[Toybox] top -H segfault

[enh]

On Wed, May 25, 2016 at 1:59 PM, enh <enh at google.com> wrote:
> On Tue, May 24, 2016 at 2:23 PM, Rob Landley <rob at landley.net> wrote:
>> On 05/23/2016 07:59 PM, enh wrote:
>>> just running home, so no time to debug further, but in case you
>>> haven't seen this yet... plain "top -H" is segfaulting for me before
>>> displaying anything.
>>
>> Hmmm, no I hadn't seen that. But I do see that ./toybox top -H isn't
>> displaying anything when I do that...
>>
>> Ah. The active node logic changed and I missed updating a spot. (I
>> tested it, but nothing I tested used "collate". Oops. I need to work out
>> how to add this sort of stuff to the test suite. Probably have to use
>> archival snapshots of "ps" contents to get consistent reproducible test
>> output...)
>>
>>> Program received signal SIGSEGV, Segmentation fault.
>>>                                                     0x00000000004219c1
>>> in top_common (filter=filter at entry=0x41f738 <merge_deltas>) at
>>> toys/posix/ps.c:1349
>>> 1349      if (old.count && (!new.count || *otb->slot < *ntb->slot)) {
>>
>> Null dereference on *otb and *ntb because now you traverse the tree in
>> order and keep each node that has a non-null ->extra field.
>>
>> Try now?
>
> (sorry, was too busy to get back to this until now...)
>
> yes, works for me now, and i probably wouldn't have found that myself
> in a reasonable amount of time anyway!
>
> "toybox top -b -n 1 -o
> pid,tid,user,pr,ni,%cpu,s,vsz,rss,pcy,command,name -s 6" now looks
> close enough to what dumpstate wants for bug reports that i can give
> it a go...

actually, no, -o COMMAND isn't giving me what i thought. (previously
i'd only tested on the desktop.) on Android everything shows up as
/system/bin/app_process64 --- it's the first word of
readlink('/proc/pid/exe'). (when the zygote forks it sets argv[0] to
the package name of the app it's about to run, so you can see things
like "com.android.inputmethod.latin" here.)

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



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