Move os independent files under a new crate sys_util_core

sys_util_core won't have OS specific features so that sys_util and
win_sys_util can depend on it.

Test: Presubmit
Bug: b:213149154
Upstream-Crate: common/win_sys_util

Cq-Depend: chromium:3433709
Change-Id: I863f7a6bc7549944b4d114cca6d7be04c3093fc3
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/3426380
Reviewed-by: Dennis Kempin <denniskempin@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>

Cargo.toml

@@ -71,6 +71,7 @@ exclude = [
     "common/assertions",
     "common/audio_streams",
     "common/base",
+    "common/sys_util_core",
     "common/cros-fuzz",
     "common/cros_async",
     "common/cros_asyncv2",
@@ -172,6 +173,7 @@ base = "*"
 assertions = { path = "common/assertions" }
 audio_streams = { path = "common/audio_streams" }
 base = { path = "common/base" }
+sys_util_core = { path = "common/sys_util_core" }
 cros_async =  { path = "common/cros_async" }
 cros_fuzz = { path = "common/cros-fuzz" } # ignored by ebuild
 data_model = { path = "common/data_model" }

common/sys_util/Cargo.toml

@@ -6,9 +6,10 @@ edition = "2018"
 include = ["src/**/*", "Cargo.toml"]
 
 [dependencies]
+sys_util_core = { path = "../sys_util_core" } # provided by ebuild
 data_model = { path = "../data_model" } # provided by ebuild
 libc = "*"
-poll_token_derive = { version = "*", path = "poll_token_derive" }
+poll_token_derive = { path = "../sys_util_core/poll_token_derive" } # provided by ebuild
 remain = "0.2"
 thiserror = "*"
 serde = { version = "1", features = [ "derive" ] }

common/sys_util/src/lib.rs

@@ -4,7 +4,6 @@
 
 //! Small system utility modules for usage by other modules.
 
-mod alloc;
 #[cfg(target_os = "android")]
 mod android;
 #[cfg(target_os = "android")]
@@ -26,7 +25,6 @@ mod descriptor;
 mod descriptor_reflection;
 mod errno;
 mod eventfd;
-mod external_mapping;
 mod file_flags;
 pub mod file_traits;
 mod fork;
@@ -53,13 +51,11 @@ pub mod vsock;
 mod write_zeroes;
 
 pub use crate::acpi_event::*;
-pub use crate::alloc::LayoutAllocation;
 pub use crate::capabilities::drop_capabilities;
 pub use crate::clock::{Clock, FakeClock};
 pub use crate::descriptor::*;
 pub use crate::errno::{errno_result, Error, Result};
 pub use crate::eventfd::*;
-pub use crate::external_mapping::*;
 pub use crate::file_flags::*;
 pub use crate::fork::*;
 pub use crate::get_filesystem_type::*;
@@ -82,9 +78,8 @@ pub use descriptor_reflection::{
     SerializeDescriptors,
 };
 pub use poll_token_derive::*;
+pub use sys_util_core::*;
 
-pub use crate::external_mapping::Error as ExternalMappingError;
-pub use crate::external_mapping::Result as ExternalMappingResult;
 pub use crate::file_traits::{
     AsRawFds, FileAllocate, FileGetLen, FileReadWriteAtVolatile, FileReadWriteVolatile, FileSetLen,
     FileSync,

common/sys_util/src/mmap.rs

@@ -13,6 +13,7 @@ use std::ptr::{copy_nonoverlapping, null_mut, read_unaligned, write_unaligned};
 
 use libc::{self, c_int, c_void, read, write};
 use remain::sorted;
+use sys_util_core::ExternalMapping;
 
 use data_model::volatile_memory::*;
 use data_model::DataInit;
@@ -170,6 +171,17 @@ impl dyn MappedRegion {
     }
 }
 
+unsafe impl MappedRegion for ExternalMapping {
+    fn as_ptr(&self) -> *mut u8 {
+        self.as_ptr()
+    }
+
+    /// Returns the size of the memory region in bytes.
+    fn size(&self) -> usize {
+        self.size()
+    }
+}
+
 /// Wraps an anonymous shared memory mapping in the current process. Provides
 /// RAII semantics including munmap when no longer needed.
 #[derive(Debug)]

common/sys_util/src/netlink.rs

@@ -9,7 +9,9 @@ use std::os::unix::io::AsRawFd;
 use data_model::DataInit;
 use libc::EINVAL;
 
-use crate::{errno_result, Error, FromRawDescriptor, LayoutAllocation, Result, SafeDescriptor};
+use sys_util_core::LayoutAllocation;
+
+use crate::{errno_result, Error, FromRawDescriptor, Result, SafeDescriptor};
 
 // Custom nlmsghdr struct that can be declared DataInit.
 #[repr(C)]

common/sys_util_core/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = "sys_util_core"
+version = "0.1.0"
+authors = ["The Chromium OS Authors"]
+edition = "2018"
+include = ["src/**/*", "Cargo.toml"]
+
+[dependencies]
+libc = "*"
+remain = "0.2"
+thiserror = "*"
+
+[workspace]

common/sys_util_core/poll_token_derive/Cargo.toml

@@ -13,3 +13,5 @@ path = "poll_token_derive.rs"
 proc-macro2 = "^1"
 quote = "^1"
 syn = "^1"
+
+[workspace]

common/sys_util_core/src/external_mapping.rs

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-use crate::MappedRegion;
-
 use remain::sorted;
 use thiserror::Error;
 
@@ -70,16 +68,14 @@ impl ExternalMapping {
             unmap,
         })
     }
-}
 
-unsafe impl MappedRegion for ExternalMapping {
     /// used for passing this region to ioctls for setting guest memory.
-    fn as_ptr(&self) -> *mut u8 {
+    pub fn as_ptr(&self) -> *mut u8 {
         self.ptr as *mut u8
     }
 
     /// Returns the size of the memory region in bytes.
-    fn size(&self) -> usize {
+    pub fn size(&self) -> usize {
         self.size
     }
 }

common/sys_util_core/src/lib.rs

@@ -0,0 +1,22 @@
+// 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.
+
+//! Small system utility modules for usage by other higher level system
+//! utility modules like sys_util(on unix/linux) and win_sys_util(on windows).
+//!
+//! Crates other than sys_util and win_sys_util should not depend directly on
+//! sys_util_core.
+//!
+//! sys_util_core contains system utilities that are strictly platform/os
+//! independent. Platform dependent, conditionally compiled, code should
+//! not be added to sys_util_core.
+//!
+
+mod alloc;
+mod external_mapping;
+
+pub use crate::alloc::LayoutAllocation;
+pub use crate::external_mapping::Error as ExternalMappingError;
+pub use crate::external_mapping::Result as ExternalMappingResult;
+pub use crate::external_mapping::*;

tools/impl/test_config.py

@@ -32,6 +32,7 @@ class TestOption(enum.Enum):
 # Please add a bug number when restricting a tests.
 CRATE_OPTIONS: dict[str, list[TestOption]] = {
     "aarch64": [TestOption.BUILD_ARM_ONLY, TestOption.DO_NOT_BUILD_ARMHF], #b/210015864
+    "sys_util_core": [TestOption.SINGLE_THREADED],
     "crosvm_plugin": [TestOption.BUILD_X86_ONLY],
     "devices": [TestOption.SINGLE_THREADED, TestOption.DO_NOT_BUILD_ARMHF],
     "disk": [TestOption.RUN_X86_ONLY],  # b/202294155
@@ -49,9 +50,9 @@ CRATE_OPTIONS: dict[str, list[TestOption]] = {
     "x86_64": [TestOption.BUILD_X86_ONLY],
     "sys_util": [TestOption.SINGLE_THREADED],
     "rutabaga_gfx_ffi": [TestOption.DO_NOT_BUILD],  # b/206689789
-    "rutabaga_gfx": [TestOption.DO_NOT_BUILD_ARMHF], #b/210015864
-    "vm_control": [TestOption.DO_NOT_BUILD_ARMHF], #b/210015864
-    "libcrosvm_control": [TestOption.DO_NOT_BUILD_ARMHF], #b/210015864
+    "rutabaga_gfx": [TestOption.DO_NOT_BUILD_ARMHF],  # b/210015864
+    "vm_control": [TestOption.DO_NOT_BUILD_ARMHF],  # b/210015864
+    "libcrosvm_control": [TestOption.DO_NOT_BUILD_ARMHF],  # b/210015864
 }
 
 BUILD_FEATURES: dict[str, str] = {