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 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(fp) 53 FILE *fp; 54 { 55 off_t rv; 56 57 rv = ftello(fp); 58 if (rv > LONG_MAX) { 59 errno = EOVERFLOW; 60 return (-1); 61 } 62 return (rv); 63 } 64 65 /* 66 * ftello: return current offset. 67 */ 68 off_t 69 ftello(fp) 70 FILE *fp; 71 { 72 fpos_t rv; 73 int ret; 74 75 FLOCKFILE(fp); 76 ret = _ftello(fp, &rv); 77 FUNLOCKFILE(fp); 78 if (ret) 79 return (-1); 80 if (rv < 0) { /* Unspecified value because of ungetc() at 0 */ 81 errno = ESPIPE; 82 return (-1); 83 } 84 return (rv); 85 } 86 87 int 88 _ftello(fp, offset) 89 FILE *fp; 90 fpos_t *offset; 91 { 92 fpos_t pos; 93 size_t n; 94 95 if (fp->_seek == NULL) { 96 errno = ESPIPE; /* historic practice */ 97 return (1); 98 } 99 100 /* 101 * Find offset of underlying I/O object, then 102 * adjust for buffered bytes. 103 */ 104 if (fp->_flags & __SOFF) 105 pos = fp->_offset; 106 else { 107 pos = _sseek(fp, (fpos_t)0, SEEK_CUR); 108 if (pos == -1) 109 return (1); 110 } 111 if (fp->_flags & __SRD) { 112 /* 113 * Reading. Any unread characters (including 114 * those from ungetc) cause the position to be 115 * smaller than that in the underlying object. 116 */ 117 if ((pos -= (HASUB(fp) ? fp->_ur : fp->_r)) < 0) { 118 fp->_flags |= __SERR; 119 errno = EIO; 120 return (1); 121 } 122 if (HASUB(fp)) 123 pos -= fp->_r; /* Can be negative at this point. */ 124 } else if ((fp->_flags & __SWR) && fp->_p != NULL) { 125 /* 126 * Writing. Any buffered characters cause the 127 * position to be greater than that in the 128 * underlying object. 129 */ 130 n = fp->_p - fp->_bf._base; 131 if (pos > OFF_MAX - n) { 132 errno = EOVERFLOW; 133 return (1); 134 } 135 pos += n; 136 } 137 *offset = pos; 138 return (0); 139 } 140