Intermediate changes

1 files changed, 77 insertions, 0 deletions

diff --git a/library/cpp/on_disk/multi_blob/multiblob.h b/library/cpp/on_disk/multi_blob/multiblob.h
new file mode 100644
index 0000000000..b40a5ae6af
--- /dev/null
+++ b/library/cpp/on_disk/multi_blob/multiblob.h
@@ -0,0 +1,77 @@
+#pragma once
+
+#include <util/generic/vector.h>
+#include <util/memory/blob.h>
+
+#define BLOBMETASIG 0x3456789Au
+
+enum E_Multiblob_Flags {
+    // if EMF_INTERLAY is clear
+    //     multiblob format
+    //       HeaderSize()       bytes for TMultiBlobHeader
+    //       Count*sizeof(ui64) bytes for blob sizes
+    //       blob1
+    //       (alignment)
+    //       blob2
+    //       (alignment)
+    //       ...
+    //       (alignment)
+    //       blobn
+    // if EMF_INTERLAY is set
+    //     multiblob format
+    //       HeaderSize()       bytes for TMultiBlobHeader
+    //       size1              ui64, the size of 1st blob
+    //       blob1
+    //       (alignment)
+    //       size2              ui64, the size of 2nd blob
+    //       blob2
+    //       (alignment)
+    //       ...
+    //       (alignment)
+    //       sizen              ui64, the size of n'th blob
+    //       blobn
+    EMF_INTERLAY = 1,
+
+    // Means that multiblob contains blocks in TChunkedDataReader format
+    // Legacy, use it only for old files, created for TChunkedDataReader
+    EMF_CHUNKED_DATA_READER = 2,
+
+    // Flags that may be configured for blobbuilder in client code
+    EMF_WRITEABLE = EMF_INTERLAY,
+};
+
+struct TMultiBlobHeader {
+    // data
+    ui32 BlobMetaSig;
+    ui32 BlobRecordSig;
+    ui64 Count; // count of sub blobs
+    ui32 Align; // alignment for every subblob
+    ui32 Flags;
+    static const ui32 RecordSig = 0x23456789;
+    static inline size_t HeaderSize() {
+        return 4 * sizeof(ui64);
+    }
+    inline const ui64* Sizes(const void* Data) const {
+        return (const ui64*)((const char*)Data + HeaderSize());
+    }
+};
+
+class TSubBlobs: public TVector<TBlob> {
+public:
+    TSubBlobs() {
+    }
+    TSubBlobs(const TBlob& multi) {
+        ReadMultiBlob(multi);
+    }
+    void ReadMultiBlob(const TBlob& multi);
+    const TMultiBlobHeader* GetHeader() const {
+        return (const TMultiBlobHeader*)&Header;
+    }
+
+protected:
+    TMultiBlobHeader Header;
+    TBlob Multi;
+
+private:
+    bool ReadChunkedData(const TBlob& multi) noexcept;
+};