RomFS: Difference between revisions

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=== Overview ===

RomFS or Read-Only Filesystem is part of the [[NCCH]] format, and is used as external file storage.

RomFS (or Read-Only Filesystem) is part of the [[NCCH]] format, and is used as external file storage.

RomFS can be used:

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=== Format ===

~~All of the content (including the header) in~~ RomFS ~~appears to be aligned to 0x1000 byte blocks~~, the ~~first block starts~~ at ~~0x1000~~. ~~Starting with the second block~~, ~~every block begins~~ with a ~~SHA-256 hash. This hashes~~ the ~~whole 0x1000-byte block following this block~~. ~~For the last block~~, ~~this hash hashes~~ the ~~first block at 0x1000. The total RomFS filesize is always at least 0x4000~~.

The RomFS is wrapped inside a IVFC hash-tree container, and the actual data is structured like a node-based tree, starting at the root level directory node, moving down to other directory and file nodes. Each directory node has pointers to child directory nodes and siblings, together with a pointer to the first file node for that directory. Each file node has pointers to their next file node, together with information about the actual file data.

The RomFS header is ~~0x80~~ bytes long and ~~following~~ is ~~known about the structure~~:

The RomFS IVFC hash-tree header is 0x5C bytes long and is structured as follows:

{| class="wikitable" border="1"

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| Optional info size.

|}

~~The block hash from the header hashes the second block at 0x2000.~~

@@ Line 1: / Line 1: @@
 {{Stub}}
 === Overview ===
-RomFS or Read-Only Filesystem is part of the [[NCCH]] format, and is used as external file storage.
+RomFS (or Read-Only Filesystem) is part of the [[NCCH]] format, and is used as external file storage.
 RomFS can be used:
@@ Line 18: / Line 18: @@
 === Format ===
-All of the content (including the header) in RomFS appears to be aligned to 0x1000 byte blocks, the first block starts at 0x1000. Starting with the second block, every block begins with a SHA-256 hash. This hashes the whole 0x1000-byte block following this block. For the last block, this hash hashes the first block at 0x1000. The total RomFS filesize is always at least 0x4000.
+The RomFS is wrapped inside a IVFC hash-tree container, and the actual data is structured like a node-based tree, starting at the root level directory node, moving down to other directory and file nodes. Each directory node  has pointers to child directory nodes and siblings, together with a pointer to the first file node for that directory. Each file node has pointers to their next file node, together with information about the actual file data.
-The RomFS header is 0x80 bytes long and following is known about the structure:
+The RomFS IVFC hash-tree header is 0x5C bytes long and is structured as follows:
 {| class="wikitable" border="1"
@@ Line 96: / Line 96: @@
 | Optional info size.
 |}
-The block hash from the header hashes the second block at 0x2000.