child_process: fix stdin close event when child closes fd 0#64626
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Fixes nodejs#25131 When a child process closes its stdin file descriptor (fd 0), the parent process should receive a 'close' event on the stdin socket. This was working in v8.11.4 but broke in PR nodejs#18701. The root cause: PR nodejs#18701 explicitly set `readable: true` when creating child stdio sockets, which prevented net.Socket from calling `read(0)`. Without `read(0)`, libuv doesn't listen for EOF/HUP events from the child closing fd 0, so the 'close' event is never emitted. Solution: For stdin specifically (index 0), create the socket without explicitly setting the `readable` option. This allows net.Socket to call `read(0)` in its constructor. After the socket is created, manually set `readable = false` and `writable = true` to maintain the correct semantic properties of stdin. For all other stdio sockets (stdout, stderr, and custom pipes), the original behavior is preserved. Reviewed-By: Mhayk Whandson <hi@mhayk.com>
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Fixes #25131
Problem
When a child process closes its stdin file descriptor (fd 0), the parent process should receive a 'close' event on the stdin socket. This was working in v8.11.4 but broke in PR #18701.
Root Cause
PR #18701 explicitly set
readable: truewhen creating child stdio sockets, which prevented net.Socket from callingread(0). Withoutread(0), libuv doesn't listen for EOF/HUP events from the child closing fd 0, so the 'close' event is never emitted.Solution
For stdin specifically (index 0), create the socket without explicitly setting the
readableoption. This allows net.Socket to callread(0)in its constructor. After socket creation, manually setreadable = falseandwritable = trueto maintain correct semantic properties.For all other stdio sockets (stdout, stderr, custom pipes), the original behavior is preserved.
Testing
test-child-process-stdin-close.jspasses ✅test-child-process-stdin.jspasses ✅