NRO is the executable format for non-ExeFS binaries.
It starts with the NRO-start structure then the "NRO" header and mainly describes .text, .rodata, and .data segments (like a short-form of ELF program headers):
Start
| Offset
|
Size
|
Description
|
| 0x0
|
0x4
|
Unused
|
| 0x4
|
0x4
|
MOD0 offset
|
| 0x8
|
0x8
|
Padding
|
| Offset
|
Size
|
Description
|
| 0x0
|
0x4
|
Magic "NRO0"
|
| 0x4
|
0x4
|
Version (always 0)
|
| 0x8
|
4
|
Size (total NRO file size)
|
| 0xC
|
0x4
|
Flags (unused)
|
| 0x10
|
0x8 * 3
|
SegmentHeader[3] {.text, .ro, .data}
|
| 0x28
|
0x4
|
BssSize
|
| 0x2C
|
0x4
|
Reserved
|
| 0x30
|
0x20
|
#ModuleId
|
| 0x50
|
0x04
|
DsoHandleOffset (unused)
|
| 0x54
|
0x04
|
Reserved (unused)
|
| 0x58
|
0x8 * 3
|
SegmentHeader[3] {.apiInfo, .dynstr, .dynsym}
|
| Offset
|
Size
|
Description
|
| 0x0
|
0x4
|
MemoryOffset
|
| 0x4
|
0x4
|
Size
|
ModuleId
Value of "build id" from ELF's GNU .note section. Contains variable sized digest, up to 32bytes.
Assets
This is an optional custom assets section for homebrew, this is located at file offset {NroHeader.size}. See also switch-tools for implementation.
The below offsets are relative to the beginning of the assets section (AssetHeader).
| Offset
|
Size
|
Description
|
| 0x0
|
0x4
|
Magic "ASET"
|
| 0x4
|
0x4
|
Format version, currently 0.
|
| 0x8
|
0x10
|
AssetSection icon. Used by the Homebrew Launcher. Like official icons, this is a 256x256 JPEG.
|
| 0x18
|
0x10
|
AssetSection NACP. Used by the Homebrew Launcher.
|
| 0x28
|
0x10
|
AssetSection romfs. Can be used by the application.
|
AssetSection
| Offset
|
Size
|
Description
|
| 0x0
|
0x8
|
Offset
|
| 0x8
|
0x8
|
Size, 0 indicates this section is empty.
|