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(SIGQUIT, SIG_IGN);
  41   signal(SIGTSTP, SIG_IGN);
  42
  43   if (uid > 0 || envuser == NULL) {
  44     /* get the password entry */
  45     struct passwd *pw = getpwuid(uid);
  46
  47     if (pw == NULL) {
  48       if (errno != 0)
  49         perror("vlock-current: getpwuid() failed");
  50       else
  51         fprintf(stderr, "vlock-current: getpwuid() failed\n");
  52
  53       exit (111);
  54     }
  55
  56     /* copy the username */
  57     strncpy(user, pw->pw_name, sizeof user - 1);
  58     user[sizeof user - 1] = '\0';
  59   } else {
  60     /* copy the username */
  61     strncpy(user, envuser, sizeof user - 1);
  62     user[sizeof user - 1] = '\0';
  63   }
  64
  65   /* get the vlock message from the environment */
  66   vlock_message = getenv("VLOCK_MESSAGE");
  67
  68   /* disable terminal echoing and signals */
  69   if (tcgetattr(STDIN_FILENO, &term) == 0) {
  70     term_bak = term;
  71     term.c_lflag &= ~(ECHO|ISIG);
  72     (void) tcsetattr(STDIN_FILENO, TCSANOW, &term);
  73   }
  74
  75   for (;;) {
  76     /* clear the screen */
  77     fprintf(stderr, CLEAR_SCREEN);
  78
  79     if (vlock_message)
  80       /* print vlock message */
  81       fprintf(stderr, "%s\n", vlock_message);
  82
  83     /* wait for enter to be pressed */
  84     fprintf(stderr, "Please press [ENTER] to unlock.\n");
  85     while (fgetc(stdin) != '\n');
  86
  87     if (auth(user))
  88       break;
  89     else
  90       sleep(1);
  91
  92 #ifndef NO_ROOT_PASS
  93     if (auth("root"))
  94       break;
  95     else
  96       sleep(1);
  97 #endif
  98   }
  99
 100   /* restore the terminal */
 101   (void) tcsetattr(STDIN_FILENO, TCSANOW, &term_bak);
 102
 103   exit (0);
 104 }