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 <stdio.h> 48 #include <errno.h> 49 #include "un-namespace.h" 50 #include "local.h" 51 #include "libc_private.h" 52 53 /* 54 * standard ftell function. 55 */ 56 long 57 ftell(fp) 58 register FILE *fp; 59 { 60 register off_t rv; 61 rv = ftello(fp); 62 if ((long)rv != rv) { 63 errno = EOVERFLOW; 64 return (-1); 65 } 66 return (rv); 67 } 68 69 /* 70 * ftello: return current offset. 71 */ 72 off_t 73 ftello(fp) 74 register FILE *fp; 75 { 76 register fpos_t pos; 77 78 if (fp->_seek == NULL) { 79 errno = ESPIPE; /* historic practice */ 80 return (-1L); 81 } 82 83 FLOCKFILE(fp); 84 /* 85 * Find offset of underlying I/O object, then 86 * adjust for buffered bytes. 87 */ 88 if (fp->_flags & __SOFF) 89 pos = fp->_offset; 90 else { 91 pos = (*fp->_seek)(fp->_cookie, (fpos_t)0, SEEK_CUR); 92 if (pos == -1) { 93 FUNLOCKFILE(fp); 94 return (pos); 95 } 96 } 97 if (fp->_flags & __SRD) { 98 /* 99 * Reading. Any unread characters (including 100 * those from ungetc) cause the position to be 101 * smaller than that in the underlying object. 102 */ 103 pos -= fp->_r; 104 if (HASUB(fp)) 105 pos -= fp->_ur; 106 } else if (fp->_flags & __SWR && fp->_p != NULL) { 107 /* 108 * Writing. Any buffered characters cause the 109 * position to be greater than that in the 110 * underlying object. 111 */ 112 pos += fp->_p - fp->_bf._base; 113 } 114 FUNLOCKFILE(fp); 115 return (pos); 116 } 117