Win32: Drastically improve load times with unpacked planet/

C4Group::SearchNextEntry would waste lots of cycles looking up file
attributes that were never inspected afterwards. Since all we want is
the file size, and we already get that for free from FindFirstFile and
FindNextFile, store it with the directory iterator instead of querying
it at every iteration.

This reduces load times on my machine by almost half, tested across
several different scenarios.

src/c4group/C4Group.cpp

@@ -422,7 +422,7 @@ void C4GroupEntry::Set(const DirectoryIterator &iter, const char * path)
 
 	SCopy(GetFilename(*iter),FileName,_MAX_FNAME);
 	SCopy(*iter, DiskPath, _MAX_PATH-1);
-	Size = FileSize(*iter);
+	Size = iter.GetFileSize();
 	Status=C4GRES_OnDisk;
 	Packed=false;
 	ChildGroup=false;

src/platform/StdFile.cpp

@@ -989,7 +989,10 @@ void DirectoryIterator::Read(const char *dirname)
 		// ...unless they're . or ..
 		if (file.cFileName[0] == '.' && (file.cFileName[1] == '\0' || (file.cFileName[1] == '.' && file.cFileName[2] == '\0')))
 			continue;
-		p->files.push_back(StdStrBuf(file.cFileName).getData());
+
+		size_t size = (file.nFileSizeHigh * (size_t(MAXDWORD) + 1)) + file.nFileSizeLow;
+
+		p->files.emplace_back(StdStrBuf(file.cFileName).getData(), size);
 	}
 	while (FindNextFileW(fh, &file));
 	FindClose(fh);
@@ -1016,14 +1019,14 @@ void DirectoryIterator::Read(const char *dirname)
 		// ...unless they're . or ..
 		if (file->d_name[0] == '.' && (file->d_name[1] == '\0' || (file->d_name[1] == '.' && file->d_name[2] == '\0')))
 			continue;
-		p->files.push_back(file->d_name);
+		p->files.emplace_back(file->d_name, 0);
 	}
 	closedir(fh);
 #endif
 	// Sort list
 	std::sort(p->files.begin(), p->files.end());
 	for (FileList::iterator it = p->files.begin(); it != p->files.end(); ++it)
-		it->insert(0, search_path); // prepend path to all file entries
+		it->first.insert(0, search_path); // prepend path to all file entries
 	iter = p->files.begin();
 	p->directory = dirname;
 }
@@ -1039,7 +1042,7 @@ const char * DirectoryIterator::operator*() const
 {
 	if (iter == p->files.end())
 		return NULL;
-	return iter->c_str();
+	return iter->first.c_str();
 }
 DirectoryIterator DirectoryIterator::operator++(int)
 {
@@ -1048,6 +1051,15 @@ DirectoryIterator DirectoryIterator::operator++(int)
 	return tmp;
 }
 
+size_t DirectoryIterator::GetFileSize() const
+{
+#ifdef _WIN32
+	return iter->second;
+#else
+	return FileSize(iter->first.c_str());
+#endif
+}
+
 int ForEachFile(const char *szDirName, bool (*fnCallback)(const char *))
 {
 	if (!szDirName || !fnCallback)

src/platform/StdFile.h

@@ -94,6 +94,9 @@ public:
 	~DirectoryIterator();
 
 	const char * operator * () const;
+	const char *GetName() const { return **this; }
+	size_t GetFileSize() const;
+
 	DirectoryIterator& operator ++ ();
 	DirectoryIterator operator ++ (int);
 	void Clear(); // put iterator into empty state and clear any cached directory listing
@@ -102,7 +105,7 @@ public:
 private:
 	void Read(const char *dirname);
 	friend struct DirectoryIteratorP;
-	typedef std::vector<std::string> FileList;
+	typedef std::vector<std::pair<std::string, size_t>> FileList;
 	DirectoryIteratorP *p;
 	FileList::iterator iter;
 };