termios/echo_off.c

   1 #include <fcntl.h>
   2 #include <stdio.h>
   3 #include <stdlib.h>
   4 #include <termios.h>
   5
   6 #define PASSLEN 64
   7
   8 /* function prototypes */
   9 void diep(const char *s);
  10
  11 int main(int argc, char *argv[])
  12 {
  13     struct termios oldt, newt;
  14     char password[PASSLEN];
  15     int fd;
  16
  17     /* check argument count */
  18     if (argc != 2) {
  19         fprintf(stderr, "Usage: %s tty\n", argv[0]);
  20         exit(EXIT_FAILURE);
  21     }
  22
  23     /* open terminal device */
  24     if ((fd = open(argv[1], O_RDONLY | O_NOCTTY) == -1))
  25         diep("open");
  26
  27     /* get current termios structure */
  28     if (tcgetattr(fd, &oldt) == -1)
  29         diep("tcgetattr");
  30
  31     /* set new termios structure */
  32     newt = oldt;
  33     newt.c_lflag &= ~ECHO;     /* disable echoing */
  34     newt.c_lflag |= ECHONL;    /* echo NL even if ECHO is off */
  35
  36     if (tcsetattr(fd, TCSANOW, &newt) == -1)
  37         diep("tcsetattr");
  38
  39     /* prompt for password and get it*/
  40     printf("Password: ");
  41     scanf("%64s", password);
  42
  43     /* restole old termios structure */
  44     if (tcsetattr(fd, TCSANOW, &oldt) == -1)
  45         diep("tcsetattr");
  46
  47     return EXIT_SUCCESS;
  48 }
  49
  50 void diep(const char *s) {
  51     perror(s);
  52     exit(EXIT_FAILURE);
  53 }