/// <summary>
/// Like {@link
/// #checkHeader(DataInput,String,int,int)} except this
/// version assumes the first int has already been read
/// and validated from the input.
/// </summary>
public static int CheckHeaderNoMagic(DataInput @in, string codec, int minVersion, int maxVersion)
{
string actualCodec = @in.ReadString();
if (!actualCodec.Equals(codec))
{
throw new System.IO.IOException("codec mismatch: actual codec=" + actualCodec + " vs expected codec=" + codec + " (resource: " + @in + ")");
}
int actualVersion = @in.ReadInt();
if (actualVersion < minVersion)
{
throw new System.IO.IOException("Version: " + actualVersion + " is not supported. Minimum Version number is " + minVersion + ".");
}
if (actualVersion > maxVersion)
{
throw new System.IO.IOException("Version: " + actualVersion + " is not supported. Maximum Version number is " + maxVersion + ".");
}
return actualVersion;
}
/// <summary>
/// Reads and validates a header previously written with
/// <seealso cref="#writeHeader(DataOutput, String, int)"/>.
/// <p>
/// When reading a file, supply the expected <code>codec</code> and
/// an expected version range (<code>minVersion to maxVersion</code>).
/// </summary>
/// <param name="in"> Input stream, positioned at the point where the
/// header was previously written. Typically this is located
/// at the beginning of the file. </param>
/// <param name="codec"> The expected codec name. </param>
/// <param name="minVersion"> The minimum supported expected version number. </param>
/// <param name="maxVersion"> The maximum supported expected version number. </param>
/// <returns> The actual version found, when a valid header is found
/// that matches <code>codec</code>, with an actual version
/// where <code>minVersion <= actual <= maxVersion</code>.
/// Otherwise an exception is thrown. </returns>
/// <exception cref="CorruptIndexException"> If the first four bytes are not
/// <seealso cref="#CODEC_MAGIC"/>, or if the actual codec found is
/// not <code>codec</code>. </exception>
/// <exception cref="IndexFormatTooOldException"> If the actual version is less
/// than <code>minVersion</code>. </exception>
/// <exception cref="IndexFormatTooNewException"> If the actual version is greater
/// than <code>maxVersion</code>. </exception>
/// <exception cref="IOException"> If there is an I/O error reading from the underlying medium. </exception>
/// <seealso cref= #writeHeader(DataOutput, String, int) </seealso>
public static int CheckHeader(DataInput @in, string codec, int minVersion, int maxVersion)
{
// Safety to guard against reading a bogus string:
int actualHeader = @in.ReadInt();
if (actualHeader != CODEC_MAGIC)
{
throw new System.IO.IOException("codec header mismatch: actual header=" + actualHeader + " vs expected header=" + CODEC_MAGIC + " (resource: " + @in + ")");
}
return CheckHeaderNoMagic(@in, codec, minVersion, maxVersion);
}
