fix: Tests should not leave resources behind. (#2176)

Author: kevinferrare

.github/copilot-instructions.md

@@ -40,10 +40,12 @@ dotnet build
 # Run with executable
 dotnet run --project src/Spice86 -- -e path\to\program.exe
 
-# Run tests
-dotnet test tests/Spice86.Tests
+# Run tests (excluding SingleStepTest - see note below)
+dotnet test tests/Spice86.Tests --filter "FullyQualifiedName!~SingleStepTest"
 ```
 
+> **SingleStepTest exclusion rule**: `SingleStepTest` runs millions of CPU instruction test cases and take an extremely long time to complete. **Always exclude it** using `--filter "FullyQualifiedName!~SingleStepTest"` unless the change being tested directly touches CPU instruction decoding, execution, or flag handling (e.g. changes to `CfgCpu`, instruction parsers, ALU operations, or flag computation). When in doubt, exclude it.
+
 ### Debugging Workflow
 - **GDB Integration**: Server runs on port 10000 by default (`--GdbPort 10000`)
   - Use `--Debug` to pause at startup for breakpoint setup
@@ -158,7 +160,6 @@ Variants: `MemoryBasedDataStructureWithCsBaseAddress`, `MemoryBasedDataStructure
   }
   ```
   - **NEVER use generic `catch (Exception)`, `catch (Exception e)`, or empty `catch`**
-  - Never use SegmentedAddress.Linear for address computations. Segmented addresses can rollover and Linear doesn't handle this correctly.
   - Each exception type must be caught explicitly
   - This is non-negotiable - the .editorconfig enforces this rule
 
@@ -242,7 +243,7 @@ Variants: `MemoryBasedDataStructureWithCsBaseAddress`, `MemoryBasedDataStructure
 - **Function Tracking**: `FunctionHandler` intercepts calls/rets for CFG building and override dispatch
 
 ## Common Gotchas
-- **Segmented addressing**: Use `SegmentedAddress` not raw offsets; linear address = segment * 16 + offset
+- **Segmented addressing**: Use `SegmentedAddress` not raw offsets; linear address = segment * 16 + offset. Avoid computing addresses from `SegmentedAddress.Linear` because segmented addresses can roll over and `.Linear` does not handle this correctly. Use the `IMmu` (`TranslateAddress`) for address translation instead, as it handles rollover and access validation. Passing `.Linear` to an API that already expects a linear address is fine.
 - **A20 Gate**: Memory wrapping at 1MB boundary controlled by `A20Gate` (toggle via `--A20Gate` flag)
 - **EMS/XMS**: Enabled by default; disable with `--Xms false` / `--Ems false`
 - **Time handling**: Real-time vs instruction-based via `--InstructionTimeScale` or `--TimeMultiplier`

src/Spice86.Core/Emulator/CPU/CfgCpu/Parser/SpecificParsers/JccParser.cs

@@ -63,7 +63,7 @@ private CfgInstruction ParseJcc(ParsingContext context, int conditionCode, BitWi
 
         (int offsetValue, FieldWithValue offsetField) = ReadSignedOffset(offsetWidth);
 
-        CfgInstruction instr = new(context.Address, context.OpcodeField, context.Prefixes, 1);
+        CfgInstruction instr = new(context.Address, context.OpcodeField, context.Prefixes, 1) { Kind = InstructionKind.Jump };
         instr.AddField(offsetField);
         instr.MaxSuccessorsCount = 2;
         ushort targetIp = (ushort)(instr.NextInMemoryAddress32.Offset + offsetValue);

src/Spice86.Core/Emulator/CPU/CfgCpu/Parser/SpecificParsers/JcxzParser.cs

@@ -18,7 +18,7 @@ public JcxzParser(ParsingTools parsingTools) : base(parsingTools) {
 
     public CfgInstruction Parse(ParsingContext context) {
         (int offsetValue, FieldWithValue offsetField) = ReadSignedOffset(BitWidth.BYTE_8);
-        CfgInstruction instr = new(context.Address, context.OpcodeField, context.Prefixes, 1);
+        CfgInstruction instr = new(context.Address, context.OpcodeField, context.Prefixes, 1) { Kind = InstructionKind.Jump };
         instr.AddField(offsetField);
         instr.MaxSuccessorsCount = 2;
         ushort targetIp = (ushort)(instr.NextInMemoryAddress32.Offset + offsetValue);

src/Spice86.Core/Emulator/CPU/CfgCpu/Parser/SpecificParsers/LoopParser.cs

@@ -31,7 +31,7 @@ private CfgInstruction ParseLoop(ParsingContext context, InstructionOperation di
         BitWidth addressWidth = context.AddressWidthFromPrefixes;
         (int offsetValue, FieldWithValue offsetField) = ReadSignedOffset(BitWidth.BYTE_8);
 
-        CfgInstruction instr = new(context.Address, context.OpcodeField, context.Prefixes, 1);
+        CfgInstruction instr = new(context.Address, context.OpcodeField, context.Prefixes, 1) { Kind = InstructionKind.Jump };
         instr.AddField(offsetField);
         instr.MaxSuccessorsCount = 2;
 

src/Spice86.Core/Emulator/Gdb/GdbCommandBreakPointHandler.cs

@@ -35,7 +35,7 @@ public GdbCommandBreakpointHandler(
         EmulatorBreakpointsManager emulatorBreakpointsManager,
         IPauseHandler pauseHandler, GdbIo gdbIo, ILoggerService loggerService,
         CPU.State state, IMemory memory) {
-        _loggerService = loggerService.WithLogLevel(LogEventLevel.Verbose);
+        _loggerService = loggerService;
         _emulatorBreakpointsManager = emulatorBreakpointsManager;
         _pauseHandler = pauseHandler;
         _pauseHandler.Paused += OnPauseFromEmulator;

src/Spice86.Core/Emulator/Gdb/GdbIo.cs

@@ -27,7 +27,7 @@ public sealed class GdbIo : IDisposable {
     /// <param name="port">The port number to listen on.</param>
     /// <param name="loggerService">The logger service implementation.</param>
     public GdbIo(int port, ILoggerService loggerService) {
-        _loggerService = loggerService.WithLogLevel(LogEventLevel.Debug);
+        _loggerService = loggerService;
         // Listen to connections in IPv4 or IPv6
         _tcpListener = new TcpListener(IPAddress.IPv6Any, port);
         _tcpListener.Server.DualMode = true;

src/Spice86.Core/Emulator/Memory/MemoryMap.cs

@@ -79,9 +79,4 @@ public static class MemoryMap {
     /// <see cref="VirtualDeviceBase"/>
     /// </summary>
     public const ushort DeviceDriversSegment = 0xF800;
-
-    /// <summary>
-    /// Segment for DOS Current Directory Structure (CDS).
-    /// </summary>
-    public const ushort DosCdsSegment = 0x108;
 }

src/Spice86.Core/Emulator/OperatingSystem/Dos.cs

@@ -193,7 +193,8 @@ public Dos(Configuration configuration, IMemory memory,
             MemoryUtils.ToPhysicalAddress(DosSysVars.Segment, 0x0));
 
         DosSysVars.ConsoleDeviceHeaderPointer = ((IVirtualDevice)dosDevices[1]).Header.BaseAddress;
-        DosSysVars.CurrentDirectoryStructureListPointer = DosTables.CurrentDirectoryStructure.BaseAddress;
+        SegmentedAddress cdsAddress = DosTables.CdsSegmentedAddress;
+        DosSysVars.CurrentDirectoryStructureListPointer = (uint)(cdsAddress.Segment << 16 | cdsAddress.Offset);
         DosSysVars.CurrentDirectoryStructureCount = 26;
 
         DosSwappableDataArea = new(_memory,

src/Spice86.Core/Emulator/OperatingSystem/DosPathResolver.cs

@@ -286,46 +286,12 @@ internal DosPathBuilderResult GetFullDosPathIncludingRoot(string? dosPath, out s
     /// <param name="dosPath">The DOS path to convert.</param>
     /// <returns>A string containing the full file path in the host file system, or <see langword="null"/> if nothing was found or the DOS path cannot be resolved.</returns>
     public string? GetFullHostPathFromDosOrDefault(string? dosPath) {
-        if (string.IsNullOrWhiteSpace(dosPath)) {
-            return null;
-        }
-
-        dosPath = GetFullDosPathIncludingRoot(dosPath);
-        if (dosPath is null) {
-            return null;
-        }
-
-        (string? hostPrefix, string dosRelativePath) = DeconstructDosPath(dosPath);
-        if (hostPrefix is null) {
-            return null;
-        }
-
-        if (string.IsNullOrWhiteSpace(dosRelativePath)) {
-            return ConvertUtils.ToSlashPath(hostPrefix);
-        }
-
-        string slashedRelative = ConvertUtils.ToSlashPath(dosRelativePath);
-        int lastSlash = slashedRelative.LastIndexOf('/');
-        string dirPart = lastSlash >= 0 ? slashedRelative[..lastSlash] : string.Empty;
-        string lastSegment = lastSlash >= 0 ? slashedRelative[(lastSlash + 1)..] : slashedRelative;
-
-        string? resolvedHostDir = ResolveCaseInsensitiveDirectory(hostPrefix, dirPart);
-        if (string.IsNullOrWhiteSpace(resolvedHostDir)) {
+        (string resolvedHostDir, string lastSegment)? components = ResolveDosPathComponents(dosPath);
+        if (components is null) {
             return null;
         }
 
-        if (string.IsNullOrWhiteSpace(lastSegment)) {
-            return ConvertUtils.ToSlashPath(resolvedHostDir);
-        }
-
-        EnumerationOptions options = new EnumerationOptions {
-            RecurseSubdirectories = false,
-            MatchCasing = MatchCasing.CaseInsensitive,
-            ReturnSpecialDirectories = false
-        };
-
-        string? firstMatch = FindFilesUsingWildCmp(resolvedHostDir, lastSegment, options).FirstOrDefault();
-        return string.IsNullOrWhiteSpace(firstMatch) ? null : ConvertUtils.ToSlashPath(firstMatch);
+        return ResolveFileInDirectory(components.Value.resolvedHostDir, components.Value.lastSegment);
     }
 
     /// <summary>
@@ -377,6 +343,29 @@ internal DosPathBuilderResult GetFullDosPathIncludingRoot(string? dosPath, out s
     /// <param name="dosPath">The DOS path to convert.</param>
     /// <returns>A string containing the full file path in the host file system, or <see langword="null"/> if nothing was found or the DOS path cannot be resolved.</returns>
     public string? GetFullHostExecutablePathFromDosOrDefault(string? dosPath) {
+        (string resolvedHostDir, string lastSegment)? components = ResolveDosPathComponents(dosPath);
+        if (components is null) {
+            return null;
+        }
+
+        string resolvedHostDir = components.Value.resolvedHostDir;
+        string lastSegment = components.Value.lastSegment;
+
+        string? result = ResolveFileInDirectory(resolvedHostDir, lastSegment);
+        if (result is not null) {
+            return result;
+        }
+
+        string? extensionProbeMatch = TryResolveExecutableWithoutExtension(resolvedHostDir, lastSegment);
+        return string.IsNullOrWhiteSpace(extensionProbeMatch) ? null : ConvertUtils.ToSlashPath(extensionProbeMatch);
+    }
+
+    /// <summary>
+    /// Resolves the DOS path into its host directory and filename components.
+    /// Returns <see langword="null"/> when the path cannot be resolved (invalid, empty, or missing directory).
+    /// When the path refers to a directory (no filename), <c>lastSegment</c> is empty.
+    /// </summary>
+    private (string resolvedHostDir, string lastSegment)? ResolveDosPathComponents(string? dosPath) {
         if (string.IsNullOrWhiteSpace(dosPath)) {
             return null;
         }
@@ -392,7 +381,7 @@ internal DosPathBuilderResult GetFullDosPathIncludingRoot(string? dosPath, out s
         }
 
         if (string.IsNullOrWhiteSpace(dosRelativePath)) {
-            return ConvertUtils.ToSlashPath(hostPrefix);
+            return (ConvertUtils.ToSlashPath(hostPrefix), string.Empty);
         }
 
         string slashedRelative = ConvertUtils.ToSlashPath(dosRelativePath);
@@ -405,6 +394,14 @@ internal DosPathBuilderResult GetFullDosPathIncludingRoot(string? dosPath, out s
             return null;
         }
 
+        return (resolvedHostDir, lastSegment);
+    }
+
+    /// <summary>
+    /// Resolves a filename within a host directory, trying an exact case-insensitive match first
+    /// to avoid 8.3 truncation false positives, then falling back to DOS wildcard comparison.
+    /// </summary>
+    private string? ResolveFileInDirectory(string resolvedHostDir, string lastSegment) {
         if (string.IsNullOrWhiteSpace(lastSegment)) {
             return ConvertUtils.ToSlashPath(resolvedHostDir);
         }
@@ -415,16 +412,20 @@ internal DosPathBuilderResult GetFullDosPathIncludingRoot(string? dosPath, out s
             ReturnSpecialDirectories = false
         };
 
-        string? firstMatch = FindFilesUsingWildCmp(resolvedHostDir, lastSegment, options).FirstOrDefault();
-        if (!string.IsNullOrWhiteSpace(firstMatch)) {
-            return ConvertUtils.ToSlashPath(firstMatch);
+        // Try exact case-insensitive match first to avoid 8.3 truncation false positives
+        // (e.g. bios_int70_wait.com and bios_int1a.com both truncating to BIOS_INT.COM).
+        string? exactMatch = Directory
+            .EnumerateFileSystemEntries(resolvedHostDir, lastSegment, options)
+            .FirstOrDefault();
+        if (!string.IsNullOrWhiteSpace(exactMatch)) {
+            return ConvertUtils.ToSlashPath(exactMatch);
         }
 
-        string? extensionProbeMatch = TryResolveExecutableWithoutExtension(resolvedHostDir, lastSegment, options);
-        return string.IsNullOrWhiteSpace(extensionProbeMatch) ? null : ConvertUtils.ToSlashPath(extensionProbeMatch);
+        string? firstMatch = FindFilesUsingWildCmp(resolvedHostDir, lastSegment, options).FirstOrDefault();
+        return string.IsNullOrWhiteSpace(firstMatch) ? null : ConvertUtils.ToSlashPath(firstMatch);
     }
 
-    private string? TryResolveExecutableWithoutExtension(string resolvedHostDir, string lastSegment, EnumerationOptions options) {
+    private string? TryResolveExecutableWithoutExtension(string resolvedHostDir, string lastSegment) {
         if (string.IsNullOrWhiteSpace(lastSegment)) {
             return null;
         }
@@ -434,7 +435,7 @@ internal DosPathBuilderResult GetFullDosPathIncludingRoot(string? dosPath, out s
         }
 
         return ExecutableExtensionLookupOrder
-            .Select(extension => FindFilesUsingWildCmp(resolvedHostDir, $"{lastSegment}{extension}", options).FirstOrDefault())
+            .Select(extension => ResolveFileInDirectory(resolvedHostDir, $"{lastSegment}{extension}"))
             .FirstOrDefault(match => !string.IsNullOrWhiteSpace(match));
     }
 

src/Spice86.Core/Emulator/OperatingSystem/Structures/DosTables.cs

@@ -2,6 +2,7 @@ namespace Spice86.Core.Emulator.OperatingSystem.Structures;
 
 using Spice86.Core.Emulator.Memory;
 using Spice86.Core.Emulator.Memory.ReaderWriter;
+using Spice86.Core.Emulator.OperatingSystem;
 using Spice86.Shared.Emulator.Memory;
 using Spice86.Shared.Utils;
 
@@ -26,6 +27,11 @@ public class DosTables {
     /// </summary>
     public CurrentDirectoryStructure CurrentDirectoryStructure { get; private set; }
 
+    /// <summary>
+    /// Gets the segmented address where the CDS is allocated.
+    /// </summary>
+    public SegmentedAddress CdsSegmentedAddress { get; private set; }
+
     /// <summary>
     /// Gets the Double Byte Character Set (DBCS) lead-byte table.
     /// </summary>
@@ -36,8 +42,13 @@ public class DosTables {
     /// </summary>
     /// <param name="memory">The memory interface to write structures to.</param>
     public DosTables(IByteReaderWriter memory) {
-        uint cdsAddress = MemoryUtils.ToPhysicalAddress(MemoryMap.DosCdsSegment, 0);
-        CurrentDirectoryStructure = new CurrentDirectoryStructure(memory, cdsAddress);
+        // CDS needs one entry per drive (A-Z), rounded up to the nearest paragraph.
+        const int bytesPerParagraph = 16;
+        int cdsSizeInBytes = DosDriveManager.MaxDriveCount * CurrentDirectoryStructure.CdsEntrySize;
+        ushort cdsParagraphs = (ushort)((cdsSizeInBytes + bytesPerParagraph - 1) / bytesPerParagraph);
+        ushort cdsSegment = ReserveDosPrivateSegment(cdsParagraphs);
+        CdsSegmentedAddress = new SegmentedAddress(cdsSegment, 0);
+        CurrentDirectoryStructure = new CurrentDirectoryStructure(memory, CdsSegmentedAddress.Linear);
 
         ushort currentMemorySegment = ReserveDosPrivateSegment(DosDoubleByteCharacterSet.DbcsTableSizeInParagraphs);
         ushort doubleByteCharacterSetSegment = (ushort)(currentMemorySegment + 1);