97 lines
3 KiB
C
97 lines
3 KiB
C
/* $OpenBSD: fgets.c,v 1.10 2005/08/08 08:05:36 espie Exp $ */
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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. 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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#include <stdio.h>
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#include <string.h>
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#include "local.h"
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/*
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* Read at most n-1 characters from the given file.
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* Stop when a newline has been read, or the count runs out.
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* Return first argument, or NULL if no characters were read.
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* Do not return NULL if n == 1.
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*/
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char *
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fgets(char *buf, int n, FILE *fp)
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{
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size_t len;
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char *s;
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unsigned char *p, *t;
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if (n <= 0) /* sanity check */
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return (NULL);
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_SET_ORIENTATION(fp, -1);
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s = buf;
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n--; /* leave space for NUL */
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while (n != 0) {
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/*
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* If the buffer is empty, refill it.
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*/
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if (fp->_r <= 0) {
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if (__srefill(fp)) {
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/* EOF/error: stop with partial or no line */
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if (s == buf)
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return (NULL);
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break;
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}
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}
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len = fp->_r;
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p = fp->_p;
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/*
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* Scan through at most n bytes of the current buffer,
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* looking for '\n'. If found, copy up to and including
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* newline, and stop. Otherwise, copy entire chunk
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* and loop.
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*/
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if ((int)len > n)
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len = n;
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t = memchr((void *)p, '\n', len);
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if (t != NULL) {
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len = ++t - p;
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fp->_r -= len;
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fp->_p = t;
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(void)memcpy((void *)s, (void *)p, len);
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s[len] = '\0';
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return (buf);
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}
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fp->_r -= len;
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fp->_p += len;
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(void)memcpy((void *)s, (void *)p, len);
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s += len;
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n -= len;
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}
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*s = '\0';
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return (buf);
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}
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