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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.Build.Utilities;
using Microsoft.Build.Framework;
using System.IO;
namespace DotNetOpenAuth.BuildTasks {
public class CompareFiles : Task {
/// <summary>
/// One set of items to compare.
/// </summary>
[Required]
public ITaskItem[] OriginalItems { get; set; }
/// <summary>
/// The other set of items to compare.
/// </summary>
[Required]
public ITaskItem[] NewItems { get; set; }
/// <summary>
/// Gets whether the items lists contain items that are identical going down the list.
/// </summary>
[Output]
public bool AreSame { get; private set; }
/// <summary>
/// Same as <see cref="AreSame"/>, but opposite.
/// </summary>
[Output]
public bool AreChanged { get { return !AreSame; } }
public override bool Execute() {
AreSame = AreFilesIdentical();
return true;
}
private bool AreFilesIdentical() {
if (OriginalItems.Length != NewItems.Length) {
return false;
}
for (int i = 0; i < OriginalItems.Length; i++) {
if (!IsContentOfFilesTheSame(OriginalItems[i].ItemSpec, NewItems[i].ItemSpec)) {
return false;
}
}
return true;
}
private bool IsContentOfFilesTheSame(string file1, string file2) {
// If exactly one file is missing, that's different.
if (File.Exists(file1) ^ File.Exists(file2)) return false;
// If both are missing, that's the same.
if (!File.Exists(file1)) return true;
// If both are present, we need to do a content comparison.
using (FileStream fileStream1 = File.OpenRead(file1)) {
using (FileStream fileStream2 = File.OpenRead(file2)) {
if (fileStream1.Length != fileStream2.Length) return false;
byte[] buffer1 = new byte[4096];
byte[] buffer2 = new byte[buffer1.Length];
int bytesRead;
do {
bytesRead = fileStream1.Read(buffer1, 0, buffer1.Length);
if (fileStream2.Read(buffer2, 0, buffer2.Length) != bytesRead) {
// We should never get here since we compared file lengths, but
// this is a sanity check.
return false;
}
for (int i = 0; i < bytesRead; i++) {
if (buffer1[i] != buffer2[i]) {
return false;
}
}
} while (bytesRead == buffer1.Length);
}
}
return true;
}
/// <summary>
/// Tests whether a file is up to date with respect to another,
/// based on existence, last write time and file size.
/// </summary>
/// <param name="sourcePath">The source path.</param>
/// <param name="destPath">The dest path.</param>
/// <returns><c>true</c> if the files are the same; <c>false</c> if the files are different</returns>
internal static bool FastFileEqualityCheck(string sourcePath, string destPath) {
FileInfo sourceInfo = new FileInfo(sourcePath);
FileInfo destInfo = new FileInfo(destPath);
if (sourceInfo.Exists ^ destInfo.Exists) {
// Either the source file or the destination file is missing.
return false;
}
if (!sourceInfo.Exists) {
// Neither file exists.
return true;
}
// We'll say the files are the same if their modification date and length are the same.
return
sourceInfo.LastWriteTimeUtc == destInfo.LastWriteTimeUtc &&
sourceInfo.Length == destInfo.Length;
}
}
}
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