IABSD.fr/src/usr.bin/less/ttyin.c

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• Author : deraadt
  Date : 2019-09-03 23:08:42
  Hash : d65139b4
  Message : less uses a correct raceless signal method of indicating signal events in a volatile sig_atomic_t variable, and then processing events in the mainloop. But only one variable was used for 3 signals, with |= bit operations which are signal interruptable! Rewrite the code to use 3 independent variables and cleanup how the mainloop observes indications. ok schwarze

• usr.bin/less/ttyin.c

• /*
   * Copyright (C) 1984-2012  Mark Nudelman
   * Modified for use with illumos by Garrett D'Amore.
   * Copyright 2014 Garrett D'Amore <garrett@damore.org>
   *
   * You may distribute under the terms of either the GNU General Public
   * License or the Less License, as specified in the README file.
   *
   * For more information, see the README file.
   */
  
  /*
   * Routines dealing with getting input from the keyboard (i.e. from the user).
   */
  
  #include "less.h"
  
  int tty;
  extern int utf_mode;
  
  /*
   * Open keyboard for input.
   */
  void
  open_getchr(void)
  {
  	/*
  	 * Try /dev/tty.
  	 * If that doesn't work, use file descriptor 2,
  	 * which in Unix is usually attached to the screen,
  	 * but also usually lets you read from the keyboard.
  	 */
  	tty = open("/dev/tty", O_RDONLY);
  	if (tty == -1)
  		tty = STDERR_FILENO;
  }
  
  /*
   * Get a character from the keyboard.
   */
  int
  getchr(void)
  {
  	unsigned char c;
  	int result;
  
  	do {
  		result = iread(tty, &c, sizeof (char));
  		if (result == READ_INTR)
  			return (READ_INTR);
  		if (result < 0) {
  			/*
  			 * Don't call error() here,
  			 * because error calls getchr!
  			 */
  			quit(QUIT_ERROR);
  		}
  		/*
  		 * Various parts of the program cannot handle
  		 * an input character of '\0'.
  		 * If a '\0' was actually typed, convert it to '\340' here.
  		 */
  		if (c == '\0')
  			c = 0340;
  	} while (result != 1);
  
  	return (c & 0xFF);
  }