Re: [Vala] private extern class methods.

[Yu Feng <rainwoodman gmail com>]

The generated (problematic) ccode, declares a static prototype for an
extern symbol, which I believe is the cause of the problem. After
replacing the declaration with extern keyword, the library is no longer
a SE trouble maker.

The library was built with a DISABLE_STATIC libtool with
-Wl,--as-needed. I believe -fPIC are always automatically added when
real shared-libraries are built on applicable platforms.

I am totally confused with what was happening inside the linker world.
I had same issues when I forgot declaring the prototypes of extern
symbols in the source files for building shared libraries though.

Yu
On Mon, 2009-04-06 at 19:38 +0200, pancake wrote:
> The same bug should appear with Solaris and the Sun Studio (aka Forte 
> compiler)
>
> you should build everything with -fPIC, can you provide more information 
> about your
> build ? console output?
>
> SElinux doesnt allows symbol relocation because it can be dangerous (can 
> be used
> for in-memory patching using the linux loader) which is permitted, on 
> normal linux,
> but forbidden in selinux for obvious reasons.
>
> This also happens when you link a blob compiled without -fPIC against a 
> static library
> that isnot compiled with relocatable code (no -fPIC) the reason is taht 
> the non-relocatable
> code is compiled to live at a certain offset, and pic code generates 
> some stubs to know
> where is and how to reach all the data from their position (like 
> oldschool viruses did),
> you cannot mix pic-nonpic code in an application. well.. default linux 
> allows you to do this,
> but its a bit ugly workaround ;)
>
> Yu Feng wrote:
> > Dear list,
> >
> > I encountered a very hidden problem with private extern class methods,
> > which I would like to share with you.
> >
> > The scenario is like this. It compiles, links. everything seems fine
> > until the library is installed: the produced .so file will have a wrong
> > reloc symbol which doesn't work with SELinux!):
> >
> > A member function of a class is externally written in C.
> >
> > # Class.vala
> > public class Class {
> >     private extern static void func();
> > }
> > # Class-ccode.c
> > void class_func() {
> > // Do stuff
> > }
> >
> > The generated ccode:
> > # Class.c
> > ...
> > ...
> > static void func();
> > ...
> > ...
> >
> > This seems to be a bug in valac. 
> > The private extern method actually should be declared without the static
> > keyword but with an extern instead.
> >
> > Regards,
> >
> > Yu
> >
> > _______________________________________________
> > Vala-list mailing list
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> >
> >   
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