rx/mem: cross platform implementation

fixed compilation errors
avoid memfd_create usage on android

rx/include/rx/Mappable.hpp

@@ -2,21 +2,11 @@
 
 #include "AddressRange.hpp"
 #include "EnumBitSet.hpp"
+#include "mem.hpp"
 #include <system_error>
 #include <utility>
 
 namespace rx {
-enum class Protection {
-  R,
-  W,
-  X,
-
-  bitset_last = X
-};
-
-std::errc reserveVirtualSpace(rx::AddressRange range);
-std::errc releaseVirtualSpace(rx::AddressRange range, std::size_t alignment);
-
 class Mappable {
 #ifdef _WIN32
   using NativeHandle = void *;
@@ -46,7 +36,8 @@ public:
   static std::pair<Mappable, std::errc> CreateMemory(std::size_t size);
   static std::pair<Mappable, std::errc> CreateSwap(std::size_t size);
   std::errc map(rx::AddressRange virtualRange, std::size_t offset,
-                rx::EnumBitSet<Protection> protection, std::size_t alignment);
+                rx::EnumBitSet<mem::Protection> protection,
+                std::size_t alignment);
 
   [[nodiscard]] NativeHandle release() {
     return std::exchange(m_handle, kInvalidHandle);

rx/include/rx/mem.hpp

@@ -1,14 +1,31 @@
 #pragma once
 
+#include "AddressRange.hpp"
+#include "EnumBitSet.hpp"
 #include <cstddef>
+#include <system_error>
+#include <utility>
 
 namespace rx::mem {
+enum class Protection {
+  R,
+  W,
+  X,
+
+  bitset_last = X
+};
+
+struct VirtualQueryEntry : rx::AddressRange {
+  rx::EnumBitSet<Protection> flags{};
+
+  VirtualQueryEntry() = default;
+  VirtualQueryEntry(rx::AddressRange range, rx::EnumBitSet<Protection> prot)
+      : AddressRange(range), flags(prot) {}
+};
+
 extern const std::size_t pageSize;
-void *map(void *address, std::size_t size, int prot, int flags, int fd = -1,
-          std::ptrdiff_t offset = 0);
-void *reserve(std::size_t size);
-bool reserve(void *address, std::size_t size);
-bool protect(void *address, std::size_t size, int prot);
-bool unmap(void *address, std::size_t size);
-void printStats();
+std::errc reserve(rx::AddressRange range);
+std::errc release(rx::AddressRange range, std::size_t alignment);
+std::errc protect(rx::AddressRange range, rx::EnumBitSet<Protection> prot);
+std::vector<VirtualQueryEntry> query(rx::AddressRange range);
 } // namespace rx::mem