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59 lines
1.8 KiB
C
59 lines
1.8 KiB
C
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/* Copyright (C) 1991, 1993 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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/* Push the character C back onto the input stream of STREAM. */
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int
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DEFUN(ungetc, (c, stream), register int c AND register FILE *stream)
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{
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if (!__validfp(stream) || !stream->__mode.__read)
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{
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errno = EINVAL;
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return EOF;
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}
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if (c == EOF)
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return EOF;
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if (stream->__pushed_back)
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/* There is already a char pushed back. */
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return EOF;
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if ((stream->__linebuf_active || stream->__put_limit > stream->__buffer) &&
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/* This is a read-write stream with something in its buffer.
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Flush the stream. */
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__flshfp (stream, EOF) == EOF)
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return EOF;
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stream->__pushback = (unsigned char) c;
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/* Tell __fillbf we've pushed back a char. */
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stream->__pushed_back = 1;
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stream->__pushback_bufp = stream->__bufp;
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/* Make the next getc call __fillbf. It will return C. */
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stream->__bufp = stream->__get_limit;
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/* We just gave it another character to read, so it's not at EOF. */
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stream->__eof = 0;
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return stream->__pushback;
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}
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