workspace: move crates under crates

crates/utils/src/pipe.rs

@@ -0,0 +1,32 @@
+use {
+    crate::oserror::{OsError, OsErrorExt},
+    uapi::{OwnedFd, c, pipe2},
+};
+
+pub struct Pipe<L, R> {
+    pub read: L,
+    pub write: R,
+}
+
+pub fn pipe() -> Result<Pipe<OwnedFd, OwnedFd>, OsError> {
+    let (read, write) = pipe2(c::O_CLOEXEC).to_os_error()?;
+    Ok(Pipe { read, write })
+}
+
+impl<L, R> Pipe<L, R> {
+    #[allow(dead_code)]
+    pub fn map_read<Lprime>(self, map: impl FnOnce(L) -> Lprime) -> Pipe<Lprime, R> {
+        Pipe {
+            read: map(self.read),
+            write: self.write,
+        }
+    }
+
+    #[allow(dead_code)]
+    pub fn map_write<Rprime>(self, map: impl FnOnce(R) -> Rprime) -> Pipe<L, Rprime> {
+        Pipe {
+            read: self.read,
+            write: map(self.write),
+        }
+    }
+}