[jira] Updated: (EXEC-30) Make environment variables respect casing rules of platforms

["Benjamin Bentmann (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/EXEC-30?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Benjamin Bentmann updated EXEC-30:
----------------------------------

    Attachment: EXEC-30.patch

> Make environment variables respect casing rules of platforms
> ------------------------------------------------------------
>
>                 Key: EXEC-30
>                 URL: https://issues.apache.org/jira/browse/EXEC-30
>             Project: Commons Exec
>          Issue Type: Improvement
>    Affects Versions: 1.0
>         Environment: Windows
>            Reporter: Benjamin Bentmann
>            Priority: Critical
>         Attachments: EXEC-30.patch
>
>
> Intro: Environment variables on Windows are case-insensitive (see [ExpandEnvironmentStrings|http://msdn.microsoft.com/en-us/library/ms724265(VS.85).aspx]). As a little experiment, run the following code snippet on Windows with Java 1.5
> {code:java}
> System.out.println(System.getenv("PATH"));
> System.out.println(System.getenv("path"));
> System.out.println(System.getenv("Path"));
> System.out.println(System.getenv().get("PATH"));
> System.out.println(System.getenv().get("path"));
> System.out.println(System.getenv().get("Path"));
> {code}
> which can for example output
> {noformat}
> <successfully resolved variable>
> <successfully resolved variable>
> <successfully resolved variable>
> null
> null
> <successfully resolved variable>{noformat}
> IMHO, this is an example of how an API should *not* be designed. The two overloads of {{System.getenv()}} look very similar but behave completely different. Even having this documented, this subtle peculiarity makes Java programming prone to errors that prevent platform-independence.
> Commons Exec is currently providing a case-sensitive view of the Windows shell environment. This makes it effectively impossible for client to code to reliably lookup an environment variable without performing further tweaks to the map returned from {{EnvironmentUtil}}. Furthermore, these tweaks would have to be performed only depending on the current OS, so the client code would need to consider platform details. I believe this violates the basic principle of platform-independence intended by Java.
> So here my suggestion: Have Commons Exec provide a case-preserving map that obeys the casing rules of the platform for key lookup. This way, the simple code line
> {code:java}
> EnvironmentUtils.getProcEnvironment().get("PATH")
> {code}
> will consistently return the specified variable on Windows and Unix.
> Just to mention it: An alternative approach might be to have the map always be case-sensitive but normalize variable names to upper-case on case-insensitive platforms.
> Regardless how this issue ends, the documentation for {{getProcEnvironment()}} should clearly state how it deals with casing.

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