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 sccsid[] = "@(#)ftell.c 8.2 (Berkeley) 5/4/95"; 35 #endif /* LIBC_SCCS and not lint */ 36 #include <sys/cdefs.h> 37 __FBSDID("$FreeBSD$"); 38 39 #include "namespace.h" 40 #include <sys/types.h> 41 #include <errno.h> 42 #include <limits.h> 43 #include <stdio.h> 44 #include "un-namespace.h" 45 #include "local.h" 46 #include "libc_private.h" 47 48 /* 49 * standard ftell function. 50 */ 51 long 52 ftell(FILE *fp) 53 { 54 off_t rv; 55 56 rv = ftello(fp); 57 if (rv > LONG_MAX) { 58 errno = EOVERFLOW; 59 return (-1); 60 } 61 return (rv); 62 } 63 64 /* 65 * ftello: return current offset. 66 */ 67 off_t 68 ftello(FILE *fp) 69 { 70 fpos_t rv; 71 int ret; 72 73 FLOCKFILE(fp); 74 ret = _ftello(fp, &rv); 75 FUNLOCKFILE(fp); 76 if (ret) 77 return (-1); 78 if (rv < 0) { /* Unspecified value because of ungetc() at 0 */ 79 errno = ESPIPE; 80 return (-1); 81 } 82 return (rv); 83 } 84 85 int 86 _ftello(FILE *fp, fpos_t *offset) 87 { 88 fpos_t pos; 89 size_t n; 90 91 if (fp->_seek == NULL) { 92 errno = ESPIPE; /* historic practice */ 93 return (1); 94 } 95 96 /* 97 * Find offset of underlying I/O object, then 98 * adjust for buffered bytes. 99 */ 100 if (!(fp->_flags & __SRD) && (fp->_flags & __SWR) && 101 fp->_p != NULL && fp->_p - fp->_bf._base > 0 && 102 ((fp->_flags & __SAPP) || (fp->_flags2 & __S2OAP))) { 103 pos = _sseek(fp, (fpos_t)0, SEEK_END); 104 if (pos == -1) 105 return (1); 106 } else if (fp->_flags & __SOFF) 107 pos = fp->_offset; 108 else { 109 pos = _sseek(fp, (fpos_t)0, SEEK_CUR); 110 if (pos == -1) 111 return (1); 112 } 113 if (fp->_flags & __SRD) { 114 /* 115 * Reading. Any unread characters (including 116 * those from ungetc) cause the position to be 117 * smaller than that in the underlying object. 118 */ 119 if ((pos -= (HASUB(fp) ? fp->_ur : fp->_r)) < 0) { 120 fp->_flags |= __SERR; 121 errno = EIO; 122 return (1); 123 } 124 if (HASUB(fp)) 125 pos -= fp->_r; /* Can be negative at this point. */ 126 } else if ((fp->_flags & __SWR) && fp->_p != NULL && 127 (n = fp->_p - fp->_bf._base) > 0) { 128 /* 129 * Writing. Any buffered characters cause the 130 * position to be greater than that in the 131 * underlying object. 132 */ 133 if (pos > OFF_MAX - n) { 134 errno = EOVERFLOW; 135 return (1); 136 } 137 pos += n; 138 } 139 *offset = pos; 140 return (0); 141 } 142