ubase/getty.c

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C
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/* See LICENSE file for copyright and license details. */
#include <fcntl.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
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#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include "util.h"
static void
usage(void)
{
eprintf("usage: %s [tty] [term]\n", argv0);
}
static char *tty = "/dev/tty1";
static char *defaultterm = "TERM=linux";
int
main(int argc, char *argv[])
{
int fd;
struct sigaction sa;
char term[128], logname[128], c;
int i = 0;
ssize_t n;
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ARGBEGIN {
default:
usage();
} ARGEND;
if (argc > 2)
usage();
strlcpy(term, defaultterm, sizeof(term));
if (argc > 0) {
tty = argv[0];
if (argc > 1) {
strlcpy(term, "TERM=", sizeof(term));
strlcat(term, argv[1], sizeof(term));
}
}
sa.sa_handler = SIG_IGN;
sa.sa_flags = 0;
sigemptyset(&sa.sa_mask);
sigaction(SIGHUP, &sa, NULL);
putenv(term);
setsid();
fd = open(tty, O_RDWR);
if (fd < 0)
eprintf("open %s:", tty);
if (isatty(fd) == 0)
eprintf("%s is not a tty\n", tty);
if (ioctl(fd, TIOCSCTTY, (void *)1) == 0) {
if (vhangup() < 0)
eprintf("vhangup:");
} else {
fprintf(stderr, "could not set controlling tty\n");
}
close(fd);
fd = open(tty, O_RDWR);
if (fd < 0)
eprintf("open %s:", tty);
dup2(fd, STDIN_FILENO);
dup2(fd, STDOUT_FILENO);
dup2(fd, STDERR_FILENO);
sa.sa_handler = SIG_DFL;
sa.sa_flags = 0;
sigemptyset(&sa.sa_mask);
sigaction(SIGHUP, &sa, NULL);
printf("Login: ");
fflush(stdout);
/* Flush pending input */
ioctl(STDIN_FILENO, TCFLSH, (void *)0);
memset(logname, 0, sizeof(logname));
while (1) {
n = read(STDIN_FILENO, &c, 1);
if (n < 0)
eprintf("read:");
if (n == 0)
return EXIT_FAILURE;
if (i >= sizeof(logname) - 1)
eprintf("login name too long\n");
if (c == '\n' || c == '\r')
break;
logname[i++] = c;
}
if (logname[0] == '-')
eprintf("login name cannot start with '-'\n");
if (logname[0] == '\0')
return EXIT_FAILURE;
return execvp("/bin/login", (char *[]){ "login", logname, NULL });
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}