public static RevisionID RevIDForJSON(IEnumerable <byte> json, bool deleted, RevisionID prevRevID)
{
// Revision IDs have a generation count, a hyphen, and a hex digest
var generation = 0;
if (prevRevID != null)
{
generation = prevRevID.Generation;
if (generation == 0)
{
return(null);
}
}
// Generate a digest for this revision based on the previous revision ID, document JSON,
// and attachment digests. This doesn't need to be secure; we just need to ensure that this
// code consistently generates the same ID given equivalent revisions.
MessageDigest md5Digest;
try {
md5Digest = MessageDigest.GetInstance("MD5");
} catch (NotSupportedException) {
throw Misc.CreateExceptionAndLog(Log.To.Database, Tag, "Failed to acquire a class to create MD5");
}
if (prevRevID != null)
{
var prevIDData = prevRevID.AsData();
var length = prevIDData.Length;
var lengthByte = unchecked ((byte)(length & unchecked ((0xFF))));
md5Digest.Update(lengthByte);
if (lengthByte > 0)
{
md5Digest.Update(prevIDData);
}
}
var isDeleted = deleted ? 1 : 0;
md5Digest.Update((byte)isDeleted);
if (json != null)
{
md5Digest.Update(json.ToArray());
}
var md5DigestResult = md5Digest.Digest();
var digestAsHex = BitConverter.ToString(md5DigestResult).Replace("-", String.Empty);
int generationIncremented = generation + 1;
return(RevisionIDFactory.FromString(String.Format("{0}-{1}", generationIncremented, digestAsHex).ToLower()));
}
public static IEnumerable <RevisionID> AsMaybeRevIDs(this IList list)
{
foreach (var obj in list)
{
var str = obj as string;
if (str == null)
{
yield return(null);
}
yield return(RevisionIDFactory.FromString(str));
}
}
public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
{
var str = reader.Value as string;
return(RevisionIDFactory.FromString(str));
}
public static IEnumerable <RevisionID> AsRevIDs(this IList <string> list)
{
return(list?.Select(x => RevisionIDFactory.FromString(x)));
}
public static RevisionID AsRevID(this string str)
{
return(RevisionIDFactory.FromString(str));
}
