move more tools for the client into subcrates

Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>

pbs-tools/src/tokio/mod.rs

@@ -0,0 +1,2 @@
+pub mod tokio_writer_adapter;
+pub use tokio_writer_adapter::TokioWriterAdapter;

pbs-tools/src/tokio/tokio_writer_adapter.rs

@@ -0,0 +1,26 @@
+use std::io::Write;
+
+use tokio::task::block_in_place;
+
+/// Wrapper around a writer which implements Write
+///
+/// wraps each write with a 'block_in_place' so that
+/// any (blocking) writer can be safely used in async context in a
+/// tokio runtime
+pub struct TokioWriterAdapter<W: Write>(W);
+
+impl<W: Write> TokioWriterAdapter<W> {
+    pub fn new(writer: W) -> Self {
+        Self(writer)
+    }
+}
+
+impl<W: Write> Write for TokioWriterAdapter<W> {
+    fn write(&mut self, buf: &[u8]) -> Result<usize, std::io::Error> {
+        block_in_place(|| self.0.write(buf))
+    }
+
+    fn flush(&mut self) -> Result<(), std::io::Error> {
+        block_in_place(|| self.0.flush())
+    }
+}