ubase/getty.c

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2.9 KiB
C
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/* See LICENSE file for copyright and license details. */
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#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/types.h>
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#include <fcntl.h>
#include <limits.h>
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#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
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#include <unistd.h>
#include <utmp.h>
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#include "util.h"
static void
usage(void)
{
eprintf("usage: %s [tty] [term] [cmd] [args...]\n", argv0);
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}
static char *tty = "/dev/tty1";
static char *defaultterm = "linux";
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int
main(int argc, char *argv[])
{
char term[128], logname[LOGIN_NAME_MAX], c;
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char hostname[HOST_NAME_MAX + 1];
struct utmp usr;
struct sigaction sa;
FILE *fp;
int fd;
unsigned int i = 0;
ssize_t n;
long pos;
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ARGBEGIN {
default:
usage();
} ARGEND;
strlcpy(term, defaultterm, sizeof(term));
if (argc > 0) {
tty = argv[0];
if (argc > 1)
strlcpy(term, argv[1], sizeof(term));
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}
sa.sa_handler = SIG_IGN;
sa.sa_flags = 0;
sigemptyset(&sa.sa_mask);
sigaction(SIGHUP, &sa, NULL);
setenv("TERM", term, 1);
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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)
vhangup();
else
weprintf("TIOCSCTTY: could not set controlling tty\n");
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close(fd);
fd = open(tty, O_RDWR);
if (fd < 0)
eprintf("open %s:", tty);
if (dup2(fd, STDIN_FILENO) != STDIN_FILENO)
eprintf("dup2:");
if (dup2(fd, STDOUT_FILENO) != STDOUT_FILENO)
eprintf("dup2:");
if (dup2(fd, STDERR_FILENO) != STDERR_FILENO)
eprintf("dup2:");
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sa.sa_handler = SIG_DFL;
sa.sa_flags = 0;
sigemptyset(&sa.sa_mask);
sigaction(SIGHUP, &sa, NULL);
if (fchown(fd, 0, 0) < 0)
eprintf("fchown %s:", tty);
if (fchmod(fd, 0600) < 0)
eprintf("chmod %s:", tty);
/* Clear all utmp entries for this tty */
fp = fopen("/var/run/utmp", "r+");
if (fp) {
do {
pos = ftell(fp);
if (fread(&usr, sizeof(usr), 1, fp) != 1)
break;
if (usr.ut_line[0] == '\0')
continue;
if (strcmp(usr.ut_line, tty) != 0)
continue;
memset(&usr, 0, sizeof(usr));
fseek(fp, pos, SEEK_SET);
if (fwrite(&usr, sizeof(usr), 1, fp) != 1)
break;
} while (1);
if (ferror(fp))
weprintf("%s: I/O error:", "/var/run/utmp");
fclose(fp);
}
if (argc > 2)
return execvp(argv[2], argv + 2);
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if (gethostname(hostname, sizeof(hostname)) == 0)
printf("%s ", hostname);
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 execlp("/bin/login", "login", "-p", logname, NULL);
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}