226f69422a
This patch alters the behaviour of dll_list::topsort to preserve the order of dlopen'd units. The load order of unrelated DLLs is reversed every time fork is called, since dll_list::topsort finds the tail of the list and then unwinds to reinsert items. My change takes advantage of what should be undefined behaviour in dll_list::populate_deps (ndeps non-zero and ndeps and deps not initialised) to allow the deps field to be initialised prior to the call and appended to, rather than overwritten. All DLLs which have been dlopen'd have their deps list initialised with the list of all previously dlopen'd units. These extra dependencies mean that the unwind preserves the order of dlopen'd units. The motivation for this is the FlexDLL linker used in OCaml. The FlexDLL linker allows a dlopen'd unit to refer to symbols in previously dlopen'd units and it resolves these symbols in DllMain before anything else has initialised (including the Cygwin DLL). This means that dependencies may exist between dlopen'd units (which the OCaml runtime system understands) but which Windows is unaware of. During fork, the process-level table which FlexDLL uses to get the symbol table of each DLL is copied over but because the load order of dlopen'd DLLs is reversed, it is possible for FlexDLL to attempt to access memory in the DLL before it has been loaded and hence it fails with an access violation. Because the list is reversed on each call to fork, it means that a subsequent call to fork puts the DLLs back into the correct order, hence "even" invocations of fork work! An interesting side-effect is that this only occurs if the DLLs load at their preferred base address - if they have to be rebased, then FlexDLL works because at the time that the dependent unit is loaded out of order, there is still in memory the "dummy" DONT_RESOLVE_DLL_REFERENCES version of the dependency which, as it happens, will contain the correct symbol table in the data section. For my tests, this initially appeared to be an x86-only problem, but that was only because the two DLLs on x64 should have been rebased. Signed-off-by: David Allsopp <david.allsopp@metastack.com>
95 lines
3.9 KiB
Plaintext
95 lines
3.9 KiB
Plaintext
This file contains a list of individuals who submit their patches to
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the Cygwin sources under 2-clause BSD license, as well as a list of
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individuals who signed the former Cygwin Copyright Assignment up to 2016.
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=========================================================================
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2-clause BSD:
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=========================================================================
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Copyright (c) <YEAR>, <OWNER>
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All rights reserved.
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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 are
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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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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND 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 COPYRIGHT HOLDER OR CONTRIBUTORS BE
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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=========================================================================
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Individuals submitting their patches under 2-clause BSD:
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David Allsopp David.Allsopp@cl.cam.ac.uk
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Erik M. Bray erik.bray@lri.fr
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=========================================================================
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Individuals who signed the former Cygwin Copyright Assignment:
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AJ Reins tbisp@qwest.net
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Brian E. Dessent brian@dessent.net
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Brian Kenneth Ford Brian.Ford@FlightSafety.com
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Charles K. Moore keithmo@exmsft.com
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Christian Franke franke@computer.org
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Christian Lestrade christian.lestrade@free.fr
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Christopher Faylor me@cgf.cx
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Christopher January chris@atomice.net
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Conrad Scott conrad.scott@dsl.pipex.com
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Corinna Vinschen corinna@vinschen.de
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Craig Iain McGeachie slapdau@yahoo.com.au
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David Korn dave.korn.cygwin@gmail.com
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Davis Euresti davie@alum.mit.edu
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Dennis Vshivkov walrus@amur.ru
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Elfyn McBratney elfyn@ubertales.co.uk
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Eric Blake eblake@redhat.com
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Ernie Coskrey ernie.coskrey@steeleye.com
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Gerd Spalink Gerd.Spalink@t-online.de
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Hartmut Honisch hhonisch@users.sourceforge.net
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Igor Pechtchanski pechtcha@cs.nyu.edu
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Jacek Trzcinski jacek@certum.pl
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Jeffrey Eric Altman jaltman@openafs.org
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Jerry D. Hedden jerry@hedden.us
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Joe Loh joel@pivot3.com
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Johan Rydberg johan@rydberg.com
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Johannes Schindelin johannes.schindelin@gmx.de
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John Hood cgull@glup.org
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Jon Turney jon.turney@dronecode.org.uk
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Yoni Londner yonihola2@gmail.com
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Joseph H. Buehler jbuehler@hekimian.com
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Joshua Daniel Franklin joshuadfranklin@yahoo.com
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Ken Brown kbrown@cornell.edu
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Lapo Luchini lapo@lapo.it
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Lev Bishop lev.bishop@gmail.com
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Max Kaehn slothman@electric-cloud.com
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Micha Nelissen mdvpost@hotmail.com
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Michael Haubenwallner michael.haubenwallner@ssi-schaefer.com
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Nicholas S. Wourms nwourms@netscape.com
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Pavel Yonkov Tsekov ptsekov@gmx.net
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Peter Foley pefoley2@pefoley.com
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Pierre A. Humblet phumblet@phumblet.no-ip.org
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Robert G. Byrnes byrnes@curl.com
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Ryan C. Gordon icculus@icculus.org
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Sam Steingold sds@gnu.org
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Stephen Cleary shammah@spamcop.net
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Stephen Osborn bub@io.com
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Takashi Yano takashi.yano@nifty.ne.jp
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Thomas Pfaff tpfaff@gmx.net
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Vaclav Haisman vhaisman@gmail.com
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Yaakov Selkovitz yselkowi@redhat.com
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Yitzchak Scott-Thoennes sthoenna@efn.org
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