Simplify zygisk log pipe

native/src/core/logging.rs

@@ -44,6 +44,7 @@ extern "C" {
     fn strftime(buf: *mut c_char, len: usize, fmt: *const c_char, tm: *const tm) -> usize;
 
     fn zygisk_fetch_logd() -> RawFd;
+    fn zygisk_close_logd();
     fn new_daemon_thread(entry: ThreadEntry, arg: *mut c_void);
 }
 
@@ -159,26 +160,13 @@ fn magisk_log_to_pipe(prio: i32, msg: &Utf8CStr) {
 }
 
 fn zygisk_log_to_pipe(prio: i32, msg: &Utf8CStr) {
-    let magiskd = match MAGISKD.get() {
-        None => return,
-        Some(s) => s,
-    };
-
-    let logd_cell = magiskd.logd.lock().unwrap();
-    let mut logd_ref = logd_cell.borrow_mut();
-    if logd_ref.is_none() {
-        android_logging();
-        unsafe {
-            let fd = zygisk_fetch_logd();
-            if fd < 0 {
-                return;
-            }
-            *logd_ref = Some(File::from_raw_fd(fd));
+    let mut logd = unsafe {
+        let fd = zygisk_fetch_logd();
+        if fd < 0 {
+            return;
         }
-        // Only re-enable zygisk logging if success
-        zygisk_logging();
+        File::from_raw_fd(fd)
     };
-    let logd = logd_ref.as_mut().unwrap();
 
     // Block SIGPIPE
     let mut mask: sigset_t;
@@ -190,18 +178,21 @@ fn zygisk_log_to_pipe(prio: i32, msg: &Utf8CStr) {
         pthread_sigmask(SIG_BLOCK, &mask, &mut orig_mask);
     }
 
-    let result = write_log_to_pipe(logd, prio, msg);
+    let result = write_log_to_pipe(&mut logd, prio, msg);
 
     // Consume SIGPIPE if exists, then restore mask
     unsafe {
         let ts: timespec = std::mem::zeroed();
+
         sigtimedwait(&mask, null_mut(), &ts);
         pthread_sigmask(SIG_SETMASK, &orig_mask, null_mut());
     }
 
     // If any error occurs, shut down the logd pipe
     if result.is_err() {
-        *logd_ref = None;
+        unsafe {
+            zygisk_close_logd();
+        }
     }
 }
 

native/src/zygisk/entry.cpp

@@ -62,6 +62,8 @@ extern "C" void zygisk_inject_entry(void *handle) {
 
 // The following code runs in zygote/app process
 
+int zygisk_logd = -1;
+
 extern "C" int zygisk_fetch_logd() {
     // If we don't have the log pipe set, request magiskd for it. This could actually happen
     // multiple times in the zygote daemon (parent process) because we had to close this
@@ -77,18 +79,28 @@ extern "C" int zygisk_fetch_logd() {
     // add this FD into fds_to_ignore to pass the check. For other cases, we accomplish this by
     // hooking __android_log_close and closing it at the same time as the rest of logging FDs.
 
-    if (int fd = zygisk_request(ZygiskRequest::GET_LOG_PIPE); fd >= 0) {
-        int log_pipe = -1;
-        if (read_int(fd) == 0) {
-            log_pipe = recv_fd(fd);
-        }
-        close(fd);
-        if (log_pipe >= 0) {
-            return log_pipe;
+    if (zygisk_logd < 0) {
+        android_logging();
+        if (int fd = zygisk_request(ZygiskRequest::GET_LOG_PIPE); fd >= 0) {
+            int log_pipe = -1;
+            if (read_int(fd) == 0) {
+                log_pipe = recv_fd(fd);
+            }
+            close(fd);
+            if (log_pipe >= 0) {
+                zygisk_logd = log_pipe;
+                // Only re-enable zygisk logging if success
+                zygisk_logging();
+            }
         }
     }
 
-    return -1;
+    return zygisk_logd;
+}
+
+extern "C" void zygisk_close_logd() {
+    close(zygisk_logd);
+    zygisk_logd = -1;
 }
 
 static inline bool should_load_modules(uint32_t flags) {

native/src/zygisk/hook.cpp

@@ -20,8 +20,6 @@ using namespace std;
 using jni_hook::hash_map;
 using jni_hook::tree_map;
 using xstring = jni_hook::string;
-using rust::MagiskD;
-using rust::get_magiskd;
 
 // Extreme verbose logging
 //#define ZLOGV(...) ZLOGD(__VA_ARGS__)
@@ -70,7 +68,6 @@ struct HookContext {
         AppSpecializeArgs_v3 *app;
         ServerSpecializeArgs_v1 *server;
     } args;
-    const MagiskD &magiskd;
 
     const char *process;
     list<ZygiskModule> modules;
@@ -97,7 +94,7 @@ struct HookContext {
     vector<IgnoreInfo> ignore_info;
 
     HookContext(JNIEnv *env, void *args) :
-    env(env), args{args}, magiskd(get_magiskd()), process(nullptr), pid(-1), info_flags(0),
+    env(env), args{args}, process(nullptr), pid(-1), info_flags(0),
     hook_info_lock(PTHREAD_MUTEX_INITIALIZER) {
         static bool restored_env = false;
         if (!restored_env) {
@@ -174,7 +171,7 @@ DCL_HOOK_FUNC(int, unshare, int flags) {
 DCL_HOOK_FUNC(void, android_log_close) {
     if (g_ctx == nullptr) {
         // Happens during un-managed fork like nativeForkApp, nativeForkUsap
-        get_magiskd().close_log_pipe();
+        zygisk_close_logd();
     } else {
         g_ctx->sanitize_fds();
     }
@@ -424,8 +421,8 @@ void HookContext::fork_pre() {
         // The dirfd will be closed once out of scope
         allowed_fds[dirfd(dir.get())] = false;
         // logd_fd should be handled separately
-        if (int logd_fd = magiskd.get_log_pipe(); logd_fd >= 0) {
-            allowed_fds[logd_fd] = false;
+        if (zygisk_logd >= 0) {
+            allowed_fds[zygisk_logd] = false;
         }
     }
 
@@ -445,14 +442,14 @@ void HookContext::sanitize_fds() {
         return;
 
     if (!is_child() || g_allowed_fds == nullptr) {
-        magiskd.close_log_pipe();
+        zygisk_close_logd();
         return;
     }
 
     auto &allowed_fds = *g_allowed_fds;
     if (can_exempt_fd()) {
-        if (int logd_fd = magiskd.get_log_pipe(); logd_fd >= 0) {
-            exempted_fds.push_back(logd_fd);
+        if (zygisk_logd >= 0) {
+            exempted_fds.push_back(zygisk_logd);
         }
 
         auto update_fd_array = [&](int old_len) -> jintArray {
@@ -492,7 +489,7 @@ void HookContext::sanitize_fds() {
             update_fd_array(0);
         }
     } else {
-        magiskd.close_log_pipe();
+        zygisk_close_logd();
         // Switch to plain old android logging because we cannot talk
         // to magiskd to fetch our log pipe afterwards anyways.
         android_logging();
@@ -589,7 +586,7 @@ void HookContext::app_specialize_post() {
 
     // Cleanups
     env->ReleaseStringUTFChars(args.app->nice_name, process);
-    magiskd.close_log_pipe();
+    zygisk_close_logd();
     android_logging();
 }
 

native/src/zygisk/zygisk.hpp

@@ -37,6 +37,9 @@ enum : int {
 #define HIJACK_BIN HIJACK_BIN32
 #endif
 
+extern int zygisk_logd;
+extern "C" void zygisk_close_logd();
+
 // Unmap all pages matching the name
 void unmap_all(const char *name);