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18 lines
925 B
Markdown
18 lines
925 B
Markdown
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# Relay
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Relay is a WSL2 linux process creating by a [session leader](session-leader.md). Its job is to create a linux process on behalf of the user, and relay its output back to Windows.
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## Creating a user process
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A relay is created when a `LxInitMessageCreateProcessUtilityVm` message is sent to a [session leader](session-leader.md). Once created, the `relay` creates multiple `hvsocket` channels with [wslservice.exe](wslservice.exe.md).
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These channels are used to:
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- Relay standard file descriptors (stdin, stdout, stderr)
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- Relay information about the terminal (for instance when the terminal window is resized from Windows)
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- Notify Windows when the linux process exits
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Once those channels are configured, the `relay` forks() into two processes:
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- The parent, which will read & write to the child's standard file descriptors and relay it to Windows
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- The child, which calls `exec()` and starts the user process
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