On my system, this brings up the throughput from ~20 to ~600 MiB/s. Inspired by: https://www.reddit.com/r/unix/comments/6gxduc/how_is_gnu_yes_so_fast/ Reviewed by: cognet Approved by: cognet
86 lines
2.6 KiB
C
86 lines
2.6 KiB
C
/*
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* Copyright (c) 1987, 1993
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* The Regents of the University of California. All rights reserved.
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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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#ifndef lint
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static const char copyright[] =
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"@(#) Copyright (c) 1987, 1993\n\
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The Regents of the University of California. All rights reserved.\n";
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#endif /* not lint */
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#ifndef lint
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#if 0
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static char sccsid[] = "@(#)yes.c 8.1 (Berkeley) 6/6/93";
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#else
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static const char rcsid[] = "$FreeBSD$";
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#endif
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#endif /* not lint */
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#include <capsicum_helpers.h>
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#include <err.h>
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#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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int
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main(int argc, char **argv)
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{
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char buf[8192];
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char y[2] = { 'y', '\n' };
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char * exp = y;
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size_t buflen = 0;
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size_t explen = sizeof(y);
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if (caph_limit_stdio() < 0 || (cap_enter() < 0 && errno != ENOSYS))
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err(1, "capsicum");
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if (argc > 1)
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{
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exp = argv[1];
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explen = strlen(exp) + 1;
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exp[explen - 1] = '\n';
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}
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if (explen <= sizeof(buf))
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{
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while (buflen < sizeof(buf) - explen)
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{
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memcpy(buf + buflen, exp, explen);
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buflen += explen;
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}
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exp = buf;
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explen = buflen;
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}
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while (write(STDOUT_FILENO, exp, explen) > 0)
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;
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err(1, "stdout");
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/*NOTREACHED*/
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}
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