ksud: catch bootlog when post-fs-data

userspace/ksud/src/defs.rs

@@ -3,6 +3,7 @@ use const_format::concatcp;
 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 LOG_DIR: &str = concatcp!(WORKING_DIR, "log/");
 
 pub const KSURC_PATH: &str = concatcp!(WORKING_DIR, ".ksurc");
 pub const KSU_OVERLAY_SOURCE: &str = "KSU";

userspace/ksud/src/event.rs

@@ -86,6 +86,9 @@ pub fn mount_systemlessly(module_dir: &str) -> Result<()> {
 pub fn on_post_data_fs() -> Result<()> {
     crate::ksu::report_post_fs_data();
 
+    #[cfg(unix)]
+    let _ = catch_bootlog();
+
     if utils::has_magisk() {
         warn!("Magisk detected, skip post-fs-data!");
         return Ok(());
@@ -235,3 +238,42 @@ fn link_ksud_to_bin() -> Result<()> {
     }
     Ok(())
 }
+
+#[cfg(unix)]
+fn catch_bootlog() -> Result<()> {
+    use std::os::unix::process::CommandExt;
+    use std::process::Stdio;
+
+    let logdir = Path::new(defs::LOG_DIR);
+    utils::ensure_dir_exists(logdir)?;
+    let bootlog = logdir.join("boot.log");
+    let oldbootlog = logdir.join("boot.old.log");
+
+    if bootlog.exists() {
+        std::fs::rename(&bootlog, &oldbootlog)?;
+    }
+
+    let bootlog = std::fs::File::create(bootlog)?;
+
+    // timeout -s 9 30s logcat > boot.log
+    let result = unsafe {
+        std::process::Command::new("timeout")
+            .process_group(0)
+            .pre_exec(|| {
+                utils::switch_cgroups();
+                Ok(())
+            })
+            .arg("-s")
+            .arg("9")
+            .arg("30s")
+            .arg("logcat")
+            .stdout(Stdio::from(bootlog))
+            .spawn()
+    };
+
+    if let Err(e) = result {
+        warn!("Failed to start logcat: {:#}", e);
+    }
+
+    Ok(())
+}