1 /* $NetBSD: ftello.c,v 1.2 2000/07/26 08:52:57 kleink Exp $ */ 2 3 /*- 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 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 */ 38 39 #include <sys/cdefs.h> 40 #if defined(LIBC_SCCS) && !defined(lint) 41 __RCSID("$NetBSD: ftello.c,v 1.2 2000/07/26 08:52:57 kleink Exp $"); 42 #endif /* LIBC_SCCS and not lint */ 43 44 #include "namespace.h" 45 #include <assert.h> 46 #include <errno.h> 47 #include <stdio.h> 48 #include "local.h" 49 #include "reentrant.h" 50 51 #ifdef __weak_alias 52 __weak_alias(ftello, _ftello) 53 #endif 54 55 /* 56 * ftell: return current offset. 57 */ 58 off_t 59 ftello(fp) 60 FILE *fp; 61 { 62 fpos_t pos; 63 64 65 FLOCKFILE(fp); 66 67 if (fp->_seek == NULL) { 68 FUNLOCKFILE(fp); 69 errno = ESPIPE; /* historic practice */ 70 return ((off_t)-1); 71 } 72 73 /* 74 * Find offset of underlying I/O object, then 75 * adjust for buffered bytes. 76 */ 77 __sflush(fp); /* may adjust seek offset on append stream */ 78 if (fp->_flags & __SOFF) 79 pos = fp->_offset; 80 else { 81 pos = (*fp->_seek)(fp->_cookie, (fpos_t)0, SEEK_CUR); 82 if (pos == (fpos_t)-1) { 83 FUNLOCKFILE(fp); 84 return (pos); 85 } 86 } 87 if (fp->_flags & __SRD) { 88 /* 89 * Reading. Any unread characters (including 90 * those from ungetc) cause the position to be 91 * smaller than that in the underlying object. 92 */ 93 pos -= fp->_r; 94 if (HASUB(fp)) 95 pos -= fp->_ur; 96 } else if (fp->_flags & __SWR && fp->_p != NULL) { 97 /* 98 * Writing. Any buffered characters cause the 99 * position to be greater than that in the 100 * underlying object. 101 */ 102 pos += fp->_p - fp->_bf._base; 103 } 104 FUNLOCKFILE(fp); 105 return (pos); 106 } 107