1 files changed, 122 insertions, 0 deletions
diff --git a/src/DotNetOpenAuth.BuildTasks/GetBuildVersion.cs b/src/DotNetOpenAuth.BuildTasks/GetBuildVersion.cs
new file mode 100644
index 0000000..1d60ca4
--- /dev/null
+++ b/src/DotNetOpenAuth.BuildTasks/GetBuildVersion.cs
@@ -0,0 +1,122 @@
+using System;
+using System.Collections.Generic;
+using System.ComponentModel;
+using System.Diagnostics;
+using System.IO;
+using System.Linq;
+using System.Text;
+using Microsoft.Build.Framework;
+using Microsoft.Build.Utilities;
+
+namespace DotNetOpenAuth.BuildTasks {
+	public class GetBuildVersion : Task {
+
+		/// <summary>
+		/// Gets the version string to use in the compiled assemblies.
+		/// </summary>
+		[Output]
+		public string Version { get; private set; }
+
+		/// <summary>
+		/// Gets the Git revision control commit id for HEAD (the current source code version).
+		/// </summary>
+		[Output]
+		public string GitCommitId { get; private set; }
+
+		/// <summary>
+		/// The file that contains the version base (Major.Minor.Build) to use.
+		/// </summary>
+		[Required]
+		public string VersionFile { get; set; }
+
+		/// <summary>
+		/// Gets or sets the parent directory of the .git directory.
+		/// </summary>
+		public string GitRepoRoot { get; set; }
+
+		public override bool Execute() {
+			try {
+				Version typedVersion = ReadVersionFromFile();
+				typedVersion = new Version(typedVersion.Major, typedVersion.Minor, typedVersion.Build, CalculateJDate(DateTime.Now));
+				Version = typedVersion.ToString();
+
+				this.GitCommitId = GetGitHeadCommitId();
+			} catch (ArgumentOutOfRangeException ex) {
+				Log.LogErrorFromException(ex);
+				return false;
+			}
+
+			return true;
+		}
+
+		private string GetGitHeadCommitId() {
+			if (string.IsNullOrEmpty(this.GitRepoRoot)) {
+				return string.Empty;
+			}
+
+			string commitId = string.Empty;
+
+			// First try asking Git for the HEAD commit id
+			try {
+				string cmdPath = Path.Combine(System.Environment.GetFolderPath(Environment.SpecialFolder.System), "cmd.exe");
+				ProcessStartInfo psi = new ProcessStartInfo(cmdPath, "/c git rev-parse HEAD");
+				psi.WindowStyle = ProcessWindowStyle.Hidden;
+				psi.CreateNoWindow = true;
+				psi.RedirectStandardOutput = true;
+				psi.UseShellExecute = false;
+				Process git = Process.Start(psi);
+				commitId = git.StandardOutput.ReadLine();
+				git.WaitForExit();
+				if (git.ExitCode != 0) {
+					commitId = string.Empty;
+				}
+				if (commitId != null) {
+					commitId = commitId.Trim();
+					if (commitId.Length == 40) {
+						return commitId;
+					}
+				}
+			} catch (InvalidOperationException) {
+			} catch (Win32Exception) {
+			}
+
+			// Failing being able to use the git command to figure out the HEAD commit ID, try the filesystem directly.
+			try {
+				string headContent = File.ReadAllText(Path.Combine(this.GitRepoRoot, @".git/HEAD")).Trim();
+				if (headContent.StartsWith("ref:", StringComparison.Ordinal)) {
+					string refName = headContent.Substring(5).Trim();
+					string refPath = Path.Combine(this.GitRepoRoot, ".git/" + refName);
+					if (File.Exists(refPath)) {
+						commitId = File.ReadAllText(refPath).Trim();
+					} else {
+						string packedRefPath = Path.Combine(this.GitRepoRoot, ".git/packed-refs");
+						string matchingLine = File.ReadAllLines(packedRefPath).FirstOrDefault(line => line.EndsWith(refName));
+						if (matchingLine != null) {
+							commitId = matchingLine.Substring(0, matchingLine.IndexOf(' '));
+						}
+					}
+				} else {
+					commitId = headContent;
+				}
+			} catch (FileNotFoundException) {
+			} catch (DirectoryNotFoundException) {
+			}
+
+			return commitId.Trim();
+		}
+
+		private Version ReadVersionFromFile() {
+			string[] lines = File.ReadAllLines(VersionFile);
+			string versionLine = lines[0];
+			return new Version(versionLine);
+		}
+
+		private int CalculateJDate(DateTime date) {
+			int yearLastDigit = date.Year - 2000; // can actually be two digits in or after 2010
+			DateTime firstOfYear = new DateTime(date.Year, 1, 1);
+			int dayOfYear = (date - firstOfYear).Days + 1;
+			int jdate = yearLastDigit * 1000 + dayOfYear;
+			return jdate;
+		}
+	}
+}