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. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 */ 36 37 #if defined(LIBC_SCCS) && !defined(lint) 38 #if 0 39 static char sccsid[] = "@(#)ftell.c 8.2 (Berkeley) 5/4/95"; 40 #endif 41 static const char rcsid[] = 42 "$Id: ftell.c,v 1.9 1998/04/11 07:40:44 jb Exp $"; 43 #endif /* LIBC_SCCS and not lint */ 44 45 #include <sys/types.h> 46 #include <stdio.h> 47 #include <errno.h> 48 #include "local.h" 49 #include "libc_private.h" 50 51 /* 52 * standard ftell function. 53 */ 54 long 55 ftell(fp) 56 register FILE *fp; 57 { 58 register off_t rv; 59 rv = ftello(fp); 60 if ((long)rv != rv) { 61 errno = EOVERFLOW; 62 return (-1); 63 } 64 return (rv); 65 } 66 67 /* 68 * ftello: return current offset. 69 */ 70 off_t 71 ftello(fp) 72 register FILE *fp; 73 { 74 register fpos_t pos; 75 76 if (fp->_seek == NULL) { 77 errno = ESPIPE; /* historic practice */ 78 return (-1L); 79 } 80 81 FLOCKFILE(fp); 82 /* 83 * Find offset of underlying I/O object, then 84 * adjust for buffered bytes. 85 */ 86 if (fp->_flags & __SOFF) 87 pos = fp->_offset; 88 else { 89 pos = (*fp->_seek)(fp->_cookie, (fpos_t)0, SEEK_CUR); 90 if (pos == -1) { 91 FUNLOCKFILE(fp); 92 return (pos); 93 } 94 } 95 if (fp->_flags & __SRD) { 96 /* 97 * Reading. Any unread characters (including 98 * those from ungetc) cause the position to be 99 * smaller than that in the underlying object. 100 */ 101 pos -= fp->_r; 102 if (HASUB(fp)) 103 pos -= fp->_ur; 104 } else if (fp->_flags & __SWR && fp->_p != NULL) { 105 /* 106 * Writing. Any buffered characters cause the 107 * position to be greater than that in the 108 * underlying object. 109 */ 110 pos += fp->_p - fp->_bf._base; 111 } 112 FUNLOCKFILE(fp); 113 return (pos); 114 } 115