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/* No user fns here.  Pesch 15apr92. */

/*

 * Copyright (c) 1990 The Regents of the University of California.

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms are permitted

 * provided that the above copyright notice and this paragraph are

 * duplicated in all such forms and that any documentation,

 * advertising materials, and other materials related to such

 * distribution and use acknowledge that the software was developed

 * by the University of California, Berkeley.  The name of the

 * University may not be used to endorse or promote products derived

 * from this software without specific prior written permission.

 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR

 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED

 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.

 */

#include <stdio.h>

#include <stdlib.h>

#include <sys/stat.h>

#include <sys/types.h>

#include <sys/unistd.h>

#include "local.h"

/*

 * Allocate a file buffer, or switch to unbuffered I/O.

 * Per the ANSI C standard, ALL tty devices default to line buffered.

 *

 * As a side effect, we set __SOPT or __SNPT (en/dis-able fseek

 * optimization) right after the _fstat() that finds the buffer size.

 */

void

__smakebuf (fp)

     register FILE *fp;

{

  register size_t size, couldbetty;

  register _PTR p;

  struct stat st;

  if (fp->_flags & __SNBF)

    {

      fp->_bf._base = fp->_p = fp->_nbuf;

      fp->_bf._size = 1;

      return;

    }

  if (fp->_file < 0 || _fstat_r (fp->_data, fp->_file, &st) < 0)

    {

      couldbetty = 0;

      size = BUFSIZ;

      /* do not try to optimise fseek() */

      fp->_flags |= __SNPT;

    }

  else

    {

      couldbetty = (st.st_mode & S_IFMT) == S_IFCHR;

#ifdef HAVE_BLKSIZE

      size = st.st_blksize <= 0 ? BUFSIZ : st.st_blksize;

#else

      size = BUFSIZ;

#endif

      /*

       * Optimize fseek() only if it is a regular file.

       * (The test for __sseek is mainly paranoia.)

       */

      if ((st.st_mode & S_IFMT) == S_IFREG && fp->_seek == __sseek)

        {

          fp->_flags |= __SOPT;

#ifdef HAVE_BLKSIZE

          fp->_blksize = st.st_blksize;

#else

          fp->_blksize = 1024;

#endif

        }

      else

        fp->_flags |= __SNPT;

    }

  if ((p = _malloc_r (fp->_data, size)) == NULL)

    {

      fp->_flags |= __SNBF;

      fp->_bf._base = fp->_p = fp->_nbuf;

      fp->_bf._size = 1;

    }

  else

    {

      fp->_data->__cleanup = _cleanup_r;

      fp->_flags |= __SMBF;

      fp->_bf._base = fp->_p = (unsigned char *) p;

      fp->_bf._size = size;

      if (couldbetty && isatty (fp->_file))

        fp->_flags |= __SLBF;

    }

}