protected GZipAccess(Stream stream, CompressedArchiveAccessMode mode)
{
IsReadOnly = mode == CompressedArchiveAccessMode.Read;
BaseStream = stream;
var fileStream = stream as FileStream;
if (fileStream != null)
{
RootLocation = fileStream.Name;
}
_entries = GZipMemberEntry.GetMemberEntries(stream, Properties.Settings.Default.MaxGZipEntriesSearch).ToList();
if (IsReadOnly)
{
if (!_entries.Any())
{
throw new InvalidDataException(Resources.Strings.GZipAccess_NoEntriesFound);
}
}
else
{
if (_entries.Any())
{
throw new InvalidOperationException(Resources.Strings.GZipAccess_EntriesAlreadyPresent);
}
}
}
/// <summary>
/// Creates an instance of <see cref="GZipMemberEntry"/> with the given name.
/// </summary>
/// <param name="name">The name for the entry.</param>
/// <returns>A new instance of <see cref="GZipMemberEntry"/>.</returns>
/// <remarks>NOTE: This instance is a placeholder only, and none of the relevant metadata is set. It is used in implementations of
/// ICompressedArchiveAccess that provide a means to create new GZIP files. Note also that only minimal name validation is done.</remarks>
/// <exception cref="ArgumentException">Thrown if name is <c>null</c>or empty. Perhaps other more stringent checks could be added.</exception>
internal static GZipMemberEntry CreateEmptyEntry(string name)
{
if (string.IsNullOrEmpty(name))
{
throw new ArgumentException("name");
}
var entry = new GZipMemberEntry()
{
_name = name
};
return(entry);
}
private static long FindNextEntry(Core.Utility.BinaryReader reader, GZipMemberEntry currentEntry)
{
var foundMagic = false;
var positionOfNextEntry = -1L;
try
{
var magic = reader.ReadByte();
while (true)
{
if (magic == MagicIdentifier[0])
{
magic = reader.ReadByte();
if (magic == MagicIdentifier[1])
{
foundMagic = true;
break;
}
}
else
{
magic = reader.ReadByte();
}
}
}
catch (EndOfStreamException)
{
positionOfNextEntry = reader.BaseStream.Length;
}
catch (IOException)
{
}
if (foundMagic || (positionOfNextEntry == reader.BaseStream.Length))
{
// go back 4 (CRC32) + 4 (size mod 2^32) [+ 2 (magic)]
var offset = sizeof(uint) + sizeof(int);
var origin = SeekOrigin.End;
if (foundMagic)
{
offset += MagicIdentifier.Length;
origin = SeekOrigin.Current;
}
reader.BaseStream.Seek(-offset, origin);
currentEntry.Crc32 = reader.ReadUInt32();
currentEntry._length = reader.ReadInt32();
positionOfNextEntry = reader.BaseStream.Position;
}
return(positionOfNextEntry);
}
/// <inheritdoc />
public override ICompressedArchiveEntry CreateEntry(string name)
{
if (IsReadOnly)
{
throw new InvalidOperationException(Resources.Strings.GZipAccess_InvalidModeForCreateEntryError);
}
if (_entries.Count > 0)
{
throw new NotSupportedException(Resources.Strings.GZipAccess_MultipleMembersNotSupportedError);
}
var entry = GZipMemberEntry.CreateEmptyEntry(name);
_entries.Add(entry);
return(entry);
}
/// <inheritdoc />
protected override Stream OpenStreamForEntry(GZipMemberEntry entry)
{
Stream entryStream = null;
if (IsReadOnly)
{
entryStream = new GZipInputStream(BaseStream)
{
IsStreamOwner = false
};
}
else
{
entryStream = new GZipOutputStream(BaseStream)
{
IsStreamOwner = false
};
}
return(entryStream);
}
/// <summary> /// Opens a stream for the given entry. /// </summary> /// <param name="entry">The entry to open the stream for.</param> /// <returns>The stream to access the entry.</returns> /// <remarks>Note that <see cref="BaseStream"/> will already be position to the beginning of the entry by the caller.</remarks> protected abstract Stream OpenStreamForEntry(GZipMemberEntry entry);
/// <inheritdoc />
protected override Stream OpenStreamForEntry(GZipMemberEntry entry)
{
var entryStream = new GZipStream(BaseStream, Mode, leaveOpen: true);
return(entryStream);
}
