bool DoRead(Stream stream)
{
if (stream.Length < _metadataTable.MinLength + SegmentLength)
{
return(false); // 虽然插件数据文件存在，但并未包含有效的数据
}
// 1. 读取各个分段的长度
stream.Position = stream.Length - SegmentLength;
var addinRecordSegmentLength = stream.ReadInt64();
var addinMetadataSegmentLength = stream.ReadInt64();
var invalidAddinFilePacksSegmentLength = stream.ReadInt64();
var dataSegmentLength = stream.ReadInt64();
if (dataSegmentLength + SegmentLength != stream.Length)
{
return(false); // 插件数据文件已被破坏，返回 false 以便让系统重新解析插件
}
// 2. 读取 AddinMetadata 分段 (AddinMetadataTable)
stream.Position = addinRecordSegmentLength; // 指针指向 AddinMetadata 分段 (AddinMetadataTable) 的起始位置
var hasAddins = _metadataTable.Read(stream);
if (!hasAddins || _metadataTable.AddinCount == 0)
{
return(false); // 虽然插件数据文件存在，但并未包含有效的数据
}
// 3. 根据 AddinMetadata 读取 AddinRecord 分段，并进行验证
foreach (var metadata in _metadataTable.Addins)
{
stream.Position = metadata.Position;
var addin = new AddinRecord(metadata);
addin.Read(stream);
if (stream.Position - metadata.Position != metadata.Length || addin.Uid != metadata.AddinUid)
{
return(false); // 插件数据文件已被破坏，返回 false 以便让系统重新解析插件
}
_addinRecords.Add(addin);
}
// 4. 读取 InvalidAddinFilePack 分段
stream.Position = addinRecordSegmentLength + addinMetadataSegmentLength; // 指针指向 InvalidAddinFilePack 分段的起始位置
_invalidAddinFilePacks = RecordHelpers.Read(stream, ref AddinFilePack.Factory);
if (stream.Position - (addinRecordSegmentLength + addinMetadataSegmentLength) != invalidAddinFilePacksSegmentLength)
{
return(false); // 插件数据文件已被破坏，返回 false 以便让系统重新解析插件
}
// 5. 读取 Uid 分段
stream.Position = addinRecordSegmentLength + addinMetadataSegmentLength + invalidAddinFilePacksSegmentLength; // 指针指向 Uid 分段的起始位置
UidStorage.Read(stream);
return(true);
}
bool DoWrite(Stream stream)
{
long addinRecordSegmentLength = 0,
addinMetadataSegmentLength = 0,
invalidAddinFilePacksSegmentLength = 0,
dataSegmentLength = 0;
// 1. 写入 AddinRecord 分段
long startPosition = 0;
foreach (var addin in _addinRecords)
{
var addinMetadata = addin.AddinMetadata;
addinMetadata.AddinUid = addin.Uid;
// 记录 AddinRecord 的起始位置
addinMetadata.Position = stream.Position;
// 写入 AddinRecord
addin.Write(stream);
// 记录 AddinRecord 的长度
addinMetadata.Length = stream.Position - addinMetadata.Position;
}
addinRecordSegmentLength = stream.Position - startPosition;
// 2. 写入 AddinMetadata 分段 (AddinMetadataTable)
startPosition = stream.Position;
_metadataTable.Write(stream);
addinMetadataSegmentLength = stream.Position - startPosition;
// 3. 写入 InvalidAddinFilePack 分段
startPosition = stream.Position;
RecordHelpers.Write(stream, _invalidAddinFilePacks);
invalidAddinFilePacksSegmentLength = stream.Position - startPosition;
// 4. 写入 Uid 分段
UidStorage.Write(stream);
// 5. 获取数据段的长度
dataSegmentLength = stream.Position;
// 6. 写入各个分段 (segemtnt) 的长度
stream.WriteInt64(addinRecordSegmentLength);
stream.WriteInt64(addinMetadataSegmentLength);
stream.WriteInt64(invalidAddinFilePacksSegmentLength);
stream.WriteInt64(dataSegmentLength);
return(true);
}
