refactor: scatter mmap.rs contents to unix/windows modules

This is some duplication, but it once and for all eliminates all cfg
fuckery and code that expects precisely one module to be defined.

Admittedly, for windows/unix we could have stuck with the cfg stuff, but
I wanted a clean slate for now. The windows parts are compile-tested
only, as I do not have a windows system available.

The handling of various from_range functions is based on the assumption
that these were only used in test code and nowhere else (hence all the
preceding refactors of test code). In unit tests, their use has been
eliminated, and doc tests now got a cfg(target_family="unix",
not(feature="xen")) so that they only run when mmap_unix is available.
This is fine, because they are examples of how to use specific
functions, and not any serious tests (e.g. dont need to run for all
supported backends).

Signed-off-by: Patrick Roy <[email protected]>

Author: roypat

benches/guest_memory.rs

@@ -1,7 +1,7 @@
 // Copyright (C) 2020 Alibaba Cloud Computing. All rights reserved.
 //
 // SPDX-License-Identifier: Apache-2.0 OR BSD-3-Clause
-#![cfg(feature = "backend-mmap")]
+#![cfg(all(feature = "backend-mmap", not(feature = "xen")))]
 
 use core::hint::black_box;
 pub use criterion::Criterion;

benches/main.rs

@@ -5,7 +5,7 @@
 extern crate criterion;
 
 pub use criterion::{criterion_group, criterion_main, Criterion};
-#[cfg(feature = "backend-mmap")]
+#[cfg(all(feature = "backend-mmap", not(feature = "xen")))]
 use vm_memory::{GuestAddress, GuestMemoryMmap};
 
 mod guest_memory;
@@ -14,7 +14,7 @@ mod volatile;
 
 use volatile::benchmark_for_volatile;
 
-#[cfg(feature = "backend-mmap")]
+#[cfg(all(feature = "backend-mmap", not(feature = "xen")))]
 // Use this function with caution. It does not check against overflows
 // and `GuestMemoryMmap::from_ranges` errors.
 fn create_guest_memory_mmap(size: usize, count: u64) -> GuestMemoryMmap<()> {
@@ -27,12 +27,12 @@ fn create_guest_memory_mmap(size: usize, count: u64) -> GuestMemoryMmap<()> {
 }
 
 pub fn criterion_benchmark(_c: &mut Criterion) {
-    #[cfg(feature = "backend-mmap")]
+    #[cfg(all(feature = "backend-mmap", not(feature = "xen")))]
     mmap::benchmark_for_mmap(_c);
 }
 
 pub fn benchmark_guest_memory(_c: &mut Criterion) {
-    #[cfg(feature = "backend-mmap")]
+    #[cfg(all(feature = "backend-mmap", not(feature = "xen")))]
     guest_memory::benchmark_for_guest_memory(_c)
 }
 

benches/mmap/mod.rs

@@ -1,7 +1,7 @@
 // Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 //
 // SPDX-License-Identifier: Apache-2.0 OR BSD-3-Clause
-#![cfg(feature = "backend-mmap")]
+#![cfg(all(feature = "backend-mmap", not(feature = "xen")))]
 #![allow(clippy::undocumented_unsafe_blocks)]
 
 extern crate criterion;

src/bitmap/mod.rs

@@ -125,7 +125,7 @@ pub(crate) mod tests {
     use std::sync::atomic::Ordering;
 
     use crate::{Bytes, VolatileMemory};
-    #[cfg(feature = "backend-mmap")]
+    #[cfg(all(feature = "backend-mmap", target_family = "unix", not(feature = "xen")))]
     use crate::{GuestAddress, MemoryRegionAddress};
 
     // Helper method to check whether a specified range is clean.
@@ -219,7 +219,7 @@ pub(crate) mod tests {
     // them to test the mmap-based backend implementations for now. Going forward, the generic
     // test functions defined here can be placed in a separate module (i.e. `test_utilities`)
     // which is gated by a feature and can be used for testing purposes by other crates as well.
-    #[cfg(feature = "backend-mmap")]
+    #[cfg(all(feature = "backend-mmap", target_family = "unix", not(feature = "xen")))]
     fn test_guest_memory_region<R: GuestMemoryRegion>(region: &R) {
         let dirty_addr = MemoryRegionAddress(0x0);
         let val = 123u64;
@@ -253,7 +253,7 @@ pub(crate) mod tests {
         );
     }
 
-    #[cfg(feature = "backend-mmap")]
+    #[cfg(all(feature = "backend-mmap", target_family = "unix", not(feature = "xen")))]
     // Assumptions about M generated by f ...
     pub fn test_guest_memory_and_region<M, F>(f: F)
     where

src/bytes.rs

@@ -331,7 +331,7 @@ pub trait Bytes<A> {
     /// * Read bytes from /dev/urandom (uses the `backend-mmap` feature)
     ///
     /// ```
-    /// # #[cfg(all(feature = "backend-mmap", feature = "rawfd"))]
+    /// # #[cfg(all(feature = "backend-mmap", feature = "rawfd", target_family = "unix", not(feature = "xen")))]
     /// # {
     /// # use vm_memory::{Address, GuestMemory, Bytes, GuestAddress, GuestMemoryMmap};
     /// # use std::fs::File;

src/guest_memory.rs

@@ -176,7 +176,7 @@ impl FileOffset {
 /// # Examples (uses the `backend-mmap` and `backend-atomic` features)
 ///
 /// ```
-/// # #[cfg(feature = "backend-mmap")]
+/// # #[cfg(all(feature = "backend-mmap", target_family = "unix", not(feature = "xen")))]
 /// # {
 /// # use std::sync::Arc;
 /// # use vm_memory::{GuestAddress, GuestAddressSpace, GuestMemory, GuestMemoryMmap};
@@ -294,7 +294,7 @@ pub trait GuestMemory {
     ///   `backend-mmap` feature)
     ///
     /// ```
-    /// # #[cfg(feature = "backend-mmap")]
+    /// # #[cfg(all(feature = "backend-mmap", target_family = "unix", not(feature = "xen")))]
     /// # {
     /// # use vm_memory::{GuestAddress, GuestMemory, GuestMemoryRegion, GuestMemoryMmap};
     /// #
@@ -318,7 +318,7 @@ pub trait GuestMemory {
     /// # Examples (uses the `backend-mmap` feature)
     ///
     /// ```
-    /// # #[cfg(feature = "backend-mmap")]
+    /// # #[cfg(all(feature = "backend-mmap", target_family = "unix", not(feature = "xen")))]
     /// # {
     /// # use vm_memory::{Address, GuestAddress, GuestMemory, GuestMemoryMmap};
     /// #
@@ -433,7 +433,7 @@ pub trait GuestMemory {
     /// # Examples (uses the `backend-mmap` feature)
     ///
     /// ```
-    /// # #[cfg(feature = "backend-mmap")]
+    /// # #[cfg(all(feature = "backend-mmap", target_family = "unix", not(feature = "xen")))]
     /// # {
     /// # use vm_memory::{GuestAddress, GuestMemory, GuestMemoryMmap};
     /// #
@@ -592,7 +592,7 @@ impl<T: GuestMemory + ?Sized> Bytes<GuestAddress> for T {
     /// * Write a slice at guestaddress 0x1000. (uses the `backend-mmap` feature)
     ///
     /// ```
-    /// # #[cfg(feature = "backend-mmap")]
+    /// # #[cfg(all(feature = "backend-mmap", target_family = "unix", not(feature = "xen")))]
     /// # {
     /// # use vm_memory::{Bytes, GuestAddress, mmap::GuestMemoryMmap};
     /// #
@@ -620,7 +620,7 @@ impl<T: GuestMemory + ?Sized> Bytes<GuestAddress> for T {
     /// * Read a slice of length 16 at guestaddress 0x1000. (uses the `backend-mmap` feature)
     ///
     /// ```
-    /// # #[cfg(feature = "backend-mmap")]
+    /// # #[cfg(all(feature = "backend-mmap", target_family = "unix", not(feature = "xen")))]
     /// # {
     /// # use vm_memory::{Bytes, GuestAddress, mmap::GuestMemoryMmap};
     /// #

src/lib.rs

@@ -67,14 +67,22 @@ pub use io::{ReadVolatile, WriteVolatile};
 #[cfg(feature = "backend-mmap")]
 pub mod mmap;
 
-#[cfg(feature = "backend-mmap")]
-pub use mmap::{GuestMemoryMmap, GuestRegionMmap, MmapRegion};
 #[cfg(all(feature = "backend-mmap", feature = "xen", target_family = "unix"))]
 pub use mmap::{MmapRange, MmapXenFlags};
 
-#[cfg(all(feature = "xen", unix))]
+#[cfg(all(feature = "xen", target_family = "unix"))]
 pub use mmap::xen::{GuestMemoryXen, MmapRegion as MmapRegionXen};
 
+#[cfg(all(feature = "backend-mmap", target_family = "unix", not(feature = "xen")))]
+pub use mmap::unix::{Error as MmapRegionError, GuestMemoryMmap, GuestRegionMmap, MmapRegion};
+
+#[cfg(windows)]
+pub use crate::mmap::windows::{
+    GuestMemoryWindows as GuestMemoryMmap, GuestRegionWindows as GuestRegionMmap, MmapRegion,
+}; // rename for backwards compat
+#[cfg(windows)]
+pub use std::io::Error as MmapRegionError;
+
 pub mod volatile_memory;
 pub use volatile_memory::{
     Error as VolatileMemoryError, Result as VolatileMemoryResult, VolatileArrayRef, VolatileMemory,