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