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 "$FreeBSD$"; 43 #endif /* LIBC_SCCS and not lint */ 44 45 #include "namespace.h" 46 #include <sys/types.h> 47 #include <errno.h> 48 #include <limits.h> 49 #include <stdio.h> 50 #include "un-namespace.h" 51 #include "local.h" 52 #include "libc_private.h" 53 54 /* 55 * standard ftell function. 56 */ 57 long 58 ftell(fp) 59 register FILE *fp; 60 { 61 register off_t rv; 62 63 rv = ftello(fp); 64 if (rv > LONG_MAX) { 65 errno = EOVERFLOW; 66 return (-1); 67 } 68 return (rv); 69 } 70 71 /* 72 * ftello: return current offset. 73 */ 74 off_t 75 ftello(fp) 76 register FILE *fp; 77 { 78 fpos_t rv; 79 int ret; 80 81 FLOCKFILE(fp); 82 ret = _ftello(fp, &rv); 83 FUNLOCKFILE(fp); 84 if (ret) 85 return (-1); 86 if (rv < 0) { /* Unspecified value because of ungetc() at 0 */ 87 errno = ESPIPE; 88 return (-1); 89 } 90 return (rv); 91 } 92 93 int 94 _ftello(fp, offset) 95 register FILE *fp; 96 fpos_t *offset; 97 { 98 register fpos_t pos; 99 size_t n; 100 101 if (fp->_seek == NULL) { 102 errno = ESPIPE; /* historic practice */ 103 return (1); 104 } 105 106 /* 107 * Find offset of underlying I/O object, then 108 * adjust for buffered bytes. 109 */ 110 if (fp->_flags & __SOFF) 111 pos = fp->_offset; 112 else { 113 pos = _sseek(fp, (fpos_t)0, SEEK_CUR); 114 if (pos == -1) 115 return (1); 116 } 117 if (fp->_flags & __SRD) { 118 /* 119 * Reading. Any unread characters (including 120 * those from ungetc) cause the position to be 121 * smaller than that in the underlying object. 122 */ 123 if ((pos -= (HASUB(fp) ? fp->_ur : fp->_r)) < 0) { 124 fp->_flags |= __SERR; 125 errno = EIO; 126 return (1); 127 } 128 if (HASUB(fp)) 129 pos -= fp->_r; /* Can be negative at this point. */ 130 } else if ((fp->_flags & __SWR) && fp->_p != NULL) { 131 /* 132 * Writing. Any buffered characters cause the 133 * position to be greater than that in the 134 * underlying object. 135 */ 136 n = fp->_p - fp->_bf._base; 137 if (pos > OFF_MAX - n) { 138 errno = EOVERFLOW; 139 return (1); 140 } 141 pos += n; 142 } 143 *offset = pos; 144 return (0); 145 } 146