Emulate non-blocking STDIN console on Windows
#14947
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HertzDevil
added
kind:feature
topic:stdlib:concurrency
platform:windows
…tdin-non-blocking
straight-shoota
approved these changes
Sep 4, 2024
straight-shoota
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Sep 16, 2024
The following should print the compiler help message to the file `foo.txt`:
```crystal
File.open("foo.txt", "w") do |f|
Process.exec("crystal", output: f)
end
```
It used to work on Windows in Crystal 1.12, but is now broken since 1.13. This is because `LibC._wexecvp` only inherits file descriptors in the C runtime, not arbitrary Win32 file handles; since we stopped calling `LibC._open_osfhandle`, the C runtime knows nothing about any reopened standard streams in Win32. Thus the above merely prints the help message to the standard output.
This PR creates the missing C file descriptors right before `LibC._wexecvp`. It also fixes a different regression of #14947 where reconfiguring `STDIN.blocking` always fails.
Co-authored-by: Johannes Müller <straightshoota@gmail.com>
straight-shoota
added a commit
that referenced
this pull request
Sep 17, 2024
The following should print the compiler help message to the file `foo.txt`:
```crystal
File.open("foo.txt", "w") do |f|
Process.exec("crystal", output: f)
end
```
It used to work on Windows in Crystal 1.12, but is now broken since 1.13. This is because `LibC._wexecvp` only inherits file descriptors in the C runtime, not arbitrary Win32 file handles; since we stopped calling `LibC._open_osfhandle`, the C runtime knows nothing about any reopened standard streams in Win32. Thus the above merely prints the help message to the standard output.
This PR creates the missing C file descriptors right before `LibC._wexecvp`. It also fixes a different regression of #14947 where reconfiguring `STDIN.blocking` always fails.
Co-authored-by: Johannes Müller <straightshoota@gmail.com>
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Resolves part of #14576.
Thread::ConditionVariableis now used again.There is no opt-out mechanism; while technically possible, there is probably no real benefit to it.