95 lines
2.7 KiB
C
95 lines
2.7 KiB
C
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/*-
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* Copyright 1999 John D. Polstra.
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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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*
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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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* $FreeBSD$
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*/
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/*
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* Default thread locking implementation for the dynamic linker. It
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* is used until the client registers a different implementation with
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* dllockinit(). The default implementation does mutual exclusion
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* by blocking the SIGVTALRM, SIGPROF, and SIGALRM signals. This is
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* based on the observation that most userland thread packages use one
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* of these signals to support preemption.
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*/
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#include <dlfcn.h>
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#include <signal.h>
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#include <stdlib.h>
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#include "debug.h"
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#include "rtld.h"
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typedef struct Struct_LockDflt {
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sigset_t lock_mask;
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sigset_t old_mask;
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int depth;
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} LockDflt;
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void
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lockdflt_acquire(void *lock)
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{
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LockDflt *l = (LockDflt *)lock;
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sigprocmask(SIG_BLOCK, &l->lock_mask, &l->old_mask);
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assert(l->depth == 0);
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l->depth++;
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}
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void *
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lockdflt_create(void *context)
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{
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LockDflt *l;
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l = NEW(LockDflt);
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l->depth = 0;
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sigemptyset(&l->lock_mask);
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sigaddset(&l->lock_mask, SIGVTALRM);
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sigaddset(&l->lock_mask, SIGPROF);
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sigaddset(&l->lock_mask, SIGALRM);
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return l;
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}
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void
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lockdflt_destroy(void *lock)
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{
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LockDflt *l = (LockDflt *)lock;
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free(l);
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}
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void
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lockdflt_release(void *lock)
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{
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LockDflt *l = (LockDflt *)lock;
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assert(l->depth == 1);
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l->depth--;
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sigprocmask(SIG_SETMASK, &l->old_mask, NULL);
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}
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void
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lockdflt_init(void)
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{
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dllockinit(NULL, lockdflt_create, lockdflt_acquire, lockdflt_acquire,
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lockdflt_release, lockdflt_destroy, NULL);
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}
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