contrib/sendmail-8.14/libsm/fpos.c

   1 /*
   2  * Copyright (c) 2000-2001, 2004 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: fpos.c,v 1.39 2005/06/14 23:07:20 ca Exp $")
  17 #include <errno.h>
  18 #include <setjmp.h>
  19 #include <sm/time.h>
  20 #include <sm/heap.h>
  21 #include <sm/signal.h>
  22 #include <sm/clock.h>
  23 #include <sm/io.h>
  24 #include <sm/assert.h>
  25 #include "local.h"
  26
  27 static void     tellalrm __P((int));
  28 static jmp_buf TellTimeOut;
  29
  30 /*
  31 **  TELLALRM -- handler when timeout activated for sm_io_tell()
  32 **
  33 **  Returns flow of control to where setjmp(TellTimeOut) was set.
  34 **
  35 **      Parameters:
  36 **              sig -- unused
  37 **
  38 **      Returns:
  39 **              does not return
  40 **
  41 **      Side Effects:
  42 **              returns flow of control to setjmp(TellTimeOut).
  43 **
  44 **      NOTE:   THIS CAN BE CALLED FROM A SIGNAL HANDLER.  DO NOT ADD
  45 **              ANYTHING TO THIS ROUTINE UNLESS YOU KNOW WHAT YOU ARE
  46 **              DOING.
  47 */
  48
  49 /* ARGSUSED0 */
  50 static void
  51 tellalrm(sig)
  52         int sig;
  53 {
  54         longjmp(TellTimeOut, 1);
  55 }
  56
  57 /*
  58 **  SM_IO_TELL -- position the file pointer
  59 **
  60 **      Paramters:
  61 **              fp -- the file pointer to get repositioned
  62 **              timeout -- time to complete the tell (milliseconds)
  63 **
  64 **      Returns:
  65 **              Success -- the repositioned location.
  66 **              Failure -- -1 (minus 1) and sets errno
  67 */
  68
  69 long
  70 sm_io_tell(fp, timeout)
  71         register SM_FILE_T *fp;
  72         int SM_NONVOLATILE timeout;
  73 {
  74         register off_t pos;
  75         SM_EVENT *evt = NULL;
  76
  77         SM_REQUIRE_ISA(fp, SmFileMagic);
  78         if (fp->f_seek == NULL)
  79         {
  80                 errno = ESPIPE;                 /* historic practice */
  81                 return -1L;
  82         }
  83
  84         if (timeout == SM_TIME_DEFAULT)
  85                 timeout = fp->f_timeout;
  86         if (timeout == SM_TIME_IMMEDIATE)
  87         {
  88                 /*
  89                 **  Filling the buffer will take time and we are wanted to
  90                 **  return immediately. So...
  91                 */
  92
  93                 errno = EAGAIN;
  94                 return -1L;
  95         }
  96
  97         /*
  98         **  Find offset of underlying I/O object, then adjust byte position
  99         **  may adjust seek offset on append stream
 100         */
 101
 102         (void) sm_flush(fp, (int *) &timeout);
 103
 104         /* This is where we start the timeout */
 105         if (timeout != SM_TIME_FOREVER)
 106         {
 107                 if (setjmp(TellTimeOut) != 0)
 108                 {
 109                         errno = EAGAIN;
 110                         return -1L;
 111                 }
 112
 113                 evt = sm_seteventm(timeout, tellalrm, 0);
 114         }
 115
 116         if (fp->f_flags & SMOFF)
 117                 pos = fp->f_lseekoff;
 118         else
 119         {
 120                 /* XXX only set the timeout here? */
 121                 pos = (*fp->f_seek)(fp, (off_t) 0, SM_IO_SEEK_CUR);
 122                 if (pos == -1L)
 123                         goto clean;
 124         }
 125         if (fp->f_flags & SMRD)
 126         {
 127                 /*
 128                 **  Reading.  Any unread characters (including
 129                 **  those from ungetc) cause the position to be
 130                 **  smaller than that in the underlying object.
 131                 */
 132
 133                 pos -= fp->f_r;
 134                 if (HASUB(fp))
 135                         pos -= fp->f_ur;
 136         }
 137         else if (fp->f_flags & SMWR && fp->f_p != NULL)
 138         {
 139                 /*
 140                 **  Writing.  Any buffered characters cause the
 141                 **  position to be greater than that in the
 142                 **  underlying object.
 143                 */
 144
 145                 pos += fp->f_p - fp->f_bf.smb_base;
 146         }
 147
 148 clean:
 149         /*  We're back. So undo our timeout and handler */
 150         if (evt != NULL)
 151                 sm_clrevent(evt);
 152         return pos;
 153 }