Start Xposed logcat daemon after Xposed services

Allows us to read settings from /data via the services a bit earlier.
There's only a small chance that errors will occur while the services
start, which would now no longer be visible in the error.log (still in
the logcat though). However, even writing the logfile requires some
similar mechanisms as the services (e.g. SELinux context switches), so
the overall impact is very small.

xposed.cpp

@@ -98,7 +98,7 @@ bool initialize(bool zygote, bool startSystemServer, const char* className, int
 #endif  // XPOSED_WITH_SELINUX
 
     if (startSystemServer) {
-        xposed::logcat::start();
+        xposed::logcat::printStartupMarker();
     } else if (zygote) {
         // TODO Find a better solution for this
         // Give the primary Zygote process a little time to start first.
@@ -109,15 +109,25 @@ bool initialize(bool zygote, bool startSystemServer, const char* className, int
     printRomInfo();
 
     if (startSystemServer) {
-        if (!xposed::service::startAll())
+        if (!xposed::service::startAll()) {
             return false;
+        }
+        xposed::logcat::start();
 #if XPOSED_WITH_SELINUX
     } else if (xposed->isSELinuxEnabled) {
-        if (!xposed::service::startMembased())
+        if (!xposed::service::startMembased()) {
             return false;
+        }
 #endif  // XPOSED_WITH_SELINUX
     }
 
+#if XPOSED_WITH_SELINUX
+    // Don't let any further forks access the Zygote service
+    if (xposed->isSELinuxEnabled) {
+        xposed::service::membased::restrictMemoryInheritance();
+    }
+#endif  // XPOSED_WITH_SELINUX
+
     // FIXME Zygote has no access to input devices, this would need to be check in system_server context
     if (zygote && !isSafemodeDisabled() && detectSafemodeTrigger(shouldSkipSafemodeDelay()))
         disableXposed();

xposed_logcat.cpp

@@ -115,10 +115,12 @@ static void runDaemon(int pipefd) {
     exit(EXIT_FAILURE);
 }
 
-void start() {
+void printStartupMarker() {
     sprintf(marker, "Current time: %d, PID: %d", (int) time(NULL), getpid());
     ALOG(LOG_DEBUG, "XposedStartupMarker", marker, NULL);
+}
 
+void start() {
     // Fork to create a daemon
     pid_t pid;
     if ((pid = fork()) < 0) {

xposed_logcat.h

@@ -8,6 +8,7 @@
 namespace xposed {
 namespace logcat {
 
+    void printStartupMarker();
     void start();
 
 }  // namespace logcat

xposed_service.cpp

@@ -133,7 +133,7 @@ static bool init() {
     return true;
 }
 
-static void restrictMemoryInheritance() {
+void restrictMemoryInheritance() {
     madvise(shared, sizeof(MemBasedState), MADV_DONTFORK);
     canAlwaysAccessService = false;
 }
@@ -884,12 +884,9 @@ static void appService(bool useSingleProcess) {
 }
 
 bool checkMembasedRunning() {
-    // Don't let any further forks inherit this mapping
-    membased::restrictMemoryInheritance();
-
     // Ensure that the memory based service is running
     if (!membased::waitForRunning(5)) {
-        ALOGE("Zygote service is not running, Xposed cannot work without it");
+        ALOGE("Xposed's Zygote service is not running, cannot work without it");
         return false;
     }
 

xposed_service.h

@@ -15,6 +15,7 @@ namespace service {
         int accessFile(const char* path, int mode);
         int statFile(const char* path, struct stat* stat);
         char* readFile(const char* path, int* bytesRead);
+        void restrictMemoryInheritance();
     }  // namespace membased
 #endif  // XPOSED_WITH_SELINUX