From dd5e60445ba0852d99c6da5d4dde698db9ad0742 Mon Sep 17 00:00:00 2001
From: dev0 <dev0@iasoft.dev>
Date: Wed, 26 Nov 2025 16:39:14 +0530
Subject: [PATCH] MMFile

---
 Src/IACore/inc/IACore/File.hpp | 142 +++++++++++++++++++++++++++++++++
 Src/IACore/inc/IACore/PCH.hpp  |   3 +
 2 files changed, 145 insertions(+)

diff --git a/Src/IACore/inc/IACore/File.hpp b/Src/IACore/inc/IACore/File.hpp
index efca1b6..256759f 100644
--- a/Src/IACore/inc/IACore/File.hpp
+++ b/Src/IACore/inc/IACore/File.hpp
@@ -212,4 +212,146 @@ namespace IACore
       private:
         std::fstream m_fs;
     };
+
+    class MMFile
+    {
+      public:
+        MMFile() = default;
+
+        // RAII - Automatically unmap on destruction
+        ~MMFile()
+        {
+            Close();
+        }
+
+        // Disable copy (managing ownership of raw handles is messy)
+        MMFile(const MMFile &) = delete;
+        MMFile &operator=(const MMFile &) = delete;
+
+        // Open and Map
+        bool Map(const std::string &filepath)
+        {
+            Close(); // Cleanup any existing map
+
+#if IA_PLATFORM_WINDOWS > 0
+            // 1. Open File
+            hFile_ = ::CreateFileA(filepath.c_str(), GENERIC_READ, FILE_SHARE_READ, nullptr, OPEN_EXISTING,
+                                   FILE_ATTRIBUTE_NORMAL, nullptr);
+            if (hFile_ == INVALID_HANDLE_VALUE)
+                return false;
+
+            // 2. Get File Size
+            LARGE_INTEGER size;
+            if (!::GetFileSizeEx(hFile_, &size))
+            {
+                Close();
+                return false;
+            }
+            size_ = static_cast<size_t>(size.QuadPart);
+
+            // 3. Create Mapping Object
+            hMapping_ = ::CreateFileMappingA(hFile_, nullptr, PAGE_READONLY, 0, 0, nullptr);
+            if (!hMapping_)
+            {
+                Close();
+                return false;
+            }
+
+            // 4. Map View
+            data_ = ::MapViewOfFile(hMapping_, FILE_MAP_READ, 0, 0, 0);
+            if (!data_)
+            {
+                Close();
+                return false;
+            }
+
+#else // LINUX / POSIX
+      // 1. Open File
+            fd_ = ::open(filepath.c_str(), O_RDONLY);
+            if (fd_ == -1)
+                return false;
+
+            // 2. Get File Size
+            struct stat sb;
+            if (fstat(fd_, &sb) == -1)
+            {
+                Close();
+                return false;
+            }
+            size_ = static_cast<size_t>(sb.st_size);
+
+            // 3. mmap
+            // PROT_READ: Read only
+            // MAP_PRIVATE: Copy-on-write (safe if you accidentally modify, though we return const)
+            data_ = ::mmap(nullptr, size_, PROT_READ, MAP_PRIVATE, fd_, 0);
+            if (data_ == MAP_FAILED)
+            {
+                data_ = nullptr;
+                Close();
+                return false;
+            }
+#endif
+            return true;
+        }
+
+        void Close()
+        {
+#ifdef _WIN32
+            if (data_)
+            {
+                ::UnmapViewOfFile(data_);
+                data_ = nullptr;
+            }
+            if (hMapping_)
+            {
+                ::CloseHandle(hMapping_);
+                hMapping_ = nullptr;
+            }
+            if (hFile_ != INVALID_HANDLE_VALUE)
+            {
+                ::CloseHandle(hFile_);
+                hFile_ = INVALID_HANDLE_VALUE;
+            }
+#else
+            if (data_)
+            {
+                ::munmap(data_, size_);
+                data_ = nullptr;
+            }
+            if (fd_ != -1)
+            {
+                ::close(fd_);
+                fd_ = -1;
+            }
+#endif
+            size_ = 0;
+        }
+
+        // Accessors
+        const void *GetData() const
+        {
+            return data_;
+        }
+
+        size_t GetSize() const
+        {
+            return size_;
+        }
+
+        bool IsValid() const
+        {
+            return data_ != nullptr;
+        }
+
+      private:
+        void *data_ = nullptr;
+        size_t size_ = 0;
+
+#ifdef _WIN32
+        HANDLE hFile_ = INVALID_HANDLE_VALUE;
+        HANDLE hMapping_ = nullptr;
+#else
+        int fd_ = -1;
+#endif
+    };
 } // namespace IACore
\ No newline at end of file
diff --git a/Src/IACore/inc/IACore/PCH.hpp b/Src/IACore/inc/IACore/PCH.hpp
index efadcb9..9375ebd 100644
--- a/Src/IACore/inc/IACore/PCH.hpp
+++ b/Src/IACore/inc/IACore/PCH.hpp
@@ -495,6 +495,9 @@ STATIC CONST FLOAT64 FLOAT64_EPSILON = DBL_EPSILON;
 #elif IA_PLATFORM_UNIX
 #    include <unistd.h>
 #    include <sys/wait.h>
+#    include <sys/mman.h>
+#    include <sys/stat.h>
+#    include <fcntl.h>
 #    include <spawn.h>
 #endif