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makebuf.c

/*
 * Copyright (c) 2000-2001 Sendmail, Inc. and its suppliers.
 *      All rights reserved.
 * Copyright (c) 1990, 1993
 *    The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Chris Torek.
 *
 * By using this file, you agree to the terms and conditions set
 * forth in the LICENSE file which can be found at the top level of
 * the sendmail distribution.
 */

#include <sm/gen.h>
SM_RCSID("@(#)$Id: makebuf.c,v 1.26 2001/10/31 16:04:08 ca Exp $")
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sm/io.h>
#include <sm/heap.h>
#include <sm/conf.h>
#include "local.h"

/*
**  SM_MAKEBUF -- make a buffer for the file
**
**    Parameters:
**          fp -- the file to be buffered
**
**    Returns:
**          nothing
**
**    Allocate a file buffer, or switch to unbuffered I/O.
**    By default tty devices default to line buffered.
*/

void
sm_makebuf(fp)
      register SM_FILE_T *fp;
{
      register void *p;
      register int flags;
      size_t size;
      int couldbetty;

      if (fp->f_flags & SMNBF)
      {
            fp->f_bf.smb_base = fp->f_p = fp->f_nbuf;
            fp->f_bf.smb_size = 1;
            return;
      }
      flags = sm_whatbuf(fp, &size, &couldbetty);
      if ((p = sm_malloc(size)) == NULL)
      {
            fp->f_flags |= SMNBF;
            fp->f_bf.smb_base = fp->f_p = fp->f_nbuf;
            fp->f_bf.smb_size = 1;
            return;
      }
      if (!Sm_IO_DidInit)
            sm_init();
      flags |= SMMBF;
      fp->f_bf.smb_base = fp->f_p = p;
      fp->f_bf.smb_size = size;
      if (couldbetty && isatty(fp->f_file))
            flags |= SMLBF;
      fp->f_flags |= flags;
}

/*
**  SM_WHATBUF -- determine proper buffer for a file (internal)
**
**  Plus it fills in 'bufsize' for recommended buffer size and
**  fills in flag to indicate if 'fp' could be a tty (nothing
**  to do with "betty" :-) ).
**
**    Parameters:
**          fp -- file pointer to be buffered
**          bufsize -- new buffer size (a return)
**          couldbetty -- could be a tty (returns)
**
**    Returns:
**          Success:
**          on error:
**                SMNPT -- not seek opimized
**                SMOPT -- seek opimized
*/

int
sm_whatbuf(fp, bufsize, couldbetty)
      register SM_FILE_T *fp;
      size_t *bufsize;
      int *couldbetty;
{
      struct stat st;

      if (fp->f_file < 0 || fstat(fp->f_file, &st) < 0)
      {
            *couldbetty = 0;
            *bufsize = SM_IO_BUFSIZ;
            return SMNPT;
      }

      /* could be a tty iff it is a character device */
      *couldbetty = S_ISCHR(st.st_mode);
      if (st.st_blksize == 0)
      {
            *bufsize = SM_IO_BUFSIZ;
            return SMNPT;
      }

#if SM_IO_MAX_BUF_FILE > 0
      if (S_ISREG(st.st_mode) && st.st_blksize > SM_IO_MAX_BUF_FILE)
            st.st_blksize = SM_IO_MAX_BUF_FILE;
#endif /* SM_IO_MAX_BUF_FILE > 0 */

#if SM_IO_MAX_BUF > 0 || SM_IO_MIN_BUF > 0
      if (!S_ISREG(st.st_mode))
      {
# if SM_IO_MAX_BUF > 0
            if (st.st_blksize > SM_IO_MAX_BUF)
                  st.st_blksize = SM_IO_MAX_BUF;
#  if SM_IO_MIN_BUF > 0
            else
#  endif /* SM_IO_MIN_BUF > 0 */
# endif /* SM_IO_MAX_BUF > 0 */
# if SM_IO_MIN_BUF > 0
            if (st.st_blksize < SM_IO_MIN_BUF)
                  st.st_blksize = SM_IO_MIN_BUF;
# endif /* SM_IO_MIN_BUF > 0 */
      }
#endif /* SM_IO_MAX_BUF > 0 || SM_IO_MIN_BUF > 0 */

      /*
      **  Optimise fseek() only if it is a regular file.  (The test for
      **  sm_std_seek is mainly paranoia.)  It is safe to set _blksize
      **  unconditionally; it will only be used if SMOPT is also set.
      */

      if ((fp->f_flags & SMSTR) == 0)
      {
            *bufsize = st.st_blksize;
            fp->f_blksize = st.st_blksize;
      }
      else
            *bufsize = SM_IO_BUFSIZ;
      if ((st.st_mode & S_IFMT) == S_IFREG &&
          fp->f_seek == sm_stdseek)
            return SMOPT;
      else
            return SMNPT;
}

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