33cd251a1b
2) Optimize string buffer copy to call memcpy() and update pointers only for count > 0, it makes snprintf(NULL, 0, ...) more efficient
197 lines
5.6 KiB
C
197 lines
5.6 KiB
C
/*-
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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. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. 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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#if defined(LIBC_SCCS) && !defined(lint)
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#if 0
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static char sccsid[] = "@(#)fvwrite.c 8.1 (Berkeley) 6/4/93";
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#endif
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static const char rcsid[] =
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"$Id: fvwrite.c,v 1.6 1997/12/24 13:17:13 ache Exp $";
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#endif /* LIBC_SCCS and not lint */
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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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#include "fvwrite.h"
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/*
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* Write some memory regions. Return zero on success, EOF on error.
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*
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* This routine is large and unsightly, but most of the ugliness due
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* to the three different kinds of output buffering is handled here.
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*/
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int
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__sfvwrite(fp, uio)
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register FILE *fp;
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register struct __suio *uio;
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{
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register size_t len;
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register char *p;
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register struct __siov *iov;
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register int w, s;
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char *nl;
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int nlknown, nldist;
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if ((len = uio->uio_resid) == 0)
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return (0);
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/* make sure we can write */
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if (cantwrite(fp))
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return (EOF);
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#define MIN(a, b) ((a) < (b) ? (a) : (b))
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#define COPY(n) (void)memcpy((void *)fp->_p, (void *)p, (size_t)(n))
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iov = uio->uio_iov;
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p = iov->iov_base;
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len = iov->iov_len;
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iov++;
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#define GETIOV(extra_work) \
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while (len == 0) { \
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extra_work; \
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p = iov->iov_base; \
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len = iov->iov_len; \
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iov++; \
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}
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if (fp->_flags & __SNBF) {
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/*
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* Unbuffered: write up to BUFSIZ bytes at a time.
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*/
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do {
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GETIOV(;);
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w = (*fp->_write)(fp->_cookie, p, MIN(len, BUFSIZ));
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if (w <= 0)
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goto err;
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p += w;
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len -= w;
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} while ((uio->uio_resid -= w) != 0);
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} else if ((fp->_flags & __SLBF) == 0) {
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/*
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* Fully buffered: fill partially full buffer, if any,
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* and then flush. If there is no partial buffer, write
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* one _bf._size byte chunk directly (without copying).
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*
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* String output is a special case: write as many bytes
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* as fit, but pretend we wrote everything. This makes
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* snprintf() return the number of bytes needed, rather
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* than the number used, and avoids its write function
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* (so that the write function can be invalid).
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*/
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do {
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GETIOV(;);
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w = fp->_w;
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if (fp->_flags & __SSTR) {
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if (len < w)
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w = len;
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if (w > 0) {
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COPY(w); /* copy MIN(fp->_w,len), */
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fp->_w -= w;
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fp->_p += w;
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}
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w = len; /* but pretend copied all */
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} else if (fp->_p > fp->_bf._base && len > w) {
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/* fill and flush */
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COPY(w);
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/* fp->_w -= w; */ /* unneeded */
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fp->_p += w;
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if (fflush(fp))
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goto err;
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} else if (len >= (w = fp->_bf._size)) {
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/* write directly */
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w = (*fp->_write)(fp->_cookie, p, w);
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if (w <= 0)
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goto err;
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} else {
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/* fill and done */
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w = len;
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COPY(w);
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fp->_w -= w;
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fp->_p += w;
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}
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p += w;
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len -= w;
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} while ((uio->uio_resid -= w) != 0);
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} else {
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/*
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* Line buffered: like fully buffered, but we
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* must check for newlines. Compute the distance
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* to the first newline (including the newline),
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* or `infinity' if there is none, then pretend
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* that the amount to write is MIN(len,nldist).
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*/
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nlknown = 0;
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nldist = 0; /* XXX just to keep gcc happy */
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do {
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GETIOV(nlknown = 0);
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if (!nlknown) {
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nl = memchr((void *)p, '\n', len);
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nldist = nl ? nl + 1 - p : len + 1;
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nlknown = 1;
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}
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s = MIN(len, nldist);
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w = fp->_w + fp->_bf._size;
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if (fp->_p > fp->_bf._base && s > w) {
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COPY(w);
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/* fp->_w -= w; */
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fp->_p += w;
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if (fflush(fp))
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goto err;
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} else if (s >= (w = fp->_bf._size)) {
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w = (*fp->_write)(fp->_cookie, p, w);
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if (w <= 0)
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goto err;
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} else {
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w = s;
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COPY(w);
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fp->_w -= w;
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fp->_p += w;
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}
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if ((nldist -= w) == 0) {
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/* copied the newline: flush and forget */
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if (fflush(fp))
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goto err;
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nlknown = 0;
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}
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p += w;
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len -= w;
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} while ((uio->uio_resid -= w) != 0);
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}
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return (0);
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err:
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fp->_flags |= __SERR;
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return (EOF);
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}
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