# ZsDiff

A partial update program. Use [Zstandrard](https://github.com/facebook/zstd).

`zsdiff` products a [filename].zdiff file and [filename].zdiff.md5. It compares ALL file hashes from old with new.

```
Usage: zsdiff [OPTIONS] --filename <FILENAME> --old <OLD> --new <NEW>

Options:
  -f, --filename <FILENAME>              
  -c, --compress-level <COMPRESS_LEVEL>  [default: 11]
  -o, --old <OLD>                        
  -n, --new <NEW>                        
  -h, --help                             Print help
```

`zspatch` extract files from [filename].zdiff to [dest-dir]. If some file was deleted between old and new, `zspatch`
also delete it from [dest-dir].
Flag --hash-check compare computed hash of [filename].zdiff and hash from [filename].zdiff.md5

```
Usage: zspatch [OPTIONS] --filename <FILENAME> --dest-dir <DEST_DIR>

Options:
  -f, --filename <FILENAME>  
  -d, --dest-dir <DEST_DIR>  
  -h, --hash-check           
  --help                    Print help
```

```
metadata version: uint16 (2 bytes)
metadata size: uint32 (4 bytes)
n = 6
metadata content: bytes (n;m bytes)
m = n+6
(content -> rsa -> zstd (bytes) -> bytes) (m;o)
content entry: {
  size: uint32 (4 bytes)
  i = 4
  j = i + size
  content: (i;j bytes)
}
```