usr/src/cmd/sendmail/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 #pragma ident   "%Z%%M% %I%     %E% SMI"
  16
  17 #include <sm/gen.h>
  18 SM_RCSID("@(#)$Id: fpos.c,v 1.39 2005/06/14 23:07:20 ca Exp $")
  19 #include <errno.h>
  20 #include <setjmp.h>
  21 #include <sm/time.h>
  22 #include <sm/heap.h>
  23 #include <sm/signal.h>
  24 #include <sm/clock.h>
  25 #include <sm/io.h>
  26 #include <sm/assert.h>
  27 #include "local.h"
  28
  29 static void     tellalrm __P((int));
  30 static jmp_buf TellTimeOut;
  31
  32 /*
  33 **  TELLALRM -- handler when timeout activated for sm_io_tell()
  34 **
  35 **  Returns flow of control to where setjmp(TellTimeOut) was set.
  36 **
  37 **      Parameters:
  38 **              sig -- unused
  39 **
  40 **      Returns:
  41 **              does not return
  42 **
  43 **      Side Effects:
  44 **              returns flow of control to setjmp(TellTimeOut).
  45 **
  46 **      NOTE:   THIS CAN BE CALLED FROM A SIGNAL HANDLER.  DO NOT ADD
  47 **              ANYTHING TO THIS ROUTINE UNLESS YOU KNOW WHAT YOU ARE
  48 **              DOING.
  49 */
  50
  51 /* ARGSUSED0 */
  52 static void
  53 tellalrm(sig)
  54         int sig;
  55 {
  56         longjmp(TellTimeOut, 1);
  57 }
  58
  59 /*
  60 **  SM_IO_TELL -- position the file pointer
  61 **
  62 **      Paramters:
  63 **              fp -- the file pointer to get repositioned
  64 **              timeout -- time to complete the tell (milliseconds)
  65 **
  66 **      Returns:
  67 **              Success -- the repositioned location.
  68 **              Failure -- -1 (minus 1) and sets errno
  69 */
  70
  71 long
  72 sm_io_tell(fp, timeout)
  73         register SM_FILE_T *fp;
  74         int SM_NONVOLATILE timeout;
  75 {
  76         register off_t pos;
  77         SM_EVENT *evt = NULL;
  78
  79         SM_REQUIRE_ISA(fp, SmFileMagic);
  80         if (fp->f_seek == NULL)
  81         {
  82                 errno = ESPIPE;                 /* historic practice */
  83                 return -1L;
  84         }
  85
  86         if (timeout == SM_TIME_DEFAULT)
  87                 timeout = fp->f_timeout;
  88         if (timeout == SM_TIME_IMMEDIATE)
  89         {
  90                 /*
  91                 **  Filling the buffer will take time and we are wanted to
  92                 **  return immediately. So...
  93                 */
  94
  95                 errno = EAGAIN;
  96                 return -1L;
  97         }
  98
  99         /*
 100         **  Find offset of underlying I/O object, then adjust byte position
 101         **  may adjust seek offset on append stream
 102         */
 103
 104         (void) sm_flush(fp, (int *) &timeout);
 105
 106         /* This is where we start the timeout */
 107         if (timeout != SM_TIME_FOREVER)
 108         {
 109                 if (setjmp(TellTimeOut) != 0)
 110                 {
 111                         errno = EAGAIN;
 112                         return -1L;
 113                 }
 114
 115                 evt = sm_seteventm(timeout, tellalrm, 0);
 116         }
 117
 118         if (fp->f_flags & SMOFF)
 119                 pos = fp->f_lseekoff;
 120         else
 121         {
 122                 /* XXX only set the timeout here? */
 123                 pos = (*fp->f_seek)(fp, (off_t) 0, SM_IO_SEEK_CUR);
 124                 if (pos == -1L)
 125                         goto clean;
 126         }
 127         if (fp->f_flags & SMRD)
 128         {
 129                 /*
 130                 **  Reading.  Any unread characters (including
 131                 **  those from ungetc) cause the position to be
 132                 **  smaller than that in the underlying object.
 133                 */
 134
 135                 pos -= fp->f_r;
 136                 if (HASUB(fp))
 137                         pos -= fp->f_ur;
 138         }
 139         else if (fp->f_flags & SMWR && fp->f_p != NULL)
 140         {
 141                 /*
 142                 **  Writing.  Any buffered characters cause the
 143                 **  position to be greater than that in the
 144                 **  underlying object.
 145                 */
 146
 147                 pos += fp->f_p - fp->f_bf.smb_base;
 148         }
 149
 150 clean:
 151         /*  We're back. So undo our timeout and handler */
 152         if (evt != NULL)
 153                 sm_clrevent(evt);
 154         return pos;
 155 }