RFR: 8364816: GetLastError() in os_windows.cpp should not store value to errno [v5]

[David Holmes]

On Thu, 28 Aug 2025 09:19:48 GMT, Anton Artemov <duke at openjdk.org> wrote:

>> Hi, please consider the following changes:
>> 
>> In `os_windows.cpp` in a few places results returned by `GetLastError()` are stored to `errno`. However, `errno` has no relation to `GetLastError()`, and their ranges are not the same.
>> 
>> Results of `GetLastError()` should be stored into variables of type `DWORD`.
>> 
>> The removed section in `src/hotspot/share/cds/aotClassLocation.cpp` was relying on values returned by `GetLastError()` and stored to `errno` in `os::stat()`. Though the logic was correct, these values should not be stored to `errno`. The functionality is preserved by storing a **valid** value `ENOENT` to `errno` in `os::stat()`. 
>> 
>> Tested in tiers 1 - 3.
>
> Anton Artemov has updated the pull request incrementally with one additional commit since the last revision:
> 
>   8364816: Fixed _wopen case.

One more tweak sorry.

src/hotspot/os/windows/os_windows.cpp line 5034:

> 5032:   // if opening files failed, errno has been set to indicate the problem
> 5033:   if (fd == -1) {
> 5034:     log_debug(os)("os::open() failed to _wopen: errno->%ld.", errno);

Suggestion:

    log_debug(os)("os::open() failed to _wopen: errno->%s.", strerror(errno));

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PR Review: https://git.openjdk.org/jdk/pull/26901#pullrequestreview-3167459928
PR Review Comment: https://git.openjdk.org/jdk/pull/26901#discussion_r2309219515