Re: [Qemu-devel] [PATCH] makefile: detect corrupted elf files

[Stefan Weil]

Am 26.05.2013 14:31, schrieb Michael S. Tsirkin:
> On Sun, May 26, 2013 at 10:12:21AM +0100, Peter Maydell wrote:
>> On 26 May 2013 08:35, Michael S. Tsirkin <address@hidden> wrote:
>>> On Sat, May 25, 2013 at 05:32:24PM +0000, Blue Swirl wrote:
>>>> Another way to handle this would be to enhance GCC and linker to use
>>>> atomic operations when producing or combining object files. The tools
>>>> could also print a SHA of the object which the next user should
>>>> verify. Even better, the object files should include a robust checksum
>>>> to ensure integrity.
>>> I think we can make the makefile more robust. It can create a temporary
>>> file in same directory and rename when ready. This will prevent
>>> corrupted files from appearing in the first place.
>> I definitely think individual project makefiles are the wrong place
>> to fix this. If create-as-temp-and-rename is useful functionality
>> it needs to go in the compiler so that everybody benefits.
> This will not help users on existing systems.
> Also it's not just compiler. We'd have to do it in linker,
> asm, ... lots of work.
> You are wellcome to implement this in compiler/linker/etc if you like
> but we will still want to handle it in our makefile as well.
>
>> Or you
>> could write yourself a cc wrapper that did the renaming and use
>> configure's --cc= flag.
>>
>> thanks
>> -- PMM
> We also run lots of scripts in our makefiles. Would you like
> to also change each of them individually? Add wrapper scripts for e.g.
> python? What's the benefit as compared to just fixing it all in one
> place in the makefile?


GNU make automatically removes .o files which were built
because of a Makefile rule if that rule returns an error, so
OOM or compiler crashes should not result in corrupted .o
files. The same applies to other kinds of files built by
make.

If there are corrupted files, we have to look whether the
Makefile rules for those files are correct (or exist at all).

Are there other Open Source projects which try to detect
corrupted elf files? I know none.

Regards
Stefan W.