Fix #8713: Change OTTD2FS and FS2OTTD to return string objects instead of static buffers

17 files changed, 108 insertions, 99 deletions

diff --git a/src/debug.cpp b/src/debug.cpp
index 034af755f..eb8dc5d4f 100644
--- a/src/debug.cpp
+++ b/src/debug.cpp
@@ -134,7 +134,7 @@ static void debug_print(const char *dbg, const char *buf)
 #if defined(_WIN32)
 		wchar_t system_buf[512];
 		convert_to_fs(buffer, system_buf, lengthof(system_buf), true);
-		_fputts(system_buf, stderr);
+		fputws(system_buf, stderr);
 #else
 		fputs(buffer, stderr);
 #endif
diff --git a/src/fileio.cpp b/src/fileio.cpp
index 6b33f8aa2..f2a2b14f3 100644
--- a/src/fileio.cpp
+++ b/src/fileio.cpp
@@ -279,7 +279,7 @@ bool FioCheckFileExists(const std::string &filename, Subdirectory subdir)
  */
 bool FileExists(const std::string &filename)
 {
-	return access(OTTD2FS(filename.c_str()), 0) == 0;
+	return access(OTTD2FS(filename).c_str(), 0) == 0;
 }
 
 /**
@@ -358,7 +358,7 @@ static FILE *FioFOpenFileSp(const std::string &filename, const char *mode, Searc
 	}
 
 #if defined(_WIN32)
-	if (mode[0] == 'r' && GetFileAttributes(OTTD2FS(buf.c_str())) == INVALID_FILE_ATTRIBUTES) return nullptr;
+	if (mode[0] == 'r' && GetFileAttributes(OTTD2FS(buf).c_str()) == INVALID_FILE_ATTRIBUTES) return nullptr;
 #endif
 
 	f = fopen(buf.c_str(), mode);
@@ -506,11 +506,11 @@ void FioCreateDirectory(const std::string &name)
 	/* Ignore directory creation errors; they'll surface later on, and most
 	 * of the time they are 'directory already exists' errors anyhow. */
 #if defined(_WIN32)
-	CreateDirectory(OTTD2FS(name.c_str()), nullptr);
+	CreateDirectory(OTTD2FS(name).c_str(), nullptr);
 #elif defined(OS2) && !defined(__INNOTEK_LIBC__)
-	mkdir(OTTD2FS(name.c_str()));
+	mkdir(OTTD2FS(name).c_str());
 #else
-	mkdir(OTTD2FS(name.c_str()), 0755);
+	mkdir(OTTD2FS(name).c_str(), 0755);
 #endif
 }
 
@@ -1315,7 +1315,7 @@ static uint ScanPath(FileScanner *fs, const char *extension, const char *path, s
 	if (path == nullptr || (dir = ttd_opendir(path)) == nullptr) return 0;
 
 	while ((dirent = readdir(dir)) != nullptr) {
-		const char *d_name = FS2OTTD(dirent->d_name);
+		std::string d_name = FS2OTTD(dirent->d_name);
 
 		if (!FiosIsValidFile(path, dirent, &sb)) continue;
 
@@ -1325,7 +1325,7 @@ static uint ScanPath(FileScanner *fs, const char *extension, const char *path, s
 		if (S_ISDIR(sb.st_mode)) {
 			/* Directory */
 			if (!recursive) continue;
-			if (strcmp(d_name, ".") == 0 || strcmp(d_name, "..") == 0) continue;
+			if (d_name == "." || d_name == "..") continue;
 			AppendPathSeparator(filename);
 			num += ScanPath(fs, extension, filename.c_str(), basepath_length, recursive);
 		} else if (S_ISREG(sb.st_mode)) {
diff --git a/src/fileio_func.h b/src/fileio_func.h
index 6dbaea897..142835650 100644
--- a/src/fileio_func.h
+++ b/src/fileio_func.h
@@ -132,7 +132,7 @@ int closedir(DIR *d);
  */
 static inline DIR *ttd_opendir(const char *path)
 {
-	return opendir(OTTD2FS(path));
+	return opendir(OTTD2FS(path).c_str());
 }
 
 
diff --git a/src/fios.cpp b/src/fios.cpp
index b48bc2108..b68da08f8 100644
--- a/src/fios.cpp
+++ b/src/fios.cpp
@@ -309,7 +309,7 @@ bool FiosFileScanner::AddFile(const std::string &filename, size_t basepath_lengt
 	FiosItem *fios = file_list.Append();
 #ifdef _WIN32
 	// Retrieve the file modified date using GetFileTime rather than stat to work around an obscure MSVC bug that affects Windows XP
-	HANDLE fh = CreateFile(OTTD2FS(filename.c_str()), GENERIC_READ, FILE_SHARE_READ | FILE_SHARE_WRITE, nullptr, OPEN_EXISTING, 0, nullptr);
+	HANDLE fh = CreateFile(OTTD2FS(filename).c_str(), GENERIC_READ, FILE_SHARE_READ | FILE_SHARE_WRITE, nullptr, OPEN_EXISTING, 0, nullptr);
 
 	if (fh != INVALID_HANDLE_VALUE) {
 		FILETIME ft;
@@ -384,7 +384,7 @@ static void FiosGetFileList(SaveLoadOperation fop, fios_getlist_callback_proc *c
 	/* Show subdirectories */
 	if ((dir = ttd_opendir(_fios_path->c_str())) != nullptr) {
 		while ((dirent = readdir(dir)) != nullptr) {
-			strecpy(d_name, FS2OTTD(dirent->d_name), lastof(d_name));
+			strecpy(d_name, FS2OTTD(dirent->d_name).c_str(), lastof(d_name));
 
 			/* found file must be directory, but not '.' or '..' */
 			if (FiosIsValidFile(_fios_path->c_str(), dirent, &sb) && S_ISDIR(sb.st_mode) &&
diff --git a/src/ini.cpp b/src/ini.cpp
index 4988c778e..a5045b715 100644
--- a/src/ini.cpp
+++ b/src/ini.cpp
@@ -53,7 +53,7 @@ bool IniFile::SaveToDisk(const std::string &filename)
 	std::string file_new{ filename };
 	file_new.append(".new");
 
-	std::ofstream os(OTTD2FS(file_new.c_str()));
+	std::ofstream os(OTTD2FS(file_new));
 	if (os.fail()) return false;
 
 	for (const IniGroup *group = this->group; group != nullptr; group = group->next) {
@@ -94,8 +94,8 @@ bool IniFile::SaveToDisk(const std::string &filename)
 #if defined(_WIN32)
 	/* Allocate space for one more \0 character. */
 	wchar_t tfilename[MAX_PATH + 1], tfile_new[MAX_PATH + 1];
-	wcsncpy(tfilename, OTTD2FS(filename.c_str()), MAX_PATH);
-	wcsncpy(tfile_new, OTTD2FS(file_new.c_str()), MAX_PATH);
+	wcsncpy(tfilename, OTTD2FS(filename).c_str(), MAX_PATH);
+	wcsncpy(tfile_new, OTTD2FS(file_new).c_str(), MAX_PATH);
 	/* SHFileOperation wants a double '\0' terminated string. */
 	tfilename[MAX_PATH - 1] = '\0';
 	tfile_new[MAX_PATH - 1] = '\0';
diff --git a/src/music/cocoa_m.cpp b/src/music/cocoa_m.cpp
index a989cfe76..279e0b38a 100644
--- a/src/music/cocoa_m.cpp
+++ b/src/music/cocoa_m.cpp
@@ -134,8 +134,8 @@ void MusicDriver_Cocoa::PlaySong(const MusicSongInfo &song)
 		return;
 	}
 
-	const char *os_file = OTTD2FS(filename.c_str());
-	CFAutoRelease<CFURLRef> url(CFURLCreateFromFileSystemRepresentation(kCFAllocatorDefault, (const UInt8*)os_file, strlen(os_file), false));
+	std::string os_file = OTTD2FS(filename);
+	CFAutoRelease<CFURLRef> url(CFURLCreateFromFileSystemRepresentation(kCFAllocatorDefault, (const UInt8*)os_file.c_str(), os_file.length(), false));
 
 	if (MusicSequenceFileLoad(_sequence, url.get(), kMusicSequenceFile_AnyType, 0) != noErr) {
 		DEBUG(driver, 0, "cocoa_m: Failed to load MIDI file");
diff --git a/src/music/dmusic.cpp b/src/music/dmusic.cpp
index c9447206a..619a20d8b 100644
--- a/src/music/dmusic.cpp
+++ b/src/music/dmusic.cpp
@@ -430,7 +430,7 @@ bool DLSFile::ReadDLSWaveList(FILE *f, DWORD list_length)
 
 bool DLSFile::LoadFile(const wchar_t *file)
 {
-	DEBUG(driver, 2, "DMusic: Try to load DLS file %s", FS2OTTD(file));
+	DEBUG(driver, 2, "DMusic: Try to load DLS file %s", FS2OTTD(file).c_str());
 
 	FILE *f = _wfopen(file, L"rb");
 	if (f == nullptr) return false;
@@ -881,7 +881,7 @@ static const char *LoadDefaultDLSFile(const char *user_dls)
 				if (!dls_file.LoadFile(path)) return "Can't load GM DLS collection";
 			}
 		} else {
-			if (!dls_file.LoadFile(OTTD2FS(user_dls))) return "Can't load GM DLS collection";
+			if (!dls_file.LoadFile(OTTD2FS(user_dls).c_str())) return "Can't load GM DLS collection";
 		}
 
 		/* Get download port and allocate download IDs. */
diff --git a/src/network/core/address.cpp b/src/network/core/address.cpp
index 2e00b5b19..a45bd4914 100644
--- a/src/network/core/address.cpp
+++ b/src/network/core/address.cpp
@@ -246,7 +246,7 @@ SOCKET NetworkAddress::Resolve(int family, int socktype, int flags, SocketList *
 	if (e != 0) {
 		if (func != ResolveLoopProc) {
 			DEBUG(net, 0, "getaddrinfo for hostname \"%s\", port %s, address family %s and socket type %s failed: %s",
-				this->hostname, port_name, AddressFamilyAsString(family), SocketTypeAsString(socktype), FS2OTTD(gai_strerror(e)));
+				this->hostname, port_name, AddressFamilyAsString(family), SocketTypeAsString(socktype), FS2OTTD(gai_strerror(e)).c_str());
 		}
 		return INVALID_SOCKET;
 	}
diff --git a/src/os/os2/os2.cpp b/src/os/os2/os2.cpp
index f1128b0c6..009a3e0ed 100644
--- a/src/os/os2/os2.cpp
+++ b/src/os/os2/os2.cpp
@@ -203,9 +203,6 @@ bool GetClipboardContents(char *buffer, const char *last)
 }
 
 
-const char *FS2OTTD(const char *name) {return name;}
-const char *OTTD2FS(const char *name) {return name;}
-
 void OSOpenBrowser(const char *url)
 {
 	// stub only
diff --git a/src/os/unix/unix.cpp b/src/os/unix/unix.cpp
index 9ef2bc386..57edf1d38 100644
--- a/src/os/unix/unix.cpp
+++ b/src/os/unix/unix.cpp
@@ -146,9 +146,8 @@ static const char *GetLocalCode()
  * Convert between locales, which from and which to is set in the calling
  * functions OTTD2FS() and FS2OTTD().
  */
-static const char *convert_tofrom_fs(iconv_t convd, const char *name)
+static const char *convert_tofrom_fs(iconv_t convd, const char *name, char *outbuf, size_t outlen)
 {
-	static char buf[1024];
 	/* There are different implementations of iconv. The older ones,
 	 * e.g. SUSv2, pass a const pointer, whereas the newer ones, e.g.
 	 * IEEE 1003.1 (2004), pass a non-const pointer. */
@@ -158,9 +157,8 @@ static const char *convert_tofrom_fs(iconv_t convd, const char *name)
 	const char *inbuf = name;
 #endif
 
-	char *outbuf  = buf;
-	size_t outlen = sizeof(buf) - 1;
 	size_t inlen  = strlen(name);
+	char *buf = outbuf;
 
 	strecpy(outbuf, name, outbuf + outlen);
 
@@ -179,9 +177,10 @@ static const char *convert_tofrom_fs(iconv_t convd, const char *name)
  * @param name pointer to a valid string that will be converted
  * @return pointer to a new stringbuffer that contains the converted string
  */
-const char *OTTD2FS(const char *name)
+std::string OTTD2FS(const std::string &name)
 {
 	static iconv_t convd = (iconv_t)(-1);
+	char buf[1024] = {};
 
 	if (convd == (iconv_t)(-1)) {
 		const char *env = GetLocalCode();
@@ -192,17 +191,18 @@ const char *OTTD2FS(const char *name)
 		}
 	}
 
-	return convert_tofrom_fs(convd, name);
+	return convert_tofrom_fs(convd, name.c_str(), buf, lengthof(buf));
 }
 
 /**
  * Convert to OpenTTD's encoding from that of the local environment
- * @param name pointer to a valid string that will be converted
+ * @param name valid string that will be converted
  * @return pointer to a new stringbuffer that contains the converted string
  */
-const char *FS2OTTD(const char *name)
+std::string FS2OTTD(const std::string &name)
 {
 	static iconv_t convd = (iconv_t)(-1);
+	char buf[1024] = {};
 
 	if (convd == (iconv_t)(-1)) {
 		const char *env = GetLocalCode();
@@ -213,12 +213,9 @@ const char *FS2OTTD(const char *name)
 		}
 	}
 
-	return convert_tofrom_fs(convd, name);
+	return convert_tofrom_fs(convd, name.c_str(), buf, lengthof(buf));
 }
 
-#else
-const char *FS2OTTD(const char *name) {return name;}
-const char *OTTD2FS(const char *name) {return name;}
 #endif /* WITH_ICONV */
 
 void ShowInfo(const char *str)
diff --git a/src/os/windows/crashlog_win.cpp b/src/os/windows/crashlog_win.cpp
index 76a05eaa9..9768bcc82 100644
--- a/src/os/windows/crashlog_win.cpp
+++ b/src/os/windows/crashlog_win.cpp
@@ -189,7 +189,7 @@ static char *PrintModuleInfo(char *output, const char *last, HMODULE mod)
 	GetModuleFileName(mod, buffer, MAX_PATH);
 	GetFileInfo(&dfi, buffer);
 	output += seprintf(output, last, " %-20s handle: %p size: %d crc: %.8X date: %d-%.2d-%.2d %.2d:%.2d:%.2d\n",
-		FS2OTTD(buffer),
+		FS2OTTD(buffer).c_str(),
 		mod,
 		dfi.size,
 		dfi.crc32,
@@ -501,7 +501,7 @@ char *CrashLogWindows::AppendDecodedStacktrace(char *buffer, const char *last) c
 		MiniDumpWriteDump_t funcMiniDumpWriteDump = (MiniDumpWriteDump_t)GetProcAddress(dbghelp, "MiniDumpWriteDump");
 		if (funcMiniDumpWriteDump != nullptr) {
 			seprintf(filename, filename_last, "%scrash.dmp", _personal_dir.c_str());
-			HANDLE file  = CreateFile(OTTD2FS(filename), GENERIC_WRITE, 0, nullptr, CREATE_ALWAYS, 0, 0);
+			HANDLE file  = CreateFile(OTTD2FS(filename).c_str(), GENERIC_WRITE, 0, nullptr, CREATE_ALWAYS, 0, 0);
 			HANDLE proc  = GetCurrentProcess();
 			DWORD procid = GetCurrentProcessId();
 			MINIDUMP_EXCEPTION_INFORMATION mdei;
@@ -689,7 +689,8 @@ static INT_PTR CALLBACK CrashDialogFunc(HWND wnd, UINT msg, WPARAM wParam, LPARA
 	switch (msg) {
 		case WM_INITDIALOG: {
 			/* We need to put the crash-log in a separate buffer because the default
-			 * buffer in OTTD2FS is not large enough (512 chars) */
+			 * buffer in MB_TO_WIDE is not large enough (512 chars) */
+			wchar_t filenamebuf[MAX_PATH * 2];
 			wchar_t crash_msgW[lengthof(CrashLogWindows::current->crashlog)];
 			/* Convert unix -> dos newlines because the edit box only supports that properly :( */
 			const char *unix_nl = CrashLogWindows::current->crashlog;
@@ -704,19 +705,23 @@ static INT_PTR CALLBACK CrashDialogFunc(HWND wnd, UINT msg, WPARAM wParam, LPARA
 
 			/* Add path to crash.log and crash.dmp (if any) to the crash window text */
 			size_t len = wcslen(_crash_desc) + 2;
-			len += wcslen(OTTD2FS(CrashLogWindows::current->crashlog_filename)) + 2;
-			len += wcslen(OTTD2FS(CrashLogWindows::current->crashdump_filename)) + 2;
-			len += wcslen(OTTD2FS(CrashLogWindows::current->screenshot_filename)) + 1;
+			len += wcslen(convert_to_fs(CrashLogWindows::current->crashlog_filename, filenamebuf, lengthof(filenamebuf), false)) + 2;
+			len += wcslen(convert_to_fs(CrashLogWindows::current->crashdump_filename, filenamebuf, lengthof(filenamebuf), false)) + 2;
+			len += wcslen(convert_to_fs(CrashLogWindows::current->screenshot_filename, filenamebuf, lengthof(filenamebuf), false)) + 1;
 
 			wchar_t *text = AllocaM(wchar_t, len);
-			_snwprintf(text, len, _crash_desc, OTTD2FS(CrashLogWindows::current->crashlog_filename));
-			if (OTTD2FS(CrashLogWindows::current->crashdump_filename)[0] != L'\0') {
+			int printed = _snwprintf(text, len, _crash_desc, convert_to_fs(CrashLogWindows::current->crashlog_filename, filenamebuf, lengthof(filenamebuf), false));
+			if (printed < 0 || (size_t)printed > len) {
+				MessageBox(wnd, L"Catastrophic failure trying to display crash message. Could not perform text formatting.", L"OpenTTD", MB_ICONERROR);
+				return FALSE;
+			}
+			if (convert_to_fs(CrashLogWindows::current->crashdump_filename, filenamebuf, lengthof(filenamebuf), false)[0] != L'\0') {
 				wcscat(text, L"\n");
-				wcscat(text, OTTD2FS(CrashLogWindows::current->crashdump_filename));
+				wcscat(text, filenamebuf);
 			}
-			if (OTTD2FS(CrashLogWindows::current->screenshot_filename)[0] != L'\0') {
+			if (convert_to_fs(CrashLogWindows::current->screenshot_filename, filenamebuf, lengthof(filenamebuf), false)[0] != L'\0') {
 				wcscat(text, L"\n");
-				wcscat(text, OTTD2FS(CrashLogWindows::current->screenshot_filename));
+				wcscat(text, filenamebuf);
 			}
 
 			SetDlgItemText(wnd, 10, text);
@@ -730,18 +735,20 @@ static INT_PTR CALLBACK CrashDialogFunc(HWND wnd, UINT msg, WPARAM wParam, LPARA
 					CrashLog::AfterCrashLogCleanup();
 					ExitProcess(2);
 				case 13: // Emergency save
+					wchar_t filenamebuf[MAX_PATH * 2];
 					char filename[MAX_PATH];
 					if (CrashLogWindows::current->WriteSavegame(filename, lastof(filename))) {
-						size_t len = wcslen(_save_succeeded) + wcslen(OTTD2FS(filename)) + 1;
+						convert_to_fs(filename, filenamebuf, lengthof(filenamebuf), false);
+						size_t len = lengthof(_save_succeeded) + wcslen(filenamebuf) + 1;
 						wchar_t *text = AllocaM(wchar_t, len);
-						_snwprintf(text, len, _save_succeeded, OTTD2FS(filename));
+						_snwprintf(text, len, _save_succeeded, filenamebuf);
 						MessageBox(wnd, text, L"Save successful", MB_ICONINFORMATION);
 					} else {
 						MessageBox(wnd, L"Save failed", L"Save failed", MB_ICONINFORMATION);
 					}
 					break;
 				case 15: // Expand window to show crash-message
-					_expanded ^= 1;
+					_expanded = !_expanded;
 					SetWndSize(wnd, _expanded);
 					break;
 			}
diff --git a/src/os/windows/font_win32.cpp b/src/os/windows/font_win32.cpp
index 9a9dba2f2..1d923ddb2 100644
--- a/src/os/windows/font_win32.cpp
+++ b/src/os/windows/font_win32.cpp
@@ -83,7 +83,7 @@ FT_Error GetFontByFaceName(const char *font_name, FT_Face *face)
 	}
 
 	/* Convert font name to file system encoding. */
-	wchar_t *font_namep = wcsdup(OTTD2FS(font_name));
+	wchar_t *font_namep = wcsdup(OTTD2FS(font_name).c_str());
 
 	for (index = 0;; index++) {
 		wchar_t *s;
@@ -377,6 +377,7 @@ Win32FontCache::Win32FontCache(FontSize fs, const LOGFONT &logfont, int pixels)
 {
 	this->dc = CreateCompatibleDC(nullptr);
 	this->SetFontSize(fs, pixels);
+	this->fontname = FS2OTTD(this->logfont.lfFaceName);
 }
 
 Win32FontCache::~Win32FontCache()
@@ -438,7 +439,7 @@ void Win32FontCache::SetFontSize(FontSize fs, int pixels)
 	this->glyph_size.cx = otm->otmTextMetrics.tmMaxCharWidth;
 	this->glyph_size.cy = otm->otmTextMetrics.tmHeight;
 
-	DEBUG(freetype, 2, "Loaded font '%s' with size %d", FS2OTTD((LPTSTR)((BYTE *)otm + (ptrdiff_t)otm->otmpFullName)), pixels);
+	DEBUG(freetype, 2, "Loaded font '%s' with size %d", FS2OTTD((LPWSTR)((BYTE *)otm + (ptrdiff_t)otm->otmpFullName)).c_str(), pixels);
 }
 
 /**
@@ -541,10 +542,10 @@ void Win32FontCache::ClearFontCache()
 	/* Convert characters outside of the BMP into surrogate pairs. */
 	WCHAR chars[2];
 	if (key >= 0x010000U) {
-		chars[0] = (WCHAR)(((key - 0x010000U) >> 10) + 0xD800);
-		chars[1] = (WCHAR)(((key - 0x010000U) & 0x3FF) + 0xDC00);
+		chars[0] = (wchar_t)(((key - 0x010000U) >> 10) + 0xD800);
+		chars[1] = (wchar_t)(((key - 0x010000U) & 0x3FF) + 0xDC00);
 	} else {
-		chars[0] = (WCHAR)(key & 0xFFFF);
+		chars[0] = (wchar_t)(key & 0xFFFF);
 	}
 
 	WORD glyphs[2] = { 0, 0 };
diff --git a/src/os/windows/font_win32.h b/src/os/windows/font_win32.h
index ba413fae5..6ab304c89 100644
--- a/src/os/windows/font_win32.h
+++ b/src/os/windows/font_win32.h
@@ -21,6 +21,7 @@ private:
 	HDC dc = nullptr;     ///< Cached GDI device context.
 	HGDIOBJ old_font;     ///< Old font selected into the GDI context.
 	SIZE glyph_size;      ///< Maximum size of regular glyphs.
+	std::string fontname; ///< Cached copy of this->logfont.lfFaceName
 
 	void SetFontSize(FontSize fs, int pixels);
 
@@ -33,7 +34,7 @@ public:
 	~Win32FontCache();
 	void ClearFontCache() override;
 	GlyphID MapCharToGlyph(WChar key) override;
-	const char *GetFontName() override { return FS2OTTD(this->logfont.lfFaceName); }
+	const char *GetFontName() override { return this->fontname.c_str(); }
 	const void *GetOSHandle() override { return &this->logfont; }
 };
 
diff --git a/src/os/windows/win32.cpp b/src/os/windows/win32.cpp
index cfe7d42d9..568876ab1 100644
--- a/src/os/windows/win32.cpp
+++ b/src/os/windows/win32.cpp
@@ -57,7 +57,7 @@ bool LoadLibraryList(Function proc[], const char *dll)
 {
 	while (*dll != '\0') {
 		HMODULE lib;
-		lib = LoadLibrary(OTTD2FS(dll));
+		lib = LoadLibrary(OTTD2FS(dll).c_str());
 
 		if (lib == nullptr) return false;
 		for (;;) {
@@ -77,12 +77,12 @@ bool LoadLibraryList(Function proc[], const char *dll)
 void ShowOSErrorBox(const char *buf, bool system)
 {
 	MyShowCursor(true);
-	MessageBox(GetActiveWindow(), OTTD2FS(buf), L"Error!", MB_ICONSTOP | MB_TASKMODAL);
+	MessageBox(GetActiveWindow(), OTTD2FS(buf).c_str(), L"Error!", MB_ICONSTOP | MB_TASKMODAL);
 }
 
 void OSOpenBrowser(const char *url)
 {
-	ShellExecute(GetActiveWindow(), L"open", OTTD2FS(url), nullptr, nullptr, SW_SHOWNORMAL);
+	ShellExecute(GetActiveWindow(), L"open", OTTD2FS(url).c_str(), nullptr, nullptr, SW_SHOWNORMAL);
 }
 
 /* Code below for windows version of opendir/readdir/closedir copied and
@@ -141,14 +141,14 @@ DIR *opendir(const wchar_t *path)
 	if ((fa != INVALID_FILE_ATTRIBUTES) && (fa & FILE_ATTRIBUTE_DIRECTORY)) {
 		d = dir_calloc();
 		if (d != nullptr) {
-			wchar_t search_path[MAX_PATH];
+			std::wstring search_path = path;
 			bool slash = path[wcslen(path) - 1] == '\\';
 
 			/* build search path for FindFirstFile, try not to append additional slashes
 			 * as it throws Win9x off its groove for root directories */
-			_snwprintf(search_path, lengthof(search_path), L"%s%s*", path, slash ? L"" : L"\\");
-			*lastof(search_path) = '\0';
-			d->hFind = FindFirstFile(search_path, &d->fd);
+			if (!slash) search_path += L"\\";
+			search_path += L"*";
+			d->hFind = FindFirstFile(search_path.c_str(), &d->fd);
 
 			if (d->hFind != INVALID_HANDLE_VALUE ||
 					GetLastError() == ERROR_NO_MORE_FILES) { // the directory is empty
@@ -246,7 +246,7 @@ bool FiosGetDiskFreeSpace(const char *path, uint64 *tot)
 	UINT sem = SetErrorMode(SEM_FAILCRITICALERRORS);  // disable 'no-disk' message box
 
 	ULARGE_INTEGER bytes_free;
-	bool retval = GetDiskFreeSpaceEx(OTTD2FS(path), &bytes_free, nullptr, nullptr);
+	bool retval = GetDiskFreeSpaceEx(OTTD2FS(path).c_str(), &bytes_free, nullptr, nullptr);
 	if (retval) *tot = bytes_free.QuadPart;
 
 	SetErrorMode(sem); // reset previous setting
@@ -415,7 +415,7 @@ int APIENTRY WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLi
 	/* Convert the command line to UTF-8. We need a dedicated buffer
 	 * for this because argv[] points into this buffer and this needs to
 	 * be available between subsequent calls to FS2OTTD(). */
-	char *cmdline = stredup(FS2OTTD(GetCommandLine()));
+	char *cmdline = stredup(FS2OTTD(GetCommandLine()).c_str());
 
 #if defined(_DEBUG)
 	CreateConsole();
@@ -553,34 +553,40 @@ bool GetClipboardContents(char *buffer, const char *last)
 
 
 /**
- * Convert to OpenTTD's encoding from wide characters.
+ * Convert to OpenTTD's encoding from a wide string.
  * OpenTTD internal encoding is UTF8.
- * The returned value's contents can only be guaranteed until the next call to
- * this function. So if the value is needed for anything else, use convert_from_fs
- * @param name pointer to a valid string that will be converted (local, or wide)
- * @return pointer to the converted string; if failed string is of zero-length
+ * @param name valid string that will be converted (local, or wide)
+ * @return converted string; if failed string is of zero-length
  * @see the current code-page comes from video\win32_v.cpp, event-notification
  * WM_INPUTLANGCHANGE
  */
-const char *FS2OTTD(const wchar_t *name)
+std::string FS2OTTD(const std::wstring &name)
 {
-	static char utf8_buf[512];
-	return convert_from_fs(name, utf8_buf, lengthof(utf8_buf));
+	int name_len = (name.length() >= INT_MAX) ? INT_MAX : (int)name.length();
+	int len = WideCharToMultiByte(CP_UTF8, 0, name.c_str(), name_len, nullptr, 0, nullptr, nullptr);
+	if (len <= 0) return std::string();
+	char *utf8_buf = AllocaM(char, len + 1);
+	utf8_buf[len] = '\0';
+	WideCharToMultiByte(CP_UTF8, 0, name.c_str(), name_len, utf8_buf, len, nullptr, nullptr);
+	return std::string(utf8_buf, static_cast<size_t>(len));
 }
 
 /**
- * Convert from OpenTTD's encoding to wide characters.
+ * Convert from OpenTTD's encoding to a wide string.
  * OpenTTD internal encoding is UTF8.
- * The returned value's contents can only be guaranteed until the next call to
- * this function. So if the value is needed for anything else, use convert_from_fs
- * @param name pointer to a valid string that will be converted (UTF8)
+ * @param name valid string that will be converted (UTF8)
  * @param console_cp convert to the console encoding instead of the normal system encoding.
- * @return pointer to the converted string; if failed string is of zero-length
+ * @return converted string; if failed string is of zero-length
  */
-const wchar_t *OTTD2FS(const char *name, bool console_cp)
+std::wstring OTTD2FS(const std::string &name, bool console_cp)
 {
-	static wchar_t system_buf[512];
-	return convert_to_fs(name, system_buf, lengthof(system_buf), console_cp);
+	int name_len = (name.length() >= INT_MAX) ? INT_MAX : (int)name.length();
+	int len = MultiByteToWideChar(CP_UTF8, 0, name.c_str(), name_len, nullptr, 0);
+	if (len <= 0) return std::wstring();
+	wchar_t *system_buf = AllocaM(wchar_t, len + 1);
+	system_buf[len] = L'\0';
+	MultiByteToWideChar(CP_UTF8, 0, name.c_str(), name_len, system_buf, len);
+	return std::wstring(system_buf, static_cast<size_t>(len));
 }
 
 
@@ -594,10 +600,8 @@ const wchar_t *OTTD2FS(const char *name, bool console_cp)
  */
 char *convert_from_fs(const wchar_t *name, char *utf8_buf, size_t buflen)
 {
-	const wchar_t *wide_buf = name;
-
 	/* Convert UTF-16 string to UTF-8. */
-	int len = WideCharToMultiByte(CP_UTF8, 0, wide_buf, -1, utf8_buf, (int)buflen, nullptr, nullptr);
+	int len = WideCharToMultiByte(CP_UTF8, 0, name, -1, utf8_buf, (int)buflen, nullptr, nullptr);
 	if (len == 0) utf8_buf[0] = '\0';
 
 	return utf8_buf;
diff --git a/src/stdafx.h b/src/stdafx.h
index 42a6106e8..06860f104 100644
--- a/src/stdafx.h
+++ b/src/stdafx.h
@@ -93,6 +93,7 @@
 #include <climits>
 #include <cassert>
 #include <memory>
+#include <string>
 
 #ifndef SIZE_MAX
 #	define SIZE_MAX ((size_t)-1)
@@ -252,25 +253,26 @@
 
 #endif /* defined(_MSC_VER) */
 
-/* NOTE: the string returned by these functions is only valid until the next
- * call to the same function and is not thread- or reentrancy-safe */
 #if !defined(STRGEN) && !defined(SETTINGSGEN)
 #	if defined(_WIN32)
 		char *getcwd(char *buf, size_t size);
-#		include <tchar.h>
 #		include <io.h>
+#		include <tchar.h>
 
-		namespace std { using ::_wfopen; }
-#		define fopen(file, mode) _wfopen(OTTD2FS(file), _T(mode))
-#		define unlink(file) _wunlink(OTTD2FS(file))
+#		define fopen(file, mode) _wfopen(OTTD2FS(file).c_str(), _T(mode))
+#		define unlink(file) _wunlink(OTTD2FS(file).c_str())
 
-		const char *FS2OTTD(const wchar_t *name);
-		const wchar_t *OTTD2FS(const char *name, bool console_cp = false);
+		std::string FS2OTTD(const std::wstring &name);
+		std::wstring OTTD2FS(const std::string &name, bool console_cp = false);
+#	elif defined(WITH_ICONV)
+#		define fopen(file, mode) fopen(OTTD2FS(file).c_str(), mode)
+		std::string FS2OTTD(const std::string &name);
+		std::string OTTD2FS(const std::string &name);
 #	else
-#		define fopen(file, mode) fopen(OTTD2FS(file), mode)
-		const char *FS2OTTD(const char *name);
-		const char *OTTD2FS(const char *name);
-#	endif /* _WIN32 */
+		// no override of fopen() since no transformation is required of the filename
+		template <typename T> std::string FS2OTTD(T name) { return name; }
+		template <typename T> std::string OTTD2FS(T name) { return name; }
+#	endif /* _WIN32 or WITH_ICONV */
 #endif /* STRGEN || SETTINGSGEN */
 
 #if defined(_WIN32) || defined(__OS2__) && !defined(__INNOTEK_LIBC__)
diff --git a/src/strings.cpp b/src/strings.cpp
index 08e826141..7cbdc3cb0 100644
--- a/src/strings.cpp
+++ b/src/strings.cpp
@@ -1910,14 +1910,14 @@ static void GetLanguageList(const char *path)
 	if (dir != nullptr) {
 		struct dirent *dirent;
 		while ((dirent = readdir(dir)) != nullptr) {
-			const char *d_name    = FS2OTTD(dirent->d_name);
-			const char *extension = strrchr(d_name, '.');
+			std::string d_name = FS2OTTD(dirent->d_name);
+			const char *extension = strrchr(d_name.c_str(), '.');
 
 			/* Not a language file */
 			if (extension == nullptr || strcmp(extension, ".lng") != 0) continue;
 
 			LanguageMetadata lmd;
-			seprintf(lmd.file, lastof(lmd.file), "%s%s", path, d_name);
+			seprintf(lmd.file, lastof(lmd.file), "%s%s", path, d_name.c_str());
 
 			/* Check whether the file is of the correct version */
 			if (!GetLanguageFileHeader(lmd.file, &lmd)) {
diff --git a/src/video/win32_v.cpp b/src/video/win32_v.cpp
index 1d9cd3e2b..1b3476dab 100644
--- a/src/video/win32_v.cpp
+++ b/src/video/win32_v.cpp
@@ -214,7 +214,7 @@ bool VideoDriver_Win32Base::MakeWindow(bool full_screen, bool resize)
 			char window_title[64];
 			seprintf(window_title, lastof(window_title), "OpenTTD %s", _openttd_revision);
 
-			this->main_wnd = CreateWindow(L"OTTD", OTTD2FS(window_title), style, x, y, w, h, 0, 0, GetModuleHandle(nullptr), this);
+			this->main_wnd = CreateWindow(L"OTTD", OTTD2FS(window_title).c_str(), style, x, y, w, h, 0, 0, GetModuleHandle(nullptr), this);
 			if (this->main_wnd == nullptr) usererror("CreateWindow failed");
 			ShowWindow(this->main_wnd, showstyle);
 		}
@@ -331,7 +331,7 @@ static LRESULT HandleIMEComposition(HWND hwnd, WPARAM wParam, LPARAM lParam)
 			/* Transmit text to windowing system. */
 			if (len > 0) {
 				HandleTextInput(nullptr, true); // Clear marked string.
-				HandleTextInput(FS2OTTD(str));
+				HandleTextInput(FS2OTTD(str).c_str());
 			}
 			SetCompositionPos(hwnd);