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 <fcntl.h> 43 #include <limits.h> 44 #include <stdio.h> 45 #include "un-namespace.h" 46 #include "local.h" 47 #include "libc_private.h" 48 49 /* 50 * standard ftell function. 51 */ 52 long 53 ftell(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(FILE *fp) 70 { 71 fpos_t rv; 72 int ret; 73 74 FLOCKFILE(fp); 75 ret = _ftello(fp, &rv); 76 FUNLOCKFILE(fp); 77 if (ret) 78 return (-1); 79 if (rv < 0) { /* Unspecified value because of ungetc() at 0 */ 80 errno = ESPIPE; 81 return (-1); 82 } 83 return (rv); 84 } 85 86 int 87 _ftello(FILE *fp, fpos_t *offset) 88 { 89 fpos_t pos; 90 size_t n; 91 92 if (fp->_seek == NULL) { 93 errno = ESPIPE; /* historic practice */ 94 return (1); 95 } 96 97 /* 98 * Find offset of underlying I/O object, then 99 * adjust for buffered bytes. 100 */ 101 if (fp->_flags & __SOFF) 102 pos = fp->_offset; 103 else { 104 pos = _sseek(fp, (fpos_t)0, SEEK_CUR); 105 if (pos == -1) 106 return (1); 107 } 108 if (fp->_flags & __SRD) { 109 /* 110 * Reading. Any unread characters (including 111 * those from ungetc) cause the position to be 112 * smaller than that in the underlying object. 113 */ 114 if ((pos -= (HASUB(fp) ? fp->_ur : fp->_r)) < 0) { 115 fp->_flags |= __SERR; 116 errno = EIO; 117 return (1); 118 } 119 if (HASUB(fp)) 120 pos -= fp->_r; /* Can be negative at this point. */ 121 } else if ((fp->_flags & __SWR) && fp->_p != NULL) { 122 /* XXX: Reuse __SALC for O_APPEND. */ 123 if (fp->_flags & (__SAPP|__SALC)) { 124 int serrno = errno; 125 126 errno = 0; 127 if ((pos = _sseek(fp, (fpos_t)0, SEEK_END)) == -1) { 128 if (errno == ESPIPE || 129 (fp->_flags & __SOPT) || __sflush(fp) || 130 (pos = 131 _sseek(fp, (fpos_t)0, SEEK_CUR)) == -1) 132 return (1); 133 else { 134 errno = serrno; 135 *offset = pos; 136 return (0); 137 } 138 } 139 errno = serrno; 140 } 141 /* 142 * Writing. Any buffered characters cause the 143 * position to be greater than that in the 144 * underlying object. 145 */ 146 n = fp->_p - fp->_bf._base; 147 if (pos > OFF_MAX - n) { 148 errno = EOVERFLOW; 149 return (1); 150 } 151 pos += n; 152 } 153 *offset = pos; 154 return (0); 155 } 156