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 #include <time.h>
  26
  27 #include "vlock.h"
  28
  29 /* Lock the current terminal until proper authentication is received. */
  30 int main(void) {
  31   char user[40];
  32   char *vlock_message;
  33   char *vlock_prompt_timeout;
  34   struct timespec timeout;
  35   struct timespec *timeout_p = NULL;
  36   struct termios term, term_bak;
  37   struct sigaction sa;
  38   /* get the user id */
  39   uid_t uid = getuid();
  40   /* get the user name from the environment */
  41   char *envuser = getenv("USER");
  42
  43   /* ignore some signals */
  44   /* these signals shouldn't be delivered anyway, because
  45    * terminal signals are disabled below */
  46   (void) sigemptyset(&(sa.sa_mask));
  47   sa.sa_flags = SA_RESTART;
  48   sa.sa_handler = SIG_IGN;
  49   (void) sigaction(SIGINT, &sa, NULL);
  50   (void) sigaction(SIGQUIT, &sa, NULL);
  51   (void) sigaction(SIGTSTP, &sa, NULL);
  52
  53   if (uid > 0 || envuser == NULL) {
  54     errno = 0;
  55
  56     /* get the password entry */
  57     struct passwd *pw = getpwuid(uid);
  58
  59     if (pw == NULL) {
  60       if (errno != 0)
  61         perror("vlock-current: getpwuid() failed");
  62       else
  63         fprintf(stderr, "vlock-current: getpwuid() failed\n");
  64
  65       exit (111);
  66     }
  67
  68     /* copy the username */
  69     strncpy(user, pw->pw_name, sizeof user - 1);
  70     user[sizeof user - 1] = '\0';
  71   } else {
  72     /* copy the username */
  73     strncpy(user, envuser, sizeof user - 1);
  74     user[sizeof user - 1] = '\0';
  75   }
  76
  77   /* get the vlock message from the environment */
  78   vlock_message = getenv("VLOCK_MESSAGE");
  79
  80   /* get the timeout from the environment */
  81   vlock_prompt_timeout = getenv("VLOCK_PROMPT_TIMEOUT");
  82
  83   if (vlock_prompt_timeout != NULL) {
  84     char *n;
  85     timeout.tv_sec = strtol(vlock_prompt_timeout, &n, 10);
  86     timeout.tv_nsec = 0;
  87
  88
  89     if (*n == '\0' && timeout.tv_sec > 0)
  90       timeout_p = &timeout;
  91   }
  92
  93   /* disable terminal echoing and signals */
  94   if (tcgetattr(STDIN_FILENO, &term) == 0) {
  95     term_bak = term;
  96     term.c_lflag &= ~(ECHO|ISIG);
  97     (void) tcsetattr(STDIN_FILENO, TCSANOW, &term);
  98   }
  99
 100   for (;;) {
 101     char c = 0;
 102
 103     /* clear the screen */
 104     fprintf(stderr, CLEAR_SCREEN);
 105
 106     if (vlock_message)
 107       /* print vlock message */
 108       fprintf(stderr, "%s\n", vlock_message);
 109
 110     /* wait for enter to be pressed */
 111     fprintf(stderr, "Please press [ENTER] to unlock.\n");
 112     while (read(STDIN_FILENO, &c, 1) >= 0)
 113       if (c == '\n')
 114         break;
 115
 116     if (auth(user, timeout_p))
 117       break;
 118     else
 119       sleep(1);
 120
 121 #ifndef NO_ROOT_PASS
 122     if (auth("root", timeout_p))
 123       break;
 124     else
 125       sleep(1);
 126 #endif
 127   }
 128
 129   /* restore the terminal */
 130   (void) tcsetattr(STDIN_FILENO, TCSANOW, &term_bak);
 131
 132   exit (0);
 133 }