commit 5cc0b4179f673dfd01803c26c8e803e6ced07e48
author Dennis Kempin <denniskempin@google.com> Tue Aug 31 10:38:53 2021 -0700
committer Dennis Kempin <denniskempin@google.com> Wed Sep 01 13:36:19 2021 -0700
tree f48cd578b9a8f05a59e0daadfc9c335adb10e710
parent cdc8af38039b5d7e96d35ac760e25dac9bdd1472

minijail-sys: Enable cross-compilation in build.rs

This adds the CROSS_COMPILE variable to the make call to pass the
correct prefix for the target platform.

This is used for cross-compiling and testing crosvm on aarch64.
(Note: To cross-compile on gLinux, we will need b/198310108)

BUG=b:198305518
TEST=cargo build --target=aarch64-unknown-linux-gnu

Change-Id: Iedc11531a3fc3c304fb11b2ba13f0a55f58396ba

rust/minijail-sys/build.rs

diff --git a/rust/minijail-sys/build.rs b/rust/minijail-sys/build.rs
index f5c895e..ea0ed5c 100644
--- a/rust/minijail-sys/build.rs
+++ b/rust/minijail-sys/build.rs
@@ -12,6 +12,23 @@
 use std::path::Path;
 use std::process::Command;
 
+/// Returns the target triplet prefix for gcc commands. No prefix is required
+/// for native builds.
+fn get_cross_compile_prefix() -> String {
+    if let Ok(cross_compile) = env::var("CROSS_COMPILE") {
+        return cross_compile;
+    }
+
+    if env::var("HOST").unwrap() == env::var("TARGET").unwrap() {
+        return String::from("");
+    }
+
+    let arch = env::var("CARGO_CFG_TARGET_ARCH").unwrap();
+    let os = env::var("CARGO_CFG_TARGET_OS").unwrap();
+    let env = env::var("CARGO_CFG_TARGET_ENV").unwrap();
+    return format!("{}-{}-{}-", arch, os, env);
+}
+
 fn set_up_libminijail() -> io::Result<()> {
     // Minijail requires libcap at runtime.
     pkg_config::Config::new().probe("libcap").unwrap();
@@ -29,6 +46,7 @@
         .current_dir(&out_dir)
         .env("OUT", &out_dir)
         .env("MODE", if profile == "release" { "opt" } else { "debug" })
+        .env("CROSS_COMPILE", get_cross_compile_prefix())
         .arg("-C")
         .arg(&current_dir)
         .arg("CC_STATIC_LIBRARY(libminijail.pic.a)")