State ¶

Dependency and build state is kept inside .redo subdirectory in each directory related the build. Each corresponding target has its own, recreated with every rebuild, binary .dep file.

It starts with the header:

"GOREDO" || 0x01 || BuildUUID

0x01 is format’s version number. BuildUUID is 128-bit UUID.

After the header comes concatenation of length-prefixed chunks. Length is the length of the whole chunk, including the size of the encoded length itself. It is 16-bit big-endian integer. After the length comes single byte type of the chunk:

ifcreate

LEN || 0x01 || target

target is UTF-8 encoded target’s name.

ifchange

LEN || 0x02 ||
    size || inodeNum ||
    ctimeSec || ctimeNsec ||
    mtimeSec || mtimeNsec ||
    hash || target

target is UTF-8 encoded target’s name. hash is 256-bit BLAKE3 hash. All other inode-related fields are 64-bit big-endian integers.

always

LEN || 0x03

stamp

LEN || 0x04 || hash

hash is 256-bit BLAKE3 hash.

ifchange-nonexistent

LEN || 0x05 || target

target is UTF-8 encoded target’s name.

That .dep file can be converted to human-readable recfile format. For example:

Build: 80143f04-bfff-4673-950c-081d712f573d

Type: ifcreate
Target: foo.o.do

Type: ifchange
Target: default.o.do
Size: 123
InodeNum: 2345
CtimeSec: 1605721341
CtimeNsec: 253305000
MtimeSec: 1645606823
MtimeNsec: 369936700
Hash: f4929732f96f11e6d4ebe94536b5edef426d00ed0146853e37a87f4295e18eda

Type: always

Type: stamp
Hash: 5bbdf635932cb16b9127e69b6f3872577efed338f0a4ab6f2c7ca3df6ce50cc9

And its schema definition:

%rec: Build
%doc: Build session
%key: Build
%type: Build uuid

%rec: Dependency
%doc: Dependency information
%mandatory: Type
%allowed: Target Size InodeNum CtimeSec CtimeNsec MtimeSec MtimeNsec Hash
%unique: Type Target Size InodeNum CtimeSec CtimeNsec MtimeSec MtimeNsec Hash
%type: Type enum ifcreate ifchange always stamp
%type: Size int
%type: InodeNum int
%type: CtimeSec int
%type: CtimeNsec int
%type: MtimeSec int
%type: MtimeNsec int
%type: Hash regexp /[0-9a-f]{64}/

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