contrib/sendmail/libsm/fpos.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 #include <sm/gen.h>
  16 SM_RCSID("@(#)$Id: fpos.c,v 1.37 2001/09/11 04:04:48 gshapiro Exp $")
  17 #include <errno.h>
  18 #include <setjmp.h>
  19 #include <sys/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 jmp_buf TellTimeOut;
  28
  29 /*
  30 **  TELLALRM -- handler when timeout activated for sm_io_tell()
  31 **
  32 **  Returns flow of control to where setjmp(TellTimeOut) was set.
  33 **
  34 **      Parameters:
  35 **              sig -- unused
  36 **
  37 **      Returns:
  38 **              does not return
  39 **
  40 **      Side Effects:
  41 **              returns flow of control to setjmp(TellTimeOut).
  42 **
  43 **      NOTE:   THIS CAN BE CALLED FROM A SIGNAL HANDLER.  DO NOT ADD
  44 **              ANYTHING TO THIS ROUTINE UNLESS YOU KNOW WHAT YOU ARE
  45 **              DOING.
  46 */
  47
  48 /* ARGSUSED0 */
  49 static void
  50 tellalrm(sig)
  51         int sig;
  52 {
  53         longjmp(TellTimeOut, 1);
  54 }
  55
  56 /*
  57 **  SM_IO_TELL -- position the file pointer
  58 **
  59 **      Paramters:
  60 **              fp -- the file pointer to get repositioned
  61 **              timeout -- time to complete the tell (milliseconds)
  62 **
  63 **      Returns:
  64 **              Success -- the repositioned location.
  65 **              Failure -- -1 (minus 1) and sets errno
  66 */
  67
  68 long
  69 sm_io_tell(fp, timeout)
  70         register SM_FILE_T *fp;
  71         int SM_NONVOLATILE timeout;
  72 {
  73         register off_t pos;
  74         SM_EVENT *evt = NULL;
  75
  76         SM_REQUIRE_ISA(fp, SmFileMagic);
  77         if (fp->f_seek == NULL)
  78         {
  79                 errno = ESPIPE;                 /* historic practice */
  80                 return -1L;
  81         }
  82
  83         if (timeout == SM_TIME_DEFAULT)
  84                 timeout = fp->f_timeout;
  85         if (timeout == SM_TIME_IMMEDIATE)
  86         {
  87                 /*
  88                 **  Filling the buffer will take time and we are wanted to
  89                 **  return immediately. So...
  90                 */
  91
  92                 errno = EAGAIN;
  93                 return -1L;
  94         }
  95
  96         /*
  97         **  Find offset of underlying I/O object, then adjust byte position
  98         **  may adjust seek offset on append stream
  99         */
 100
 101         (void) sm_flush(fp, (int *) &timeout);
 102
 103         /* This is where we start the timeout */
 104         if (timeout != SM_TIME_FOREVER)
 105         {
 106                 if (setjmp(TellTimeOut) != 0)
 107                 {
 108                         errno = EAGAIN;
 109                         return -1L;
 110                 }
 111
 112                 evt = sm_seteventm(timeout, tellalrm, 0);
 113         }
 114
 115         if (fp->f_flags & SMOFF)
 116                 pos = fp->f_lseekoff;
 117         else
 118         {
 119                 /* XXX only set the timeout here? */
 120                 pos = (*fp->f_seek)(fp, (off_t) 0, SM_IO_SEEK_CUR);
 121                 if (pos == -1L)
 122                         goto clean;
 123         }
 124         if (fp->f_flags & SMRD)
 125         {
 126                 /*
 127                 **  Reading.  Any unread characters (including
 128                 **  those from ungetc) cause the position to be
 129                 **  smaller than that in the underlying object.
 130                 */
 131
 132                 pos -= fp->f_r;
 133                 if (HASUB(fp))
 134                         pos -= fp->f_ur;
 135         }
 136         else if (fp->f_flags & SMWR && fp->f_p != NULL)
 137         {
 138                 /*
 139                 **  Writing.  Any buffered characters cause the
 140                 **  position to be greater than that in the
 141                 **  underlying object.
 142                 */
 143
 144                 pos += fp->f_p - fp->f_bf.smb_base;
 145         }
 146
 147 clean:
 148         /*  We're back. So undo our timeout and handler */
 149         if (evt != NULL)
 150                 sm_clrevent(evt);
 151         return pos;
 152 }