Allow explicit offline mode.

Notice.txt

@@ -5,7 +5,7 @@ This product bundles the following components under the described licenses:
 MSBuild Locator
 
 Id:      Microsoft.Build.Locator
-Version: 1.6.1
+Version: 1.6.10
 Project: https://github.com/microsoft/MSBuildLocator
 License: MIT
 

README.md

@@ -36,14 +36,15 @@ dotnet tool install TomsToolbox.LicenseGenerator -g
 ```
 build-license [options]
 ```
-#### Options
+### Options
 ```
   -i, --input <input> (REQUIRED)  The path to the solution file to process.
   -o, --output <output>           The name of the license file that is created.
                                   An existing file will be overwritten without confirmation.
                                   Default is Notice.txt in the same folder as the solution.
   -e, --exclude <exclude>         A regular expression to specify package ids to exclude from output.
   --recursive                     A flag to indicate that all dependencies should be scanned recursively.
+  --offline                       A flag to indicate that only the locally cached packages should be scanned (requires a restor beforehand).
   --version                       Show version information
   -?, -h, --help                  Show help and usage information
 ```

src/LicenseGenerator/Builder.cs

@@ -12,6 +12,7 @@
 using NuGet.Packaging;
 using NuGet.Packaging.Core;
 using NuGet.ProjectModel;
+using NuGet.Protocol;
 using NuGet.Protocol.Core.Types;
 using NuGet.Versioning;
 
@@ -27,14 +28,16 @@ internal sealed class Builder : IDisposable
     private readonly Dictionary<string, ProjectInfo> _includedProjects = new(StringComparer.OrdinalIgnoreCase);
     private readonly string _outputPath;
     private readonly bool _recursive;
+    private readonly bool _offline;
     private readonly string _solutionDirectory;
     private readonly Regex? _excludeRegex;
     private readonly Dictionary<NuGetFramework, TargetFrameworkCollection> _targetFrameworkCollections = new();
 
-    public Builder(FileInfo input, string output, string? exclude, bool recursive)
+    public Builder(FileInfo input, string output, string? exclude, bool recursive, bool offline)
     {
         _outputPath = output;
         _recursive = recursive;
+        _offline = offline;
         _solutionDirectory = input.DirectoryName ?? ".";
         _excludeRegex = string.IsNullOrEmpty(exclude) ? null : new Regex(exclude, RegexOptions.Compiled | RegexOptions.CultureInvariant | RegexOptions.IgnoreCase);
 
@@ -187,7 +190,7 @@ private static NuGetFramework ToPlatformVersionIndependent(NuGetFramework framew
 
     private async Task LoadPackage(FrameworkSpecificProject project, PackageIdentity packageIdentity, ICollection<SourceRepository> repositories, PackageDownloadContext context, IDictionary<string, PackageArchiveReader> resolvedPackages, string globalPackagesFolder)
     {
-        List<string> lastExceptions = new List<string>();
+        var lastExceptions = new List<string>();
 
         if (resolvedPackages.TryGetValue(packageIdentity.Id, out var existingPackage) && existingPackage.GetIdentity().Version >= packageIdentity.Version)
         {
@@ -198,19 +201,7 @@ private async Task LoadPackage(FrameworkSpecificProject project, PackageIdentity
 
         foreach (var repository in repositories)
         {
-            DownloadResourceResult downloadResult;
-
-            try
-            {
-                var downloadResource = await repository.GetResourceAsync<DownloadResource>();
-
-                downloadResult = await downloadResource.GetDownloadResourceResultAsync(packageIdentity, context, globalPackagesFolder, NullLogger.Instance, CancellationToken.None);
-            }
-            catch (NuGetProtocolException ex)
-            {
-                lastExceptions.Add(ex.Message);
-                continue;  // Try next repo
-            }
+            var downloadResult = await GetDownloadResultAsync(packageIdentity, context, globalPackagesFolder, repository, lastExceptions);
 
             if (downloadResult.Status != DownloadResourceResultStatus.Available)
                 continue;  // Try next repo
@@ -224,7 +215,7 @@ private async Task LoadPackage(FrameworkSpecificProject project, PackageIdentity
 
             await using var nuspec = package.GetNuspec();
 
-            bool ScanDependencies()
+            bool ShouldScanDependencies()
             {
                 // Don't scan packages with pseudo-references, they don't get physically included.
                 if (string.Equals(packageIdentity.Id, "NETStandard.Library", StringComparison.OrdinalIgnoreCase))
@@ -241,7 +232,7 @@ bool ScanDependencies()
 
             }
 
-            if (!ScanDependencies())
+            if (!ShouldScanDependencies())
                 return;
 
             var packageDependencies = package.GetPackageDependencies()?.ToArray();
@@ -270,6 +261,25 @@ bool ScanDependencies()
         throw new InvalidOperationException($"Package {packageIdentity} not found in any of the configured repositories: {string.Join(", ", lastExceptions)}");
     }
 
+    private async Task<DownloadResourceResult> GetDownloadResultAsync(PackageIdentity packageIdentity, PackageDownloadContext context, string globalPackagesFolder, SourceRepository repository, ICollection<string> lastExceptions)
+    {
+        try
+        {
+            if (_offline)
+            {
+                return GlobalPackagesFolderUtility.GetPackage(packageIdentity, globalPackagesFolder);
+            }
+
+            var downloadResource = await repository.GetResourceAsync<DownloadResource>();
+            return await downloadResource.GetDownloadResourceResultAsync(packageIdentity, context, globalPackagesFolder, NullLogger.Instance, CancellationToken.None);
+        }
+        catch (NuGetProtocolException ex)
+        {
+            lastExceptions.Add(ex.Message);
+            return new DownloadResourceResult(DownloadResourceResultStatus.NotFound);
+        }
+    }
+
     private async Task<string> CreateLicenseFile(IEnumerable<PackageArchiveReader> packages)
     {
         var content = new StringBuilder("This product bundles the following components under the described licenses:\r\n\r\n");

src/LicenseGenerator/LicenseGenerator.csproj

@@ -55,7 +55,7 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.Build" Version="[17.4.0]" ExcludeAssets="runtime" />
-    <PackageReference Include="Microsoft.Build.Locator" Version="1.6.1" />
+    <PackageReference Include="Microsoft.Build.Locator" Version="1.6.10" />
     <PackageReference Include="Microsoft.Build.Utilities.Core" Version="[17.4.0]" ExcludeAssets="runtime" />
     <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.1.1" PrivateAssets="all" />
     <PackageReference Include="NuGet.ProjectModel" Version="6.7.0" />
@@ -65,6 +65,6 @@
   </ItemGroup>
 
   <Target Name="CreateNotice" AfterTargets="Build">
-    <Exec Command="$(RunCommand) -i ../LicenseGenerator.sln -o ..\..\Notice.txt" />
+    <Exec Command='"$(RunCommand)" -i ../LicenseGenerator.sln -o ..\..\Notice.txt' />
   </Target>
 </Project>

src/LicenseGenerator/Program.cs

@@ -49,27 +49,32 @@
     """) { IsRequired = false };
 
 var recursiveOption = new Option<bool>(new[] { "--recursive" }, """
-    A flag to indicate that all dependencies should be scanned recursively.                                                            
+    A flag to indicate that all dependencies should be scanned recursively.
+    """) { IsRequired = false };
+
+var offlineOption = new Option<bool>(new[] { "--offline" }, """
+    A flag to indicate that only the locally cached packages should be scanned (requires a restor beforehand).
     """) { IsRequired = false };
 
 rootCommand.AddOption(inputOption);
 rootCommand.AddOption(outputOption);
 rootCommand.AddOption(excludeOption);
 rootCommand.AddOption(recursiveOption);
-rootCommand.SetHandler(async (input, output, exclude, recursive) => returnValue = await Run(input, output, exclude, recursive), inputOption, outputOption, excludeOption, recursiveOption);
+rootCommand.AddOption(offlineOption);
+rootCommand.SetHandler(async (input, output, exclude, recursive, offline) => returnValue = await Run(input, output, exclude, recursive, offline), inputOption, outputOption, excludeOption, recursiveOption, offlineOption);
 
 await rootCommand.InvokeAsync(args);
 
 return returnValue;
 
-static async Task<int> Run(FileInfo input, string? output, string? exclude, bool recursive)
+static async Task<int> Run(FileInfo input, string? output, string? exclude, bool recursive, bool offline)
 {
     var visualStudioInstance = MSBuildLocator.QueryVisualStudioInstances().MaxBy(instance => instance.Version);
     MSBuildLocator.RegisterInstance(visualStudioInstance);
 
     try
     {
-        using var builder = new Builder(input, output ?? "Notice.txt", exclude, recursive);
+        using var builder = new Builder(input, output ?? "Notice.txt", exclude, recursive, offline);
         return await builder.Build();
     }
     catch (Exception ex)