67 lines
2.3 KiB
C
67 lines
2.3 KiB
C
/*
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* Find out the size of kernel's sigset_t.
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*
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* Copyright (c) 2016-2017 Dmitry V. Levin <ldv@altlinux.org>
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* 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. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "tests.h"
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#include <signal.h>
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#include <unistd.h>
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#include <asm/unistd.h>
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/*
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* If the sigset size specified to rt_sigprocmask is not equal to the size
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* of kernel's sigset_t, the kernel does not look at anything else and fails
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* with EINVAL.
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*
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* Otherwise, if both pointers specified to rt_sigprocmask are NULL,
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* the kernel just returns 0.
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*
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* This vaguely documented kernel feature can be used to probe
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* the kernel and find out the size of kernel's sigset_t.
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*/
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unsigned int
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get_sigset_size(void)
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{
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static unsigned int set_size;
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if (!set_size) {
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static const unsigned int big_size = 1024 / 8;
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for (set_size = big_size; set_size; set_size >>= 1) {
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if (!syscall(__NR_rt_sigprocmask, SIG_SETMASK,
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NULL, NULL, set_size))
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break;
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}
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if (!set_size)
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perror_msg_and_fail("rt_sigprocmask");
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}
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return set_size;
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}
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