1 /*- 2 * Copyright (c) 1990, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Chris Torek. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 */ 32 33 #if defined(LIBC_SCCS) && !defined(lint) 34 static char rcsid[] = "$OpenBSD: ftell.c,v 1.4 2003/06/02 20:18:37 millert Exp $"; 35 #endif /* LIBC_SCCS and not lint */ 36 37 #include <stdio.h> 38 #include <errno.h> 39 #include "local.h" 40 41 /* 42 * ftello: return current offset. 43 */ 44 off_t 45 ftello(fp) 46 register FILE *fp; 47 { 48 register fpos_t pos; 49 50 if (fp->_seek == NULL) { 51 errno = ESPIPE; /* historic practice */ 52 return ((off_t)-1); 53 } 54 55 /* 56 * Find offset of underlying I/O object, then 57 * adjust for buffered bytes. 58 */ 59 __sflush(fp); /* may adjust seek offset on append stream */ 60 if (fp->_flags & __SOFF) 61 pos = fp->_offset; 62 else { 63 pos = (*fp->_seek)(fp->_cookie, (fpos_t)0, SEEK_CUR); 64 if (pos == -1L) 65 return (pos); 66 } 67 if (fp->_flags & __SRD) { 68 /* 69 * Reading. Any unread characters (including 70 * those from ungetc) cause the position to be 71 * smaller than that in the underlying object. 72 */ 73 pos -= fp->_r; 74 if (HASUB(fp)) 75 pos -= fp->_ur; 76 } else if (fp->_flags & __SWR && fp->_p != NULL) { 77 /* 78 * Writing. Any buffered characters cause the 79 * position to be greater than that in the 80 * underlying object. 81 */ 82 pos += fp->_p - fp->_bf._base; 83 } 84 return (pos); 85 } 86 87 /* 88 * ftell() returns a long and sizeof(off_t) != sizeof(long) on all arches 89 */ 90 #if defined(__alpha__) && defined(__indr_reference) 91 __indr_reference(ftello, ftell); 92 #else 93 long 94 ftell(fp) 95 register FILE *fp; 96 { 97 long pos; 98 99 pos = (long)ftello(fp); 100 return(pos); 101 } 102 #endif 103