contrib/sendmail-8.14/libsm/wsetup.c

   1 /*
   2  * Copyright (c) 2000-2002 Sendmail, Inc. and its suppliers.
   3  *      All rights reserved.
   4  * Copyright (c) 1990, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * This code is derived from software contributed to Berkeley by
   8  * Chris Torek.
   9  *
  10  * By using this file, you agree to the terms and conditions set
  11  * forth in the LICENSE file which can be found at the top level of
  12  * the sendmail distribution.
  13  */
  14
  15 #include <sm/gen.h>
  16 SM_RCSID("@(#)$Id: wsetup.c,v 1.20 2002/02/07 18:02:45 ca Exp $")
  17 #include <stdlib.h>
  18 #include <errno.h>
  19 #include <sm/io.h>
  20 #include "local.h"
  21
  22 /*
  23 **  SM_WSETUP -- check writing is safe
  24 **
  25 **  Various output routines call wsetup to be sure it is safe to write,
  26 **  because either flags does not include SMMWR, or buf is NULL.
  27 **  Used in the macro "cantwrite" found in "local.h".
  28 **
  29 **      Parameters:
  30 **              fp -- the file pointer
  31 **
  32 **      Results:
  33 **              Failure: SM_IO_EOF and sets errno
  34 **              Success: 0 (zero)
  35 */
  36
  37 int
  38 sm_wsetup(fp)
  39         register SM_FILE_T *fp;
  40 {
  41         /* make sure stdio is set up */
  42         if (!Sm_IO_DidInit)
  43                 sm_init();
  44
  45         /* If we are not writing, we had better be reading and writing. */
  46         if ((fp->f_flags & SMWR) == 0)
  47         {
  48                 if ((fp->f_flags & SMRW) == 0)
  49                 {
  50                         errno = EBADF;
  51                         return SM_IO_EOF;
  52                 }
  53                 if (fp->f_flags & SMRD)
  54                 {
  55                         /* clobber any ungetc data */
  56                         if (HASUB(fp))
  57                                 FREEUB(fp);
  58
  59                         /* discard read buffer */
  60                         fp->f_flags &= ~(SMRD|SMFEOF);
  61                         fp->f_r = 0;
  62                         fp->f_p = fp->f_bf.smb_base;
  63                 }
  64                 fp->f_flags |= SMWR;
  65         }
  66
  67         /* Make a buffer if necessary, then set w. */
  68         if (fp->f_bf.smb_base == NULL)
  69                 sm_makebuf(fp);
  70         if (fp->f_flags & SMLBF)
  71         {
  72                 /*
  73                 **  It is line buffered, so make lbfsize be -bufsize
  74                 **  for the sm_putc() macro.  We will change lbfsize back
  75                 **  to 0 whenever we turn off SMWR.
  76                 */
  77
  78                 fp->f_w = 0;
  79                 fp->f_lbfsize = -fp->f_bf.smb_size;
  80         }
  81         else
  82                 fp->f_w = fp->f_flags & SMNBF ? 0 : fp->f_bf.smb_size;
  83         return 0;
  84 }