RFR: 8353440: Disable FTP fallback for non-local file URLs by default

[Daniel Fuchs]

On Wed, 23 Apr 2025 17:07:05 GMT, Eirik Bjørsnøs <eirbjo at openjdk.org> wrote:

>>> We have not really discussed a future removal of this feature in the context of this PR. This PR simply disables the feature by default.
>> 
>> Yes - sorry my bad. The disabling of this feature (and hopefully its removal in some future version of the JDK)
>> 
>>>If we want to remove it in the future, should we include text now to mention it may be removed in a future release? Or is that something to consider for a future release?
>> 
>> Good question. I believe disabling is a good first step, which will hopefully tell us whether anyone is actually using it.
>> We can decide later if/when we actually want to remove it.
>
>> Good question. I believe disabling is a good first step, which will hopefully tell us whether anyone is actually using it.
> 
> I'm curious what the feelback channel would be here? Do vendors collect metrics for use of system properties, directly or indirectly through support channels such that usage of a property like this may be gauged somehow?

@eirbjo something must be missing on windows. Two tests under `java/net/` are now failing on windows with the message: "Unsupported non-local file URL"

java/net/URL/OpenStream.java
java/net/URLConnection/UNCTest.java

Here is the stack trace for UNCTest.java for instance:


java.net.MalformedURLException: Unsupported non-local file URL
	at java.base/sun.net.www.protocol.file.FileURLConnection.requireFtpFallbackEnabled(FileURLConnection.java:242)
	at java.base/sun.net.www.protocol.file.Handler.openConnection(Handler.java:91)
	at java.base/sun.net.www.protocol.file.Handler.openConnection(Handler.java:61)
	at java.base/java.net.URL.openConnection(URL.java:1206)
	at UNCTest.main(UNCTest.java:38)


Are these tests just missing the new system property or is something more serious going on?

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PR Comment: https://git.openjdk.org/jdk/pull/24657#issuecomment-2825160827