6649594: Intermittent IOExceptions during dynamic attach on linux and solaris

[Alan Bateman]

Daniel D. Daugherty wrote:
> :
> src/os/linux/vm/attachListener_linux.cpp
>    The addition of UNIX_PATH_MAX means that the size of the buffer
>    on line 61: static char _path[PATH_MAX+1]
>    is now or can be potentially out of sync with the size of the
>    buffer on line 170 char path[UNIX_PATH_MAX]
>
>    If UNIX_PATH_MAX happens to be greater than PATH_MAX, and the
>    path to the socket is actually longer than PATH_MAX, then we'll
>    store a short path in the buffer on line 61.
>
>    Is there some reason not to use the new UNIX_PATH_MAX in both
>    locations?
Thanks Dan, I missed that one although it shouldn't cause a problem (as 
UNIX_PATH_MAX (108) will be less than PATH_MAX (usually 4096)).

>
> src/os/solaris/vm/attachListener_solaris.cpp
>    The return values from snprintf() aren't checked here for potential
>    overflow conditions. It seems to me that the Solaris logic could
>    benefit from the same sanity checks that you make in the Linux
>    version.
I didn't change or add this as it didn't seem likely that we would be 
started with java.io.tmpdir property set to a location that is close to 
the maximum path length. I suspect other things (like 
File.createTempFile) would also have problems if java.io.tmpdir were set 
this way. It is easily fixed to check for truncation, if you think it is 
important. The reason I added the check for truncation in the Linux 
implementation is because it's a path to a socket file.

>
> I would keep the warnings debug only. I see you have a debug only
> warning in the Solaris code, but no warning in the Linux code. Or
> were you talking about a different warning?
I was wondering if I should additional warnings into this code, and if 
so, if they should be in the product build. I know warning messages can 
cause products when intermingled with application output.

-Alan.