Re: new runtime pseudo-reloc in cygwin 1.3.18

[Alexander Gottwald <Alexander dot Gottwald at s1999 dot tu-chemnitz dot de>]

Alexander Gottwald wrote:

> So I don't even know where _XtInherit is called and whats different with the 
> relocation.

gdb revealed:

Dll1 (libXt) defines void _XtInherit(). Dll2 (libXaw) uses _XtInherit and 
passes it to a function in libXt which does 
if (x == _XtInherit) { foo() };

Unfortunatly it is not the same if _XtInherit is used in libXt or libXaw. 
the statement x = _XtInherit for example resulted in
x = 0xb38478 for libXt and
x = 0x641550 for libXaw. And thats why the if condition failed. 

A simple testcase is:

test.h:
typedef void (*f)(void);
extern f _foo(void);
extern void foo(void);
//#define foo _foo()
extern void test(void (*func)(void));
extern void run1(void);
extern void run2(void);

dll1.c:

#include "test.h"
#include <stdio.h>

#undef foo
f _foo(void) {
    return foo;
}

void foo(void) { 
    printf("Error\n"); 
}

void test(void (*func)(void)) {
    if (func != foo) 
        func();
    else
        printf("skipped\n");
}

void run1() {
    test(foo);
}

dll2.c:

#include "test.h"

void run2(void) {
    test(foo);
}

test.c:
#include "test.h"
#include <stdio.h>

int main(int argc, char ** argv) {
    printf("run1\n");
    run1();
    printf("run2\n");
    run2();
    return 0;
}

build (cygwin):
$ gcc -shared -out-implib=dll1.a -Wl,--enable-auto-import,--enable-runtime-pseudo-reloc -o dll1.dll dll1.c
$ gcc -shared -out-implib=dll2.a -Wl,--enable-auto-import,--enable-runtime-pseudo-reloc -o dll2.dll dll2.c dll1.a 
$ gcc test.c dll1.a dll2.a -o test.exe
$ ./test.exe
run1
skipped
run2
Error

build (linux):
$ gcc dll1.c -shared -o dll1.so
$ gcc dll2.c -shared -o dll2.so
$ gcc test.c dll1.so dll2.so -o test
$ LD_LIBRARY_PATH=. ./test
run1
skipped
run2
skipped

Enabling the define in test.h returns to the correct behaviour. I'll try 
tomorrow if I can change the XtInheritXXX defines to function calls and 
bypass these problems.

bye
    ago

NP: VNV Nation - Joy
-- 
 Alexander.Gottwald@informatik.tu-chemnitz.de 
 http://www.gotti.org           ICQ: 126018723