Add support for standard file paths on Windows.

- If the current user does not have write permissions for the directory
  zdoom.exe is located in, use standard folder paths located in their home
  directory instead. This is a common scenario when people put ZDoom into
  Program Files. (Ironically, zdoom.ini used to be in AppData, buth then
  people complained when it wasn't in the same directory as zdoom.exe, so
  it got turned into zdoom-<user>.ini so at least it could retain some
  multi-user support. I'm not sure when the AppData support was removed,
  though, since it should have still been kept around for migrating
  configs to the new name.)

src/m_misc.cpp

@@ -646,8 +646,9 @@ void M_ScreenShot (const char *filename)
 		if (dirlen == 0)
 		{
 			autoname = M_GetScreenshotsPath();
+			dirlen = autoname.Len();
 		}
-		else if (dirlen > 0)
+		if (dirlen > 0)
 		{
 			if (autoname[dirlen-1] != '/' && autoname[dirlen-1] != '\\')
 			{

src/m_misc.h

@@ -53,7 +53,7 @@ FString M_ZLibError(int zerrnum);
 #ifdef __unix__
 FString GetUserFile (const char *path);		// Prepends ~/.zdoom to path
 #endif
-FString M_GetCachePath();
+FString M_GetCachePath(bool create);
 FString M_GetAutoexecPath();
 FString M_GetCajunPath(const char *filename);
 FString M_GetConfigPath(bool for_reading);

src/m_specialpaths.cpp

@@ -14,6 +14,114 @@
 
 #if defined(_WIN32)
 
+#include "version.h"	// for GAMENAME
+typedef HRESULT (*GKFP)(REFKNOWNFOLDERID, DWORD, HANDLE, PWSTR *);
+
+//===========================================================================
+//
+// IsProgramDirectoryWritable
+//
+// If the program directory is writable, then dump everything in there for
+// historical reasons. Otherwise, known folders get used instead.
+//
+//===========================================================================
+
+bool UseKnownFolders()
+{
+	// Cache this value so the semantics don't change during a single run
+	// of the program. (e.g. Somebody could add write access while the
+	// program is running.)
+	static INTBOOL iswritable = -1;
+	FString testpath;
+	HANDLE file;
+
+	if (iswritable >= 0)
+	{
+		return !iswritable;
+	}
+	testpath << progdir << "writest";
+	file = CreateFile(testpath, GENERIC_READ | GENERIC_WRITE, 0, NULL,
+		CREATE_ALWAYS,
+		FILE_ATTRIBUTE_TEMPORARY | FILE_FLAG_DELETE_ON_CLOSE, NULL);
+	if (file != INVALID_HANDLE_VALUE)
+	{
+		CloseHandle(file);
+		Printf("Using program directory for storage\n");
+		iswritable = true;
+		return false;
+	}
+	Printf("Using known folders for storage\n");
+	iswritable = false;
+	return true;
+}
+
+//===========================================================================
+//
+// GetKnownFolder
+//
+// Returns the known_folder if SHGetKnownFolderPath is available, otherwise
+// returns the shell_folder using SHGetFolderPath.
+//
+//===========================================================================
+
+bool GetKnownFolder(int shell_folder, REFKNOWNFOLDERID known_folder, bool create, FString &path)
+{
+	static GKFP SHGetKnownFolderPath = NULL;
+	static bool tested = false;
+
+	if (!tested)
+	{
+		tested = true;
+		HMODULE shell32 = GetModuleHandle("shell32.dll");
+		if (shell32 != NULL)
+		{
+			SHGetKnownFolderPath = (GKFP)GetProcAddress(shell32, "SHGetKnownFolderPath");
+		}
+	}
+
+	char pathstr[MAX_PATH];
+
+	// SHGetKnownFolderPath knows about more folders than SHGetFolderPath, but is
+	// new to Vista, hence the reason we support both.
+	if (SHGetKnownFolderPath == NULL)
+	{
+		if (shell_folder < 0)
+		{ // Not supported by SHGetFolderPath
+			return false;
+		}
+		if (create)
+		{
+			shell_folder |= CSIDL_FLAG_CREATE;
+		}
+		if (FAILED(SHGetFolderPathA(NULL, shell_folder, NULL, 0, pathstr)))
+		{
+			return false;
+		}
+		path = pathstr;
+		return true;
+	}
+	else
+	{
+		PWSTR wpath;
+		if (FAILED(SHGetKnownFolderPath(known_folder, create ? KF_FLAG_CREATE : 0, NULL, &wpath)))
+		{
+			return false;
+		}
+		// FIXME: Support Unicode, at least for filenames. This function
+		// has no MBCS equivalent, so we have to convert it since we don't
+		// support Unicode. :(
+		bool converted = false;
+		if (WideCharToMultiByte(GetACP(), WC_NO_BEST_FIT_CHARS, wpath, -1,
+			pathstr, countof(pathstr), NULL, NULL) > 0)
+		{
+			path = pathstr;
+			converted = true;
+		}
+		CoTaskMemFree(wpath);
+		return converted;
+	}
+}
+
 //===========================================================================
 //
 // M_GetCachePath													Windows
@@ -22,19 +130,14 @@
 //
 //===========================================================================
 
-FString M_GetCachePath()
+FString M_GetCachePath(bool create)
 {
 	FString path;
 
-	char pathstr[MAX_PATH];
-	if (0 != SHGetFolderPathA(NULL, CSIDL_LOCAL_APPDATA, NULL, 0, pathstr))
+	if (!GetKnownFolder(CSIDL_LOCAL_APPDATA, FOLDERID_LocalAppData, create, path))
 	{ // Failed (e.g. On Win9x): use program directory
 		path = progdir;
 	}
-	else
-	{
-		path = pathstr;
-	}
 	// Don't use GAME_DIR and such so that ZDoom and its child ports can
 	// share the node cache.
 	path += "/zdoom/cache";
@@ -89,11 +192,19 @@ FString M_GetConfigPath(bool for_reading)
 	FString path;
 	HRESULT hr;
 
+	// Construct a user-specific config name
+	if (UseKnownFolders() && GetKnownFolder(CSIDL_APPDATA, FOLDERID_RoamingAppData, true, path))
+	{
+		path += "/zdoom";
+		CreatePath(path);
+		path += "/zdoom.ini";
+	}
+	else
+	{ // construct "$PROGDIR/zdoom-$USER.ini"
 		TCHAR uname[UNLEN+1];
 		DWORD unamelen = countof(uname);
 
-	// Because people complained, try for a user-specific .ini in the program directory first.
-	// If that is not writeable, use the one in the home directory instead.
+		path = progdir;
 		hr = GetUserName(uname, &unamelen);
 		if (SUCCEEDED(hr) && uname[0] != 0)
 		{
@@ -106,31 +217,25 @@ FString M_GetConfigPath(bool for_reading)
 					*probe = '_';
 				++probe;
 			}
+			path << "zdoom-" << uname << ".ini";
+		}
+		else
+		{ // Couldn't get user name, so just use zdoom.ini
+			path += "zdoom.ini";
+		}
+	}
 
-		path = progdir;
-		path += "zdoom-";
-		path += uname;
-		path += ".ini";
+	// If we are reading the config file, check if it exists. If not, fallback
+	// to $PROGDIR/zdoom.ini
 	if (for_reading)
 	{
-			if (!FileExists(path.GetChars()))
+		if (!FileExists(path))
 		{
-				path = "";
-			}
-		}
-		else
-		{ // check if writeable
-			FILE *checker = fopen (path.GetChars(), "a");
-			if (checker == NULL)
-			{
-				path = "";
-			}
-			else
-			{
-				fclose (checker);
-			}
+			path = progdir;
+			path << "zdoom.ini";
 		}
 	}
+
 	return path;
 }
 
@@ -142,10 +247,31 @@ FString M_GetConfigPath(bool for_reading)
 //
 //===========================================================================
 
+// I'm not sure when FOLDERID_Screenshots was added, but it was probably
+// for Windows 8, since it's not in the v7.0 Windows SDK.
+static const GUID MyFOLDERID_Screenshots = { 0xb7bede81, 0xdf94, 0x4682, 0xa7, 0xd8, 0x57, 0xa5, 0x26, 0x20, 0xb8, 0x6f };
+
 FString M_GetScreenshotsPath()
 {
 	FString path;
-	path = progdir;
+
+	if (!UseKnownFolders())
+	{
+		return progdir;
+	}
+	else if (GetKnownFolder(-1, MyFOLDERID_Screenshots, true, path))
+	{
+		path << "/" GAMENAME;
+	}
+	else if (GetKnownFolder(CSIDL_MYPICTURES, FOLDERID_Pictures, true, path))
+	{
+		path << "/Screenshots/" GAMENAME;
+	}
+	else
+	{
+		return progdir;
+	}
+	CreatePath(path);
 	return path;
 }
 
@@ -160,7 +286,28 @@ FString M_GetScreenshotsPath()
 FString M_GetSavegamesPath()
 {
 	FString path;
+
+	if (!UseKnownFolders())
+	{
+		return progdir;
+	}
+	// Try standard Saved Games folder
+	else if (GetKnownFolder(-1, FOLDERID_SavedGames, true, path))
+	{
+		path << "/" GAMENAME;
+	}
+	// Try defacto My Documents/My Games folder
+	else if (GetKnownFolder(CSIDL_PERSONAL, FOLDERID_Documents, true, path))
+	{
+		// I assume since this isn't a standard folder, it doesn't have
+		// a localized name either.
+		path << "/My Games/" GAMENAME;
+		CreatePath(path);
+	}
+	else
+	{
 		path = progdir;
+	}
 	return path;
 }
 
@@ -174,14 +321,14 @@ FString M_GetSavegamesPath()
 //
 //===========================================================================
 
-FString M_GetCachePath()
+FString M_GetCachePath(bool create)
 {
 	FString path;
 
 	char pathstr[PATH_MAX];
 	FSRef folder;
 
-	if (noErr == FSFindFolder(kLocalDomain, kApplicationSupportFolderType, kCreateFolder, &folder) &&
+	if (noErr == FSFindFolder(kLocalDomain, kApplicationSupportFolderType, create ? kCreateFolder : 0, &folder) &&
 		noErr == FSRefMakePath(&folder, (UInt8*)pathstr, PATH_MAX))
 	{
 		path = pathstr;
@@ -409,11 +556,16 @@ FString GetUserFile (const char *file)
 //
 //===========================================================================
 
-FString M_GetCachePath()
+FString M_GetCachePath(bool create)
 {
 	// Don't use GAME_DIR and such so that ZDoom and its child ports can
 	// share the node cache.
-	return NicePath("~/.config/zdoom/cache");
+	FString path = NicePath("~/.config/zdoom/cache");
+	if (create)
+	{
+		CreatePath(create);
+	}
+	return path;
 }
 
 //===========================================================================

src/p_glnodes.cpp

@@ -1041,7 +1041,7 @@ typedef TArray<BYTE> MemFile;
 
 static FString CreateCacheName(MapData *map, bool create)
 {
-	FString path = M_GetCachePath();
+	FString path = M_GetCachePath(create);
 	FString lumpname = Wads.GetLumpFullPath(map->lumpnum);
 	int separator = lumpname.IndexOf(':');
 	path << '/' << lumpname.Left(separator);
@@ -1254,7 +1254,7 @@ errorout:
 CCMD(clearnodecache)
 {
 	TArray<FFileList> list;
-	FString path = M_GetCachePath();
+	FString path = M_GetCachePath(false);
 	path += "/";
 
 	try