RFR: 8049695: nsk/jdb/options/connect/connect003 fails with "Launched jdb could not attach to debuggee during 300000 milliseconds"

[Alex Menkov]

Hi David,

On 03/19/2018 18:10, David Holmes wrote:
> Hi Alex,
> 
> On 20/03/2018 10:28 AM, Alex Menkov wrote:
>> Hi guys,
>>
>> please re-review the fix.
> 
> I still have an unanswered question about where the max of 49 is 
> enforced. I see it for the "address" but not names in general. ??

for shmem the "channel name" is the address (it's checked in 
createTransport/openTransport).
Names for mutexes/events are generated by appending some strings to the 
adddress and length of the added parts are supposed to be less than 
MAX_IPC_SUFFIX (25 symbols):
".mutex" (+ up to 3 symbols)
".hasData" (+ up to 3 symbols)
".hasSpace" (+ up to 3 symbols)
".ctos"
".stoc"
".accept" (+ up to 3 symbols)
".attach" (+ up to 3 symbols)
".<pid>" (pid is a DWORD)

> 
>> Reg.test is added the the issue.
> 
> I don't quite follow the test. I see you try to set the name with a 
> value that is too long, and if that doesn't cause an overflow and we 
> don't crash that is good. But I'd expect you to read back the name and 
> check it matches the truncated name with 49 characters.

The test specifies the maximum length supported (49 symbols)
(if longer name is specified, "address strings longer than 50 characters 
are invalid" error reported).
As far as I see there is no way to read back the name used to create the 
transport.

--alex

> 
> Thanks,
> David
> 
>> webrev: 
>> http://cr.openjdk.java.net/~amenkov/shmem_long_name/webrev_open.04/
>>
>> --alex
>>
>> On 03/13/2018 16:14, Alex Menkov wrote:
>>> Hi all,
>>>
>>> Please review a small fix for
>>> https://bugs.openjdk.java.net/browse/JDK-8049695
>>> webrev: http://cr.openjdk.java.net/~amenkov/shmem_long_name/webrev_open/
>>>
>>> Root cause of the issue is jbd hungs as a result of the buffer overflow.
>>>
>>> In the beginning of the shmemBase.c:
>>>
>>> #define MAX_IPC_PREFIX 50   /* user-specified or generated name for */
>>>                              /* shared memory seg and prefix for 
>>> other IPC */
>>> #define MAX_IPC_SUFFIX 25   /* suffix to shmem name for other IPC 
>>> names */
>>> #define MAX_IPC_NAME   (MAX_IPC_PREFIX + MAX_IPC_SUFFIX)
>>>
>>> buffer (char prefix[]) in function createStream is used to generate 
>>> base name for mutex/events, so MAX_IPC_PREFIX is not big enough.
>>>
>>> --alex