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a17de43ef1
Implements net.FileListener and net.FileConn for wasip1.
net.FileListener can be used with a pre-opened socket. If the WASM
module knows the file descriptor, a listener can be constructed with:
l, err := net.FileListener(os.NewFile(fd, ""))
If the WASM module does not know the file descriptor, but knows that at
least one of the preopens is a socket, it can find the file descriptor
and construct a listener like so:
func findListener() (net.Listener, error) {
// We start looking for pre-opened sockets at fd=3 because 0, 1,
// and 2 are reserved for stdio. Pre-opened directories also
// start at fd=3, so we skip fds that aren't sockets. Once we
// reach EBADF we know there are no more pre-opens.
for preopenFd := uintptr(3); ; preopenFd++ {
l, err := net.FileListener(os.NewFile(preopenFd, ""))
var se syscall.Errno
switch errors.As(err, &se); se {
case syscall.ENOTSOCK:
continue
case syscall.EBADF:
err = nil
}
return l, err
}
}
A similar strategy can be used with net.FileConn and pre-opened
connection sockets.
The wasmtime runtime supports pre-opening listener sockets:
$ wasmtime --tcplisten 127.0.0.1:8080 module.wasm
Change-Id: Iec6ae4ffa84b3753cce4f56a2817e150445db643
Reviewed-on: https://go-review.googlesource.com/c/go/+/493358
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Bypass: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Johan Brandhorst-Satzkorn <johan.brandhorst@gmail.com>
Auto-Submit: Johan Brandhorst-Satzkorn <johan.brandhorst@gmail.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>