114 lines
2.3 KiB
C
114 lines
2.3 KiB
C
/* See LICENSE file for copyright and license details. */
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#include <fcntl.h>
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#include <limits.h>
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/ioctl.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <unistd.h>
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#include "util.h"
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static void
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usage(void)
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{
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eprintf("usage: %s [tty] [term] [cmd] [args...]\n", argv0);
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}
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static char *tty = "/dev/tty1";
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static char *defaultterm = "linux";
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int
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main(int argc, char *argv[])
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{
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int fd;
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struct sigaction sa;
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char term[128], logname[LOGIN_NAME_MAX], c;
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char hostname[HOST_NAME_MAX + 1];
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unsigned int i = 0;
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ssize_t n;
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ARGBEGIN {
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default:
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usage();
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} ARGEND;
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strlcpy(term, defaultterm, sizeof(term));
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if (argc > 0) {
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tty = argv[0];
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if (argc > 1)
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strlcpy(term, argv[1], sizeof(term));
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}
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sa.sa_handler = SIG_IGN;
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sa.sa_flags = 0;
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sigemptyset(&sa.sa_mask);
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sigaction(SIGHUP, &sa, NULL);
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setenv("TERM", term, 1);
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setsid();
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fd = open(tty, O_RDWR);
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if (fd < 0)
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eprintf("open %s:", tty);
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if (isatty(fd) == 0)
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eprintf("%s is not a tty\n", tty);
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if (ioctl(fd, TIOCSCTTY, (void *)1) == 0)
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vhangup();
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else
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fprintf(stderr, "could not set controlling tty\n");
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close(fd);
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fd = open(tty, O_RDWR);
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if (fd < 0)
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eprintf("open %s:", tty);
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if (dup2(fd, STDIN_FILENO) != STDIN_FILENO)
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eprintf("dup2:");
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if (dup2(fd, STDOUT_FILENO) != STDOUT_FILENO)
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eprintf("dup2:");
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if (dup2(fd, STDERR_FILENO) != STDERR_FILENO)
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eprintf("dup2:");
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sa.sa_handler = SIG_DFL;
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sa.sa_flags = 0;
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sigemptyset(&sa.sa_mask);
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sigaction(SIGHUP, &sa, NULL);
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if (fchown(fd, 0, 0) < 0)
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eprintf("fchown %s:", tty);
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if (fchmod(fd, 0600) < 0)
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eprintf("chmod %s:", tty);
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if (argc > 2)
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return execvp(argv[2], argv + 2);
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if (gethostname(hostname, sizeof(hostname)) == 0)
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printf("%s ", hostname);
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printf("login: ");
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fflush(stdout);
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/* Flush pending input */
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ioctl(STDIN_FILENO, TCFLSH, (void *)0);
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memset(logname, 0, sizeof(logname));
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while (1) {
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n = read(STDIN_FILENO, &c, 1);
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if (n < 0)
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eprintf("read:");
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if (n == 0)
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return EXIT_FAILURE;
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if (i >= sizeof(logname) - 1)
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eprintf("login name too long\n");
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if (c == '\n' || c == '\r')
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break;
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logname[i++] = c;
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}
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if (logname[0] == '-')
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eprintf("login name cannot start with '-'\n");
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if (logname[0] == '\0')
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return EXIT_FAILURE;
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return execlp("/bin/login", "login", "-p", logname, NULL);
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}
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