Read storage block offsets from the archive BlocksInfo

The v9 format design changed: instead of a kArchiveBlockPaddingBetweenChunks
flag telling readers to round each block's offset up to a 16 byte boundary,
each StorageBlock now serializes a UInt64 offset giving where its stored bytes
start, relative to the start of the data section. The writer is then free to
change its padding policy without another format bump, and the reader no longer
needs the "streamed blocks are not padded, chunk blocks are" special case.

Parse that offset as the fourth field of each block record, after Flags, when
the signature is UnityFS and the version is 9 or later. Version 8 and earlier
store their blocks contiguously, so their offsets are still accumulated from
the compressed sizes. A v9 archive whose blocks are out of order or overlapping
is rejected, matching the native reader.

The archive flag is gone from the format, so it is gone from the flag table
too, and `archive info` now derives the padding total from the stored offsets.

Regenerates the LZ4 reference bundles in the new format. Their SerializedFiles
are version 26, which the C# metadata parser does not read yet (issue #130), so
`analyze` and `serialized-file` cannot inspect this data; the `archive` commands
and `dump` can. The mp3 .meta files gain explicit importer settings, which the
project needs in order to build with a 6.7 editor.

Author: SkowronskiAndrew

Archive/ArchiveTool.cs

@@ -163,14 +163,14 @@ public static int PrintSummary(FileInfo filename, OutputFormat format)
             uncompressedDataSize += block.UncompressedSize;
         }
 
-        // The data section can be larger than the sum of the blocks, because of the alignment
-        // padding that separates chunk-based blocks (the BlockPaddingBetweenChunks flag).
+        // The data section can be larger than the sum of the blocks, because the writer may leave
+        // padding between them. Only version 9 and later record where each block starts, so this is
+        // the only version where padding is detectable (and where it is currently written).
         long paddingSize = 0;
         if (blocks.Length > 0)
         {
             var lastBlock = blocks[blocks.Length - 1];
-            long dataSectionSize = lastBlock.FileOffset + lastBlock.CompressedSize - ArchiveDetector.GetDataOffset(header);
-            paddingSize = dataSectionSize - dataSize;
+            paddingSize = lastBlock.Offset + lastBlock.CompressedSize - dataSize;
         }
 
         // Determine the compression algorithm by finding the first block that uses compression.
@@ -280,7 +280,6 @@ static readonly (uint bit, string name)[] KnownArchiveFlags =
         (ArchiveFlags.BlocksInfoAtTheEnd,             "BlocksInfoAtTheEnd"),
         (ArchiveFlags.OldWebPluginCompatibility,      "OldWebPluginCompatibility"),
         (ArchiveFlags.BlockInfoNeedPaddingAtStart,    "BlockInfoNeedPaddingAtStart"),
-        (ArchiveFlags.BlockPaddingBetweenChunks,      "BlockPaddingBetweenChunks"),
     };
 
     static string[] GetArchiveFlagNames(uint flagBits)

TestCommon/Data/LeadingEdgeBuilds/AGENTS.md

@@ -7,7 +7,7 @@ The LeadingEdge build scripts regenerate this folder directly, so to update it,
 ## Layout
 
 * `AssetBundles/` - the AssetBundle build: one bundle per asset (named after the asset) plus the `AssetBundles` manifest bundle. LZMA compressed, so each archive has a single data block.
-* `AssetBundlesLz4/` - the same bundle layout built with chunk-based (LZ4) compression, giving archives with multiple data blocks separated by alignment padding (archive format version 9).
+* `AssetBundlesLz4/` - the same bundle layout built with chunk-based (LZ4) compression, giving archives with multiple data blocks. The writer leaves padding between the blocks, so these exercise the `StorageBlock.Offset` field added in archive format version 9.
 * `ContentDirectory/` - the Content Directory build: content (`.cf`) files, `.resource` files and the build manifest.
 * `BuildReport-AssetBundles/LastBuild.buildreport` - the AssetBundle build report.
 * `BuildReport-ContentDirectory/` - the Content Directory build report folder, including `ContentLayout.json`.

TestCommon/Data/LeadingEdgeBuilds/AssetBundlesLz4/6

@@ -1,16 +1,16 @@
 ManifestFileVersion: 0
-UnityVersion: 6000.7.0a6
-CRC: 1054287113
+UnityVersion: 6000.7.0b1
+CRC: 2778854771
 Hashes:
   AssetFileHash:
     serializedVersion: 2
-    Hash: ef4548464eae98b6ab651c92a869edc9
+    Hash: a19e41b950fe653a3177d32160af00b9
   TypeTreeHash:
     serializedVersion: 2
     Hash: 9a2ca7bdbd1871f7131daf57de908e0c
   IncrementalBuildHash:
     serializedVersion: 2
-    Hash: 818e83165880f042a3252a52b336d06a
+    Hash: 929d8f9d46e767e1fc66294cd024c1fa
 HashAppended: 0
 ClassTypes:
 - Class: 83

TestCommon/Data/LeadingEdgeBuilds/AssetBundlesLz4/6.manifest

@@ -1,6 +1,6 @@
 ManifestFileVersion: 0
-UnityVersion: 6000.7.0a6
-CRC: 2935431312
+UnityVersion: 6000.7.0b1
+CRC: 318228433
 HashAppended: 0
 AssetBundleManifest:
   AssetBundleInfos:

TestCommon/Data/LeadingEdgeBuilds/AssetBundlesLz4/AssetBundlesLz4

@@ -1,16 +1,16 @@
 ManifestFileVersion: 0
-UnityVersion: 6000.7.0a6
-CRC: 1988020392
+UnityVersion: 6000.7.0b1
+CRC: 3846767907
 Hashes:
   AssetFileHash:
     serializedVersion: 2
-    Hash: 6175fa89f0b4cfd7cc433b0b143ab713
+    Hash: a408b749397654c01bfaa7832600a856
   TypeTreeHash:
     serializedVersion: 2
     Hash: 9a2ca7bdbd1871f7131daf57de908e0c
   IncrementalBuildHash:
     serializedVersion: 2
-    Hash: ac9603f3b25ca1814eb4841392a9ff7e
+    Hash: aeb2216eeb5ccfe1cb3f81e62f704746
 HashAppended: 0
 ClassTypes:
 - Class: 83

TestCommon/Data/LeadingEdgeBuilds/AssetBundlesLz4/AssetBundlesLz4.manifest

@@ -1,16 +1,16 @@
 ManifestFileVersion: 0
-UnityVersion: 6000.7.0a6
-CRC: 4203871746
+UnityVersion: 6000.7.0b1
+CRC: 408809727
 Hashes:
   AssetFileHash:
     serializedVersion: 2
-    Hash: 8ae6ceb771f9c15f2dde5117d3f67798
+    Hash: f0b4981a1d1b8cf8a1bb7d53527a4e07
   TypeTreeHash:
     serializedVersion: 2
-    Hash: e4c92e7ce30487f41e62ec475c399971
+    Hash: 819240184df2798191fd853444ad58c4
   IncrementalBuildHash:
     serializedVersion: 2
-    Hash: 00f65fc945d785da9075745396600fe2
+    Hash: cf13ad57198a935f56c518df40c037d0
 HashAppended: 0
 ClassTypes:
 - Class: 114