test(runtime): decode base64 BOX_EXEC_* values in spec assertions

The exec values are now base64-encoded (BOX_EXEC_B64), so the spec tests decode
them (via a b64d helper) before comparing to the raw expected value — verifying
the encode round-trips correctly. Also rustfmt the guest decode block.

Author: Roy Lin

src/guest/init/src/main.rs

@@ -252,7 +252,9 @@ impl ExecConfig {
         // libkrun's env serialization. Decode them back; fall back to the raw value
         // on any decode error or when the marker is absent (older runtime).
         use base64::Engine;
-        let b64 = std::env::var("BOX_EXEC_B64").map(|v| v == "1").unwrap_or(false);
+        let b64 = std::env::var("BOX_EXEC_B64")
+            .map(|v| v == "1")
+            .unwrap_or(false);
         let decode = |s: String| -> String {
             if !b64 {
                 return s;
@@ -274,7 +276,11 @@ impl ExecConfig {
             .and_then(|s| s.parse::<usize>().ok())
         {
             Some(argc) => (0..argc)
-                .filter_map(|i| std::env::var(format!("BOX_EXEC_ARG_{}", i)).ok().map(&decode))
+                .filter_map(|i| {
+                    std::env::var(format!("BOX_EXEC_ARG_{}", i))
+                        .ok()
+                        .map(&decode)
+                })
                 .collect(),
             None => vec![],
         };

src/runtime/src/vm/spec.rs

@@ -756,6 +756,17 @@ mod tests {
     use tempfile::tempdir;
     use tempfile::TempDir;
 
+    /// Decode a base64 (URL-safe, no pad) `BOX_EXEC_*` value the way guest-init
+    /// does, so assertions can compare against the original raw value.
+    fn b64d(s: &str) -> String {
+        use base64::Engine;
+        base64::engine::general_purpose::URL_SAFE_NO_PAD
+            .decode(s.as_bytes())
+            .ok()
+            .and_then(|bytes| String::from_utf8(bytes).ok())
+            .unwrap_or_else(|| s.to_string())
+    }
+
     fn test_oci_config(workdir: Option<&str>, user: Option<&str>) -> OciImageConfig {
         OciImageConfig {
             entrypoint: Some(vec!["/bin/app".to_string()]),
@@ -1074,12 +1085,12 @@ mod tests {
             .entrypoint
             .env
             .iter()
-            .any(|(key, value)| key == "BOX_EXEC_USER" && value == "1000:1000"));
+            .any(|(key, value)| key == "BOX_EXEC_USER" && b64d(value) == "1000:1000"));
         assert!(spec
             .entrypoint
             .env
             .iter()
-            .any(|(key, value)| key == "BOX_EXEC_WORKDIR" && value == "/override"));
+            .any(|(key, value)| key == "BOX_EXEC_WORKDIR" && b64d(value) == "/override"));
     }
 
     #[test]
@@ -1126,12 +1137,12 @@ mod tests {
             .entrypoint
             .env
             .iter()
-            .any(|(key, value)| key == "BOX_EXEC_USER" && value == "2000:2000"));
+            .any(|(key, value)| key == "BOX_EXEC_USER" && b64d(value) == "2000:2000"));
         assert!(spec
             .entrypoint
             .env
             .iter()
-            .any(|(key, value)| key == "BOX_EXEC_WORKDIR" && value == "/oci"));
+            .any(|(key, value)| key == "BOX_EXEC_WORKDIR" && b64d(value) == "/oci"));
     }
 
     #[test]
@@ -1147,7 +1158,7 @@ mod tests {
             .entrypoint
             .env
             .iter()
-            .any(|(key, value)| key == "BOX_EXEC_WORKDIR" && value == GUEST_WORKDIR));
+            .any(|(key, value)| key == "BOX_EXEC_WORKDIR" && b64d(value) == GUEST_WORKDIR));
     }
 
     #[test]
@@ -1191,17 +1202,17 @@ mod tests {
             .entrypoint
             .env
             .iter()
-            .any(|(key, value)| key == "BOX_EXEC_ENV_FOO" && value == "cli"));
+            .any(|(key, value)| key == "BOX_EXEC_ENV_FOO" && b64d(value) == "cli"));
         assert!(spec
             .entrypoint
             .env
             .iter()
-            .any(|(key, value)| key == "BOX_EXEC_ENV_BAR" && value == "image"));
+            .any(|(key, value)| key == "BOX_EXEC_ENV_BAR" && b64d(value) == "image"));
         assert!(spec
             .entrypoint
             .env
             .iter()
-            .any(|(key, value)| key == "BOX_EXEC_ENV_BAZ" && value == "cli"));
+            .any(|(key, value)| key == "BOX_EXEC_ENV_BAZ" && b64d(value) == "cli"));
         assert!(!spec
             .entrypoint
             .env