(EXIT_SUCCESS);
+ case '\0':
+ /* BREAK. If we have speeds to try,
+ * return NULL (will switch speeds and return here) */
+ if (G.numspeed > 1)
+ return NULL;
+ /* fall through and ignore it */
default:
if ((unsigned char)c < ' ') {
/* ignore garbage characters */
}
} /* end of get char loop */
got_logname: ;
- } /* while logname is empty */
+ } while (G.line_buf[0] == '\0'); /* while logname is empty */
return G.line_buf;
}
finalize_tty_attrs();
- /* Now the newline character should be properly written */
- full_write(STDOUT_FILENO, "\n", 1);
-
/* Let the login program take care of password validation */
/* We use PATH because we trust that root doesn't set "bad" PATH,
* and getty is not suid-root applet */
projects / oweals / busybox.git / commitdiff