usr/src/cmd/sendmail/libsm/wbuf.c

   1 /*
   2  * Copyright (c) 2000-2001 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: wbuf.c,v 1.19 2001/03/05 03:22:41 ca Exp $")
  19 #include <errno.h>
  20 #include <sm/io.h>
  21 #include "local.h"
  22
  23 /* Note: This function is called from a macro located in <sm/io.h> */
  24
  25 /*
  26 **  SM_WBUF -- write character to and flush (likely now full) buffer
  27 **
  28 **  Write the given character into the (probably full) buffer for
  29 **  the given file.  Flush the buffer out if it is or becomes full,
  30 **  or if c=='\n' and the file is line buffered.
  31 **
  32 **      Parameters:
  33 **              fp -- the file pointer
  34 **              timeout -- time to complete operation (milliseconds)
  35 **              c -- int representation of the character to add
  36 **
  37 **      Results:
  38 **              Failure: -1 and sets errno
  39 **              Success: int value of 'c'
  40 */
  41
  42 int
  43 sm_wbuf(fp, timeout, c)
  44         register SM_FILE_T *fp;
  45         int timeout;
  46         register int c;
  47 {
  48         register int n;
  49
  50         /*
  51         **  In case we cannot write, or longjmp takes us out early,
  52         **  make sure w is 0 (if fully- or un-buffered) or -bf.smb_size
  53         **  (if line buffered) so that we will get called again.
  54         **  If we did not do this, a sufficient number of sm_io_putc()
  55         **  calls might wrap w from negative to positive.
  56         */
  57
  58         fp->f_w = fp->f_lbfsize;
  59         if (cantwrite(fp))
  60         {
  61                 errno = EBADF;
  62                 return SM_IO_EOF;
  63         }
  64         c = (unsigned char)c;
  65
  66         /*
  67         **  If it is completely full, flush it out.  Then, in any case,
  68         **  stuff c into the buffer.  If this causes the buffer to fill
  69         **  completely, or if c is '\n' and the file is line buffered,
  70         **  flush it (perhaps a second time).  The second flush will always
  71         **  happen on unbuffered streams, where bf.smb_size==1; sm_io_flush()
  72         **  guarantees that sm_io_putc() will always call sm_wbuf() by setting
  73         **  w to 0, so we need not do anything else.
  74         **  Note for the timeout, only one of the sm_io_flush's will get called.
  75         */
  76
  77         n = fp->f_p - fp->f_bf.smb_base;
  78         if (n >= fp->f_bf.smb_size)
  79         {
  80                 if (sm_io_flush(fp, timeout))
  81                         return SM_IO_EOF; /* sm_io_flush() sets errno */
  82                 n = 0;
  83         }
  84         fp->f_w--;
  85         *fp->f_p++ = c;
  86         if (++n == fp->f_bf.smb_size || (fp->f_flags & SMLBF && c == '\n'))
  87                 if (sm_io_flush(fp, timeout))
  88                         return SM_IO_EOF; /* sm_io_flush() sets errno */
  89         return c;
  90 }