extern struct SuperBlock [src]

Fields

file_magic: [expect_magic.len]u8

block_size: u32The block size of the internal file system. Valid values are 512, 1024, 2048, and 4096 bytes. Certain aspects of the MSF file layout vary depending on the block sizes. For the purposes of LLVM, we handle only block sizes of 4KiB, and all further discussion assumes a block size of 4KiB.

free_block_map_block: u32The index of a block within the file, at which begins a bitfield representing the set of all blocks within the file which are “free” (i.e. the data within that block is not used). See The Free Block Map for more information. Important: FreeBlockMapBlock can only be 1 or 2!

num_blocks: u32The total number of blocks in the file. NumBlocks * BlockSize should equal the size of the file on disk.

num_directory_bytes: u32The size of the stream directory, in bytes. The stream directory contains information about each stream’s size and the set of blocks that it occupies. It will be described in more detail later.

unknown: u32

block_map_addr: u32The index of a block within the MSF file. At this block is an array of ulittle32_t’s listing the blocks that the stream directory resides on. For large MSF files, the stream directory (which describes the block layout of each stream) may not fit entirely on a single block. As a result, this extra layer of indirection is introduced, whereby this block contains the list of blocks that the stream directory occupies, and the stream directory itself can be stitched together accordingly. The number of ulittle32_t’s in this array is given by ceil(NumDirectoryBytes / BlockSize).

Members

expect_magic (Constant)

Source

  pub const SuperBlock = extern struct {
    /// The LLVM docs list a space between C / C++ but empirically this is not the case.
    pub const expect_magic = "Microsoft C/C++ MSF 7.00\r\n\x1a\x44\x53\x00\x00\x00";

    file_magic: [expect_magic.len]u8,

    /// The block size of the internal file system. Valid values are 512, 1024,
    /// 2048, and 4096 bytes. Certain aspects of the MSF file layout vary depending
    /// on the block sizes. For the purposes of LLVM, we handle only block sizes of
    /// 4KiB, and all further discussion assumes a block size of 4KiB.
    block_size: u32,

    /// The index of a block within the file, at which begins a bitfield representing
    /// the set of all blocks within the file which are “free” (i.e. the data within
    /// that block is not used). See The Free Block Map for more information. Important:
    /// FreeBlockMapBlock can only be 1 or 2!
    free_block_map_block: u32,

    /// The total number of blocks in the file. NumBlocks * BlockSize should equal the
    /// size of the file on disk.
    num_blocks: u32,

    /// The size of the stream directory, in bytes. The stream directory contains
    /// information about each stream’s size and the set of blocks that it occupies.
    /// It will be described in more detail later.
    num_directory_bytes: u32,

    unknown: u32,
    /// The index of a block within the MSF file. At this block is an array of
    /// ulittle32_t’s listing the blocks that the stream directory resides on.
    /// For large MSF files, the stream directory (which describes the block
    /// layout of each stream) may not fit entirely on a single block. As a
    /// result, this extra layer of indirection is introduced, whereby this
    /// block contains the list of blocks that the stream directory occupies,
    /// and the stream directory itself can be stitched together accordingly.
    /// The number of ulittle32_t’s in this array is given by
    /// ceil(NumDirectoryBytes / BlockSize).
    // Note: microsoft-pdb code actually suggests this is a variable-length
    // array. If the indices of blocks occupied by the Stream Directory didn't
    // fit in one page, there would be other u32 following it.
    // This would mean the Stream Directory is bigger than BlockSize / sizeof(u32)
    // blocks. We're not even close to this with a 1GB pdb file, and LLVM didn't
    // implement it so we're kind of safe making this assumption for now.
    block_map_addr: u32,
}  