RARC (File Format)

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RARC files are archive files used in some Wii and GameCube games, such as Super Mario Galaxy 1 & 2. The directories is always stored inside a root node. Compared to U8, this root node is always named.

File Format

Header

The file starts with a header that is 0x20 bytes long:

Offset Type Description
0x00 String File magic. Always RARC in ASCII.
0x04 UInt32 Length of the file in bytes.
0x08 UInt32 Length of this header in bytes. Always 0x20.
0x0C UInt32 Offset to the file data. Relative to the end of this header.
0x10 UInt32 Length of the file data.
0x14 UInt32 Length of the file data again? Always the same as the previous value.
0x18 UInt32 Unknown. Seems to always be 0.
0x1C UInt32 Unknown. Seems to always be 0.

Info Block

Directly after the header comes the info block. It is a 0x20 bytes structure as follows:

Offset Type Description
0x00 UInt32 Number of nodes.
0x04 UInt32 Offset to the first node. Relative to the start of this block.
0x08 UInt32 The total number of directories including all entries.
0x0C UInt32 Offset to the first directory. Relative to the start of this block.
0x10 UInt32 Length of the whole string table.
0x14 UInt32 Offset to string table. Relative to the start of this block.
0x18 UInt16 The number of directories that are files.
0x1A UInt16 Unknown. Seems to always be 0.
0x1C UInt32 Unknown. Seems to always be 0.

Node

A node represents a folder. There is a root folder which links to other files and folders. Each node is a 0x10 bytes structure.

Offset Type Description
0x00 String Some kind of identifier. The root has ROOT, other nodes have their first 4 characters of the name in upper case. If the length of the node's name is less than 4, then the rest of this string is padded with spaces.
0x04 UInt32 Offset to a string into the string table. Relative to the start of the string table.
0x08 UInt16 Hash of the string.
0x0A UInt16 Number of directories in this folder.
0x0C UInt32 The index of the first directory.

Directory

A directory can either be a file or a folder. If it's a folder, then it refers to a node. Each entry is a 0x14 bytes structure.

Offset Type Description
0x00 UInt16 Index of this directory. 0xFFFF if it's a folder.
0x02 UInt16 Hash of the string.
0x04 UInt16 Type? Always 0x200 for folders and 0x1100 for files.
0x06 UInt16 Offset to a string into the string table. Relative to the start of the string table.
0x08 UInt32 File: Offset to file data.
Folder: Index of the node that represente this folder.
0x0C UInt32 Length of the file data in bytes. Unused if this is a folder.
0x10 UInt32 Unknown. Seems to always be 0.

String Table

The string table consist of null-termined strings. The offset and length of this string table is stored in the info block.

Hash

In all directory and node there is a hash of the name stored. To calculate the hash you need to loop through each character. Start with the hash as 0. For each character you multiply the hash by 3 and then add the character's value to the hash.

C# Example

public static UInt16 CalculateHash(string Name)
{
  UInt16 Hash = 0;
  for (int i = 0; i < Name.Length; i++)
  {
    Hash *= 3;
    Hash += Encoding.ASCII.GetBytes(new char[1] { Name[i] })[0];
  }
  return Hash;
}

Tools

The following tools can handle RARC files:

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