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/***********************************************************************
* *
* This software is part of the ast package *
* Copyright (c) 1992-2010 AT&T Intellectual Property *
* and is licensed under the *
* Common Public License, Version 1.0 *
* by AT&T Intellectual Property *
* *
* A copy of the License is available at *
* http://www.opensource.org/licenses/cpl1.0.txt *
* (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9) *
* *
* Information and Software Systems Research *
* AT&T Research *
* Florham Park NJ *
* *
* Glenn Fowler <gsf@research.att.com> *
* David Korn <dgk@research.att.com> *
* *
***********************************************************************/
#pragma prototyped
/*
* common support for tail and rev
*/
#include <cmd.h>
#include <rev.h>
#define BUFSIZE SF_BUFSIZE
#define rounddown(n,size) (((n)-1)&~((size)-1))
/*
* copy the lines starting at offset <start> from in <in> to <out>
* in reverse order
*/
int rev_line(Sfio_t *in, Sfio_t *out, off_t start)
{
register char *cp, *cpold;
register int n, nleft=0;
char buff[BUFSIZE];
off_t offset;
if(sfseek(in,(off_t)0,SEEK_CUR) < 0)
{
Sfio_t *tmp = sftmp(4*SF_BUFSIZE);
if(!tmp)
return(-1);
if(start>0 && sfmove(in, (Sfio_t*)0, start, -1) != start)
return(-1);
if(sfmove(in, tmp, SF_UNBOUND, -1) < 0 || !sfeof(in) || sferror(tmp))
return(-1);
in = tmp;
start=0;
}
if((offset = sfseek(in,(off_t)0,SEEK_END)) <= start)
return(0);
offset = rounddown(offset,BUFSIZE);
while(1)
{
n = BUFSIZE;
if(offset < start)
{
n -= (start-offset);
offset = start;
}
sfseek(in, offset, SEEK_SET);
if((n=sfread(in, buff, n)) <=0)
break;
cp = buff+n;
n = *buff;
*buff = '\n';
while(1)
{
cpold = cp;
if(nleft==0)
cp--;
if(cp==buff)
{
nleft= 1;
break;
}
while(*--cp != '\n');
if(cp==buff && n!='\n')
{
*cp = n;
nleft += cpold-cp;
break;
}
else
cp++;
if(sfwrite(out,cp,cpold-cp) < 0)
return(-1);
if(nleft)
{
if(nleft==1)
sfputc(out,'\n');
else if(sfmove(in,out,nleft,-1) != nleft)
return(-1);
nleft = 0;
}
}
if(offset <= start)
break;
offset -= BUFSIZE;
}
if(nleft)
{
sfseek(in, start, SEEK_SET);
if(sfmove(in,out,nleft,-1) != nleft)
return(-1);
}
return(0);
}
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