From 32dcb2a5b51d30877266935ef44c3c95a221133e Mon Sep 17 00:00:00 2001
From: Michael Oliver <michael.oliver_@outlook.com>
Date: Sun, 14 Jun 2026 10:06:25 +0100
Subject: [PATCH] fix(IW4-TU6): avoid large string copies for file overrides

---
 src/game/iw4/mp_tu6/components/mpsp.cpp       | 45 ++++++++++++++-----
 src/game/iw4/mp_tu6/components/scr_parser.cpp | 31 +++++++++----
 2 files changed, 57 insertions(+), 19 deletions(-)

diff --git a/src/game/iw4/mp_tu6/components/mpsp.cpp b/src/game/iw4/mp_tu6/components/mpsp.cpp
index 814615c..bca5786 100644
--- a/src/game/iw4/mp_tu6/components/mpsp.cpp
+++ b/src/game/iw4/mp_tu6/components/mpsp.cpp
@@ -308,7 +308,7 @@ void override_(MapEnts *asset)
 
 namespace RawFile_
 {
-std::unordered_map<std::string, std::unique_ptr<std::string>> rawfile_buffers;
+std::unordered_map<std::string, std::unique_ptr<char[]>> rawfile_buffers;
 
 void override_(RawFile *asset)
 {
@@ -330,14 +330,40 @@ void override_(RawFile *asset)
     }
 
     const std::string filename = Asset::get_load_dir() + "\\" + asset->name;
-    const std::string buffer = FS::ReadTextFile(filename);
+    const std::string normalized = FS::NormalizePath(filename);
+    FILE *file = fopen(normalized.c_str(), "rb");
 
-    if (buffer.empty())
+    if (!file)
+    {
+        return;
+    }
+
+    fseek(file, 0, SEEK_END);
+    const long file_size = ftell(file);
+    fseek(file, 0, SEEK_SET);
+
+    if (file_size <= 0)
+    {
+        fclose(file);
+        return;
+    }
+
+    std::unique_ptr<char[]> buffer(new (std::nothrow) char[file_size + 1]);
+    if (!buffer)
     {
+        fclose(file);
         return;
     }
 
-    // NOTE: It seems that the engine will handle us giving back uncompressed strings (tested at least for .gsc files!)
+    const size_t bytes_read = fread(buffer.get(), 1, file_size, file);
+    fclose(file);
+
+    if (bytes_read != static_cast<size_t>(file_size))
+    {
+        return;
+    }
+
+    buffer[bytes_read] = '\0';
 
     DbgPrint("Overriding rawfile asset %s from fastfile %s\n", asset->name, g_load->file->name);
 
@@ -346,15 +372,12 @@ void override_(RawFile *asset)
     {
         rawfile_buffers.erase(itr);
     }
-    rawfile_buffers[asset->name] = make_unique<std::string>();
-    itr = rawfile_buffers.find(asset->name);
-    auto rawfile_buffer = itr->second.get();
-
-    rawfile_buffer->assign(buffer);
+    rawfile_buffers[asset->name] = std::move(buffer);
+    char *rawfile_buffer = rawfile_buffers[asset->name].get();
 
     asset->compressedLen = 0; // Force the engine to treat it as an uncompressed buffer!
-    asset->len = rawfile_buffer->length();
-    asset->buffer = rawfile_buffer->data();
+    asset->len = static_cast<int>(bytes_read);
+    asset->buffer = rawfile_buffer;
 }
 
 } // namespace RawFile_
diff --git a/src/game/iw4/mp_tu6/components/scr_parser.cpp b/src/game/iw4/mp_tu6/components/scr_parser.cpp
index 4678caa..3e8f971 100644
--- a/src/game/iw4/mp_tu6/components/scr_parser.cpp
+++ b/src/game/iw4/mp_tu6/components/scr_parser.cpp
@@ -32,19 +32,34 @@ char *Scr_AddSourceBuffer_Hook(const char *filename, const char *extFilename)
     std::string overridePath = modBasePath + "\\" + extFilename;
     std::replace(overridePath.begin(), overridePath.end(), '/', '\\');
 
-    // Try to load override file
-    std::string fileContent = filesystem::read_file_to_string(overridePath);
-    if (fileContent.empty())
+    FILE *file = fopen(overridePath.c_str(), "rb");
+    if (!file)
         return callOriginal();
 
-    // Allocate buffer using game's memory allocator
-    char *buffer = (char *)Hunk_AllocateTempMemoryHighInternal(fileContent.size() + 1);
+    fseek(file, 0, SEEK_END);
+    const long fileSize = ftell(file);
+    fseek(file, 0, SEEK_SET);
+
+    if (fileSize <= 0)
+    {
+        fclose(file);
+        return callOriginal();
+    }
+
+    char *buffer = (char *)Hunk_AllocateTempMemoryHighInternal(fileSize + 1);
     if (!buffer)
+    {
+        fclose(file);
+        return callOriginal();
+    }
+
+    const size_t bytesRead = fread(buffer, 1, fileSize, file);
+    fclose(file);
+
+    if (bytesRead != static_cast<size_t>(fileSize))
         return callOriginal();
 
-    // Copy content and null terminate
-    memcpy(buffer, fileContent.c_str(), fileContent.size());
-    buffer[fileContent.size()] = '\0';
+    buffer[bytesRead] = '\0';
 
     DbgPrint("scr_parser: Loaded override script: %s\n", overridePath.c_str());
     return buffer;