Logo Search packages:      
Sourcecode: ksh version File versions  Download package

revlib.c

/***********************************************************************
*                                                                      *
*               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);
}

Generated by  Doxygen 1.6.0   Back to index