The CDPD Public Domain Collection for CDTV 3/CDPDIII.bin/pd/programming/gnuc/stdio_2/rcs/fgetline.c,v

Text File | 1992-07-04 | 5.0 KB | 190 lines

head    1.1;
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    version39-41:1.1;
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comment    @ * @;


1.1
date    92.06.08.15.10.10;    author mwild;    state Exp;
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@initial checkin
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1.1
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@Initial revision
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@/*-
 * 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[] = "@@(#)fgetline.c    5.2 (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 line buffer.  Return -1 on error.
 * The `new size' does not account for a terminating '\0',
 * so we add 1 here.
 */
__slbexpand(fp, newsize)
    FILE *fp;
    size_t newsize;
{
    void *p;

    if (fp->_lb._size >= ++newsize)
        return (0);
    if ((p = realloc(fp->_lb._base, newsize)) == NULL)
        return (-1);
    fp->_lb._base = p;
    fp->_lb._size = newsize;
    return (0);
}

/*
 * Get an input line.  The returned pointer often (but not always)
 * points into a stdio buffer.  Fgetline smashes the newline (if any)
 * in the stdio buffer; callers must not use it on streams that
 * have `magic' setvbuf() games happening.
 */
char *
fgetline(fp, lenp)
    register FILE *fp;
    size_t *lenp;
{
    register unsigned char *p;
    register size_t len;
    size_t off;

    /* make sure there is input */
    if (!fp || (fp->_r <= 0 && __srefill(fp))) {
        if (lenp != NULL)
            *lenp = 0;
        return (NULL);
    }

    /* look for a newline in the input */
    if ((p = memchr((void *)fp->_p, '\n', fp->_r)) != NULL) {
        register char *ret;

        /*
         * Found one.  Flag buffer as modified to keep
         * fseek from `optimising' a backward seek, since
         * the newline is about to be trashed.  (We should
         * be able to get away with doing this only if
         * p is not pointing into an ungetc buffer, since
         * fseek discards ungetc data, but this is the
         * usual case anyway.)
         */
        ret = (char *)fp->_p;
        len = p - fp->_p;
        fp->_flags |= __SMOD;
        *p = 0;
        fp->_r -= len + 1;
        fp->_p = p + 1;
        if (lenp != NULL)
            *lenp = len;
        return (ret);
    }

    /*
     * We have to copy the current buffered data to the line buffer.
     *
     * OPTIMISTIC is length that we (optimistically)
     * expect will accomodate the `rest' of the string,
     * on each trip through the loop below.
     */
#define OPTIMISTIC 80

    for (len = fp->_r, off = 0;; len += fp->_r) {
        register size_t diff;

        /*
         * Make sure there is room for more bytes.
         * Copy data from file buffer to line buffer,
         * refill file and look for newline.  The
         * loop stops only when we find a newline.
         */
        if (__slbexpand(fp, len + OPTIMISTIC))
            goto error;
        (void) bcopy((void *)fp->_p, (void *)(fp->_lb._base + off),
            len - off);
        off = len;
        if (__srefill(fp))
            break;    /* EOF or error: return partial line */
        if ((p = memchr((void *)fp->_p, '\n', fp->_r)) == NULL)
            continue;

        /* got it: finish up the line (like code above) */
        fp->_flags |= __SMOD;    /* soon */
        diff = p - fp->_p;
        len += diff;
        if (__slbexpand(fp, len))
            goto error;
        (void) bcopy((void *)fp->_p, (void *)(fp->_lb._base + off),
            diff);
        fp->_r -= diff + 1;
        fp->_p = p + 1;
        break;
    }
    if (lenp != NULL)
        *lenp = len;
    fp->_lb._base[len] = 0;
    return ((char *)fp->_lb._base);

error:
    if (lenp != NULL)
        *lenp = 0;    /* ??? */
    return (NULL);        /* ??? */
}
@