ksud: support .ksurc (#345)

userspace/ksud/.gitignore

@@ -1 +1,2 @@
 /target
+.cargo/

userspace/ksud/src/defs.rs

@@ -4,6 +4,7 @@ pub const ADB_DIR: &str = "/data/adb/";
 pub const WORKING_DIR: &str = concatcp!(ADB_DIR, "ksu/");
 pub const BINARY_DIR: &str = concatcp!(WORKING_DIR, "bin/");
 
+pub const KSURC_PATH: &str = concatcp!(WORKING_DIR, ".ksurc");
 pub const DAEMON_PATH: &str = concatcp!(ADB_DIR, "ksud");
 
 #[cfg(target_os = "android")]

userspace/ksud/src/ksu.rs

@@ -214,6 +214,11 @@ pub fn root_shell() -> Result<()> {
     #[cfg(any(target_os = "linux", target_os = "android"))]
     add_path_to_env(defs::BINARY_DIR)?;
 
+    // when KSURC_PATH exists and ENV is not set, set ENV to KSURC_PATH
+    if PathBuf::from(defs::KSURC_PATH).exists() && env::var("ENV").is_err() {
+        command = command.env("ENV", defs::KSURC_PATH);
+    }
+
     // escape from the current cgroup and become session leader
     // WARNING!!! This cause some root shell hang forever!
     // command = command.process_group(0);