Subtle differences in System.getenv() between Windows and Linux

[Roger Riggs]

Hi,

The code in both versions of ProcessEnvironment is mostly pre-2007
seem to have the same original author.

It is the typical inheritance vs delegation choice and likely driven by 
the details
of what was being stored and the OS specific details that need to be 
processed.
For example, Linux is case-sensitive vs Windows case-insensitive
and the handling needed to read the environment from the OS and
generate the environment for process launch.

$.02, Roger


On 3/9/21 7:15 AM, Galder Zamarreno wrote:
> Hi all,
>
> One of my colleagues discovered an intriguing difference between Linux and
> Windows, in the context of GraalVM native-image, when it comes to the
> returned value for System.getenv().
>
> On windows, the native test he's encountered that a test fails with:
>
>> Error: No instances of java.lang.ProcessEnvironment are allowed in the
> image heap as this class should be initialized at image runtime
>
> This does not happen on Linux.
>
> The reason it fails on Windows it's because on that env the System.getenv()
> method returns a ProcessEnvironment type, which happens to extend HashMap
> [1]. On linux though it returns a plain map [2].
>
> Any reason for this divergence? Is it due to historic reasons? I wondered
> whether the windows and linux version of this shouldn't be more akin.
>
> Galder
>
> [1]
> https://github.com/AdoptOpenJDK/openjdk-jdk11/blob/master/src/java.base/windows/classes/java/lang/ProcessEnvironment.java#L69
> [2]
> https://github.com/AdoptOpenJDK/openjdk-jdk11/blob/master/src/java.base/unix/classes/java/lang/ProcessEnvironment.java#L90