text: /* vi: set sw=4 ts=4: */
  /*
   * Ask for a password
   *
   * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
   *
   * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   */
  #include "libbb.h"
  
  /* do nothing signal handler */
  static void askpass_timeout(int UNUSED_PARAM ignore)
  {
  }
  
  char* FAST_FUNC bb_ask_noecho(int fd, int timeout, const char *prompt)
  {
  #define MAX_LINE 0xfff
  	char *ret;
  	int i;
  	struct sigaction sa, oldsa;
  	struct termios tio, oldtio;
  
  	tcflush(fd, TCIFLUSH);
  	/* Was buggy: was printing prompt *before* flushing input,
  	 * which was upsetting "expect" based scripts of some users.
  	 */
  	fputs_stdout(prompt);
  	fflush_all();
  
  	tcgetattr(fd, &oldtio);
  	tio = oldtio;
  	/* Switch off echo. ECHOxyz meaning:
  	 * ECHO    echo input chars
  	 * ECHOE   echo BS-SP-BS on erase character
  	 * ECHOK   echo kill char specially, not as ^c (ECHOKE controls how exactly)
  	 * ECHOKE  erase all input via BS-SP-BS on kill char (else go to next line)
  	 * ECHOCTL Echo ctrl chars as ^c (else echo verbatim:
  	 *         e.g. up arrow emits "ESC-something" and thus moves cursor up!)
  	 * ECHONL  Echo NL even if ECHO is not set
  	 * ECHOPRT On erase, echo erased chars
  	 *         [qwe<BS><BS><BS> input looks like "qwe\ewq/" on screen]
  	 */
  	tio.c_lflag &= ~(ECHO|ECHOE|ECHOK|ECHONL);
  	tcsetattr(fd, TCSANOW, &tio);
  
  	memset(&sa, 0, sizeof(sa));
  	/* sa.sa_flags = 0; - no SA_RESTART! */
  	/* SIGINT and SIGALRM will interrupt reads below */
  	sa.sa_handler = askpass_timeout;
  	sigaction(SIGINT, &sa, &oldsa);
  	if (timeout) {
  		sigaction_set(SIGALRM, &sa);
  		alarm(timeout);
  	}
  
  	ret = NULL;
  	i = 0;
  	while (1) {
  		int r;
  
  		/* User input is uber-slow, no need to optimize reallocs.
  		 * Grow it on every char.
  		 */
  		ret = xrealloc(ret, i + 2);
  		r = read(fd, &ret[i], 1);
  
  		if ((i == 0 && r == 0) /* EOF (^D) with no password */
  		 || r < 0 /* read is interrupted by timeout or ^C */
  		) {
  			ret[i] = '\0'; /* paranoia */
  			nuke_str(ret); /* paranoia */
  			free(ret);
  			ret = NULL;
  			break;
  		}
  
  		if (r == 0 /* EOF */
  		 || ret[i] == '\r' || ret[i] == '\n' /* EOL */
  		 || ++i == MAX_LINE /* line limit */
  		) {
  			ret[i] = '\0';
  			break;
  		}
  	}
  
  	if (timeout) {
  		alarm(0);
  	}
  	sigaction_set(SIGINT, &oldsa);
  	tcsetattr(fd, TCSANOW, &oldtio);
  	bb_putchar('\n');
  	fflush_all();
  	return ret;
  }
  char* FAST_FUNC bb_ask_noecho_stdin(const char *prompt)
  {
  	return bb_ask_noecho(STDIN_FILENO, 0, prompt);
  }
  