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 * 4. 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 * @(#)ftell.c 8.2 (Berkeley) 5/4/95 33 * $FreeBSD: src/lib/libc/stdio/ftell.c,v 1.27 2007/01/09 00:28:06 imp Exp $ 34 * $DragonFly: src/lib/libc/stdio/ftell.c,v 1.6 2005/07/23 20:23:06 joerg Exp $ 35 */ 36 37 #include "namespace.h" 38 #include <sys/types.h> 39 #include <errno.h> 40 #include <limits.h> 41 #include <stdio.h> 42 #include "un-namespace.h" 43 #include "local.h" 44 #include "libc_private.h" 45 #include "priv_stdio.h" 46 47 /* 48 * standard ftell function. 49 */ 50 long 51 ftell(FILE *fp) 52 { 53 off_t rv; 54 55 rv = ftello(fp); 56 if (rv > LONG_MAX) { 57 errno = EOVERFLOW; 58 return (-1); 59 } 60 return (rv); 61 } 62 63 /* 64 * ftello: return current offset. 65 */ 66 off_t 67 ftello(FILE *fp) 68 { 69 fpos_t rv; 70 int ret; 71 72 FLOCKFILE(fp); 73 ret = _ftello(fp, &rv); 74 FUNLOCKFILE(fp); 75 if (ret) 76 return (-1); 77 if (rv < 0) { /* Unspecified value because of ungetc() at 0 */ 78 errno = ESPIPE; 79 return (-1); 80 } 81 return (rv); 82 } 83 84 int 85 _ftello(FILE *fp, fpos_t *offset) 86 { 87 fpos_t pos; 88 size_t n; 89 90 if (fp->_seek == NULL) { 91 errno = ESPIPE; /* historic practice */ 92 return (1); 93 } 94 95 /* 96 * Find offset of underlying I/O object, then 97 * adjust for buffered bytes. 98 */ 99 if (fp->pub._flags & __SOFF) 100 pos = fp->_offset; 101 else { 102 pos = _sseek(fp, (fpos_t)0, SEEK_CUR); 103 if (pos == -1) 104 return (1); 105 } 106 if (fp->pub._flags & __SRD) { 107 /* 108 * Reading. Any unread characters (including 109 * those from ungetc) cause the position to be 110 * smaller than that in the underlying object. 111 */ 112 if ((pos -= (HASUB(fp) ? fp->_ur : fp->pub._r)) < 0) { 113 fp->pub._flags |= __SERR; 114 errno = EIO; 115 return (1); 116 } 117 if (HASUB(fp)) 118 pos -= fp->pub._r; /* Can be negative at this point. */ 119 } else if ((fp->pub._flags & __SWR) && fp->pub._p != NULL) { 120 /* 121 * Writing. Any buffered characters cause the 122 * position to be greater than that in the 123 * underlying object. 124 */ 125 n = fp->pub._p - fp->_bf._base; 126 if (pos > OFF_MAX - n) { 127 errno = EOVERFLOW; 128 return (1); 129 } 130 pos += n; 131 } 132 *offset = pos; 133 return (0); 134 } 135