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/* $OpenBSD: fgets.c,v 1.16 2016/09/21 04:38:56 guenther 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 <errno.h> |
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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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errno = EINVAL; |
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return (NULL); |
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} |
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FLOCKFILE(fp); |
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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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FUNLOCKFILE(fp); |
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return (NULL); |
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} |
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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 (len > n) |
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len = n; |
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t = memchr(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(s, p, len); |
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s[len] = '\0'; |
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FUNLOCKFILE(fp); |
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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(s, 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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FUNLOCKFILE(fp); |
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return (buf); |
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} |
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DEF_STRONG(fgets); |