RFR: JDK-8145099 Better error message when SA can't attach to a process

[Staffan Larsen]

Hi Thomas, 

> On 10 dec. 2015, at 15:27, Thomas Stüfe <thomas.stuefe at gmail.com> wrote:
> 
> Hi Staffan,
> 
> thanks!
> 
> It also just occurred to me that strerror is not considered threadsafe. Maybe strerror_r() would a better option (depending on the version you use you would have to check the return value for NULL, though).

Updated here: http://cr.openjdk.java.net/~sla/JDK-8145099/webrev.03/ <http://cr.openjdk.java.net/~sla/JDK-8145099/webrev.03/>

Thanks,
/Staffan

> 
> sorry for this piecemeal review.
> 
> Kind Regards, Thomas
> 
> 
> 
> On Thu, Dec 10, 2015 at 3:22 PM, Staffan Larsen <staffan.larsen at oracle.com <mailto:staffan.larsen at oracle.com>> wrote:
> Hi Thommas,
> 
>> On 10 dec. 2015, at 14:49, Thomas Stüfe <thomas.stuefe at gmail.com <mailto:thomas.stuefe at gmail.com>> wrote:
>> 
>> Hi Stefan,
>> 
>> Disclaimer: not a "R"eviewer.
>> 
>> http://cr.openjdk.java.net/~sla/JDK-8145099/webrev.01/agent/src/os/linux/LinuxDebuggerLocal.c.udiff.html <http://cr.openjdk.java.net/~sla/JDK-8145099/webrev.01/agent/src/os/linux/LinuxDebuggerLocal.c.udiff.html>
>> 
>> I am not sure why you pass sizeof(err_buf) - 1 instead of sizeof(err_buf) to Pgrab and sizeof(msg) - 1 instead of sizeof(msg) to snprintf? snprintf will always zero terminate in case of truncation, at least on posix platforms.
> 
> Good point. I was just being overly cautious without thinking.
> 
> Updated webrev: http://cr.openjdk.java.net/~sla/JDK-8145099/webrev.02/ <http://cr.openjdk.java.net/~sla/JDK-8145099/webrev.02/>
> 
> Thanks,
> /Staffan
> 
>> 
>> Otherwise this looks good.
>> 
>> Kind Regards, Thomas
>> 
>> 
>> On Thu, Dec 10, 2015 at 2:19 PM, Staffan Larsen <staffan.larsen at oracle.com <mailto:staffan.larsen at oracle.com>> wrote:
>> Please review this patch to add a better error message to SA when it fails to attach to a process on linux. Currently the error says "Can't attach to the process”. After this change the message will look something like: "Can't attach to the process: ptrace(PTRACE_ATTACH, ..) failed for 28417: Operation not permitted”
>> 
>> webrev: http://cr.openjdk.java.net/~sla/JDK-8145099/webrev.01/ <http://cr.openjdk.java.net/~sla/JDK-8145099/webrev.01/>
>> bug: https://bugs.openjdk.java.net/browse/JDK-8145099 <https://bugs.openjdk.java.net/browse/JDK-8145099>
>> 
>> Thanks,
>> /Staffan
>> 
>> 
>> 
>> 
> 
> 

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