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* cxx.cc (default_cygwin_cxx_malloc): Enhance commenting.

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* dll_init.cc (dll_dllcrt0_1): Likewise.
	* dlfcn.cc (dlopen): Prevent dlopen()'d DLL from installing any
	cxx malloc overrides.
	* include/cygwin/cygwin_dll.h (__dynamically_loaded): New variable.
	* lib/_cygwin_crt0_common.cc (_cygwin_crt0_common): Check it and only
	install cxx malloc overrides when statically loaded.  Extend comments.
This commit is contained in:
Corinna Vinschen
2009-08-13 07:35:50 +00:00
parent 61189f19de
commit ce5eb135a2
6 changed files with 70 additions and 8 deletions
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21
winsup/cygwin/dlfcn.cc
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@@ -93,7 +93,28 @@ dlopen (const char *name, int)
wchar_t *path = tp.w_get ();
pc.get_wide_win32_path (path);
/* Workaround for broken DLLs built against Cygwin versions 1.7.0-49
up to 1.7.0-57. They override the cxx_malloc pointer in their
DLL initialization code even if loaded dynamically. This is a
no-no since a later dlclose lets cxx_malloc point into nirvana.
The below kludge "fixes" that by reverting the original cxx_malloc
pointer after LoadLibrary. This implies that their overrides
won't be applied; that's OK. All overrides should be present at
final link time, as Windows doesn't allow undefined references;
it would actually be wrong for a dlopen'd DLL to opportunistically
override functions in a way that wasn't known then. We're not
going to try and reproduce the full ELF dynamic loader here! */
/* Store original cxx_malloc pointer. */
struct per_process_cxx_malloc *tmp_malloc;
tmp_malloc = __cygwin_user_data.cxx_malloc;
ret = (void *) LoadLibraryW (path);
/* Restore original cxx_malloc pointer. */
__cygwin_user_data.cxx_malloc = tmp_malloc;
if (ret == NULL)
__seterrno ();
}