Unit: manifest_delete_missing_args treats a deeper missing entry whose
destination parent directory does not exist as a no-op (run continues, nothing
created). Integration (TestMissingArgs): a deeper missing entry with an absent
parent -R bare and full-mirror layouts, single-threaded and -m, no longer
aborts --delete (the extras walk still removes an unrelated extra); --dirs +
--files-from with --ignore-missing-args skips a listed-but-missing entry and
transfers the rest.
BLOCKER: an absent mirror whose PARENT directory does not exist on the
destination (a deeper --files-from missing entry, -R or full-mirror layout) was
treated as a hard failure because file_open_secure_parent returned -1 when the
parent was missing. That aborted the whole run, skipped the --delete extras
walk, and tore down an early --delete-before/during connection, contradicting
'missing mirror = no-op / all-missing succeeds'. A parent-open failure is now a
no-op when errno is ENOENT/ENOTDIR (matching file_remove_tree_secure); only a
genuine I/O error fails the run.
Also: an already-absent mirror reached via unlinkat-ENOENT no longer prints
'Deleted: <path>' (a no-op dressed as a deletion); the per-path 'Deleted:' line
is printed only when an entry was actually removed.
Precise notes for both rows: supported algorithms (xxh64/xxhash, md5 via EVP),
rejection of unsupported names, seed semantics (full 64-bit for whole-file,
low 32 bits for the delta block hash, ignored by md5), the --cc alias, the
length-prefixed bounded handshake digest, the 2.9.0 -> 2.10.0 protocol bump,
default byte-for-byte preservation, and the divergence from rsync's randomized
seed (FastSync defaults to seed 0). Summary count line is intentionally untouched.
Adds real algorithm selection (xxh64 default, plus md5 via OpenSSL EVP) and a
64-bit seed for the per-file whole-file digest used by the --incremental/
--checksum handshake and basis-dir content verification. The seed also feeds
the delta path's per-block xxHash32 strong checksum (low 32 bits) so an
explicit seed deterministically changes those digests too. Sender and receiver
hash identically: the algorithm id and seed cross the config wire frame and the
STATUS_CHECK handshake now carries a length-prefixed, bounded digest instead of
a fixed 64-bit value. Unsupported algorithm names are rejected at parse time
(never a silent no-op). PROTOCOL_VERSION bumped 2.9.0 -> 2.10.0; defaults
(xxh64, seed 0) preserve prior byte-for-byte behavior.
Flip both rows to Implemented with precise Notes covering the tail-resume
model, the prefix-verify semantics (and the plain-append rsync-parity safety
statement), the new wire frames, and the PROTOCOL_VERSION 2.9.0 -> 2.10.0 bump.
Add a Phase-3 append-wave implementation-notes block. The Summary count line
is deliberately left untouched.
- CLI: --append/--append-verify acceptance (parse + imply --incremental,
validate) and incompatibility rejection with -s and --whole-file; both
removed from the unimplemented reject list.
- Config: on-the-wire append/append_verify round-trip.
- Unit: append_resume_eligible / append_tail_length pure resume math.
- Integration (test_append.py): matching-prefix resume is byte-identical and
tail-only (wire bytes << source size); --append with a wrong prefix keeps
prefix+tail (rsync parity) while --append-verify detects the mismatch and
falls back to a byte-exact full transfer; --append with --inplace and -m.
Implement rsync's append modes: when an existing destination file is SHORTER
than the source, the receiver negotiates a resume offset and only the tail is
transferred; the full file (retained prefix + tail) is rebuilt and installed
through the normal atomic store path, so the result is byte-identical to the
source whenever the prefix matches.
- --append: sends the tail without content-verifying the retained prefix
(rsync parity; the documented prefix-trust risk).
- --append-verify: verifies the retained prefix against the source's prefix
xxHash64 before appending and, on a mismatch, falls back to a clean full
transfer (never a corrupt prefix+tail blend).
New wire frames STATUS_APPEND / STATUS_APPEND_SIG / STATUS_APPEND_OK /
STATUS_APPEND_DATA; PROTOCOL_VERSION bumped 2.9.0 -> 2.10.0 (peers must match).
Both flags imply --incremental and are incompatible with -s (chunk
serialization) and --whole-file (rejected up front). Respects --inplace,
--partial/--partial-dir and --delay-updates via the shared store engine.
Precise Notes on the arg model (files-from entries), implies-relationships
(delete-missing implies ignore, independent of --delete), delete/timing/force/
exclude-protection interplay, the third manifest section and the 2.9.0 -> 2.10.0
wire bump, and the divergences (empty-list hard error, no negation, max-delete
not applied to explicit deletions). The files-from row now references the flags.
The Summary count line is intentionally left for a recount commit.
Unit: CLI parse + imply relationships (delete-missing implies ignore, not
delete; valid with --delete and delete timing); delete_missing_args config wire
round-trip (ignore_missing_args confirmed client-only); three-section manifest
round-trip and third-section traversal rejection; manifest_delete_missing_args
exact-path semantics; commit-time parking. Existing two-section manifest frames
updated to the three-section format. Integration: default missing entry is a
hard pre-transfer error; --ignore-missing-args transfers the rest and succeeds
(all-missing transfers nothing; empty list still errors); --delete-missing-args
removes exactly the missing mirror and leaves unrelated extras unless --delete is
also present; filter-exclusion protection never blocks the explicit deletion;
--delete-before early timing composes; all parametrized single-threaded vs -m.
New flags parse onto the config; --delete-missing-args implies
--ignore-missing-args (order-independent) and does NOT imply --delete (rsync:
independent of other delete processing). The files-from preflight now classifies
listed-but-missing entries instead of hard-failing: under the flags each is
skipped (logged + counted, never silent) and the run succeeds for the rest,
including the all-missing case; an empty list stays a hard error. Under
--delete-missing-args the missing entries' destination mirrors (bare relative
path with -R, full source mirror otherwise) ride the manifest's third section in
both the single-threaded and -m senders; --dirs listed-but-missing entries are
skipped in the scanner.
PROTOCOL_VERSION 2.9.0 -> 2.10.0. The STATUS_MANIFEST frame gains a third
section carrying destination-relative exact-delete paths (the missing
--files-from entries' mirrors); the config frame gains a delete_missing_args
bool (ignore_missing_args stays client-only). The receiver validates the third
section like the keep-set and commits it with manifest_delete_all():
manifest_delete_missing_args runs first (explicit user requests, never blocked
by protected-prefix exclusion protection; staging/basis protected; a non-empty
directory mirror removed only under --force/--delete, rsync parity) and then the
ordinary extras walk. Server --allow-delete gates it like --delete.
The suffix-trim loop using computed end offsets tripped cppcheck's
knownConditionTrueFalse value-range analysis (it unsoundly concluded the trims
always consume the whole middle). Rewrite it with explicit moving end indices
and add an inline suppression with a rationale for the residual false
positive; cppcheck --error-exitcode=1 is clean again. The trimming logic is
unchanged and was verified against a full DP reference over 200k random name
pairs.
The walker's all-or-nothing guarantee holds only while the destination is not
concurrently modified (rehearsal and delete are separate walks). The
protected-prefix list shares the 16 MB MAX_MANIFEST_BYTES budget with the
keep-set and each section is capped at MAX_MANIFEST_ENTRIES; an over-budget
frame is rejected on the receiver with STATUS_ERROR rather than truncated.
- ignore-errors scan-error test now runs single-threaded and under -m (the
exact scan_directory_multithreaded path that had the use-after-free);
- new integration test: --delete/--delete-before --ignore-errors with an
unreadable SOURCE ROOT (sequential and -m) must fail and delete NOTHING;
- new integration test: a destination-only file that merely matches an exclude
rule is deleted under plain --delete (protection is sender-derived), while a
source-excluded mirror is protected;
- delete-protects/delete-excluded coverage extended to --delete-after and
--delete-delay;
- new unit test: the 100000-entry server hard bound is all-or-nothing (more
extras than the bound -> nothing removed);
- new integration test: --force is inert under --delay-updates (documented);
- fixed the ignore-errors assertion message that stated the opposite of what it
asserted.
scan_directory_multithreaded read directory_scanner_had_io_error() /
parallel_scanner_had_io_error() AFTER destroying the scanner object (a
heap-use-after-free on every successful -m run that recorded an io_error); the
flag is now captured before the destroy. As a second line of defense against
an empty-keep-set wipe, all four manifest send sites (sequential and -m, early
pre-scan and commit data pass) now refuse to transmit a keep-set manifest when
the scan that built it recorded an io_error and produced no keep entries: a
source that merely LOOKS empty because part of it was unreadable must never
delete the whole destination. A genuinely empty source (no io_error) still
sends its empty keep-set and prunes extras.
A sequential scanner records an opendir failure of its seed/root directory as a
skippable io_error and would complete an EMPTY scan, whose keep-set manifest
would then delete every destination entry. The seed directory that maps to the
transfer root (relative path "") is now fatal regardless of --ignore-errors;
only subdirectories discovered during an otherwise-successful root scan are
skippable. The -m path never had this hole (its root open failure aborts
scanner creation), so sequential and -m now agree.
Unit (CLI): --fuzzy --no-incremental (either order) stays a valid plain-mode
config -- no forced handshake, no delta implication; --fuzzy --no-delta stays
covered.
Integration (TestFuzzy):
- worthless basis: a sibling that passes the name+size gates but shares no
blocks makes the sender reply STATUS_NEXT; the whole file is consumed inside
the delta handshake with byte-exact output (no protocol desync).
- non-displacement: an existing exact-path destination file INSIDE the delta
size bounds (same size, different content, older mtime) is used as the delta
basis instead of a byte-identical similar sibling (whole-file wire cost).
- asymmetric bases: basis larger than source (prefix reuse) and basis smaller
than source (appended tail as literals) both reconstruct byte-exactly with a
small delta.
- --no-fuzzy end-to-end equals the no-flag whole-file behavior.
CountingProxy closes its listener socket (fd hygiene).
Review follow-ups on the --fuzzy row: note that the receiver's block
signature is derived from a sibling file it may not otherwise send, exposing
destination sibling files to the sender at block granularity (the same
known-plaintext information class as the ordinary delta path); and document
that --fuzzy honors an explicit --no-incremental (unlike the basis-dir
options, which force it), with the delta implication suppressed accordingly.
The --fuzzy implication previously forced use_incremental back on even when
the user passed --no-incremental, while --no-delta and -W were honored.
Track a --no-incremental latch (like the no_delta latch): with it set, do not
force the handshake on, and because delta needs the handshake, also suppress
the delta implication so no invalid '--delta requires --incremental' config
results. A --fuzzy --no-incremental run is therefore a plain default-mode
transfer (fuzzy inert), consistent with -W/--no-delta. Documented in the
usage text (this deliberately differs from the basis-dir options, which still
force incremental unconditionally).
Review follow-ups on the --fuzzy candidate scan:
- Allocate the two DP rows once per directory scan instead of once per
candidate (4096-entry directories no longer do thousands of malloc pairs).
- Pre-prune before the DP with two cheap lower bounds on the edit distance:
the name length gap and the count of characters of one basename absent from
the other; a candidate whose gate (distance*2 <= longer) already fails on
the max of those bounds is skipped without running the DP.
- Trim the common prefix and non-overlapping common suffix before the DP so
it only runs over the differing middles.
- Note that the 4096 readdir cap bounds iterations, not per-entry DP cost,
and that the seen set is filesystem-order dependent (winner stays
deterministic via the total comparator).
- Open the chosen candidate with O_NONBLOCK so a name raced to a FIFO cannot
block the receive thread forever in open(2); the existing fstat S_ISREG gate
still rejects non-regular files. (The pre-existing basis_open_regular has
the same latent FIFO pattern and is intentionally left unchanged.)
- Free old_data in receive_delta_file's defensive NULL guard.
file_remove_tree_secure() opens the final component O_NOFOLLOW below the
authorized root and recursively wipes it with an fd-relative walk (symlinks are
removed by name, never followed); --force uses it to clear a destination
directory that blocks an incoming regular file.
--delete-excluded/--max-delete/--ignore-errors/--force/--prune-empty-dirs now
✅ with precise notes: the rsync-parity default (plain --delete protects
filter-excluded destination mirrors), the -m divergence (FastSync -m stays
multithreading, so --prune-empty-dirs is long-only), the all-or-nothing
max-delete/hard-bound error model, the 2.8.0 -> 2.9.0 protocol bump, and the
new two-section STATUS_MANIFEST frame. Summary counts left for the orchestrator
to recount after the wave.
Unit: walker all-or-nothing bounds (exceeded -> nothing removed + distinct
result; exact bound -> deletes), protected-prefix skipping, config wire
round-trip for force_delete/delete_excluded/prune_empty_dirs/max_delete, CLI
parse/validation for the new flags. Integration (TestDeletePolicy): default
delete-excluded protection and --delete-excluded opt-out (single-thread, -m,
early --delete-before, excluded-dir subtrees), --max-delete all-or-nothing over
and at the limit, --force file-over-nonempty-dir replacement, --prune-empty-dirs
(--dirs mode + recursion-mode parity), and --ignore-errors keeping deletion
active across a genuine scan I/O error (run as an unprivileged user).
The scanners now record every entry pruned by user-selection rules
(--filter/-C/per-dir, --exclude/--include, --max-size/--min-size) as a
destination-relative protected path on a caller-supplied sink (thread-safe in
the parallel scanner); --files-from subset pruning and -R relative wire paths
are never recorded. The sender transmits these as manifest protected prefixes,
giving rsync's default --delete behavior (excluded mirrors survive) with
--delete-excluded opting back into deleting them. --ignore-errors makes an
unreadable source directory a recorded, non-fatal scan error: the run continues,
the deletion still runs, and the exit code reports the ignored error.
--prune-empty-dirs omits an empty source directory's explicit --dirs entry.
Empty directories were never transferred by recursive scans (rsync -m parity).
The STATUS_MANIFEST frame now carries two count-delimited sections: the kept
paths and a protected-prefix list (excluded-on-source paths the walker must not
delete unless --delete-excluded opted out). The receiver's DeleteManifest is
passed through the commit/early paths unchanged. manifest_delete_extras
honors a client --max-delete (all-or-nothing) and produces a distinct error for
it versus the 100000-entry server bound. --force clears a non-empty directory
that blocks an incoming regular file (confined, symlink-safe) via a new
file_remove_tree_secure helper.
delete_extras_limited now rehearses a finite-capped deletion before unlinking
anything (an identical fd-relative walk that counts files and directories) and
returns DELETE_WALK_LIMIT_EXCEEDED with nothing removed when the run would
exceed the cap, so --max-delete is enforced per run instead of truncating the
deletion. A directory that still holds entries the walker leaves in place
(protected excluded prefix, manifest-kept file, symlink) is left behind rather
than failing the whole deletion, matching rsync's leave-non-empty-dirs
behavior. Rehearsal/delete each open an independent file description so a
prior pass cannot drain the directory stream.
Adds ignore_errors (client-only) and force_delete (wire) booleans, makes
max_delete default -1 (no client limit), and parses --delete-excluded,
--max-delete=NUM, --ignore-errors, --force, --prune-empty-dirs. Bumps
PROTOCOL_VERSION 2.8.0 -> 2.9.0 for the new on-the-wire force_delete field.
Document the receiver-side decision location, the exact deterministic
similarity heuristic, the byte-exactness argument, when fuzzy applies (and
when it deliberately does not), the 2.8.0 -> 2.9.0 protocol bump, and the
divergences from rsync. Update the basis-dir rows' protocol references to
the now-current 2.9.0.
Unit: parse -y/--fuzzy and --no-fuzzy negation (order-independent), -W and
--no-delta leave fuzzy inert, --fuzzy implies --incremental/--delta, and
validate_config rejects fuzzy with -s (chunk serialization) and -f
(sendfile). Config: fuzzy survives the socketpair wire round-trip.
Integration (TestFuzzy, byte counts via a new CountingProxy helper): the
rename case transfers a 2 MiB file in a few percent of its size with byte-
exact output under --fuzzy, while the no-fuzzy, no-candidate, dissimilar-
sibling and --whole-file runs send the whole file; -y alias; -m parity;
dest-holds-unsuitable-file falls back to the sibling; --delay-updates and
--remove-source-files keep their semantics on fuzzy transfers.
When a file must be transferred and the destination holds no usable content
at the exact path (file absent, or outside the delta engine's size bounds),
the receiver now searches the target's own destination directory for an
existing regular file with a similar basename and uses it as the delta basis
via the existing receiver-driven STATUS_DELTA_SIGNATURE handshake. The
sender never learns the basis was another file, so no wire change beyond the
new config flag was required.
Heuristic (deterministic, simpler than rsync's, documented): candidates are
sibling entries confined below the root and opened O_NOFOLLOW (symlinks are
never followed, nothing outside the destination root is read); dotfiles,
directories, the target's own name and stage/temp names are excluded; size
gate is delta_should_attempt; name gate is a Levenshtein distance <= half
the longer basename; the closest candidate (size tie-break, then lexical) is
loaded; the scan is capped at 4096 entries.
Byte-exactness is independent of the basis: block matches are verified by
Adler-32 + xxHash32, delta_apply validates every reference, and a basis that
shares nothing makes the sender reply with a whole-file transfer. When no
candidate qualifies the normal whole-file transfer runs unchanged.
Register --fuzzy (alias -y) as a boolean option and fuzzy as negatable so
--no-fuzzy works through the generic negation machinery. FastSync's delta
machinery is off by default (unlike rsync, where --fuzzy implies nothing
because delta is the default), so --fuzzy implies --incremental and --delta
unless --whole-file or an explicit --no-delta switched delta off (leaving
fuzzy inert, matching rsync where -W makes fuzzy irrelevant). Add help text.
-y/--fuzzy is receiver-side similar-file basis selection, so the receiver
must learn the flag: add a bool to Config, serialize it as a trailing field
on the config frame, and validate the received value. Because the config
frame layout changed, PROTOCOL_VERSION moves to 2.9.0 (peers must match).
The seed run did not preserve timestamps, so the destination copy's mtime was
the write time; the incremental --remove-source-files rerun only skipped the
file when both writes happened to land in the same whole second, making the
test flaky (observed intermittently in local full-suite runs and on CI). Seed
with -M so the destination stores the source's exact mtime.
- --link-dest destination entries share the basis inode: a later --inplace run
against such a path mutates the basis snapshot through the shared inode
(recommend --copy-dest when the destination must stay independently writable).
- basis-hit files take mode/uid/gid and mtime from the basis file, not the
sender's metadata (with --size-only the mtime can differ from the source).
- --remove-source-files sources satisfied by a basis dir are retained.
- basis runs refuse files above the 256 MiB whole-file limit up front (FastSync
caps every whole-file payload path at 256 MiB; rsync supports arbitrary sizes);
the config frame always carries a basis-count field (protocol 2.8.0).
- unit: config basis-path normalization (trailing slash, a//b, ./x/./y collapse;
degenerate inputs rejected).
- integration: same-size/same-mtime/different-content fixtures prove the xxHash
gate -- the basis changed.txt now has the SAME byte size as the source so the
size short-circuit can no longer mask the hash comparison, plus a dedicated
parametrized same-size mismatch test asserting link/copy never use a
content-mismatched basis and compare-dest transfers.
- basis-dir priority is first-match-wins: two link-dest dirs (inode of the
first), and compare-dest before link-dest stays sparse while the reverse
order hard-links.
- --size-only links a same-content basis file with a different mtime;
--ignore-times never links even an exact match.
- --delay-updates + --delete removes extras inside a nested .fastsync-stage
dir (regression guard) while keeping the real staging dir and basis tree.
- a basis run containing a file above the whole-file limit fails up front with
a clear error and transfers nothing.
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