@node State
@cindex storage
@cindex state
@unnumbered State

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

It starts with the header:

@verbatim
"GOREDO" || 0x01 || BuildUUID
@end verbatim

@code{0x01} is format's version number. @code{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:

@table @asis

@item ifcreate

@verbatim
LEN || 0x01 || target
@end verbatim

@code{target} is UTF-8 encoded target's name.

@item ifchange

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

@code{target} is UTF-8 encoded target's name.
@code{hash} is 256-bit BLAKE3 hash.
All other inode-related fields are 64-bit big-endian integers.

@item always

@verbatim
LEN || 0x03
@end verbatim

@item stamp

@verbatim
LEN || 0x04 || hash
@end verbatim

@code{hash} is 256-bit BLAKE3 hash.

@item ifchange-nonexistent

@verbatim
LEN || 0x05 || target
@end verbatim

@code{target} is UTF-8 encoded target's name.

@end table

That @file{.dep} file can be converted to human-readable
@url{https://www.gnu.org/software/recutils/, recfile} format.
For example:

@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
@end example

And its schema definition:
@verbatiminclude ../dep.rec