[LLVMdev] Questions about llvm/Object/COFF.h

[Sean Silva]

If you haven't already found it, you should look inside
tools/llvm-objdump/llvm-objdump.cpp, which is an easy-to-follow example of
how these APIs work

--Sean Silva.

On Mon, Jun 11, 2012 at 5:41 PM, Marshall Clow <mclow.lists at gmail.com>wrote:

> So, I'm trying to use this file to look inside COFF files.
> Got the header. OK.
>
> Now I want to look at the sections.
> Look, there's a section iterator. I can use that!
>
> So, I write:
>        for (llvm::object::section_iterator iter = Obj.begin_sections ();
> iter != Obj.end_sections(); ++iter )
>
> and it doesn't compile. There's no ++ for section iterators.
> Apparently, you're supposed to write.
>        for (llvm::object::section_iterator iter = Obj.begin_sections ();
> iter != Obj.end_sections(); iter.increment(ec))
> Srsly?
> [ And - how do I go from a section_iterator to a coff_section ? ]
>
> While I'm puzzling over that, I look some more, and I see:
>        error_code getSection(int32_t index, const coff_section *&Res)
> const;
>
> Cool. (A bit weird; why a signed index?, but whatever)
> So I write:
>        const llvm::object::coff_section *sect;
>        for (std::size_t i = 0; i < NumSections; ++i)
>                Obj.getSection(i, sect);
>
> And my program dies with a segmentation fault.
> Turns out that sect == NULL.
> More looking, I see that the sections are numbered 1 … N, not 0 ... N-1
>
> Now I'm really really confused.  Why?
>
> BTW - patch attached to add pre-increment to llvm::content_iterator (which
> is the template base for section_iterator, etc)
>
> -- Marshall
>
>
>
>
>
> -- Marshall
>
> Marshall Clow     Idio Software   <mailto:mclow.lists at gmail.com>
>
> A.D. 1517: Martin Luther nails his 95 Theses to the church door and is
> promptly moderated down to (-1, Flamebait).
>        -- Yu Suzuki
>
>
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