Expose remaining Environment.* public surface area from System.Private.Corelib

[stephentoub]

Known issues to address subsequently (I'll open issues for them):

• Environment.WorkingSet returns 0 on Unix. We should put that in the PAL and provide a real implementation.
• Environment.SystemDirectory returns "/" on Unix. Not sure if there's a better answer.
• Environment.Is64BitOperatingSystem returns IntPtr.Size == 8 on Unix, which isn't necessarily correct. We should come up with a better solution, such as querying uname.
• Environment.GetFolderPath on both Windows and Unix is currently taking the code path written for Windows Phone, such that only SpecialFolder.System is implemented and everything else throws PlatformNotSupportedException.
• Environment.CommandLine on Unix appears to be returning only argv[0].
• Plus the relevant ref file needs to be updated in corefx and tests added there. My testing thus far was limited to a few calls to each method via reflection.

cc: @jkotas, @danmosemsft, @weshaggard

[jkotas]

We made simplifying assumption that OS architecture == Process architecture in System.Runtime.InteropServices.RuntimeInformation:

https://github.com/dotnet/corefx/blob/d0dc5fc099946adc1035b34a8b1f6042eddb0c75/src/Native/System.Native/pal_runtimeinformation.cpp#L37

The same simplifying assumption should apply here.

[stephentoub]

The same simplifying assumption should apply here

Meaning Is64BitProcess should always equal Is64BitOperatingSystem, both of which should be true iff BIT64 is set, and both of which should be true iff IntPtr.Size == 8?

[jkotas]

Correct - on Unix.

[danmoseley]

[weshaggard]

Any ideas what OSVersion returns for non-windows?

[mklement0]

@weshaggard: It breaks with error message OSVersion's call to GetVersionEx failed., because an attempt is made to call Windows API functions:

coreclr/src/mscorlib/src/System/Environment.cs

Line 398 in cdff8b0

internal static OperatingSystem OSVersion

[jkotas]

Environment.CommandLine on Unix appears to be returning only argv[0]

This will need to be synthetized from GetCommandLineArgs() to get the subset of the command line passed in by the CoreCLR host, even on Windows.

Mono has some code for it already: https://github.com/mono/mono/blob/master/mcs/class/corlib/System/Environment.cs#L128

[stephentoub]

I'm going to close this and put up a PR instead to add Environment to CoreFx. Then I'll submit PRs to add an EnvironmentAugments class to CoreCLR and CoreRT that can be used by that type.

[riQQ]

The EnvironmentAugments PR is in #6205.