newlib/winsup/cygwin/lib/atexit.c

48 lines
1.9 KiB
C

/* atexit.c: atexit entry point
This file is part of Cygwin.
This software is a copyrighted work licensed under the terms of the
Cygwin license. Please consult the file "CYGWIN_LICENSE" for
details. */
#include <stddef.h>
#include <sys/cygwin.h>
#include <windows.h>
/* Statically linked replacement for the former cygwin_atexit. We need
the function here to be able to access the correct __dso_handle of the
caller's DSO. */
int
atexit (void (*fn) (void))
{
extern int __cxa_atexit(void (*)(void*), void*, void*);
extern void *__dso_handle;
extern void *__ImageBase;
void *fixed_dso_handle = &__dso_handle;
/* Check for being called from inside the executable. If so, use NULL
as __dso_handle. This allows to link executables with GCC versions
not providing __dso_handle in crtbegin{S}.o. In this case our own
__dso_handle defined in lib/dso_handle.c is used. However, our
__dso_handle always points to &__ImageBase, while the __dso_handle
for executables provided by crtbegin.o usually points to NULL.
That's what we remodel here. */
if (&__ImageBase == (void **) GetModuleHandleW (NULL))
fixed_dso_handle = NULL;
/* With recent Cygwin versions starting with API version 0.280 we call
__cxa_atexit (which is actually the cygwin__cxa_atexit wrapper in
dcrt0.cc) with the address of __dso_handle since that's how g++ generates
calls to __cxa_atexit as well. However, when running an application
built with this atexit under an older Cygwin version, the __cxa_atexit
entry point is the one from newlib, which expects the *value* of
__dso_handle. So, check for the Cygwin version we're running under.
Older version prior to 0.280 don't know CW_FIXED_ATEXIT and return -1.
0.280 and later return 0. */
else if (cygwin_internal (CW_FIXED_ATEXIT) != 0)
fixed_dso_handle = __dso_handle;
return __cxa_atexit ((void (*)(void*))fn, NULL, fixed_dso_handle);
}