gonzui

    1: /*      $OpenBSD: ftell.c,v 1.9 2009/11/09 00:18:27 kurt Exp $ */
    2: /*-
    3:  * Copyright (c) 1990, 1993
    4:  *      The Regents of the University of California.  All rights reserved.
    5:  *
    6:  * This code is derived from software contributed to Berkeley by
    7:  * Chris Torek.
    8:  *
    9:  * Redistribution and use in source and binary forms, with or without
   10:  * modification, are permitted provided that the following conditions
   11:  * are met:
   12:  * 1. Redistributions of source code must retain the above copyright
   13:  *    notice, this list of conditions and the following disclaimer.
   14:  * 2. Redistributions in binary form must reproduce the above copyright
   15:  *    notice, this list of conditions and the following disclaimer in the
   16:  *    documentation and/or other materials provided with the distribution.
   17:  * 3. Neither the name of the University nor the names of its contributors
   18:  *    may be used to endorse or promote products derived from this software
   19:  *    without specific prior written permission.
   20:  *
   21:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   22:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   23:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   24:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   25:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   26:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   27:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   28:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   29:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   30:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   31:  * SUCH DAMAGE.
   32:  */
   33: 
   34: #include <stdio.h>
   35: #include <errno.h>
   36: #include "local.h"
   37: 
   38: /*
   39:  * ftello: return current offset.
   40:  */
   41: off_t
   42: ftello(FILE *fp)
   43: {
   44:         fpos_t pos;
   45: 
   46:         if (fp->_seek == NULL) {
   47:                 __sseterr(fp, ESPIPE);                        /* historic practice */
   48:                 pos = -1;
   49:                 goto out;
   50:         }
   51: 
   52:         /*
   53:          * Find offset of underlying I/O object, then
   54:          * adjust for buffered bytes.
   55:          */
   56:         FLOCKFILE(fp);
   57:         __sflush(fp);          /* may adjust seek offset on append stream */
   58:         if (fp->_flags & __SOFF)
   59:                 pos = fp->_offset;
   60:         else {
   61:                 pos = (*fp->_seek)(fp->_cookie, (fpos_t)0, SEEK_CUR);
   62:                 if (pos == -1)
   63:                         goto out;
   64:         }
   65:         if (fp->_flags & __SRD) {
   66:                 /*
   67:                  * Reading.  Any unread characters (including
   68:                  * those from ungetc) cause the position to be
   69:                  * smaller than that in the underlying object.
   70:                  */
   71:                 pos -= fp->_r;
   72:                 if (HASUB(fp))
   73:                         pos -= fp->_ur;
   74:         } else if (fp->_flags & __SWR && fp->_p != NULL) {
   75:                 /*
   76:                  * Writing.  Any buffered characters cause the
   77:                  * position to be greater than that in the
   78:                  * underlying object.
   79:                  */
   80:                 pos += fp->_p - fp->_bf._base;
   81:         }
   82: out:    FUNLOCKFILE(fp);
   83:         return (pos);
   84: }
   85: 
   86: /*
   87:  * ftell() returns a long and sizeof(off_t) != sizeof(long) on all arches
   88:  */
   89: #if defined(__alpha__) && defined(__indr_reference)
   90: __indr_reference(ftello, ftell);
   91: #else
   92: long
   93: ftell(FILE *fp)
   94: {
   95:         long pos;
   96: 
   97:         pos = (long)ftello(fp);
   98:         return(pos);
   99: }
  100: #endif
  101: __weak_alias(ftell64, ftello);