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astcopy.c

/***********************************************************************
*                                                                      *
*               This software is part of the ast package               *
*          Copyright (c) 1985-2010 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>                   *
*                   Phong Vo <kpv@research.att.com>                    *
*                                                                      *
***********************************************************************/
#pragma prototyped
/*
 * Glenn Fowler
 * AT&T Bell Laboratories
 *
 * copy from rfd to wfd (with conditional mmap hacks)
 */

#include <ast.h>
#include <ast_mmap.h>

#if _mmap_worthy > 1

#include <ls.h>

#define MAPSIZE         (1024*256)

#endif

#undef      BUFSIZ
#define BUFSIZ          4096

/*
 * copy n bytes from rfd to wfd
 * actual byte count returned
 * if n<=0 then ``good'' size is used
 */

off_t
astcopy(int rfd, int wfd, off_t n)
{
      register off_t    c;
#ifdef MAPSIZE
      off_t       pos;
      off_t       mapsize;
      char*       mapbuf;
      struct stat st;
#endif

      static int  bufsiz;
      static char*      buf;

      if (n <= 0 || n >= BUFSIZ * 2)
      {
#if MAPSIZE
            if (!fstat(rfd, &st) && S_ISREG(st.st_mode) && (pos = lseek(rfd, (off_t)0, 1)) != ((off_t)-1))
            {
                  if (pos >= st.st_size) return(0);
                  mapsize = st.st_size - pos;
                  if (mapsize > MAPSIZE) mapsize = (mapsize > n && n > 0) ? n : MAPSIZE;
                  if (mapsize >= BUFSIZ * 2 && (mapbuf = (char*)mmap(NiL, mapsize, PROT_READ, MAP_SHARED, rfd, pos)) != ((caddr_t)-1))
                  {
                        if (write(wfd, mapbuf, mapsize) != mapsize || lseek(rfd, mapsize, 1) == ((off_t)-1)) return(-1);
                        munmap((caddr_t)mapbuf, mapsize);
                        return(mapsize);
                  }
            }
#endif
            if (n <= 0) n = BUFSIZ;
      }
      if (n > bufsiz)
      {
            if (buf) free(buf);
            bufsiz = roundof(n, BUFSIZ);
            if (!(buf = newof(0, char, bufsiz, 0))) return(-1);
      }
      if ((c = read(rfd, buf, (size_t)n)) > 0 && write(wfd, buf, (size_t)c) != c) c = -1;
      return(c);
}

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