Merge branch 'wgrs-constant-rebuild'

wireguard-go-rs/Cargo.toml

@@ -4,13 +4,16 @@ description = "Rust bindings to wireguard-go with DAITA support"
 edition = "2021"
 license.workspace = true
 
+[build-dependencies]
+anyhow = "1.0"
+
 [target.'cfg(unix)'.dependencies]
 thiserror.workspace = true
 log.workspace = true
 zeroize = "1.8.1"
 
 [target.'cfg(any(target_os = "linux", target_os = "macos"))'.dependencies]
-# The app does not depend on maybenot-ffi itself, but adds it as a dependency to expose FFI symbols to wireguard-go. 
+# The app does not depend on maybenot-ffi itself, but adds it as a dependency to expose FFI symbols to wireguard-go.
 # This is done, instead of using the makefile in wireguard-go to build maybenot-ffi into its archive, to prevent
 # name clashes induced by link-time optimization.
 # NOTE: the version of maybenot-ffi below must be the same as the version checked into the wireguard-go submodule

wireguard-go-rs/build.rs

@@ -1,68 +1,194 @@
-use core::{panic, str};
-use std::{env, path::PathBuf};
+use std::{borrow::BorrowMut, env, path::PathBuf, process::Command, str};
 
-fn main() {
-    let out_dir = env::var("OUT_DIR").expect("Missing OUT_DIR");
+use anyhow::{anyhow, bail, Context};
 
-    // Add DAITA as a conditional configuration
+fn main() -> anyhow::Result<()> {
+    let target_os = env::var("CARGO_CFG_TARGET_OS").context("Missing 'CARGO_CFG_TARGET_OS")?;
+
+    // Mark "daita" as a conditional configuration flag
     println!("cargo::rustc-check-cfg=cfg(daita)");
 
-    let target_os = env::var("CARGO_CFG_TARGET_OS").expect("Missing 'CARGO_CFG_TARGET_OS");
-    let mut cmd = std::process::Command::new("bash");
-    cmd.arg("./build-wireguard-go.sh");
+    // Rerun build-script if libwg (or wireguard-go) is changed
+    println!("cargo::rerun-if-changed=libwg");
 
     match target_os.as_str() {
-        "linux" | "macos" => {
-            // Enable DAITA
-            println!(r#"cargo::rustc-cfg=daita"#);
-            // Tell the build script to build wireguard-go with DAITA support
-            cmd.arg("--daita");
-        }
-        "android" => {
-            cmd.arg("--android");
-        }
+        "linux" => build_static_lib(Os::Linux, true)?,
+        "macos" => build_static_lib(Os::MacOs, true)?,
+        "android" => build_android_dynamic_lib()?,
         // building wireguard-go-rs for windows is not implemented
-        _ => return,
+        _ => {}
     }
 
-    let output = cmd.output().expect("build-wireguard-go.sh failed");
-    if !output.status.success() {
-        let stdout = str::from_utf8(&output.stdout).unwrap();
-        let stderr = str::from_utf8(&output.stderr).unwrap();
-        eprintln!("build-wireguard-go.sh failed.");
-        eprintln!("stdout:\n{stdout}");
-        eprintln!("stderr:\n{stderr}");
-        panic!();
+    Ok(())
+}
+
+#[derive(PartialEq, Eq)]
+enum Os {
+    MacOs,
+    Linux,
+}
+
+#[derive(PartialEq, Eq)]
+enum Arch {
+    Amd64,
+    Arm64,
+}
+
+fn host_os() -> anyhow::Result<Os> {
+    // this ugliness is a limitation of rust, where we can't directly
+    // access the target triple of the build script.
+    if cfg!(target_os = "linux") {
+        Ok(Os::Linux)
+    } else if cfg!(target_os = "macos") {
+        Ok(Os::MacOs)
+    } else {
+        bail!("Unsupported host OS")
     }
+}
 
-    if target_os.as_str() != "android" {
-        println!("cargo::rustc-link-lib=static=wg");
+fn host_arch() -> anyhow::Result<Arch> {
+    if cfg!(target_arch = "x86_64") {
+        Ok(Arch::Amd64)
+    } else if cfg!(target_arch = "aarch64") {
+        Ok(Arch::Arm64)
     } else {
-        // NOTE: Link dynamically to libwg on Android, as go cannot produce archives
-        println!("cargo::rustc-link-lib=dylib=wg");
+        bail!("Unsupported host architecture")
     }
-    declare_libs_dir("../build/lib");
+}
 
-    println!("cargo::rerun-if-changed=libwg");
+/// Compile libwg as a static library and place it in `OUT_DIR`.
+fn build_static_lib(target_os: Os, daita: bool) -> anyhow::Result<()> {
+    let out_dir = env::var("OUT_DIR").context("Missing OUT_DIR")?;
+    let target_arch =
+        env::var("CARGO_CFG_TARGET_ARCH").context("Missing 'CARGO_CFG_TARGET_ARCH")?;
+
+    let target_arch = match target_arch.as_str() {
+        "x86_64" => Arch::Amd64,
+        "aarch64" => Arch::Arm64,
+        _ => bail!("Unsupported architecture: {target_arch}"),
+    };
+
+    let out_file = format!("{out_dir}/libwg.a");
+    let mut go_build = Command::new("go");
+    go_build
+        .args(["build", "-v", "-o", &out_file])
+        .args(["-buildmode", "c-archive"])
+        .args(if daita { &["--tags", "daita"][..] } else { &[] })
+        .env("CGO_ENABLED", "1")
+        .current_dir("./libwg");
+
+    // are we cross compiling?
+    let cross_compiling = host_os()? != target_os || host_arch()? != target_arch;
+
+    match target_arch {
+        Arch::Amd64 => go_build.env("GOARCH", "amd64"),
+        Arch::Arm64 => go_build.env("GOARCH", "arm64"),
+    };
+
+    match target_os {
+        Os::Linux => {
+            go_build.env("GOOS", "linux");
+
+            if cross_compiling {
+                match target_arch {
+                    Arch::Arm64 => go_build.env("CC", "aarch64-linux-gnu-gcc"),
+                    Arch::Amd64 => bail!("cross-compiling to linux x86_64 is not implemented"),
+                };
+            }
+        }
+        Os::MacOs => {
+            go_build.env("GOOS", "darwin");
 
-    // Add `OUT_DIR` to the library search path to facilitate linking of libwg for debug artifacts,
-    // such as test binaries.
-    if cfg!(debug_assertions) {
-        println!("cargo::rustc-link-search={out_dir}");
+            if cross_compiling {
+                let sdkroot = env::var("SDKROOT").context("Missing 'SDKROOT'")?;
+
+                let c_arch = match target_arch {
+                    Arch::Amd64 => "x86_64",
+                    Arch::Arm64 => "arm64",
+                };
+
+                let xcrun_output =
+                    exec(Command::new("xcrun").args(["-sdk", &sdkroot, "--find", "clang"]))?;
+                go_build.env("CC", xcrun_output);
+
+                let cflags = format!("-isysroot {sdkroot} -arch {c_arch} -I{sdkroot}/usr/include");
+                go_build.env("CFLAGS", cflags);
+                go_build.env("CGO_CFLAGS", format!("-isysroot {sdkroot} -arch {c_arch}"));
+                go_build.env("CGO_LDFLAGS", format!("-isysroot {sdkroot} -arch {c_arch}"));
+                go_build.env("LD_LIBRARY_PATH", format!("{sdkroot}/usr/lib"));
+            }
+        }
     }
+
+    exec(go_build)?;
+
+    // make sure to link to the resulting binary
+    println!("cargo::rustc-link-search={out_dir}");
+    println!("cargo::rustc-link-lib=static=wg");
+
+    // if daita is enabled, also enable the corresponding rust feature flag
+    if daita {
+        println!(r#"cargo::rustc-cfg=daita"#);
+    }
+
+    Ok(())
 }
 
-/// Tell linker to check `base`/$TARGET for shared libraries.
-fn declare_libs_dir(base: &str) {
-    let target_triplet = env::var("TARGET").expect("TARGET is not set");
-    let lib_dir = manifest_dir().join(base).join(target_triplet);
-    println!("cargo::rerun-if-changed={}", lib_dir.display());
+/// Compile libwg as a dynamic library for android and place it in `../build/lib/$TARGET`.
+// NOTE: We use dynamic linking as Go cannot produce static binaries specifically for Android.
+fn build_android_dynamic_lib() -> anyhow::Result<()> {
+    let target_triplet = env::var("TARGET").context("TARGET is not set")?;
+
+    exec(Command::new("./libwg/build-android.sh"))?;
+
+    // Tell linker to check `base`/$TARGET for the dynamic library.
+    let lib_dir = manifest_dir()?.join("../build/lib").join(target_triplet);
     println!("cargo::rustc-link-search={}", lib_dir.display());
+    println!("cargo::rustc-link-lib=dylib=wg");
+
+    Ok(())
 }
 
 /// Get the directory containing `Cargo.toml`
-fn manifest_dir() -> PathBuf {
+fn manifest_dir() -> anyhow::Result<PathBuf> {
     env::var("CARGO_MANIFEST_DIR")
         .map(PathBuf::from)
-        .expect("CARGO_MANIFEST_DIR env var not set")
+        .context("CARGO_MANIFEST_DIR env var not set")
+}
+
+/// Execute a command, assert that it succeeds, and return stdout as a string.
+fn exec(mut command: impl BorrowMut<Command>) -> anyhow::Result<String> {
+    let command = command.borrow_mut();
+
+    let output = command
+        .output()
+        .with_context(|| anyhow!("Failed to execute command: {command:?}"))?;
+
+    let stdout = str::from_utf8(&output.stdout).unwrap_or("Invalid UTF-8");
+
+    if !output.status.success() {
+        let stderr = str::from_utf8(&output.stdout).unwrap_or("Invalid UTF-8");
+
+        eprintln!("Error from {command:?}");
+        eprintln!();
+        eprintln!("stdout:");
+        eprintln!();
+        eprintln!("{stdout}");
+        eprintln!();
+        eprintln!("-------");
+        eprintln!("stderr:");
+        eprintln!();
+        eprintln!("{stderr}");
+        eprintln!();
+        eprintln!("-------");
+
+        return Err(anyhow!("Failed to execute command: {command:?}")).with_context(|| {
+            anyhow!(
+                "Command exited with a non-zero exit code: {}",
+                output.status
+            )
+        });
+    }
+
+    Ok(stdout.to_string())
 }