RFR: 8316468: os::write incorrectly handles partial write

[Man Cao]

On Tue, 19 Sep 2023 01:55:48 GMT, Man Cao <manc at openjdk.org> wrote:

> Hello,
> 
> Could anyone review this small but important fix?
> This bug was introduced in bddf48380e658df630fecad5eda40106a24b6e1c, and regressed the fix for https://bugs.openjdk.org/browse/JDK-8303937.
> 
> -Man

Thanks for the quick reviews!

> Ouch! Good catch. Obviously there is no regression test that could catch this. :(

Yeah, I'm attempting to write a gtest in test_os.cpp for `os::write()`. It seems difficult that I need to find a way to mock and create my own adversarial `pd_write()` that does partial write. I may create a separate RFE if I succeed writing this test.

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PR Comment: https://git.openjdk.org/jdk/pull/15808#issuecomment-1726396240