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/*-
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 * Copyright (c) 1990, 1993
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 *      The Regents of the University of California.  All rights reserved.
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 *
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 * This code is derived from software contributed to Berkeley by
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 * Chris Torek.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 * 1. Redistributions of source code must retain the above copyright
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 *    notice, this list of conditions and the following disclaimer.
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 * 2. Redistributions in binary form must reproduce the above copyright
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 *    notice, this list of conditions and the following disclaimer in the
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 *    documentation and/or other materials provided with the distribution.
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 * 3. All advertising materials mentioning features or use of this software
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 *    must display the following acknowledgement:
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 *      This product includes software developed by the University of
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 *      California, Berkeley and its contributors.
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 * 4. Neither the name of the University nor the names of its contributors
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 *    may be used to endorse or promote products derived from this software
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 *    without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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 * SUCH DAMAGE.
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 */
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#if defined(LIBC_SCCS) && !defined(lint)
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#if 0
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static char sccsid[] = "@(#)fgetln.c    8.2 (Berkeley) 1/2/94";
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#endif
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static const char rcsid[] =
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                "$\Id: fgetln.c,v 1.3 1996/06/22 10:33:08 jraynard Exp $";
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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 line buffer.  Return -1 on error.
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#ifdef notdef
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 * The `new size' does not account for a terminating '\0',
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 * so we add 1 here.
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#endif
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 */
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int
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__slbexpand(fp, newsize)
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        FILE *fp;
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        size_t newsize;
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{
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        void *p;
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#ifdef notdef
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        ++newsize;
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#endif
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        if (fp->_lb._size >= newsize)
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                return (0);
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        if ((p = realloc(fp->_lb._base, newsize)) == NULL)
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                return (-1);
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        fp->_lb._base = p;
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        fp->_lb._size = newsize;
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        return (0);
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}
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/*
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 * Get an input line.  The returned pointer often (but not always)
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 * points into a stdio buffer.  Fgetln does not alter the text of
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 * the returned line (which is thus not a C string because it will
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 * not necessarily end with '\0'), but does allow callers to modify
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 * it if they wish.  Thus, we set __SMOD in case the caller does.
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 */
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char *
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fgetln(fp, lenp)
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        register FILE *fp;
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        size_t *lenp;
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{
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        register unsigned char *p;
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        register size_t len;
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        size_t off;
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        /* make sure there is input */
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        if (fp->_r <= 0 && __srefill(fp)) {
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                *lenp = 0;
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                return (NULL);
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        }
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        /* look for a newline in the input */
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        if ((p = memchr((void *)fp->_p, '\n', (size_t)fp->_r)) != NULL) {
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                register char *ret;
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                /*
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                 * Found one.  Flag buffer as modified to keep fseek from
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                 * `optimising' a backward seek, in case the user stomps on
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                 * the text.
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                 */
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                p++;            /* advance over it */
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                ret = (char *)fp->_p;
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                *lenp = len = p - fp->_p;
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                fp->_flags |= __SMOD;
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                fp->_r -= len;
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                fp->_p = p;
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                return (ret);
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        }
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        /*
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         * We have to copy the current buffered data to the line buffer.
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         * As a bonus, though, we can leave off the __SMOD.
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         *
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         * OPTIMISTIC is length that we (optimistically) expect will
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         * accomodate the `rest' of the string, on each trip through the
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         * loop below.
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         */
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#define OPTIMISTIC 80
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        for (len = fp->_r, off = 0;; len += fp->_r) {
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                register size_t diff;
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                /*
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                 * Make sure there is room for more bytes.  Copy data from
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                 * file buffer to line buffer, refill file and look for
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                 * newline.  The loop stops only when we find a newline.
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                 */
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                if (__slbexpand(fp, len + OPTIMISTIC))
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                        goto error;
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                (void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p,
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                    len - off);
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                off = len;
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                if (__srefill(fp))
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                        break;  /* EOF or error: return partial line */
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                if ((p = memchr((void *)fp->_p, '\n', (size_t)fp->_r)) == NULL)
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                        continue;
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                /* got it: finish up the line (like code above) */
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                p++;
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                diff = p - fp->_p;
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                len += diff;
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                if (__slbexpand(fp, len))
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                        goto error;
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                (void)memcpy((void *)(fp->_lb._base + off), (void *)fp->_p,
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                    diff);
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                fp->_r -= diff;
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                fp->_p = p;
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                break;
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        }
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        *lenp = len;
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#ifdef notdef
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        fp->_lb._base[len] = 0;
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#endif
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        return ((char *)fp->_lb._base);
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error:
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        *lenp = 0;              /* ??? */
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        return (NULL);          /* ??? */
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}