[Toybox] [landley/toybox] Segfault using toybox stat on Android emulator (#36)

[enh]

On Fri, Jul 22, 2016 at 12:42 AM, Rob Landley <rob at landley.net> wrote:
> On 07/21/2016 02:58 AM, Michael Eder wrote:
>> |toybox stat| is crashing on Android emulator running Android 5.1.1
>> (Lollipop)
>>
>> |root at generic:/data/local # ./toybox-armv6l stat script.sh File:
>> `script.sh' Size: 14722 Blocks: 32 IO Blocks: 4096 regular file Device:
>> 1f01h/7937d Inode: 14524 Links: 1 Access: (770/-rwxrwx---Segmentation
>> fault |
>
> Hmmm... Under qemu-system-arm I get:
>
> $ ./toybox stat toybox
>   File: `toybox'
>   Size: 297768   Blocks: 588     IO Blocks: 1024        regular file
> Device: 810h/2064d       Inode: 23       Links: 1
> Access: (555/-r-xr-xr-x)        Uid: (0/    root)       Gid: (0/    root)
> Access: 2016-07-22 06:43:49.980000000
> Modify: 2016-07-22 06:43:50.010000000
> Change: 2016-07-22 06:43:50.020000000
>
> I tried building current git from source, and "wget
> http://landley.net/toybox/bin/toybox-armv6l" and both behaved the same
> for me.
>
> Possibly qemu isn't complaining about an unaligned access correctly? (I
> thought it was...)
>
>> I tried with the latest release version from the toybox website
>> <http://landley.net/toybox/bin/> for arm-v6l as well as a version built
>> from latest git using your cross-compiler for armv6 from your homepage:
>>
>> |root at generic:/data/local # ./toybox stat toybox File: `toybox' Size:
>> 467296 Blocks: 920 IO Blocks: 4096 regular file Device: 1f01h/7937d
>> Inode: 14531 Links: 1 Access: (555/-r-xr-xr-xSegmentation fault |
>>
>> It seems that the emulator is running ARMv7l, but AFAIK it should be
>> compatible to ARMv6l binaries:
>
> Yeah, it should.
>
> You're running a binary statically built against uClibc with the old gcc
> 4.2 toolchain, so it's not a bionic thing nor a toolchain thing. You
> built current git so it's not version skew.
>
> What it really sounds like is the vanilla qemu I'm using and the android
> emulator you're using are doing something different? Or maybe a kernel
> .config issue? (I rebuilt qemu from current git to make sure it wasn't
> the oldish version i was using, and I still get the full unsegfaulted
> output.
>
> Now it's possible what's happening is that the next thing it tries to do
> is fetch the uid, and the android kernel code is behaving differently
> because of how they've set up user ID's.
>
> Or maybe it's a problem trying to display a uid that's not in
> /etc/passwd, which sadly I can't easily test here at the moment because
> I just noticed that "chown 123:123 toybox" is saying:
>
>   chown: user '123'
>
> Which is broken in a couple ways (there should be a ":errno message" on
> the end of that if it's an actual error, and numeric user IDs should
> work even if they're not in /etc/passwd) so I need to off and fix THAT
> before cycling back to this. :)
>
> If I can't reproduce this with a bit more fiddling here, I should
> download this android emulator and build environment. I'm guessing that
> would be from... Android NDK version 10c?

i'd assume they're using the current NDK r12b, and i'd definitely wait
until they tell you before you waste any more time. you'll also want
to know whether they were using GCC or clang.

there should be a tombstone in their log that they should send you.
https://source.android.com/devices/tech/debug/

>   https://developer.android.com/about/versions/android-5.0-changes.html
>   https://developer.android.com/ndk/downloads/revision_history.html
>
> (Sigh, is the NDK standalone with its own emulator or does it assume you
> have the SDK installed already? The NDK page assumes you already know
> this. Oh well, I can dig through it, lemme fix the chown thing first...)

no, there's no emulator in the NDK. there are (aiui) two in the SDK:
qemu and qemu2. that's about the limit of my emulator knowledge
though.

> Thanks,
>
> Rob
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-- 
Elliott Hughes - http://who/enh - http://jessies.org/~enh/
Android native code/tools questions? Mail me/drop by/add me as a reviewer.