From 897da6f67744355c5bbc0084936490ebd9f32a08 Mon Sep 17 00:00:00 2001
From: LTRData <ol@ltr-data.se>
Date: Sat, 13 Apr 2024 21:42:24 +0200
Subject: [PATCH] Path concatenation fix for .NET Standard

Fixes cases where paths were built with mix of \ and / directory delimiter characters on non-Windows systems. This happened with .NET Standard libraries.
---
 Library/DiscUtils.Core/Internal/Utilities.cs    |  6 +++---
 Tests/LibraryTests/Iso9660/IsoFileSystemTest.cs | 13 +++++++++++++
 Tests/LibraryTests/LibraryTests.csproj          |  4 ++--
 3 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/Library/DiscUtils.Core/Internal/Utilities.cs b/Library/DiscUtils.Core/Internal/Utilities.cs
index a0a8eab24..5f843d4a5 100644
--- a/Library/DiscUtils.Core/Internal/Utilities.cs
+++ b/Library/DiscUtils.Core/Internal/Utilities.cs
@@ -207,10 +207,10 @@ public static string GetFileFromPath(string path)
     /// <returns>The combined path.</returns>
     public static string CombinePaths(string a, string b)
     {
-#if NETCOREAPP
+#if NETSTANDARD2_1_OR_GREATER || NETCOREAPP
         return Path.Combine(a, b);
 #else
-        if (string.IsNullOrEmpty(a) || (b.Length > 0 && b[0] == '\\'))
+        if (string.IsNullOrEmpty(a) || (b.Length > 0 && b[0] is '\\' or '/'))
         {
             return b;
         }
@@ -220,7 +220,7 @@ public static string CombinePaths(string a, string b)
             return a;
         }
 
-        return a.TrimEnd('\\') + '\\' + b.TrimStart('\\');
+        return a.TrimEnd(PathSeparators) + Path.DirectorySeparatorChar + b.TrimStart(PathSeparators);
 #endif
     }
 
diff --git a/Tests/LibraryTests/Iso9660/IsoFileSystemTest.cs b/Tests/LibraryTests/Iso9660/IsoFileSystemTest.cs
index 765655014..fb65fc269 100644
--- a/Tests/LibraryTests/Iso9660/IsoFileSystemTest.cs
+++ b/Tests/LibraryTests/Iso9660/IsoFileSystemTest.cs
@@ -77,6 +77,19 @@ public void Root()
             Assert.Null(fs.Root.Parent);
         }
 
+        [Fact]
+        public void Dirs()
+        {
+            var dir1 = Path.DirectorySeparatorChar + "DIR1";
+            var dir2 = Path.DirectorySeparatorChar + "DIR2";
+
+            var builder = new CDBuilder();
+            builder.AddDirectory(dir1);
+            builder.AddDirectory(dir2);
+            var fs = new CDReader(builder.Build(), true);
+            Assert.Equal(fs.GetDirectories(""), [dir1, dir2]);
+        }
+
         [Fact]
         public void LargeDirectory()
         {
diff --git a/Tests/LibraryTests/LibraryTests.csproj b/Tests/LibraryTests/LibraryTests.csproj
index 4c019a5de..b754a2783 100644
--- a/Tests/LibraryTests/LibraryTests.csproj
+++ b/Tests/LibraryTests/LibraryTests.csproj
@@ -18,7 +18,7 @@
     <ProjectReference Include="..\..\Library\DiscUtils.Core\DiscUtils.Core.csproj" />
     <ProjectReference Include="..\..\Library\DiscUtils\DiscUtils.csproj" />
   </ItemGroup>
-  <ItemGroup Condition=" '$(TargetFramework.CompareTo(`net462`))' &lt; 0">
+  <ItemGroup Condition="'$(TargetFramework.CompareTo(`net462`))' &lt; 0 Or '$(TargetFramework)' == 'netcoreapp3.1'">
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.*" />
     <PackageReference Include="System.IO.Compression" Version="4.3.*" />
     <PackageReference Include="xunit.extensibility.core" Version="2.6.*" />
@@ -28,7 +28,7 @@
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
   </ItemGroup>
-  <ItemGroup Condition=" '$(TargetFramework.CompareTo(`net462`))' &gt;= 0">
+  <ItemGroup Condition=" '$(TargetFramework.CompareTo(`net462`))' &gt;= 0 And '$(TargetFramework)' != 'netcoreapp3.1'">
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="*" />
     <PackageReference Include="System.IO.Compression" Version="*" />
     <PackageReference Include="xunit.extensibility.core" Version="*" />