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/* $OpenBSD: fgetln.c,v 1.17 2017/03/17 14:53:08 deraadt 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"
/*
* Expand the line buffer. Return -1 on error.
*/
static int
__slbexpand(FILE *fp, size_t newsize)
{
void *p;
if (fp->_lb._size >= newsize)
return (0);
if ((p = recallocarray(fp->_lb._base, fp->_lb._size, newsize, 1)) == 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 does not alter the text of
* the returned line (which is thus not a C string because it will
* not necessarily end with '\0'), but does allow callers to modify
* it if they wish. Thus, we set __SMOD in case the caller does.
*/
char *
fgetln(FILE *fp, size_t *lenp)
{
unsigned char *p;
char *ret;
size_t len;
size_t off;
FLOCKFILE(fp);
_SET_ORIENTATION(fp, -1);
/* make sure there is input */
if (fp->_r <= 0 && __srefill(fp))
goto error;
/* look for a newline in the input */
if ((p = memchr(fp->_p, '\n', fp->_r)) != NULL) {
/*
* Found one. Flag buffer as modified to keep fseek from
* `optimising' a backward seek, in case the user stomps on
* the text.
*/
p++; /* advance over it */
ret = (char *)fp->_p;
*lenp = len = p - fp->_p;
fp->_flags |= __SMOD;
fp->_r -= len;
fp->_p = p;
FUNLOCKFILE(fp);
return (ret);
}
/*
* We have to copy the current buffered data to the line buffer.
* As a bonus, though, we can leave off the __SMOD.
*
* OPTIMISTIC is length that we (optimistically) expect will
* accommodate the `rest' of the string, on each trip through the
* loop below.
*/
#define OPTIMISTIC 80
for (len = fp->_r, off = 0;; len += fp->_r) {
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)memcpy(fp->_lb._base + off, fp->_p, len - off);
off = len;
if (__srefill(fp)) {
if (fp->_flags & __SEOF)
break;
goto error;
}
if ((p = memchr(fp->_p, '\n', fp->_r)) == NULL)
continue;
/* got it: finish up the line (like code above) */
p++;
diff = p - fp->_p;
len += diff;
if (__slbexpand(fp, len))
goto error;
(void)memcpy(fp->_lb._base + off, fp->_p, diff);
fp->_r -= diff;
fp->_p = p;
break;
}
*lenp = len;
ret = (char *)fp->_lb._base;
FUNLOCKFILE(fp);
return (ret);
error:
FUNLOCKFILE(fp);
*lenp = 0;
return (NULL);
}
DEF_WEAK(fgetln);
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