ExeFS

Overview

ExeFS or Executable Filesystem contains information related to the executable program, and is the part of the CXI format.

The ExeFS usually contains one or more of the following files:

• .code Contains the code binary, which can be optionally reverse-LZSS compressed via an exheader flag.
• .logo Contains distribution licensing Binary data.
• .banner Contains the banner which homemenu uses for this CXI.
• .icon Contains the icon which homemenu displays for this CXI.

Format

The ExeFS header is 0x200 bytes long and follows this simple structure:

START	SIZE	DESCRIPTION
0x00	0xa0	File headers (10 headers maximum, 16 bytes each)
0xa0	0x20	Reserved
0xc0	0x140	File hashes (10 hashes maximum, 32 bytes each, one for each header)

File hashes are stored in reverse order, i.e. the hash at offset 0x1E0 corresponds to the first ExeFS section.

File headers

There are a maximum of 10* file headers in the ExeFS format, which have the following structure:

START	SIZE	DESCRIPTION
0x0	0x8	File name
0x8	0x4	File offset
0xC	0x4	File size

* The maximum number of ExeFS file headers, is disputable. With makerom indicating a maximum of 8 sections, and makecia indicating a maximum of 10. From a non-SDK point of view ExeFS header format can hold no more than 10 file headers within the currently define size of 0x200 bytes.

File offsets are non-inclusive of the header's size (0x200 bytes). Also, file headers which are not used are filled with all zeros.

File hashes

Each file header has a corresponding file hash, which is the SHA256 hash calculated over the entire file contents.