Files
FastSync/HANDOFF.md
T
TapTap e77dfbec70 fix(fs): differential-test and reclassify basis dirs, delay-updates, fuzzy, dry-run
Each row's exact residual reproduced against rsync 3.4.1:
- basis dirs (--compare/copy/link-dest): FastSync xxHash-verifies a basis hit
  while rsync --size-only installs the wrong same-size basis content.
- --delay-updates: the fixed .fastsync-stage name wipes an unrelated
  destination entry of that name even without --delete; rsync leaves it.
- --fuzzy: deterministic name/size heuristic (10x window), not rsync's matcher.
- --dry-run: would-delete report over-reports the updated file and an
  excluded-but-protected extra, and ordering differs.
Docs: RSYNC_COMPAT tally 109/16/31; HANDOFF item 9. clang-format + cppcheck +
ASan + full suite clean.
2026-09-18 20:49:51 +02:00

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8.1 KiB
Markdown

# FastSync — Session Handoff (2026-09-17)
## Current status
- **Release `v2.21.0`** tagged (`919a729`, "Release v2.21.0"); full CI green
(run 552: lint, build-and-test, ASan, UBSan, fuzz-build, coverage, valgrind).
`dev` has the release commit plus later doc-only merges (a README refresh and
this handoff).
- **Release PR #284 (`dev` -> `main`)** open, CI green (run 553).
`main` is protected: it needs review/approval to merge.
https://gitea.tap-tap.win/TapTap/FastSync/pulls/284
- **`PROTOCOL_VERSION` = `"2.26.0"`** (`src/shared/config.h`); CMake
`project(FastFileTransfer VERSION 2.26.0)`.
- Working tree clean; no wave worktrees remain.
## What landed this session
1. **Wave 8 (refactors):** Config X-macro wire table; single-owner `authorized_root`;
daemon per-module/per-host caps + cross-process auth lockout (`daemon_limits.[ch]`);
`Data` charge returns to its owning `ProtocolSession`.
2. **Wave 9 (protocol 2.21.0):** optional `STATUS_ERROR_DETAIL` rejection reasons;
server-contacting `--dry-run` (`STATUS_DRY_RUN_TRANSFER`, receiver mutates nothing).
3. **Security wave:** ran 5 parallel audits (wire parsing; daemon/transport/TLS/auth;
receiver confinement; client/CLI/SSH; crypto/memory/limits). Fixed all HIGH and the
confirmed MEDIUMs:
- SSH `-o ProxyCommand=…` argument injection (RCE) — reject leading `-`, insert `--`.
- Truncated zstd frame infinite CPU loop (remote DoS).
- FIFO receiver opens lacked `O_NONBLOCK` (indefinite hang).
- `--inplace` could write a FIFO/device (bypass of `--write-devices` gate).
- `--force` not gated by server `--allow-delete`.
- Privileged standalone server defaulted super activities on; added `--allow-super`
(never honored with `--stdio`).
- `--dry-run` content/hash oracle on `read only`/basis files removed.
- Empty `hosts allow`/`deny`/`auth users` now rejected.
- TLS: AEAD-only 1.2 + server preference, TOCTOU-safe key load, IP-SAN verify,
CN-truncation guard. Glob backtracking bounded; line reads bounded; ACL xattrs
gated on `--acls`; decompression/chunk memory charged; pre-auth `basis_count`
NULL-deref fixed.
4. **Tooling:** benchmark accuracy (data mix, verification, percentiles, `tc`,
`build-bench/`, `--warm` mode); `shell.nix` full toolchain and no build-on-entry;
docs state push-only / remote-source unsupported.
5. **Preserve-attribute split (protocol 2.22.0)** landed on `feat/preserve-attr-split`: per-attribute `-p/-t/-o/-g` + `--no-*` negations, `-a` = `-rlptgoD`, and the 2.21.0 → 2.22.0 wire bump.
6. **Rsync-parity wave (protocol 2.23.0)** on `feat/rsync-parity`: rsync short options/clustering/attached values (`-r`/`-b`/`-L`/`-B`, `-av`, `-aAX`, `-B1000`, `-essh`, `-MOPT`), `-c` checksum quick-check, `--checksum-choice`/`--compress-choice` validation and seed randomization, rsync timeout/max-alloc defaults, temp-dir confinement + `EXDEV` fallback, ownership/mapping parity (numeric-ids modifier, map ranges/`*`/empty-FROM, `--chown`+map conflicts, fake-super resolved-owner record), verbatim symlink storage with rsync `--safe-links`/`--munge-links`, socket recreation under `--specials`, `--chmod` 3.4.1 semantics, and delete scoping + `--max-delete` partial/exit-25. Wire: appended delete-manifest synchronized-directory section and `STATUS_DELETE_LIMIT`.
7. **Parity-completion wave (protocol 2.24.0 → 2.26.0)** on `feat/parity-completion`: per-directory delete plans (`STATUS_DELETE_PLAN`) for `--delete-during`/`--delete-delay`; receiver `STATUS_STATS` counters feeding `--stats`/`--progress` and `--out-format %b/%c/%C`, plus `-n --delete` lines; `lz4`/`zlib`/`zlibx` compression and `md4`/`sha1`/`none` checksums with `auto` negotiation (default `xxh128`/`zstd`); general `-R`/`--no-implied-dirs`/`-d`; the full filter grammar (`merge`/`dir-merge`/`hide`/`show`/`protect`/`risk`/`clear` + modifiers) and corrected `-F`/`-FF`; receiver-side `--chown`/map TO-name resolution; absolute basis dirs + `--link-dest` relink; receiver-side `--ignore-existing` short-circuit; `--preallocate` over `--sparse` via `fallocate(2)`; `--iconv=.`/`-`/`--no-iconv`; lone `-h` help; aliases `--ignore-non-existing`/`--protect-args`/`--msgs2stderr`; and the full `--info`/`--debug` vocabulary. `RSYNC_COMPAT.md` reclassifies the matrix to 106 ✅ / 27 ⚠️ / 23 ❌; the later rsync-parity-stats pass (`fix/parity-stats`) moves it to 107 ✅ / 25 ⚠️ / 24 ❌ (see item 8).
8. **rsync-parity-stats pass** on `fix/parity-stats` (no wire change, `PROTOCOL_VERSION` stays `2.26.0`): `--delete-delay` now counts/budgets only entries actually removed (a refilled deferred directory that survives `ENOTEMPTY` is not counted; `--max-delete` partial-delete count matches rsync); `--stats` gained the `(reg/dir/link/special)` `Number of files` breakdown and now counts only regular files actually stored for `Number of regular files transferred`/transferred size/literal data (up-to-date re-runs report 0); `Total file size` includes symlink target lengths; `--progress` prints the leading `./` root line and counts it in `to-chk` so a single-file transfer matches rsync; and `%C` uses the selected transfer checksum with `checksum_digest_file` supporting md4/sha1/none, byte-identical to rsync for every algorithm. `--out-format` reclassified ❌ (`%b`/delta-`%c` are protocol-specific). Differential + regression tests added; full suite + ASan + clang-format + cppcheck clean.
9. **rsync-parity-fs pass** on `fix/parity-fs` (no wire change, `PROTOCOL_VERSION`
stays `2.26.0`): recursive transfers now recreate empty source directories (and
`-m/--prune-empty-dirs` still suppresses them), a directory entry replaces a
blocking destination regular file, and `-R --no-implied-dirs --files-from`
places a listed file under a missing implied parent with default attributes
instead of refusing (real rsync 3.4.1 parity, differential-tested). `--iconv`
now reproduces rsync's push direction (destination charset = the spec's REMOTE
half; a server `--iconv` overrides), and `-T/--temp-dir` relative semantics are
confirmed identical while the absolute-path confinement is a deliberate
divergence. The basis-dir options, `--delay-updates`, `--fuzzy` and `--dry-run`
were reclassified to ❌ after a differential test reproduced each exact residual
(basis content verification, fixed staging-name collision, heuristic size
window, and dry-run would-delete over-report). Differential-gate allowlist
entries `min_size`/`empty_dirs_recursive`/`dirs_plain` were removed. The
`RSYNC_COMPAT.md` tally is now **109 ✅ / 16 ⚠️ / 31 ❌ = 156**; full suite +
ASan + clang-format + cppcheck clean.
## Next steps
1. **Merge PR #284** (`dev` -> `main`) once reviewed (protected branch).
2. **Deferred security items** (documented, not implemented):
- Pre-auth config/daemon-auth handshake has no aggregate wall-clock deadline
(per-message timeout only) — slowloris holds connection slots.
- Per-source registry fails open when the shared table is full (per-module/global
caps and host ACLs still apply); consider fail-closed or larger/evicting table.
- SCRAM-like daemon auth has no TLS channel binding (and is not RFC 5802).
- `cleanup()` signal handler calls non-async-signal-safe teardown; daemon `umask(0)`.
- Wire protocol assumes homogeneous word size/endianness (lengths are native
`size_t`) — document or move to fixed-width framing.
3. **Out of scope / intentional:** pull (remote source) mode is **not** planned —
FastSync is push-only; see `RSYNC_COMPAT.md#direction`.
## Key facts / commands
- CI image: `gitea.tap-tap.win/taptap/fastsync-ci:v11` (alias `fastsync-ci:local`).
- Build/test: `cmake -B build -S . -DSTRICT_WARNINGS=ON && cmake --build build -j$(nproc) && ./build/tests`
then `python3 -m pytest tests/integration/ -n 4 --dist=load -m "not setpriv"`.
- Dev shell: `nix-shell` (provides clang-format, cppcheck, pytest-xdist, openssh,
rsync, iproute2, valgrind, lcov; does not build on entry).
- Gitea API token: supplied out-of-band via the `TOKEN` environment variable; it is
intentionally **not** recorded in this file.
- CI polling: `GET /api/v1/repos/TapTap/FastSync/actions/runs?limit=N`, match `head_sha`,
then `/actions/runs/<id>/jobs`.