Implement uid_on_allowlist for Magisk

zygiskd/src/root_impl/magisk.rs

@@ -24,8 +24,20 @@ pub fn get_magisk() -> Option<Version> {
 }
 
 pub fn uid_on_allowlist(uid: i32) -> bool {
-    // TODO: uid_on_allowlist
-    return false;
+    let output: Option<String> = Command::new("magisk")
+        .arg("--sqlite")
+        .arg("select uid from policies where policy=2")
+        .stdout(Stdio::piped())
+        .spawn().ok()
+        .and_then(|child| child.wait_with_output().ok())
+        .and_then(|output| String::from_utf8(output.stdout).ok());
+    let lines = match &output {
+        Some(output) => output.lines(),
+        None => return false,
+    };
+    lines.into_iter().any(|line| {
+        line.trim().strip_prefix("uid=").and_then(|uid| uid.parse().ok()) == Some(uid)
+    })
 }
 
 pub fn uid_on_denylist(uid: i32) -> bool {