/// <summary>
/// Checks a zip file to see if its directory is consistent,
/// and optionally fixes the directory if necessary.
/// </summary>
///
/// <remarks>
///
/// <para>
/// In cases of data error, the directory within a zip file can get out of
/// synch with the entries in the zip file. This method checks the given
/// zip file, and returns true if this has occurred. It also optionally
/// fixes the zipfile, saving the fixed copy in <em>Name</em>_Fixed.zip.
/// </para>
///
/// <para>
/// This method may take a long time to run for large zip files. It
/// will take even longer if the file actually needs to be fixed, and if
/// <c>fixIfNecessary</c> is true.
/// </para>
///
/// <para>
/// This method is not supported in the Reduced or Compact
/// Framework versions of DotNetZip.
/// </para>
///
/// </remarks>
///
/// <param name="zipFileName">The filename to of the zip file to check.</param>
///
/// <param name="fixIfNecessary">If true, the method will fix the zip file if
/// necessary.</param>
///
/// <param name="writer">
/// a TextWriter in which messages generated while checking will be written.
/// </param>
///
/// <returns>true if the named zip is OK; false if the file needs to be fixed.</returns>
///
/// <seealso cref="CheckZip(string)"/>
/// <seealso cref="FixZipDirectory(string)"/>
public static bool CheckZip(string zipFileName, bool fixIfNecessary,
TextWriter writer)
{
ZipFile zip1 = null, zip2 = null;
bool isOk = true;
try
{
zip1 = new ZipFile();
zip1.FullScan = true;
zip1.Initialize(zipFileName);
zip2 = ZipFile.Read(zipFileName);
foreach (var e1 in zip1)
{
foreach (var e2 in zip2)
{
if (e1.FileName == e2.FileName)
{
if (e1._RelativeOffsetOfLocalHeader != e2._RelativeOffsetOfLocalHeader)
{
isOk = false;
if (writer != null)
writer.WriteLine("{0}: mismatch in RelativeOffsetOfLocalHeader (0x{1:X16} != 0x{2:X16})",
e1.FileName, e1._RelativeOffsetOfLocalHeader,
e2._RelativeOffsetOfLocalHeader);
}
if (e1._CompressedSize != e2._CompressedSize)
{
isOk = false;
if (writer != null)
writer.WriteLine("{0}: mismatch in CompressedSize (0x{1:X16} != 0x{2:X16})",
e1.FileName, e1._CompressedSize,
e2._CompressedSize);
}
if (e1._UncompressedSize != e2._UncompressedSize)
{
isOk = false;
if (writer != null)
writer.WriteLine("{0}: mismatch in UncompressedSize (0x{1:X16} != 0x{2:X16})",
e1.FileName, e1._UncompressedSize,
e2._UncompressedSize);
}
if (e1.CompressionMethod != e2.CompressionMethod)
{
isOk = false;
if (writer != null)
writer.WriteLine("{0}: mismatch in CompressionMethod (0x{1:X4} != 0x{2:X4})",
e1.FileName, e1.CompressionMethod,
e2.CompressionMethod);
}
if (e1.Crc != e2.Crc)
{
isOk = false;
if (writer != null)
writer.WriteLine("{0}: mismatch in Crc32 (0x{1:X4} != 0x{2:X4})",
e1.FileName, e1.Crc,
e2.Crc);
}
// found a match, so stop the inside loop
break;
}
}
}
zip2.Dispose();
zip2 = null;
if (!isOk && fixIfNecessary)
{
string newFileName = Path.GetFileNameWithoutExtension(zipFileName);
newFileName = System.String.Format("{0}_fixed.zip", newFileName);
zip1.Save(newFileName);
}
}
finally
{
if (zip1 != null) zip1.Dispose();
if (zip2 != null) zip2.Dispose();
}
return isOk;
}