fix(build.rs): keep CARGO_HOME and RUSTUP_HOME

Signed-off-by: Martin Kröning <martin.kroening@eonerc.rwth-aachen.de>

rftrace/build.rs

@@ -90,9 +90,13 @@ fn main() {
 
 /// Returns the Rustup proxy for Cargo.
 // Adapted from Hermit.
-fn cargo() -> Command {
-    let cargo = {
-        let exe = format!("cargo{}", env::consts::EXE_SUFFIX);
+pub fn cargo() -> Command {
+    sanitize("cargo")
+}
+
+fn sanitize(cmd: &str) -> Command {
+    let cmd = {
+        let exe = format!("{cmd}{}", env::consts::EXE_SUFFIX);
         // On windows, the userspace toolchain ends up in front of the rustup proxy in $PATH.
         // To reach the rustup proxy nonetheless, we explicitly query $CARGO_HOME.
         let mut cargo_home = PathBuf::from(env::var_os("CARGO_HOME").unwrap());
@@ -105,17 +109,22 @@ fn cargo() -> Command {
         }
     };
 
-    let mut cargo = Command::new(cargo);
+    let mut cmd = Command::new(cmd);
+
+    cmd.current_dir(env::var_os("CARGO_MANIFEST_DIR").unwrap());
 
     // Remove rust-toolchain-specific environment variables from kernel cargo
-    cargo.env_remove("LD_LIBRARY_PATH");
+    cmd.env_remove("LD_LIBRARY_PATH");
     env::vars()
-        .filter(|(key, _value)| key.starts_with("CARGO") || key.starts_with("RUST"))
+        .filter(|(key, _value)| {
+            key.starts_with("CARGO") && !key.starts_with("CARGO_HOME")
+                || key.starts_with("RUST") && !key.starts_with("RUSTUP_HOME")
+        })
         .for_each(|(key, _value)| {
-            cargo.env_remove(&key);
+            cmd.env_remove(&key);
         });
 
-    cargo
+    cmd
 }
 
 /// Makes all internal symbols private to avoid duplicated symbols.