Log to zygiskd

zygiskd/src/constants.rs

@@ -15,6 +15,7 @@ pub const PATH_DAEMON_LOCK: &str = concatcp!(PATH_ZYGISKSU_DIR, "/zygiskd.lock")
 #[repr(u8)]
 pub enum DaemonSocketAction {
     PingHeartbeat,
+    RequestLogcatFd,
     ReadNativeBridge,
     ReadModules,
     RequestCompanionSocket,

zygiskd/src/utils.rs

@@ -39,8 +39,10 @@ pub trait UnixStreamExt {
     fn read_u8(&mut self) -> Result<u8>;
     fn read_u32(&mut self) -> Result<u32>;
     fn read_usize(&mut self) -> Result<usize>;
+    fn read_string(&mut self) -> Result<String>;
     fn write_u8(&mut self, value: u8) -> Result<()>;
     fn write_usize(&mut self, value: usize) -> Result<()>;
+    fn write_string(&mut self, value: &str) -> Result<()>;
 }
 
 impl UnixStreamExt for UnixStream {
@@ -62,6 +64,13 @@ impl UnixStreamExt for UnixStream {
         Ok(usize::from_ne_bytes(buf))
     }
 
+    fn read_string(&mut self) -> Result<String> {
+        let len = self.read_usize()?;
+        let mut buf = vec![0u8; len];
+        self.read_exact(&mut buf)?;
+        Ok(String::from_utf8(buf)?)
+    }
+
     fn write_u8(&mut self, value: u8) -> Result<()> {
         self.write_all(&value.to_ne_bytes())?;
         Ok(())
@@ -71,6 +80,12 @@ impl UnixStreamExt for UnixStream {
         self.write_all(&value.to_ne_bytes())?;
         Ok(())
     }
+
+    fn write_string(&mut self, value: &str) -> Result<()> {
+        self.write_usize(value.len())?;
+        self.write_all(value.as_bytes())?;
+        Ok(())
+    }
 }
 
 // TODO: Replace with SockAddrExt::from_abstract_name when it's stable

zygiskd/src/zygisk.rs

@@ -8,10 +8,9 @@ use nix::{
     unistd::getppid,
 };
 use passfd::FdPassingExt;
-use std::io::Write;
 use std::sync::Arc;
 use std::thread;
-use std::ffi::c_void;
+use std::ffi::{c_char, c_void};
 use std::fs;
 use std::os::unix::{
     net::{UnixListener, UnixStream},
@@ -187,15 +186,28 @@ fn handle_daemon_action(mut stream: UnixStream, context: &Context) -> Result<()>
         DaemonSocketAction::PingHeartbeat => {
             restore_native_bridge()?;
         }
+        DaemonSocketAction::RequestLogcatFd => {
+            loop {
+                let level = match stream.read_u8() {
+                    Ok(level) => level,
+                    Err(_) => break,
+                };
+                let tag = stream.read_string()?;
+                let tag = std::ffi::CString::new(tag)?;
+                let message = stream.read_string()?;
+                let message = std::ffi::CString::new(message)?;
+                unsafe {
+                    __android_log_print(level as i32, tag.as_ptr(), message.as_ptr());
+                }
+            }
+        }
         DaemonSocketAction::ReadNativeBridge => {
-            stream.write_usize(context.native_bridge.len())?;
-            stream.write_all(context.native_bridge.as_bytes())?;
+            stream.write_string(&context.native_bridge)?;
         }
         DaemonSocketAction::ReadModules => {
             stream.write_usize(context.modules.len())?;
             for module in context.modules.iter() {
-                stream.write_usize(module.name.len())?;
-                stream.write_all(module.name.as_bytes())?;
+                stream.write_string(&module.name)?;
                 stream.send_fd(module.memfd.as_raw_fd())?;
             }
         }
@@ -225,3 +237,7 @@ fn handle_daemon_action(mut stream: UnixStream, context: &Context) -> Result<()>
     }
     Ok(())
 }
+
+extern "C" {
+    fn __android_log_print(prio: i32, tag: *const c_char, fmt: *const c_char, ...) -> i32;
+}