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/* $OpenBSD: fgets.c,v 1.15 2015/08/31 02:53:57 guenther 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 <errno.h>
#include <stdio.h>
#include <string.h>
#include "local.h"
/*
* Read at most n-1 characters from the given file.
* Stop when a newline has been read, or the count runs out.
* Return first argument, or NULL if no characters were read.
* Do not return NULL if n == 1.
*/
char *
fgets(char *buf, int n, FILE *fp)
{
size_t len;
char *s;
unsigned char *p, *t;
if (n <= 0) { /* sanity check */
errno = EINVAL;
return (NULL);
}
FLOCKFILE(fp);
_SET_ORIENTATION(fp, -1);
s = buf;
n--; /* leave space for NUL */
while (n != 0) {
/*
* If the buffer is empty, refill it.
*/
if (fp->_r <= 0) {
if (__srefill(fp)) {
/* EOF/error: stop with partial or no line */
if (s == buf) {
FUNLOCKFILE(fp);
return (NULL);
}
break;
}
}
len = fp->_r;
p = fp->_p;
/*
* Scan through at most n bytes of the current buffer,
* looking for '\n'. If found, copy up to and including
* newline, and stop. Otherwise, copy entire chunk
* and loop.
*/
if (len > n)
len = n;
t = memchr((void *)p, '\n', len);
if (t != NULL) {
len = ++t - p;
fp->_r -= len;
fp->_p = t;
(void)memcpy((void *)s, (void *)p, len);
s[len] = '\0';
FUNLOCKFILE(fp);
return (buf);
}
fp->_r -= len;
fp->_p += len;
(void)memcpy((void *)s, (void *)p, len);
s += len;
n -= len;
}
*s = '\0';
FUNLOCKFILE(fp);
return (buf);
}
DEF_STRONG(fgets);
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