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55 lines
1.8 KiB
C
55 lines
1.8 KiB
C
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/* Copyright (C) 1991, 1992, 1994 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If
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not, write to the Free Software Foundation, Inc., 675 Mass Ave,
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Cambridge, MA 02139, USA. */
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#include <ansidecl.h>
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#include <errno.h>
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#include <stdio.h>
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/* Return the offset in bytes from the beginning
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of the file of the file position of STREAM. */
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long int
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DEFUN(ftell, (stream), FILE *stream)
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{
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long int pos;
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if (!__validfp (stream))
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{
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errno = EINVAL;
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return -1L;
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}
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if (__stdio_check_offset (stream) == EOF)
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return -1L;
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/* Start with the file position associated with the beginning
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of our buffer. */
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pos = stream->__target;
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if (stream->__pushed_back)
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/* ungetc was just called, so our real buffer pointer is squirreled
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away in STREAM->__pushback_bufp, not in STREAM->__bufp as normal.
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Calling ungetc is supposed to decrement the file position. ANSI
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says the file position is unspecified if you ungetc when the
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position is zero; -1 seems as good as anything to me. */
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pos += stream->__pushback_bufp - stream->__buffer - 1;
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else
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pos += stream->__bufp - stream->__buffer;
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return pos;
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}
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