bpfloader: refactor C++ loader to just one function

no need for the complexity, as it is only for vendor now

Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: Ia807f7ee8aeca25d92e60e46f180ffe536eef87c

loader/Loader.cpp

@@ -936,23 +936,19 @@ int createSysFsBpfSubDir(const char* const prefix) {
 
 // ----- extern C stuff for rust below here -----
 
-void initLogging() {
+void vendorBpfLoader() {
     // since we only ever get called from mainline NetBpfLoad
     // (see packages/modules/Connectivity/netbpfload/NetBpfLoad.cpp around line 516)
     // and there no arguments, so we can just pretend/assume this is the case.
     const char* argv[] = {"/system/bin/bpfloader", NULL};
     android::base::InitLogging(const_cast<char**>(argv), &android::base::KernelLogger);
-}
 
-void createBpfFsSubDirectories() {
     for (const auto& location : android::bpf::locations) {
         if (android::bpf::createSysFsBpfSubDir(location.prefix)) {
             exit(120);
         }
     }
-}
 
-void legacyBpfLoader() {
     // Load all ELF objects, create programs and maps, and pin them
     for (const auto& location : android::bpf::locations) {
         if (android::bpf::loadAllElfObjects(location)) {
@@ -965,9 +961,7 @@ void legacyBpfLoader() {
             exit(121);
         }
     }
-}
 
-void execNetBpfLoadDone() {
     const char* args[] = {"/apex/com.android.tethering/bin/netbpfload", "done", NULL};
     execve(args[0], (char**)args, environ);
     ALOGE("FATAL: execve(): %d[%s]", errno, strerror(errno));

loader/bpfloader.rs

@@ -640,14 +640,11 @@ fn main() {
     load_libbpf_progs();
     info!("Loading legacy BPF progs");
 
-    // SAFETY: Linking in the existing legacy bpfloader functionality.
-    // Any of the four following bindgen functions can abort() or exit()
-    // on failure and execNetBpfLoadDone() execve()'s.
+    // SAFETY: Linking in the existing legacy vendor bpfloader functionality.
+    // The following bindgen function can abort() or exit() on failure,
+    // but will usually execve().
     unsafe {
-        bpf_android_bindgen::initLogging();
-        bpf_android_bindgen::createBpfFsSubDirectories();
-        bpf_android_bindgen::legacyBpfLoader();
-        bpf_android_bindgen::execNetBpfLoadDone();
+        bpf_android_bindgen::vendorBpfLoader();
     }
 }
 

loader/include/libbpf_android.h

@@ -47,11 +47,8 @@ extern "C" {
 #define __noreturn
 #endif // __cplusplus
 
-// The C++ portion of the BpfLoader is exposed as 3 functions to be called in order.
-void initLogging();
-void createBpfFsSubDirectories();
-void legacyBpfLoader();
-__noreturn void execNetBpfLoadDone();
+// The C++ portion of the BpfLoader is exposed as a terminal function.
+__noreturn void vendorBpfLoader();
 
 #ifdef __cplusplus
 }  // extern C