[jira] [Created] (MESOS-5880) Make `environment` semantics uniform across Windows and POSIX

["Alex Clemmer (JIRA)" <ji...@apache.org>]

Alex Clemmer created MESOS-5880:
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             Summary: Make `environment` semantics uniform across Windows and POSIX
                 Key: MESOS-5880
                 URL: https://issues.apache.org/jira/browse/MESOS-5880
             Project: Mesos
          Issue Type: Bug
          Components: stout
            Reporter: Alex Clemmer
            Assignee: Alex Clemmer


Preliminary investigation shows that our current Windows implementations of `os::environment`, `os::setenv`, and `os::getenv` fail to set flags in some cases. This leads to test failures on Windows in:

* `flags_tests.cpp` (MESOS-3437), namely `LoadFromEnvironment`
* `os_tests.cpp` (MESOS-3441), namely `Environment`

A preliminary investigation shows:

* These failures occur because the C standard API for environment variables are incompatible. That is, `os::environment` uses the C standard implementation of the `environ` macro, while `os::setenv` and `os::putenv` use the Win32 APIs for environment variables, like `GetEnvironmentVariable` and `SetEnvironmentVariable`. But, `SetEnvironmentVariable` does not affect the environment reported by `environ`, so updates are not reflected when we call `os::environ`.
* It is unlikely we will want to use the C equivalents of the `Get/SetEnvironmentVariable`, (that is, `setenv_s` and friends), because they have different behavior on Windows than on other libc implementations. Specifically, on Windows `setenv_s("yourvar", "")` unsets the variable `yourvar`, while on other implementations, it sets the value of `yourvar` to be the empty string.
* But, transitioning to a pure Win32 implementation (i.e., one using `Set/GetEnvironmentVariable`, `GetEnvironmentStrings`, etc.), probably requires changing or getting rid of `os::environment*` APIs. Specifically, `os::raw::environment` and `os::environmentp` will probably be eliminated.



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