/*
 * Copyright (c) 2000-2001, 2004 Sendmail, Inc. and its suppliers.
 *      All rights reserved.
 * Copyright (c) 1990, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Chris Torek.
 *
 * By using this file, you agree to the terms and conditions set
 * forth in the LICENSE file which can be found at the top level of
 * the sendmail distribution.
 */

#include <sm/gen.h>
SM_RCSID("@(#)$Id: fpos.c,v 1.39 2005/06/14 23:07:20 ca Exp $")
#include <errno.h>
#include <setjmp.h>
#include <sm/time.h>
#include <sm/heap.h>
#include <sm/signal.h>
#include <sm/clock.h>
#include <sm/io.h>
#include <sm/assert.h>
#include "local.h"

static void     tellalrm __P((int));
static jmp_buf TellTimeOut;

/*
**  TELLALRM -- handler when timeout activated for sm_io_tell()
**
**  Returns flow of control to where setjmp(TellTimeOut) was set.
**
**      Parameters:
**              sig -- unused
**
**      Returns:
**              does not return
**
**      Side Effects:
**              returns flow of control to setjmp(TellTimeOut).
**
**      NOTE:   THIS CAN BE CALLED FROM A SIGNAL HANDLER.  DO NOT ADD
**              ANYTHING TO THIS ROUTINE UNLESS YOU KNOW WHAT YOU ARE
**              DOING.
*/

/* ARGSUSED0 */
static void
tellalrm(sig)
        int sig;
{
        longjmp(TellTimeOut, 1);
}

/*
**  SM_IO_TELL -- position the file pointer
**
**      Paramters:
**              fp -- the file pointer to get repositioned
**              timeout -- time to complete the tell (milliseconds)
**
**      Returns:
**              Success -- the repositioned location.
**              Failure -- -1 (minus 1) and sets errno
*/

long
sm_io_tell(fp, timeout)
        register SM_FILE_T *fp;
        int SM_NONVOLATILE timeout;
{
        register off_t pos;
        SM_EVENT *evt = NULL;

        SM_REQUIRE_ISA(fp, SmFileMagic);
        if (fp->f_seek == NULL)
        {
                errno = ESPIPE;                 /* historic practice */
                return -1L;
        }

        if (timeout == SM_TIME_DEFAULT)
                timeout = fp->f_timeout;
        if (timeout == SM_TIME_IMMEDIATE)
        {
                /*
                **  Filling the buffer will take time and we are wanted to
                **  return immediately. So...
                */

                errno = EAGAIN;
                return -1L;
        }

        /*
        **  Find offset of underlying I/O object, then adjust byte position
        **  may adjust seek offset on append stream
        */

        (void) sm_flush(fp, (int *) &timeout);

        /* This is where we start the timeout */
        if (timeout != SM_TIME_FOREVER)
        {
                if (setjmp(TellTimeOut) != 0)
                {
                        errno = EAGAIN;
                        return -1L;
                }

                evt = sm_seteventm(timeout, tellalrm, 0);
        }

        if (fp->f_flags & SMOFF)
                pos = fp->f_lseekoff;
        else
        {
                /* XXX only set the timeout here? */
                pos = (*fp->f_seek)(fp, (off_t) 0, SM_IO_SEEK_CUR);
                if (pos == -1L)
                        goto clean;
        }
        if (fp->f_flags & SMRD)
        {
                /*
                **  Reading.  Any unread characters (including
                **  those from ungetc) cause the position to be
                **  smaller than that in the underlying object.
                */

                pos -= fp->f_r;
                if (HASUB(fp))
                        pos -= fp->f_ur;
        }
        else if (fp->f_flags & SMWR && fp->f_p != NULL)
        {
                /*
                **  Writing.  Any buffered characters cause the
                **  position to be greater than that in the
                **  underlying object.
                */

                pos += fp->f_p - fp->f_bf.smb_base;
        }

clean:
        /*  We're back. So undo our timeout and handler */
        if (evt != NULL)
                sm_clrevent(evt);
        return pos;
}