A bug in filesystem bootstrap (unix/ linux) prevents

Xueming Shen xueming.shen at oracle.com
Thu Jul 5 07:52:59 UTC 2012

The code cited is a little shortcut, if there is locale over there is 
indeed using
utf-16, or any encoding that needs to switch/shift into ASCII (or its 
single byte
charset area) with a shift/in/out character.. So far I'm not aware of 
any such
a locale on any our supported platform. Historically, this kind of 
might run into trouble when being ported to other platform, such as ebcdic
based system (but I don't think it's a problem in this case). Ideally, 
the code
probably should be coded to be able to deal with a mb type of "/", but 
it was decided to take the short-cut for better performance here.

"We" have been taking the stand that file.encoding is an 
system property for a long time, mainly because of two reasons. First this
property is really defined/implemented/used as the default encoding that 
the jvm
uses to communicated with the underlying platform for local/encoding 
stuff, the default encoding of the file content, the encoding of the 
file path and
the "text" encoding when use the platform APIs, for example. It's like a 
between the jvm and the underlying platform, it needs to be understood 
by both
and agreed on by both. So it needs to be set based on what your 
underlying system
is using,  not something you want to set via either -D or 
System.setProperty. If
your underlying locale is not UTF-16, I don't think you should expect 
the jvm
could work correctly if it keeps "talking" in UTF-16 to the underlying 
for example, pass in a file name in utf-16, when your are running on a utf-8
locale (it is more complicated on a windows platform, when you have system
locale and user locale, and historically file.encoding was used for 
both, consider
if your system locale and user locale are set differently...).

The property sun.jnu.encoding introduced in jdk6 (this is mainly
to address the issue we have with file.encoding on windows platform though)
somehow helps remove some "pressure" from the file.encoding, so in theory
file.encoding should be used to only for the encoding of "file content", and
the sun.jnu.encoding should be used when you need the encoding to talk to
those  platform APIs, so something might be done here (currently 
and sun.jnu.encoding are set to the same thing on non-Windows platform).

The other reason is the timing of how the file.encoding is being 
initialized and
how it is being used during the "complicated" system initialization 
stage, almost
everyone touched System. initializeSystemClass() got burned here and there
in the past:-)  So sometime you want to ask if it is worth the risk to 
something work for a use scenario that is not "supported". That said, as
I said above,  something might be done  to address this issue, but obviously
not a priority for now.


if you want to do -Dfile.encoding=xyz, you
are on your own, it might work, it might not work.

On 7/4/2012 11:00 PM, Dawid Weiss wrote:
> Well, what's the "right" way to enforce an initial encoding for
> charset-less string-to-byte conversions and legacy streams? I still
> think that snippet of code is buggy, no matter if file.encoding is or
> isn't a supported settable property.
> Besides, from what I see in JDK code base everything seems to be code
> in a way to allow external definition of file.encoding (comments
> inside System.c for example). Where is it stated that file.encoding is
> read-only?
> Dawid
> On Thu, Jul 5, 2012 at 3:09 AM, Xueming Shen<xueming.shen at oracle.com>  wrote:
>> -Dfile.encoding=xyz is NOT a supported configuration. file.encoding is
>> supposed to be a read-only informative system property.
>> -Sherman
>> On 7/4/2012 1:21 PM, Dawid Weiss wrote:
>>>> There is a similar bug:
>>>> Bug 6795536 - No system start for file.encoding=x-SJIS_0213
>>> Yeah... I looked at the sources in that package and there is at least
>>> one more place which converts a String to bytes using getBytes(). This
>>> seems to be a trivial fix in UnixFileSystem though. Anyway, bug ID for
>>> this is:
>>> http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7181721
>>> Dawid
>>>> In this case on Windows.
>>>> -Ulf
>>>> Am 04.07.2012 14:43, schrieb Dawid Weiss:
>>>> Hi folks.
>>>> Run the following with -Dfile.encoding=UTF-16:
>>>> public class TestBlah {
>>>>     public static void main(String []) throws Exception {
>>>>       TimeZone.getDefault();
>>>>     }
>>>> }
>>>> This on linux (and any unixish system I think) will result in:
>>>> java.lang.ExceptionInInitializerError
>>>>          at java.nio.file.FileSystems.getDefault(FileSystems.java:176)
>>>>          at sun.util.calendar.ZoneInfoFile$1.run(ZoneInfoFile.java:482)
>>>>          at sun.util.calendar.ZoneInfoFile$1.run(ZoneInfoFile.java:477)
>>>> ...
>>>> There is an encoding-sensitive part calling getBytes on the initial
>>>> path (and this screws it up):
>>>>       // package-private
>>>>       UnixFileSystem(UnixFileSystemProvider provider, String dir) {
>>>>           this.provider = provider;
>>>>           this.defaultDirectory =
>>>> UnixPath.normalizeAndCheck(dir).getBytes();
>>>>           if (this.defaultDirectory[0] != '/') {
>>>>               throw new RuntimeException("default directory must be
>>>> absolute");
>>>>           }
>>>> Filed a bug for this but don't have the ID yet.
>>>> Dawid

More information about the core-libs-dev mailing list