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Index > Windows > Idiomatic setup for win32 application

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drobole



Joined: 03 Nov 2010
Posts: 67
Location: Norway
drobole
After looking at WIN32AX.INC I got the impression that a idiomatic win32 application would look something like this:

Code:
format PE console 4.0

include 'WIN32AX.INC'

all_api

.data

    ; ...
       
.code

main:

    ; ...

.end main
    


Is this how its supposed to be done?
Also, what happened to
section '.reloc' fixups data readable discardable
I cant see that line being added by the macros, still it seems to work without it
Post 14 Nov 2010, 18:20
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f0dder



Joined: 19 Feb 2004
Posts: 3170
Location: Denmark
f0dder
drobole wrote:
Also, what happened to
section '.reloc' fixups data readable discardable
I cant see that line being added by the macros, still it seems to work without it
You don't really need relocs for win32 apps, since each process is given it's own virtual address space; if you stick with a sane load address, your app is guaranteed to load fine without relocs.

You might want to keep relocs, though, to take advantage of ASLR on newer windows versions.
Post 14 Nov 2010, 18:24
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drobole



Joined: 03 Nov 2010
Posts: 67
Location: Norway
drobole
f0dder wrote:
drobole wrote:
Also, what happened to
section '.reloc' fixups data readable discardable
I cant see that line being added by the macros, still it seems to work without it
You don't really need relocs for win32 apps, since each process is given it's own virtual address space; if you stick with a sane load address, your app is guaranteed to load fine without relocs.

You might want to keep relocs, though, to take advantage of ASLR on newer windows versions.


Is that to say that the process is guaranteed to reside entirely on a single virtual memory page (given a sane load address), so no relocation will be done either way?

edit:
After all that cleaning up of the framework it would be nice with a .reloc macro to get rid of that last section declaration. Not a big thing maybe, just seems intuitive
Post 14 Nov 2010, 18:29
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rugxulo



Joined: 09 Aug 2005
Posts: 2341
Location: Usono (aka, USA)
rugxulo
Relocs are (I think) a relic of the past. Not sure about Win16 proper, but at least Win32s ["subset" for Win16] required 'em. So almost no PE .EXEs nowadays include 'em.
Post 15 Nov 2010, 18:12
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f0dder



Joined: 19 Feb 2004
Posts: 3170
Location: Denmark
f0dder
rugxulo wrote:
Relocs are (I think) a relic of the past. Not sure about Win16 proper, but at least Win32s ["subset" for Win16] required 'em. So almost no PE .EXEs nowadays include 'em.
They're pretty much required for DLLs, and as I mentioned you need them for ASLR as well - so definitely not a thing of the past.

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Post 15 Nov 2010, 18:24
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baldr



Joined: 19 Mar 2008
Posts: 1651
baldr
PE is compiled (or linked) to be loaded at appropriate virtual address (IMAGE_OPTIONAL_HEADER.ImageBase). When it can't (for main .Exe this rarely wil be the case, yet one can produce 0-based PE), base relocations are needed to adjust image so it can be loaded at different base virtual address. Consider two DLLs with the same base being loaded into the same process' VAS: first will probably load fine, second should be relocated, as its base address is already occupied.
Post 15 Nov 2010, 19:05
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