Set bpf.progs_loaded property when programs finish loading

The property bpf.progs_loaded will be used by services expecting BPF
programs to be loaded and wait before they are loaded.

Bug: 112334572

Change-Id: I19daa0caa84e2659e8790f0dd551d95ab824e13b
Signed-off-by: Joel Fernandes <joelaf@google.com>
diff --git a/bpfloader/BpfLoader.cpp b/bpfloader/BpfLoader.cpp
index 966f3f6..3224cec 100644
--- a/bpfloader/BpfLoader.cpp
+++ b/bpfloader/BpfLoader.cpp
@@ -38,6 +38,7 @@
 #include <sys/stat.h>
 #include <sys/types.h>
 
+#include <android-base/properties.h>
 #include <android-base/stringprintf.h>
 #include <android-base/strings.h>
 #include <android-base/unique_fd.h>
@@ -86,6 +87,19 @@
 }
 
 int main() {
+    std::string value = android::base::GetProperty("bpf.progs_loaded", "");
+    if (value == "1") {
+        ALOGI("Property bpf.progs_loaded is set, progs already loaded.\n");
+        return 0;
+    }
+
     // Load all ELF objects, create programs and maps, and pin them
     loadAllElfObjects();
+
+    if (android::base::SetProperty("bpf.progs_loaded", "1") == false) {
+        ALOGE("Failed to set bpf.progs_loaded property\n");
+        return 1;
+    }
+
+    return 0;
 }