1 /* $OpenBSD: ftell.c,v 1.6 2005/08/08 08:05:36 espie 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 errno = ESPIPE; /* historic practice */ 48 return ((off_t)-1); 49 } 50 51 /* 52 * Find offset of underlying I/O object, then 53 * adjust for buffered bytes. 54 */ 55 __sflush(fp); /* may adjust seek offset on append stream */ 56 if (fp->_flags & __SOFF) 57 pos = fp->_offset; 58 else { 59 pos = (*fp->_seek)(fp->_cookie, (fpos_t)0, SEEK_CUR); 60 if (pos == -1L) 61 return (pos); 62 } 63 if (fp->_flags & __SRD) { 64 /* 65 * Reading. Any unread characters (including 66 * those from ungetc) cause the position to be 67 * smaller than that in the underlying object. 68 */ 69 pos -= fp->_r; 70 if (HASUB(fp)) 71 pos -= fp->_ur; 72 } else if (fp->_flags & __SWR && fp->_p != NULL) { 73 /* 74 * Writing. Any buffered characters cause the 75 * position to be greater than that in the 76 * underlying object. 77 */ 78 pos += fp->_p - fp->_bf._base; 79 } 80 return (pos); 81 } 82 83 /* 84 * ftell() returns a long and sizeof(off_t) != sizeof(long) on all arches 85 */ 86 #if defined(__alpha__) && defined(__indr_reference) 87 __indr_reference(ftello, ftell); 88 #else 89 long 90 ftell(FILE *fp) 91 { 92 long pos; 93 94 pos = (long)ftello(fp); 95 return(pos); 96 } 97 #endif 98