pgpkbmsdos.c

著名的加密软件的应用于电子邮件中

/*
* pgpKBMSDOS.c -- MS-DOS non-echoing keyboard routines.
*
* Copyright (C) 1993-1997 Pretty Good Privacy, Inc. All rights reserved.
*
* $Id: pgpKBMSDOS.c,v 1.2.2.1 1997/06/07 09:52:00 mhw Exp $
*/

#include <conio.h>		/* For getch() and kbhit() */
#include <signal.h>		/* For raise() */
#ifdef _MSC_VER
#include <time.h>		/* For clock() */
#else
#include <dos.h>		/* For sleep() */
#endif

#if HAVE_CONFIG_H
#include "config.h"
#endif

#include "pgpKB.h"
#include "pgpRndPool.h"	/* For pgpRandPoolKeystroke() */

/* These are pretty boring */
void kbCbreak(void) { }
void kbNorm(void) { }

int kbGet(void)
{
		int c;

		c = getch();
		if (c == 0)
			c = 0x100 + getch();

		/*
		* Borland C's getch() uses int 0x21 function 0x7,
		* which does not detect break. So we do it explicitly.
		*/
		if (c == 3)
			raise(SIGINT);

		pgpRandPoolKeystroke(c);

		return c;
}

#ifdef _MSC_VER
/*
* Microsoft Visual C 1.5 (at least) does not have sleep() in the
* library. So we use this crude approximation. ("crude" because,
* assuming CLOCKS_PER_SEC is 18.2, it rounds to 18 to avoid floating
* point math.)
*/
#ifndef CLOCKS_PER_SEC
#define CLOCKS_PER_SEC CLK_TCK
#endif
static unsigned
sleep(unsigned t)
{
		clock_t target;

		target = clock() + t * (unsigned)CLOCKS_PER_SEC;
		while (clock() < target)
			;
		return 0;
}
#endif

void kbFlush(int thorough)
{
		do {
				while(kbhit())
					(void)getch();
				if (!thorough)
					break;
				/* Extra thorough: wait for one second of quiet */
				sleep(1);
		} while (kbhit());
}