142 lines
4.1 KiB
C
142 lines
4.1 KiB
C
/* $OpenBSD: ungetc.c,v 1.9 2005/08/08 08:05:36 espie Exp $ */
|
|
/*-
|
|
* Copyright (c) 1990, 1993
|
|
* The Regents of the University of California. All rights reserved.
|
|
*
|
|
* This code is derived from software contributed to Berkeley by
|
|
* Chris Torek.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
|
* 3. Neither the name of the University nor the names of its contributors
|
|
* may be used to endorse or promote products derived from this software
|
|
* without specific prior written permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
|
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
|
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
* SUCH DAMAGE.
|
|
*/
|
|
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include "local.h"
|
|
|
|
static int __submore(FILE *);
|
|
/*
|
|
* Expand the ungetc buffer `in place'. That is, adjust fp->_p when
|
|
* the buffer moves, so that it points the same distance from the end,
|
|
* and move the bytes in the buffer around as necessary so that they
|
|
* are all at the end (stack-style).
|
|
*/
|
|
static int
|
|
__submore(FILE *fp)
|
|
{
|
|
int i;
|
|
unsigned char *p;
|
|
|
|
if (_UB(fp)._base == fp->_ubuf) {
|
|
/*
|
|
* Get a new buffer (rather than expanding the old one).
|
|
*/
|
|
if ((p = malloc((size_t)BUFSIZ)) == NULL)
|
|
return (EOF);
|
|
_UB(fp)._base = p;
|
|
_UB(fp)._size = BUFSIZ;
|
|
p += BUFSIZ - sizeof(fp->_ubuf);
|
|
for (i = sizeof(fp->_ubuf); --i >= 0;)
|
|
p[i] = fp->_ubuf[i];
|
|
fp->_p = p;
|
|
return (0);
|
|
}
|
|
i = _UB(fp)._size;
|
|
p = realloc(_UB(fp)._base, i << 1);
|
|
if (p == NULL)
|
|
return (EOF);
|
|
/* no overlap (hence can use memcpy) because we doubled the size */
|
|
(void)memcpy((void *)(p + i), (void *)p, (size_t)i);
|
|
fp->_p = p + i;
|
|
_UB(fp)._base = p;
|
|
_UB(fp)._size = i << 1;
|
|
return (0);
|
|
}
|
|
|
|
int
|
|
ungetc(int c, FILE *fp)
|
|
{
|
|
if (c == EOF)
|
|
return (EOF);
|
|
if (!__sdidinit)
|
|
__sinit();
|
|
_SET_ORIENTATION(fp, -1);
|
|
if ((fp->_flags & __SRD) == 0) {
|
|
/*
|
|
* Not already reading: no good unless reading-and-writing.
|
|
* Otherwise, flush any current write stuff.
|
|
*/
|
|
if ((fp->_flags & __SRW) == 0)
|
|
return (EOF);
|
|
if (fp->_flags & __SWR) {
|
|
if (__sflush(fp))
|
|
return (EOF);
|
|
fp->_flags &= ~__SWR;
|
|
fp->_w = 0;
|
|
fp->_lbfsize = 0;
|
|
}
|
|
fp->_flags |= __SRD;
|
|
}
|
|
c = (unsigned char)c;
|
|
|
|
/*
|
|
* If we are in the middle of ungetc'ing, just continue.
|
|
* This may require expanding the current ungetc buffer.
|
|
*/
|
|
if (HASUB(fp)) {
|
|
if (fp->_r >= _UB(fp)._size && __submore(fp))
|
|
return (EOF);
|
|
*--fp->_p = c;
|
|
fp->_r++;
|
|
return (c);
|
|
}
|
|
fp->_flags &= ~__SEOF;
|
|
|
|
/*
|
|
* If we can handle this by simply backing up, do so,
|
|
* but never replace the original character.
|
|
* (This makes sscanf() work when scanning `const' data.)
|
|
*/
|
|
if (fp->_bf._base != NULL && fp->_p > fp->_bf._base &&
|
|
fp->_p[-1] == c) {
|
|
fp->_p--;
|
|
fp->_r++;
|
|
return (c);
|
|
}
|
|
|
|
/*
|
|
* Create an ungetc buffer.
|
|
* Initially, we will use the `reserve' buffer.
|
|
*/
|
|
fp->_ur = fp->_r;
|
|
fp->_up = fp->_p;
|
|
_UB(fp)._base = fp->_ubuf;
|
|
_UB(fp)._size = sizeof(fp->_ubuf);
|
|
fp->_ubuf[sizeof(fp->_ubuf) - 1] = c;
|
|
fp->_p = &fp->_ubuf[sizeof(fp->_ubuf) - 1];
|
|
fp->_r = 1;
|
|
return (c);
|
|
}
|