[LLVMdev] Android, llvm-ar and setLastModificationAndAccessTime

[Stephen Hines]

futimens() is available in Android KitKat. We work extensively with LLVM
and this allowed us to remove our ugly workaround for not having this
functionality.

Steve


On Mon, Nov 25, 2013 at 8:30 AM, James Lyon <jameslyon0 at gmail.com> wrote:

>  Hi,
>
> I've been trying to get LLVM working as a JIT compiler on Android for a
> while. It works now, except that the setLastModificationAndAccessTime
> function won't build because the Bionic C library lacks both futimes and
> futimens. There doesn't appear to be any "nice" workaround for this
> problem: the only ways I can think of to make
> setLastModificationAndAccessTime work are either to go by /proc/self/fd or
> invoke the system call directly (the second option isn't helped by the fact
> that the Android headers don't define the relevant system call number and
> it varies between platforms).
>
> Right now the only part of LLVM that uses this function is llvm-ar, so
> it's not as if lack of support for this function is a serious shortcoming.
> I don't really know the history of PathV1/PathV2 but I think the simplest
> solutions are:
>
>    1. Have setLastModificationAndAccessTime fail on platforms without
>    futimes/futimens (by ENOSYS). This is pretty ugly because having a function
>    which can never succeed seems likely to confuse users.
>    2. Only declare setLastModificationAndAccessTime if it is actually
>    available (add something to llvm-config.h to indicate this). The downside
>    here is that (in theory at least) users need to know that
>    setLastModificationAndAccessTime might be missing, although in practise
>    they can probably ignore the issue.
>
> (1) is trivial to implement and is what I'm doing now; I can also create a
> patch to do (2), I just thought I'd ask for opinions first.
>
> Regards,
>
> James
>
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