Language/OS - Multiplatform Resource Library/LANGUAGE OS.iso/gnu/amiga/ixmlb920.lha/stdio_2/rcs/ungetc.c,v

Text File | 1992-07-04 | 5KB | 177 lines

head    1.1;
access;
symbols
    version39-41:1.1;
locks;
comment    @ * @;


1.1
date    92.06.08.15.10.10;    author mwild;    state Exp;
branches;
next    ;


desc
@initial checkin
@


1.1
log
@Initial revision
@
text
@/*-
 * Copyright (c) 1990 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    This product includes software developed by the University of
 *    California, Berkeley and its contributors.
 * 4. 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.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@@(#)ungetc.c    5.6 (Berkeley) 5/4/91";
#endif /* LIBC_SCCS and not lint */

#define KERNEL
#include "ixemul.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "local.h"

/*
 * 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
__submore(fp)
    register FILE *fp;
{
    register int i;
    register unsigned char *p;

    if (fp->_ub._base == fp->_ubuf) {
        /*
         * Get a new buffer (rather than expanding the old one).
         */
        if ((p = malloc((size_t)BUFSIZ)) == NULL)
            return (EOF);
        fp->_ub._base = p;
        fp->_ub._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 = fp->_ub._size;
    p = realloc(fp->_ub._base, i << 1);
    if (p == NULL)
        return (EOF);
    (void) bcopy((void *)p, (void *)(p + i), (size_t)i);
    fp->_p = p + i;
    fp->_ub._base = p;
    fp->_ub._size = i << 1;
    return (0);
}

ungetc(c, fp)
    int c;
    register FILE *fp;
{
    if (c == EOF)
        return (EOF);
#if 0
    if (!__sdidinit)
        __sinit();
#endif
    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 >= fp->_ub._size && __submore(fp))
            return (EOF);
        *--fp->_p = c;
        fp->_r++;
        return (c);
    }

    /*
     * 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;
    fp->_ub._base = fp->_ubuf;
    fp->_ub._size = sizeof(fp->_ubuf);
    fp->_ubuf[sizeof(fp->_ubuf) - 1] = c;
    fp->_p = &fp->_ubuf[sizeof(fp->_ubuf) - 1];
    fp->_r = 1;
    return (c);
}
@