usr/src/cmd/sendmail/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 #pragma ident   "%Z%%M% %I%     %E% SMI"
  16
  17 #include <sm/gen.h>
  18 SM_RCSID("@(#)$Id: wsetup.c,v 1.20 2002/02/07 18:02:45 ca Exp $")
  19 #include <stdlib.h>
  20 #include <errno.h>
  21 #include <sm/io.h>
  22 #include "local.h"
  23
  24 /*
  25 **  SM_WSETUP -- check writing is safe
  26 **
  27 **  Various output routines call wsetup to be sure it is safe to write,
  28 **  because either flags does not include SMMWR, or buf is NULL.
  29 **  Used in the macro "cantwrite" found in "local.h".
  30 **
  31 **      Parameters:
  32 **              fp -- the file pointer
  33 **
  34 **      Results:
  35 **              Failure: SM_IO_EOF and sets errno
  36 **              Success: 0 (zero)
  37 */
  38
  39 int
  40 sm_wsetup(fp)
  41         register SM_FILE_T *fp;
  42 {
  43         /* make sure stdio is set up */
  44         if (!Sm_IO_DidInit)
  45                 sm_init();
  46
  47         /* If we are not writing, we had better be reading and writing. */
  48         if ((fp->f_flags & SMWR) == 0)
  49         {
  50                 if ((fp->f_flags & SMRW) == 0)
  51                 {
  52                         errno = EBADF;
  53                         return SM_IO_EOF;
  54                 }
  55                 if (fp->f_flags & SMRD)
  56                 {
  57                         /* clobber any ungetc data */
  58                         if (HASUB(fp))
  59                                 FREEUB(fp);
  60
  61                         /* discard read buffer */
  62                         fp->f_flags &= ~(SMRD|SMFEOF);
  63                         fp->f_r = 0;
  64                         fp->f_p = fp->f_bf.smb_base;
  65                 }
  66                 fp->f_flags |= SMWR;
  67         }
  68
  69         /* Make a buffer if necessary, then set w. */
  70         if (fp->f_bf.smb_base == NULL)
  71                 sm_makebuf(fp);
  72         if (fp->f_flags & SMLBF)
  73         {
  74                 /*
  75                 **  It is line buffered, so make lbfsize be -bufsize
  76                 **  for the sm_putc() macro.  We will change lbfsize back
  77                 **  to 0 whenever we turn off SMWR.
  78                 */
  79
  80                 fp->f_w = 0;
  81                 fp->f_lbfsize = -fp->f_bf.smb_size;
  82         }
  83         else
  84                 fp->f_w = fp->f_flags & SMNBF ? 0 : fp->f_bf.smb_size;
  85         return 0;
  86 }