adbd is root, so the raw partitions are readable. A full byte-exact backup was taken (md5-verified partition images + a file-level copy of /system and /vendor).

Note on the old ADB: a normal shell corrupts binary data (the PTY translates line endings) and exec-out is unsupported on this old adbd, so binary is streamed through base64 + gzip (7-bit, PTY-safe). adb pull itself is binary-safe (it uses the sync protocol).