#include <fcntl.h>
#include <termio.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <stdio.h>

/*
 * How to read a password of up to 256 charaqcters and prevent
 * the characters from being displayed.
 */

/* Maximum number of characters allowed for the password entered */
#define NUM_CHARACTERS      256

/* Reads a password but turns off the echoing of characters */
const char*
get_passstring(const char *prompt)
{
  struct termio save_tty;
  int ch;
  char *p;
  FILE *fp;
  FILE *outfp;  /* points to either /dev/tty or stderr */
  int fd;
  tcflag_t svlflag;
  static char input_buf[NUM_CHARACTERS + 1];

  /* Try to read and write to /dev/tty */
  fd = open("/dev/tty", O_RDWR);
  if (fd < 0 || (outfp = fp = fdopen(fd, "r+")) == NULL) {
    /* Can't read/write to /dev/tty, try to read from stdin and write
     * to stderr.  */
    outfp = stderr;
    fp = stdin;
  }

  ioctl(fileno(fp), TCGETA, &save_tty);  /* Get terminal attributes */
  svlflag = save_tty.c_lflag;		/* Save current settings */
  save_tty.c_lflag &= ~ECHO;		/* Turn off character echoing */
  ioctl(fileno(fp), TCSETA, &save_tty); /* Save these settings */
  fprintf(outfp, "%s", prompt);
  rewind(outfp);              /* rewind has an implied flush */
  for (p = input_buf; p < &input_buf[NUM_CHARACTERS]; p++) {
    if ((ch = getc(fp)) == EOF || ch == '\n') {
      break;
    }
    *p = ch;
  }
  *p = '\0';
  write(fileno(outfp), "\n", 1);	/* Put in a visible newline */

  save_tty.c_lflag = svlflag;		/* Restore original settings */
  ioctl(fileno(fp), TCSETA, &save_tty); /* Save these settings */

  if (fp != stdin) {
    fclose(fp);
  }

  return input_buf;

}

int
main(int argc, char *argv[]) {
   const char *p = get_passstring("Enter password:  ");

   printf("The password entered is '%s'\n", p);
}