newlib/winsup
Corinna Vinschen 33297d810d Cygwin: dlfcn: Fix reference counting
The original dll_init code was living under the wrong assumption that
dll_dllcrt0_1 and in turn dll_list::alloc will be called for each
LoadLibrary call.  The same wrong assumption was made for
cygwin_detach_dll/dll_list::detach called via FreeLibrary.

In reality, dll_dllcrt0_1 gets only called once at first LoadLibrary
and cygwin_detach_dll once at last FreeLibrary.

In effect, reference counting for DLLs was completely broken after fork:

  parent:
    l1 = dlopen ("lib1");  // LoadLibrary, LoadCount = 1
    l2 = dlopen ("lib1");  // LoadLibrary, LoadCount = 2

    fork ();               // LoadLibrary in the child, LoadCount = 1!
      child:
        dlclose (l1);      // FreeLibrary actually frees the lib
        x = dlsym (l2);    // SEGV

* Move reference counting to dlopen/dlclose since only those functions
  have to keep track of loading/unloading DLLs in the application context.

* Remove broken accounting code from dll_list::alloc and dll_list::detach.

* Fix error handling in dlclose.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2017-03-21 14:31:03 +01:00
..
CVSChangeLogs.old winsup: Move all old CVS Changelogs into CVSChangeLogs.old dir 2016-03-19 13:59:52 +01:00
cygserver Switching the Cygwin DLL to LGPLv3+, dropping commercial buyout option 2016-06-23 10:09:17 +02:00
cygwin Cygwin: dlfcn: Fix reference counting 2017-03-21 14:31:03 +01:00
doc Belatedly bump Cygwin DLL version to 2.8.0 2017-03-10 20:50:35 +01:00
lsaauth Switching the Cygwin DLL to LGPLv3+, dropping commercial buyout option 2016-06-23 10:09:17 +02:00
testsuite Switching the Cygwin DLL to LGPLv3+, dropping commercial buyout option 2016-06-23 10:09:17 +02:00
utils Generate output with Unix line endings even from Mingw64 utils 2017-02-24 20:55:14 +01:00
CONTRIBUTORS Preserve order of dlopen'd modules in dll_list::topsort 2017-02-28 16:12:03 +01:00
COPYING * COPYING: Replace with the GPLv3 definition. 2011-04-19 16:52:51 +00:00
COPYING.LIB Switching the Cygwin DLL to LGPLv3+, dropping commercial buyout option 2016-06-23 10:09:17 +02:00
CYGWIN_LICENSE Clarify source file license in CYGWIN_LICENSE 2016-06-23 21:52:12 +02:00
Makefile.common Switching the Cygwin DLL to LGPLv3+, dropping commercial buyout option 2016-06-23 10:09:17 +02:00
Makefile.in Switching the Cygwin DLL to LGPLv3+, dropping commercial buyout option 2016-06-23 10:09:17 +02:00
README Fix typo and wrong URL in winsup/README 2016-05-24 10:25:18 +02:00
acinclude.m4 ChangeLog: 2012-11-23 13:22:47 +00:00
aclocal.m4 winsup/ChangeLog: 2013-11-07 00:19:52 +00:00
autogen.sh ChangeLog: 2012-11-23 13:22:47 +00:00
c++wrap ChangeLog: 2012-11-23 13:22:47 +00:00
ccwrap ccwrap: fix build with non-english locale set (v2) 2016-02-29 14:44:23 +01:00
config.guess ChangeLog: 2012-11-23 13:22:47 +00:00
config.sub ChangeLog: 2012-11-23 13:22:47 +00:00
configure Rename without-mingw-progs to with-cross-bootstrap 2016-04-04 16:39:41 +02:00
configure.ac Switching the Cygwin DLL to LGPLv3+, dropping commercial buyout option 2016-06-23 10:09:17 +02:00
configure.cygwin winsup/ChangeLog: 2013-11-07 00:19:52 +00:00
install-sh ChangeLog: 2012-11-23 13:22:47 +00:00

README

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WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.

Cygwin documentation is available on the net at https://cygwin.com
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