Applied modified and cleaned up patch #4275 from ihsan for bug #13874.

It deletes existing copies of a downloaded campaign before writing the new one.

src/filesystem.cpp

@@ -49,7 +49,8 @@ BPath be_path;
 
 //for getenv
 #include <cstdlib>
-
+#include <cerrno>
+#include <cstring>
 #include <algorithm>
 #include <fstream>
 #include <iostream>
@@ -316,6 +317,41 @@ void make_directory(const std::string& path)
 #endif
 }
 
+//this deletes a directory with no hidden files and subdirectories
+//also deletes a single file
+bool delete_directory(const std::string& path) 
+{
+	bool ret = true;
+	std::vector<std::string> files;
+	std::vector<std::string> dirs;
+
+	get_files_in_dir(path, &files, &dirs, ENTIRE_FILE_PATH);
+
+	if(!files.empty()) {
+		for(std::vector<std::string>::const_iterator i = files.begin(); i != files.end(); ++i) {
+			errno = 0;
+			if(remove((*i).c_str()) != 0) {
+				LOG_FS << "remove(" << (*i) << "): " << strerror(errno) << "\n";
+				ret = false;
+			}
+		}
+	}
+
+	if(!dirs.empty()) {
+		for(std::vector<std::string>::const_iterator j = dirs.begin(); j != dirs.end(); ++j) {
+			if(!delete_directory(*j))
+				ret = false;
+		}
+	}
+
+	errno = 0;
+	if(remove(path.c_str()) != 0) {
+		LOG_FS << "remove(" << path << "): " << strerror(errno) << "\n";
+		ret = false;
+	}
+	return ret;
+}
+
 std::string get_cwd()
 {
 	char buf[1024];

src/filesystem.hpp

@@ -56,6 +56,7 @@ std::string get_user_data_dir();
 std::string get_cwd();
 
 void make_directory(const std::string& dirname);
+bool delete_directory(const std::string& dirname);
 
 //basic disk I/O
 bool filesystem_init();

src/game.cpp

@@ -120,6 +120,7 @@ private:
 	void download_campaigns();
 	void upload_campaign(const std::string& campaign, network::connection sock);
 	void delete_campaign(const std::string& campaign, network::connection sock);
+	void remove_campaign(const std::string& campaign);
 
 	const int argc_;
 	int arg_;
@@ -987,6 +988,11 @@ void game_controller::download_campaigns()
 			return;
 		}
 
+		//remove any existing versions of the just downloaded campaign
+		//assuming it consists of a dir and a cfg file
+		remove_campaign(campaigns[index]);
+
+		//put a break at line below to see that it really works.
 		unarchive_campaign(cfg);
 
 		// when using zipios, force a reread zip and directory indices
@@ -1093,6 +1099,13 @@ void game_controller::delete_campaign(const std::string& campaign, network::conn
 	}
 }
 
+void game_controller::remove_campaign(const std::string& campaign)
+{
+	const std::string campaign_dir = get_user_data_dir() + "/data/campaigns/" + campaign;
+	delete_directory(campaign_dir);
+	delete_directory(campaign_dir + ".cfg");
+}
+
 bool game_controller::play_multiplayer()
 {
 	state_ = game_state();