Fix localDrive not listing '.' and '..' entries when using certain Li…

…nux file systems (#519)

This fixes a crash during boot of an installed operating system on Android which expects these entries to exist.

src/dos/drive_cache.cpp

@@ -851,6 +851,21 @@ bool DOS_Drive_Cache::ReadDir(Bit16u id, char* &result) {
 			sprintf(buffer,"DIR: Caching in %s (%d Files)",dirPath,dirSearch[srchNr]->fileList.size());
 			LOG_DEBUG(buffer);
 		};*/
+
+		//DBP: Make sure "." and ".." exist in directories (some Linux filesystems don't report them)
+		//DBP: Make sure "." and ".." doesn't exist in the drive root
+		const bool isroot = (strlen(dirPath) == strlen(basePath));
+		std::vector<CFileInfo*>& filelist = dirSearch[id]->fileList;
+		for (std::vector<CFileInfo*>::iterator it = filelist.begin(), itend = filelist.end(); it != itend; ++it)
+			if ((*it)->shortname[0] == '.' && (*it)->shortname[1] != '\0')
+				{ if (isroot) filelist.erase(it); goto founddot; } // remove superfluous entry
+		if (!isroot) CreateEntry(dirSearch[id], ".",  true); // add missing entry
+		founddot:
+		for (std::vector<CFileInfo*>::iterator it = filelist.begin(), itend = filelist.end(); it != itend; ++it)
+			if ((*it)->shortname[0] == '.' && (*it)->shortname[1] == '.' && (*it)->shortname[2] == '\0')
+				{ if (isroot) filelist.erase(it); goto founddotdot; } // remove superfluous entry
+		if (!isroot) CreateEntry(dirSearch[id], "..",  true); // add missing entry
+		founddotdot:;
 	};
 	if (SetResult(dirSearch[id], result, dirSearch[id]->nextEntry)) return true;
 	if (dirSearch[id]) {

src/ints/bios_disk.cpp

@@ -1,6 +1,6 @@
 /*
  *  Copyright (C) 2002-2021  The DOSBox Team
- *  Copyright (C) 2022-2023  Bernhard Schelling
+ *  Copyright (C) 2022-2024  Bernhard Schelling
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
@@ -345,7 +345,7 @@ struct fatFromDOSDrive
 					dta.GetResult(dta_name, dta_size, dta_date, dta_time, dta_attr);
 					const char *fend = dta_name + strlen(dta_name);
 					const bool dot = (dta_name[0] == '.' && dta_name[1] == '\0'), dotdot = (dta_name[0] == '.' && dta_name[1] == '.' && dta_name[2] == '\0');
-					if (!dirlen && (dot || dotdot)) continue; // root shouldn't have dot entries (yet localDrive does...)
+					if (!dirlen && (dot || dotdot)) continue; // root shouldn't have dot entries (yet unpatched localDrive can)
 
 					ffddFile f;
 					memcpy(f.path, dir, dirlen);