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