160 lines
4.0 KiB
C
160 lines
4.0 KiB
C
/*
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* Copyright (c) 1990 The Regents of the University of California.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms are permitted
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* provided that the above copyright notice and this paragraph are
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* duplicated in all such forms and that any documentation,
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* advertising materials, and other materials related to such
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* distribution and use acknowledge that the software was developed
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* by the University of California, Berkeley. The name of the
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* University may not be used to endorse or promote products derived
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* from this software without specific prior written permission.
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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*/
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#if defined(LIBC_SCCS) && !defined(lint)
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static char sccsid[] = "%W% (Berkeley) %G%";
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#endif /* LIBC_SCCS and not lint */
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "local.h"
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/*
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* Expand the ungetc buffer `in place'. That is, adjust fp->_p when
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* the buffer moves, so that it points the same distance from the end,
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* and move the bytes in the buffer around as necessary so that they
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* are all at the end (stack-style).
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*/
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/*static*/
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int
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__submore (fp)
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register FILE *fp;
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{
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register int i;
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register unsigned char *p;
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if (fp->_ub._base == fp->_ubuf)
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{
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/*
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* Get a new buffer (rather than expanding the old one).
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*/
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if ((p = (unsigned char *) _malloc_r (fp->_data, (size_t) BUFSIZ)) == NULL)
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return EOF;
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fp->_ub._base = p;
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fp->_ub._size = BUFSIZ;
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p += BUFSIZ - sizeof (fp->_ubuf);
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for (i = sizeof (fp->_ubuf); --i >= 0;)
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p[i] = fp->_ubuf[i];
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fp->_p = p;
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return 0;
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}
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i = fp->_ub._size;
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p = (unsigned char *) _realloc_r (fp->_data, (_PTR) (fp->_ub._base), i << 1);
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if (p == NULL)
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return EOF;
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(void) memcpy ((void *) (p + i), (void *) p, (size_t) i);
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fp->_p = p + i;
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fp->_ub._base = p;
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fp->_ub._size = i << 1;
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return 0;
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}
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int
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ungetc (c, fp)
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int c;
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register FILE *fp;
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{
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if (c == EOF)
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return (EOF);
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_flockfile(fp);
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/* Ensure stdio has been initialized.
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??? Might be able to remove this as some other stdio routine should
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have already been called to get the char we are un-getting. */
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CHECK_INIT (fp);
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/* After ungetc, we won't be at eof anymore */
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fp->_flags &= ~__SEOF;
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if ((fp->_flags & __SRD) == 0)
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{
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/*
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* Not already reading: no good unless reading-and-writing.
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* Otherwise, flush any current write stuff.
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*/
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if ((fp->_flags & __SRW) == 0)
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{
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_funlockfile(fp);
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return EOF;
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}
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if (fp->_flags & __SWR)
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{
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if (fflush (fp))
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{
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_funlockfile(fp);
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return EOF;
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}
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fp->_flags &= ~__SWR;
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fp->_w = 0;
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fp->_lbfsize = 0;
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}
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fp->_flags |= __SRD;
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}
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c = (unsigned char) c;
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/*
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* If we are in the middle of ungetc'ing, just continue.
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* This may require expanding the current ungetc buffer.
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*/
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if (HASUB (fp))
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{
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if (fp->_r >= fp->_ub._size && __submore (fp))
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{
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_funlockfile(fp);
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return EOF;
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}
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*--fp->_p = c;
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fp->_r++;
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_funlockfile(fp);
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return c;
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}
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/*
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* If we can handle this by simply backing up, do so,
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* but never replace the original character.
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* (This makes sscanf() work when scanning `const' data.)
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*/
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if (fp->_bf._base != NULL && fp->_p > fp->_bf._base && fp->_p[-1] == c)
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{
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fp->_p--;
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fp->_r++;
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_funlockfile(fp);
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return c;
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}
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/*
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* Create an ungetc buffer.
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* Initially, we will use the `reserve' buffer.
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*/
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fp->_ur = fp->_r;
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fp->_up = fp->_p;
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fp->_ub._base = fp->_ubuf;
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fp->_ub._size = sizeof (fp->_ubuf);
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fp->_ubuf[sizeof (fp->_ubuf) - 1] = c;
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fp->_p = &fp->_ubuf[sizeof (fp->_ubuf) - 1];
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fp->_r = 1;
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_funlockfile(fp);
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return c;
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}
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