Here's a basic getty.
It just reopens the current tty in such a way as to allow blocking code
to work, then calls the login program of your choice (-l).
/etc/issue is ignored, so -i is a nop.
It does NOT modify the environment (including setting TERM), support
baud rate setting or autodetection, do anything with modems, prompt for
any user input, or open new ttys.
Supporting
getty ttyN $TERM
should be something like this...
char * prepend(char *arg, char *pfix)
{
if (!arg) return NULL;
int alen = strlen(arg), plen = strlen(pfix);
char * ret = xzalloc(alen + plen + 1);
strcpy(ret, pfix);
strcpy(ret+plen, arg);
return ret;
}
char *tty = prepend(toys.optargs[0], "/dev/")
if (!tty) tty = ttyname(0);
if (toys.optc > 1) {
char *termname = prepend(toys.optargs[1], "TERM=");
if (termname) putenv(termname);
}
--
With this, I can boot to a login prompt using only a shell and a toybox
binary (with several pending applets enabled, and a hacked version of
one of the many submissions for mount).
I also have a small applet (resolve_modalias) that is mainly useful for
testing, which I've sent a couple times to illustrate issues;
maybe sometime I should see about putting the core code into a library
function so modprobe and modinfo can share it....
Thanks,
Isaac Dunham
/* getty.c - get a controlling tty
*
* Copyright 2013 Isaac Dunham <[email protected]>
*
* No standard.
USE_GETTY(NEWTOY(getty, "il:", TOYFLAG_NEEDROOT|TOYFLAG_SBIN))
config GETTY
bool "getty"
default n
help
usage: getty [-i] [-l LOGIN_CMD]
open a tty as controlling terminal, spawn a login program
-i Ignore /etc/issue (default for now)
-l login command (instead of "login")
*/
#define FOR_getty
#include <toys.h>
GLOBALS(
char *login;
char *nul; // so we can xexec(&TT.login)
)
void getty_main(void)
{
char *tty = ttyname(0);
int fd;
if (!TT.login) TT.login = "login";
if (!tty) perror_exit("no tty");
close(0); close(1); close(2);
errno = 0;
fd = xopen(tty, O_RDWR);
if (fd) dup2(fd, 0);
dup2(0, 1);
dup2(0, 2);
if (errno) xexit();
xexec(&TT.login);
}
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