From 2131a614e52814942aa10a51c2f3da1fbf2f8dce Mon Sep 17 00:00:00 2001
From: Noah Gold <nkgold@google.com>
Date: Thu, 10 Nov 2022 13:30:26 -0800
Subject: [PATCH] protos: migrate to new build tool & cleanup.

As part of migrating to proto_build_tools, we've cleaned up some old
code that was unused:
* All of the ExternalProto tooling that was unused.
* The vsock proto doesn't exist.

BUG=b:256951877
TEST=builds

Change-Id: I647395b4900d487179139050ab6750a464b528e7
Reviewed-on: https://chromium-review.googlesource.com/c/crosvm/crosvm/+/4021592
Reviewed-by: Vikram Auradkar <auradkar@google.com>
Commit-Queue: Noah Gold <nkgold@google.com>
---
 Cargo.lock        |  2 +-
 protos/Cargo.toml |  2 +-
 protos/build.rs   | 90 ++++++-----------------------------------------
 3 files changed, 13 insertions(+), 81 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 50bbd87bd5..5ef602b024 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1603,8 +1603,8 @@ name = "protos"
 version = "0.1.0"
 dependencies = [
  "kvm_sys",
+ "proto_build_tools",
  "protobuf",
- "protoc-rust",
 ]
 
 [[package]]
diff --git a/protos/Cargo.toml b/protos/Cargo.toml
index 736d7555e8..494bb10db3 100644
--- a/protos/Cargo.toml
+++ b/protos/Cargo.toml
@@ -13,4 +13,4 @@ kvm_sys = { path = "../kvm_sys", optional = true }
 protobuf = "2.3"
 
 [build-dependencies]
-protoc-rust = "2.3"
+proto_build_tools = { path = "../proto_build_tools" }
diff --git a/protos/build.rs b/protos/build.rs
index a46e88785b..f75c76d78c 100644
--- a/protos/build.rs
+++ b/protos/build.rs
@@ -4,105 +4,37 @@
 
 use std::env;
 use std::error::Error;
-use std::fs;
-use std::fs::File;
-use std::io::Write;
-use std::path::Path;
 use std::path::PathBuf;
 
 type Result<T> = std::result::Result<T, Box<dyn Error>>;
 
-struct ExternalProto {
-    // Where to find protos during builds within cros_sdk. Relative to
-    // $SYSROOT environment variable set by emerge builds.
-    dir_relative_to_sysroot: &'static str,
-
-    // Where to find protos during "cargo build" in a local developer
-    // environment. Relative to the platform/crosvm/protos directory.
-    dir_relative_to_us: &'static str,
-
-    // *.proto file expected to exist in both of the above directories.
-    proto_file_name: &'static str,
-
-    // Code generated by proto compiler will be placed under
-    // protos::generated::$module_name.
-    module: &'static str,
-}
-
-// Rustfmt bug: https://github.com/rust-lang/rustfmt/issues/3498
-#[rustfmt::skip]
-static EXTERNAL_PROTOS: &[ExternalProto] = &[];
-
 struct LocalProto {
     // Corresponding to the input file src/$module.proto.
     module: &'static str,
 }
 
-#[rustfmt::skip]
 static LOCAL_PROTOS: &[LocalProto] = &[
     #[cfg(feature = "plugin")]
     LocalProto { module: "plugin" },
     #[cfg(feature = "composite-disk")]
-    LocalProto { module: "cdisk_spec" },
+    LocalProto {
+        module: "cdisk_spec",
+    },
 ];
 
 fn main() -> Result<()> {
-    let out_dir = env::var("OUT_DIR")?;
-    let sysroot = env::var_os("SYSROOT");
-
-    // Write out a Rust module that imports the modules generated by protoc.
-    let generated = PathBuf::from(&out_dir).join("generated.rs");
-    let out = File::create(generated)?;
-
-    // Compile external protos.
-    for proto in EXTERNAL_PROTOS {
-        let dir = match &sysroot {
-            Some(dir) => PathBuf::from(dir).join(proto.dir_relative_to_sysroot),
-            None => PathBuf::from(proto.dir_relative_to_us),
-        };
-        let input_path = dir.join(proto.proto_file_name);
-        protoc(proto.module, input_path, &out)?;
-    }
+    let out_dir = PathBuf::from(env::var("OUT_DIR")?);
 
     // Compile protos from the local src directory.
+    let mut proto_paths = Vec::new();
     for proto in LOCAL_PROTOS {
-        let input_path = format!("src/{}.proto", proto.module);
-        protoc(proto.module, input_path, &out)?;
+        proto_paths.push(
+            ["src", &format!("{}.proto", proto.module)]
+                .iter()
+                .collect::<PathBuf>(),
+        );
     }
-
-    Ok(())
-}
-
-// Compile a single proto file located at $input_path, placing the generated
-// code at $OUT_DIR/$module and emitting the right `pub mod $module` into the
-// output file.
-fn protoc<P: AsRef<Path>>(module: &str, input_path: P, mut out: &File) -> Result<()> {
-    let input_path = input_path.as_ref();
-    let input_dir = input_path.parent().unwrap();
-
-    // Place output in a subdirectory so that different protos with the same
-    // common filename (like interface.proto) do not conflict.
-    let out_dir = format!("{}/{}", env::var("OUT_DIR")?, module);
-    fs::create_dir_all(&out_dir)?;
-
-    // Invoke protobuf compiler.
-    protoc_rust::Codegen::new()
-        .input(input_path.as_os_str().to_str().unwrap())
-        .include(input_dir.as_os_str().to_str().unwrap())
-        .out_dir(&out_dir)
-        .run()
-        .expect("protoc");
-
-    // Write out a `mod` that refers to the generated module.
-    //
-    // The lint suppression is because protoc-rust emits
-    //   #![cfg_attr(feature = "cargo-clippy", allow(clippy))]
-    // which still works but is deprecated in favor of tool attributes:
-    //   #![allow(clippy::all)].
-    let file_stem = input_path.file_stem().unwrap().to_str().unwrap();
-    writeln!(out, "#[path = \"{}/{}.rs\"]", out_dir, file_stem)?;
-    writeln!(out, "#[allow(renamed_and_removed_lints)]")?;
-    writeln!(out, "pub mod {};", module)?;
+    proto_build_tools::build_protos(&out_dir, proto_paths.as_slice());
 
     Ok(())
 }