diff options
Diffstat (limited to 'src/Initialize.c')
| -rw-r--r-- | src/Initialize.c | 62 |
1 files changed, 61 insertions, 1 deletions
diff --git a/src/Initialize.c b/src/Initialize.c index c79ddc2..e590666 100644 --- a/src/Initialize.c +++ b/src/Initialize.c @@ -32,7 +32,7 @@ OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. ******************************************************************/ -/* $XFree86: xc/lib/Xt/Initialize.c,v 3.21 2003/04/21 16:34:27 herrb Exp $ */ +/* $XFree86: xc/lib/Xt/Initialize.c,v 3.22 2003/12/22 21:10:25 dickey Exp $ */ /* @@ -184,6 +184,66 @@ void _XtInherit() #define _XtInherit __XtInherit #endif + +#if defined(__CYGWIN__) +/* + * The Symbol _XtInherit is used in two different manners. + * First it could be used as a generic function and second + * as an absolute address reference, which will be used to + * check the initialisation process of several other libraries. + * Because of this the symbol must be accessable by all + * client dll's and applications. In unix environments + * this is no problem, because the used shared libraries + * format (elf) supports this immediatly. Under Windows + * this isn't true, because a functions address in a dll + * is different from the same function in another dll or + * applications, because the used Portable Executable + * File adds a code stub to each client to provide the + * exported symbol name. This stub uses an indirect + * pointer to get the original symbol address, which is + * then jumped to, like in this example: + * + * --- client --- --- dll ---- + * ... + * call foo + * + * foo: jmp (*_imp_foo) ----> foo: .... + * nop + * nop + * + * _imp_foo: .long <index of foo in dll export table, is + * set to the real address by the runtime linker> + * + * Now it is clear why the clients symbol foo isn't the same + * as in the dll and we can think about how to deal which + * this two above mentioned requirements, to export this + * symbol to all clients and to allow calling this symbol + * as a function. The solution I've used exports the + * symbol _XtInherit as data symbol, because global data + * symbols are exported to all clients. But how to deal + * with the second requirement, that this symbol should + * be used as function. The Trick is to build a little + * code stub in the data section in the exact manner as + * above explained. This is done with the assembler code + * below. + * + * Ralf Habacker + * + * References: + * msdn http://msdn.microsoft.com/msdnmag/issues/02/02/PE/PE.asp + * cygwin-xfree: http://www.cygwin.com/ml/cygwin-xfree/2003-10/msg00000.html + */ + +asm (".data\n\ + .globl __XtInherit \n\ + __XtInherit: jmp *_y \n\ + _y: .long ___XtInherit \n\ + .text \n"); + +#define _XtInherit __XtInherit +#endif + + void _XtInherit() { XtErrorMsg("invalidProcedure","inheritanceProc",XtCXtToolkitError, |