sue.c

<B>Digital的Unix操作系统VAX 4.2源码</B>

#ifndef lint
static char	*sccsid = " @(#)sue.c	1.2	(ULTRIX)	1/16/86";
#endif lint

/************************************************************************
 *									*
 *			Copyright (c) 1986 by				*
 *		Digital Equipment Corporation, Maynard, MA		*
 *			All rights reserved.				*
 *									*
 *   This software is furnished under a license and may be used and	*
 *   copied  only  in accordance with the terms of such license and	*
 *   with the  inclusion  of  the  above  copyright  notice.   This	*
 *   software  or  any  other copies thereof may not be provided or	*
 *   otherwise made available to any other person.  No title to and	*
 *   ownership of the software is hereby transferred.			*
 *									*
 *   This software is  derived  from  software  received  from  the	*
 *   University    of   California,   Berkeley,   and   from   Bell	*
 *   Laboratories.  Use, duplication, or disclosure is  subject  to	*
 *   restrictions  under  license  agreements  with  University  of	*
 *   California and with AT&T.						*
 *									*
 *   The information in this software is subject to change  without	*
 *   notice  and should not be construed as a commitment by Digital	*
 *   Equipment Corporation.						*
 *									*
 *   Digital assumes no responsibility for the use  or  reliability	*
 *   of its software on equipment which is not supplied by Digital.	*
 *									*
 ************************************************************************/

/************************************************************************
*
*			Modification History
*
*	David Metsky		10-Jan-86
*
* 001	Replaced old version with BSD 4.3 version as part of upgrade.
*
*	Based on:	sue.c		5.1		6/7/85
*
*************************************************************************/

/*
 * sequential unformatted external read/write routines
 */

#include "fio.h"

extern int reclen;
LOCAL long recloc;
LOCAL char rsue[] = "read sue";
LOCAL char wsue[] = "write sue";

s_rsue(a) cilist *a;
{
	int n;
	reading = YES;
	if(n=c_sue(a,READ)) return(n);
	if(curunit->uwrt && ! nowreading(curunit)) err(errflag, errno, rsue)
	recpos = 0;
	if(fread(&reclen,sizeof(int),1,cf) == 1) return(OK);
	if(feof(cf))
	{	curunit->uend = YES;
		err(endflag, EOF, rsue)
	}
	clearerr(cf);
	err(errflag, errno, rsue)
}

s_wsue(a) cilist *a;
{
	int n;
	reading = NO;
	if(n=c_sue(a,WRITE)) return(n);
	if(!curunit->uwrt && ! nowwriting(curunit)) err(errflag, errno, wsue)
	reclen = 0;
	recloc=ftell(cf);
	fseek(cf,(long)sizeof(int),1);
	curunit->uend = NO;
	return(OK);
}

LOCAL
c_sue(a,flag) cilist *a;
{	int n;
	external = sequential = YES;
	formatted = NO;
	lfname = NULL;
	elist = NO;
	errflag = a->cierr;
	endflag = a->ciend;
	lunit = a->ciunit;
	if(not_legal(lunit)) err(errflag,F_ERUNIT,rsue+5)
	curunit = &units[lunit];
	if(!curunit->ufd && (n=fk_open(flag,SEQ,UNF,(ftnint)lunit)))
		err(errflag,n,rsue+5)
	cf = curunit->ufd;
	elist = YES;
	lfname = curunit->ufnm;
	if(curunit->ufmt) err(errflag,F_ERNOUIO,rsue+5)
	if(curunit->url) err(errflag,F_ERNOSIO,rsue+5)
	if(!curunit->useek) err(errflag,F_ERSEEK,rsue+5)
	return(OK);
}

e_wsue()
{	long loc;
	fwrite(&reclen,sizeof(int),1,cf);
	loc=ftell(cf);
	fseek(cf,recloc,0);
	fwrite(&reclen,sizeof(int),1,cf);
	fseek(cf,loc,0);
	return(OK);
}

e_rsue()
{
	fseek(cf,(long)(reclen-recpos+sizeof(int)),1);
	return(OK);
}