base: move descriptor traits and fns out of lib.rs

Common descriptor code can be moved into the appropriate descriptor.rs
and platform-specific files instead of living in the top-level base
lib.rs file.

BUG=None
TEST=tools/presubmit
TEST=kokoro ci

Change-Id: I07b8d822c40b563cffd12c7726a5c126bc1a0e10
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/3573363
Reviewed-by: Dennis Kempin <denniskempin@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Noah Gold <nkgold@google.com>
Commit-Queue: Daniel Verkamp <dverkamp@chromium.org>

base/src/descriptor.rs

@@ -1,3 +1,7 @@
+// Copyright 2022 The Chromium OS Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
 use crate::{PollToken, RawDescriptor};
 use serde::{Deserialize, Serialize};
 use std::{
@@ -24,6 +28,11 @@ pub trait AsRawDescriptor {
     fn as_raw_descriptor(&self) -> RawDescriptor;
 }
 
+/// A trait similar to `AsRawDescriptor` but supports an arbitrary number of descriptors.
+pub trait AsRawDescriptors {
+    fn as_raw_descriptors(&self) -> Vec<RawDescriptor>;
+}
+
 pub trait FromRawDescriptor {
     /// # Safety
     /// Safe only if the caller ensures nothing has access to the descriptor after passing it to
@@ -37,6 +46,15 @@ impl AsRawDescriptor for SafeDescriptor {
     }
 }
 
+impl<T> AsRawDescriptors for T
+where
+    T: AsRawDescriptor,
+{
+    fn as_raw_descriptors(&self) -> Vec<RawDescriptor> {
+        vec![self.as_raw_descriptor()]
+    }
+}
+
 impl IntoRawDescriptor for SafeDescriptor {
     fn into_raw_descriptor(self) -> RawDescriptor {
         let descriptor = self.descriptor;

base/src/lib.rs

@@ -57,27 +57,7 @@ cfg_if::cfg_if! {
 }
 
 pub use crate::descriptor::{
-    AsRawDescriptor, Descriptor, FromRawDescriptor, IntoRawDescriptor, SafeDescriptor,
+    AsRawDescriptor, AsRawDescriptors, Descriptor, FromRawDescriptor, IntoRawDescriptor,
+    SafeDescriptor,
 };
 pub use platform::*;
-
-/// Verifies that |raw_descriptor| is actually owned by this process and duplicates it
-/// to ensure that we have a unique handle to it.
-#[cfg(unix)]
-pub fn validate_raw_descriptor(raw_descriptor: RawDescriptor) -> Result<RawDescriptor> {
-    validate_raw_fd(raw_descriptor)
-}
-
-/// A trait similar to `AsRawDescriptor` but supports an arbitrary number of descriptors.
-pub trait AsRawDescriptors {
-    fn as_raw_descriptors(&self) -> Vec<RawDescriptor>;
-}
-
-impl<T> AsRawDescriptors for T
-where
-    T: AsRawDescriptor,
-{
-    fn as_raw_descriptors(&self) -> Vec<RawDescriptor> {
-        vec![self.as_raw_descriptor()]
-    }
-}

base/src/unix/mod.rs

@@ -484,6 +484,12 @@ impl Drop for UnlinkUnixListener {
     }
 }
 
+/// Verifies that |raw_descriptor| is actually owned by this process and duplicates it
+/// to ensure that we have a unique handle to it.
+pub fn validate_raw_descriptor(raw_descriptor: RawDescriptor) -> Result<RawDescriptor> {
+    validate_raw_fd(raw_descriptor)
+}
+
 /// Verifies that |raw_fd| is actually owned by this process and duplicates it to ensure that
 /// we have a unique handle to it.
 pub fn validate_raw_fd(raw_fd: RawFd) -> Result<RawFd> {