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When libvirt calls virInitialize it creates a thread local for the virErrorPtr storage, and registers a callback to cleanup memory when a thread exits. When libvirt is dlclose()d or otherwise made non-resident, the callback function is removed from memory, but the thread local may still exist and if a thread later exists, it will invoke the callback and SEGV. There may also be other thread locals with callbacks pointing to libvirt code, so it is in general never safe to unload libvirt.so from memory once initialized. To allow dlclose() to succeed, but keep libvirt.so resident in memory, link with '-z nodelete'. This issue was first found with the libvirt CIM provider, but can potentially hit many of the dynamic language bindings which all ultimately involve dlopen() in some way, either on libvirt.so itself, or on the glue code for the binding which in turns links to libvirt * configure.ac, src/Makefile.am: Ensure libvirt.so is linked with -z nodelete * cfg.mk, .gitignore, tests/Makefile.am, tests/shunloadhelper.c, tests/shunloadtest.c: A test case to unload libvirt while a thread is still running.
53 lines
1.5 KiB
C
53 lines
1.5 KiB
C
/*
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* Copyright (C) 2011 Red Hat, Inc.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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*/
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/*
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* This is a helper for shunloadtest.c. This function is built into
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* a shared library and linked with libvirto.so
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*
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* The function initializes libvirt and primes the thread local with
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* an error which needs to be freed at thread exit
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*/
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#include <config.h>
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#include "internal.h"
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#include <libvirt/libvirt.h>
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#include <libvirt/virterror.h>
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#include <stdlib.h>
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static void shunloadError(void *userData ATTRIBUTE_UNUSED,
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virErrorPtr error ATTRIBUTE_UNUSED)
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{
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}
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void shunloadStart(void);
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void shunloadStart(void) {
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virConnectPtr conn;
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virSetErrorFunc(NULL, shunloadError);
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virInitialize();
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conn = virConnectOpen("test:///default");
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virDomainDestroy(NULL);
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if (conn)
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virConnectClose(conn);
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}
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