C#: Move dependency related files into a new project.

csharp/extractor/Semmle.Extraction.CSharp.DependencyFetching/NugetPackages.cs

@@ -0,0 +1,139 @@
+using Semmle.Util;
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.IO;
+using System.Linq;
+
+namespace Semmle.BuildAnalyser
+{
+    /// <summary>
+    /// Manage the downloading of NuGet packages.
+    /// Locates packages in a source tree and downloads all of the
+    /// referenced assemblies to a temp folder.
+    /// </summary>
+    internal class NugetPackages
+    {
+        /// <summary>
+        /// Create the package manager for a specified source tree.
+        /// </summary>
+        public NugetPackages(string sourceDir, TemporaryDirectory packageDirectory, ProgressMonitor progressMonitor)
+        {
+            SourceDirectory = sourceDir;
+            PackageDirectory = packageDirectory;
+            this.progressMonitor = progressMonitor;
+
+            // Expect nuget.exe to be in a `nuget` directory under the directory containing this exe.
+            var currentAssembly = System.Reflection.Assembly.GetExecutingAssembly().Location;
+            var directory = Path.GetDirectoryName(currentAssembly)
+                ?? throw new FileNotFoundException($"Directory path '{currentAssembly}' of current assembly is null");
+            nugetExe = Path.Combine(directory, "nuget", "nuget.exe");
+
+            if (!File.Exists(nugetExe))
+                throw new FileNotFoundException(string.Format("NuGet could not be found at {0}", nugetExe));
+
+            packages = new DirectoryInfo(SourceDirectory)
+                .EnumerateFiles("packages.config", SearchOption.AllDirectories)
+                .ToArray();
+        }
+
+        // List of package files to download.
+        private readonly FileInfo[] packages;
+
+        /// <summary>
+        /// The list of package files.
+        /// </summary>
+        public IEnumerable<FileInfo> PackageFiles => packages;
+
+        /// <summary>
+        /// Download the packages to the temp folder.
+        /// </summary>
+        /// <param name="pm">The progress monitor used for reporting errors etc.</param>
+        public void InstallPackages()
+        {
+            foreach (var package in packages)
+            {
+                RestoreNugetPackage(package.FullName);
+            }
+        }
+
+        /// <summary>
+        /// The source directory used.
+        /// </summary>
+        public string SourceDirectory
+        {
+            get;
+            private set;
+        }
+
+        /// <summary>
+        /// The computed packages directory.
+        /// This will be in the Temp location
+        /// so as to not trample the source tree.
+        /// </summary>
+        public TemporaryDirectory PackageDirectory { get; }
+
+        /// <summary>
+        /// Restore all files in a specified package.
+        /// </summary>
+        /// <param name="package">The package file.</param>
+        /// <param name="pm">Where to log progress/errors.</param>
+        private void RestoreNugetPackage(string package)
+        {
+            progressMonitor.NugetInstall(package);
+
+            /* Use nuget.exe to install a package.
+             * Note that there is a clutch of NuGet assemblies which could be used to
+             * invoke this directly, which would arguably be nicer. However they are
+             * really unwieldy and this solution works for now.
+             */
+
+            string exe, args;
+            if (Util.Win32.IsWindows())
+            {
+                exe = nugetExe;
+                args = string.Format("install -OutputDirectory {0} {1}", PackageDirectory, package);
+            }
+            else
+            {
+                exe = "mono";
+                args = string.Format("{0} install -OutputDirectory {1} {2}", nugetExe, PackageDirectory, package);
+            }
+
+            var pi = new ProcessStartInfo(exe, args)
+            {
+                RedirectStandardOutput = true,
+                RedirectStandardError = true,
+                UseShellExecute = false
+            };
+
+            try
+            {
+                using var p = Process.Start(pi);
+
+                if (p is null)
+                {
+                    progressMonitor.FailedNugetCommand(pi.FileName, pi.Arguments, "Couldn't start process.");
+                    return;
+                }
+
+                var output = p.StandardOutput.ReadToEnd();
+                var error = p.StandardError.ReadToEnd();
+
+                p.WaitForExit();
+                if (p.ExitCode != 0)
+                {
+                    progressMonitor.FailedNugetCommand(pi.FileName, pi.Arguments, output + error);
+                }
+            }
+            catch (Exception ex)
+                when (ex is System.ComponentModel.Win32Exception || ex is FileNotFoundException)
+            {
+                progressMonitor.FailedNugetCommand(pi.FileName, pi.Arguments, ex.Message);
+            }
+        }
+
+        private readonly string nugetExe;
+        private readonly ProgressMonitor progressMonitor;
+    }
+}