projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| 15637ed4 RG |
1 | /*- |
| 2 | * Copyright (c) 1990 The Regents of the University of California. | |
| 3 | * 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 | static char sccsid[] = "@(#)ftell.c 5.4 (Berkeley) 2/5/91"; | |
| 39 | #endif /* LIBC_SCCS and not lint */ | |
| 40 | ||
| 41 | #include <stdio.h> | |
| 42 | #include <errno.h> | |
| 43 | #include "local.h" | |
| 44 | ||
| 45 | /* | |
| 46 | * ftell: return current offset. | |
| 47 | */ | |
| 48 | long | |
| 49 | ftell(fp) | |
| 50 | register const FILE *fp; | |
| 51 | { | |
| 52 | register fpos_t pos; | |
| 53 | ||
| 54 | if (fp->_seek == NULL) { | |
| 55 | errno = ESPIPE; /* historic practice */ | |
| 56 | return (-1L); | |
| 57 | } | |
| 58 | ||
| 59 | /* | |
| 60 | * Find offset of underlying I/O object, then | |
| 61 | * adjust for buffered bytes. | |
| 62 | */ | |
| 63 | if (fp->_flags & __SOFF) | |
| 64 | pos = fp->_offset; | |
| 65 | else { | |
| 66 | pos = (*fp->_seek)(fp->_cookie, (fpos_t)0, SEEK_CUR); | |
| 67 | if (pos == -1L) | |
| 68 | return (pos); | |
| 69 | } | |
| 70 | if (fp->_flags & __SRD) { | |
| 71 | /* | |
| 72 | * Reading. Any unread characters (including | |
| 73 | * those from ungetc) cause the position to be | |
| 74 | * smaller than that in the underlying object. | |
| 75 | */ | |
| 76 | pos -= fp->_r; | |
| 77 | if (HASUB(fp)) | |
| 78 | pos -= fp->_ur; | |
| 79 | } else if (fp->_flags & __SWR && fp->_p != NULL) { | |
| 80 | /* | |
| 81 | * Writing. Any buffered characters cause the | |
| 82 | * position to be greater than that in the | |
| 83 | * underlying object. | |
| 84 | */ | |
| 85 | pos += fp->_p - fp->_bf._base; | |
| 86 | } | |
| 87 | return (pos); | |
| 88 | } |