Add fork-based supervisor daemon for instant restart

app/build.gradle.kts

@@ -116,7 +116,7 @@ androidComponents {
                     )
                 ) {
                     into("lib") // Place them in the 'lib' subfolder of the staging directory.
-                    include("**/libinject.so", "**/libTEESimulator.so")
+                    include("**/libinject.so", "**/libTEESimulator.so", "**/libsupervisor.so")
                 }
 
                 // Now, copy and process the files from 'module' directory.

app/src/main/cpp/CMakeLists.txt

@@ -22,6 +22,9 @@ add_executable(libinject.so inject/main.cpp inject/utils.cpp)
 target_include_directories(libinject.so PUBLIC include)
 target_link_libraries(libinject.so PRIVATE lsplt_static)
 
+add_executable(libsupervisor.so supervisor.cpp)
+target_link_libraries(libsupervisor.so PRIVATE log)
+
 add_library(${CMAKE_PROJECT_NAME} SHARED binder_interceptor.cpp)
 target_include_directories(${CMAKE_PROJECT_NAME} PUBLIC external/linux-kernel/include include)
 target_link_libraries(${CMAKE_PROJECT_NAME} PRIVATE binder lsplt_static utils)

app/src/main/cpp/supervisor.cpp

@@ -0,0 +1,57 @@
+// Fork-based supervisor for instant daemon restart
+#include <unistd.h>
+#include <sys/wait.h>
+#include <sys/prctl.h>
+#include <signal.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+
+static volatile sig_atomic_t should_exit = 0;
+
+static void signal_handler(int sig) {
+    should_exit = 1;
+}
+
+int main(int argc, char *argv[]) {
+    if (argc < 2) {
+        fprintf(stderr, "Usage: %s <daemon> [args...]\n", argv[0]);
+        return 1;
+    }
+
+    // Forward termination signals to exit cleanly
+    signal(SIGTERM, signal_handler);
+    signal(SIGINT, signal_handler);
+
+    const char *daemon_path = argv[1];
+    char **daemon_argv = &argv[1];
+
+    while (!should_exit) {
+        pid_t pid = fork();
+
+        if (pid < 0) {
+            perror("fork failed");
+            usleep(100000); // 100ms backoff on fork failure
+            continue;
+        }
+
+        if (pid == 0) {
+            // Child: become the daemon
+            prctl(PR_SET_PDEATHSIG, SIGKILL); // Die if parent dies
+            execv(daemon_path, daemon_argv);
+            perror("execv failed");
+            _exit(127);
+        }
+
+        // Parent: wait for child to exit
+        int status;
+        waitpid(pid, &status, 0);
+
+        if (should_exit) break;
+
+        // Instant restart - no delay
+    }
+
+    return 0;
+}