src/vlock-current.c

   1 /* vlock-current.c -- locking routine for vlock,
   2  *                    the VT locking program for linux
   3  *
   4  * This program is copyright (C) 2007 Frank Benkstein, and is free
   5  * software which is freely distributable under the terms of the
   6  * GNU General Public License version 2, included as the file COPYING in this
   7  * distribution.  It is NOT public domain software, and any
   8  * redistribution not permitted by the GNU General Public License is
   9  * expressly forbidden without prior written permission from
  10  * the author.
  11  *
  12  */
  13
  14 #include <stdlib.h>
  15 #include <string.h>
  16 #include <stdio.h>
  17
  18 #include <pwd.h>
  19
  20 #include <termios.h>
  21 #include <unistd.h>
  22 #include <sys/types.h>
  23 #include <signal.h>
  24 #include <errno.h>
  25
  26 #include "vlock.h"
  27
  28 /* Lock the current terminal until proper authentication is received. */
  29 int main(void) {
  30   char user[40];
  31   char *vlock_message;
  32   struct termios term, term_bak;
  33   /* get the user id */
  34   uid_t uid = getuid();
  35   /* get the user name from the environment */
  36   char *envuser = getenv("USER");
  37
  38   /* ignore some signals */
  39   signal(SIGINT, SIG_IGN);
  40   signal(SIGHUP, SIG_IGN);
  41   signal(SIGQUIT, SIG_IGN);
  42   signal(SIGTSTP, SIG_IGN);
  43
  44   if (uid > 0 || envuser == NULL) {
  45     /* get the password entry */
  46     struct passwd *pw = getpwuid(uid);
  47
  48     if (pw == NULL) {
  49       if (errno != 0)
  50         perror("vlock-current: getpwuid() failed");
  51       else
  52         fprintf(stderr, "vlock-current: getpwuid() failed\n");
  53
  54       exit (111);
  55     }
  56
  57     /* copy the username */
  58     strncpy(user, pw->pw_name, sizeof user - 1);
  59     user[sizeof user - 1] = '\0';
  60   } else {
  61     /* copy the username */
  62     strncpy(user, envuser, sizeof user - 1);
  63     user[sizeof user - 1] = '\0';
  64   }
  65
  66   /* get the vlock message from the environment */
  67   vlock_message = getenv("VLOCK_MESSAGE");
  68
  69   /* disable terminal echoing and signals */
  70   if (tcgetattr(STDIN_FILENO, &term) == 0) {
  71     term_bak = term;
  72     term.c_lflag &= ~(ECHO|ISIG);
  73     (void) tcsetattr(STDIN_FILENO, TCSANOW, &term);
  74   }
  75
  76   for (;;) {
  77     /* clear the screen */
  78     fprintf(stderr, CLEAR_SCREEN);
  79
  80     if (vlock_message)
  81       /* print vlock message */
  82       fprintf(stderr, "%s\n", vlock_message);
  83
  84     /* wait for enter to be pressed */
  85     fprintf(stderr, "Please press [ENTER] to unlock.\n");
  86     while (fgetc(stdin) != '\n');
  87
  88     if (auth(user))
  89       break;
  90     else
  91       sleep(1);
  92
  93 #ifndef NO_ROOT_PASS
  94     if (auth("root"))
  95       break;
  96     else
  97       sleep(1);
  98 #endif
  99   }
 100
 101   /* restore the terminal */
 102   (void) tcsetattr(STDIN_FILENO, TCSANOW, &term_bak);
 103
 104   exit (0);
 105 }