feat: faster reading of local files

should be around 10x faster then what it was before

src/EterPack/Folder.cpp

@@ -76,23 +76,32 @@ bool Folder::fileExists(const std::string& fileName)
 
 bool Folder::getFile(const std::string& fileName, std::shared_ptr<std::vector<char>>& fileData)
 {
-    std::string realFileName = fileName;
+    constexpr char ymirPrefix[] = "d:/";
-    std::string ymirPrefix = "d:/";
+    std::string relative = fileName;
+    if (relative.rfind(ymirPrefix, 0) == 0)
+        relative.erase(0, sizeof(ymirPrefix) - 1);
 
-    if (fileName.find(ymirPrefix) == 0)
+    std::filesystem::path p = folderPath;
-        realFileName = realFileName.substr(ymirPrefix.length());
+    p /= relative;
 
-    realFileName = this->folderPath + "/" + realFileName;
+    std::ifstream file(p, std::ios::binary | std::ios::ate);
-
-    // Try to open the file
-    std::ifstream file(realFileName, std::ios::binary);
     if (!file.is_open())
         return false;
 
-    // Read the file's contents
+    // get size in one call
-    fileData = std::make_shared<std::vector<char>>(
+    std::ifstream::pos_type sz = file.tellg();
-        std::istreambuf_iterator<char>(file),
+    if (sz < 0)
-        std::istreambuf_iterator<char>()
+        return false;
-    );
+
+    // allocate exactly once
+    auto buf = std::make_shared<std::vector<char>>(static_cast<size_t>(sz));
+
+    // rewind and read in one go
+    file.seekg(0, std::ios::beg);
+    file.read(buf->data(), sz);
+    if (!file)
+        return false;
+
+    fileData = std::move(buf);
     return true;
 }