117ade20e9
This is the backing feature to implement C++11 thread storage duration specified by the thread_local keyword. A destructor for given thread-local object is registered to be executed at the thread termination time using __cxa_thread_atexit(). Libc calls the __cxa_thread_calls_dtors() during exit(3), before finalizers and atexit functions, and libthr calls the function at the thread termination time, after the stack unwinding and thread-specific key destruction. There are several uncertainties in the API which lacks a formal specification. Among them: - is it allowed to register destructors during destructing; we allow, but limiting the nesting level. If too many iterations detected, a diagnostic is issued to stderr and thread forcibly terminates for now. - how to handle destructors which belong to an unloading dso; for now, we ignore destructor calls for such entries, and issue a diagnostic. Linux does prevent dso unload until all threads with destructors from the dso terminated. It is supposed that the diagnostics allow to detect real-world applications relying on the above details and possibly adjust our implementation. Right now the choices were to provide the slim API (but that rarely stands the practice test). Tests are added to check generic functionality and to specify some of the above implementation choices. Submitted by: Mahdi Mokhtari <mokhi64_gmail.com> Reviewed by: theraven Discussed with: dim (detection of -std=c++11 supoort for tests) Sponsored by: The FreeBSD Foundation (my involvement) MFC after: 2 weeks Differential revisions: https://reviews.freebsd.org/D7224, https://reviews.freebsd.org/D7427
77 lines
2.7 KiB
C
77 lines
2.7 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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* 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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#if defined(LIBC_SCCS) && !defined(lint)
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static char sccsid[] = "@(#)exit.c 8.1 (Berkeley) 6/4/93";
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#endif /* LIBC_SCCS and not lint */
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "namespace.h"
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#include <stdlib.h>
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#include <unistd.h>
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#include "un-namespace.h"
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#include "atexit.h"
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#include "libc_private.h"
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void (*__cleanup)(void);
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/*
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* This variable is zero until a process has created a thread.
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* It is used to avoid calling locking functions in libc when they
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* are not required. By default, libc is intended to be(come)
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* thread-safe, but without a (significant) penalty to non-threaded
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* processes.
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*/
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int __isthreaded = 0;
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/*
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* Exit, flushing stdio buffers if necessary.
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*/
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void
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exit(int status)
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{
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/* Ensure that the auto-initialization routine is linked in: */
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extern int _thread_autoinit_dummy_decl;
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_thread_autoinit_dummy_decl = 1;
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/*
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* We're dealing with cleaning up thread_local destructors in the case of
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* the process termination through main() exit.
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* Other cases are handled elsewhere.
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*/
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__cxa_thread_call_dtors();
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__cxa_finalize(NULL);
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if (__cleanup)
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(*__cleanup)();
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_exit(status);
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}
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