Store all native JNI methods in data structures

native/jni/inject/memory.cpp

@@ -0,0 +1,30 @@
+#include "memory.hpp"
+
+namespace jni_hook {
+
+// We know our minimum alignment is WORD size (size of pointer)
+static constexpr size_t ALIGN = sizeof(long);
+
+static constexpr size_t CAPACITY = (1 << 24);
+
+// No need to be thread safe as the initial mmap always happens on the main thread
+static uint8_t *_area = nullptr;
+
+static std::atomic<uint8_t *> _curr = nullptr;
+
+void *memory_block::allocate(size_t sz) {
+    if (!_area) {
+        // Memory will not actually be allocated because physical pages are mapped in on-demand
+        _area = static_cast<uint8_t *>(xmmap(
+                nullptr, CAPACITY, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0));
+        _curr = _area;
+    }
+    return _curr.fetch_add(do_align(sz, ALIGN));
+}
+
+void memory_block::release() {
+    if (_area)
+        munmap(_area, CAPACITY);
+}
+
+} // namespace jni_hook