1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
|
/* Copyright (C) 1991, 1992, 1994, 1996, 1997 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
#include <errno.h>
#include <stdio.h>
/* Return the offset in bytes from the beginning
of the file of the file position of STREAM. */
long int
ftell (stream)
FILE *stream;
{
long int pos;
if (!__validfp (stream))
{
__set_errno (EINVAL);
return -1L;
}
if (__stdio_check_offset (stream) == EOF)
return -1L;
/* Start with the file position associated with the beginning
of our buffer. */
pos = stream->__target;
if (stream->__pushed_back)
/* ungetc was just called, so our real buffer pointer is squirreled
away in STREAM->__pushback_bufp, not in STREAM->__bufp as normal.
Calling ungetc is supposed to decrement the file position. ANSI
says the file position is unspecified if you ungetc when the
position is zero; -1 seems as good as anything to me. */
pos += stream->__pushback_bufp - stream->__buffer - 1;
else
pos += stream->__bufp - stream->__buffer;
return pos;
}
|
