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feat(basis): rsync quick-check default + FastSync-only --verify-basis

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- default basis match is rsync's metadata quick-check (size + mtime; size-only
  drops mtime; -I disables), no mandatory content digest
- new long-only --verify-basis (wire bool, protocol stays 2.28.0) restores the
  strict whole-file content equality
- --copy-dest re-applies source attributes; basis-hit 256 MiB cap removed by
  streaming the copy/hash; basis miss keeps the normal payload bound
- compare/copy/link-dest rows -> caveat; tally 116/13/28
This commit is contained in:
TapTap
2026-09-19 15:55:51 +02:00
parent 8ec8cb7203
commit 67076bf218
23 changed files with 940 additions and 255 deletions
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tests/integration/test_parity_quickwins.py
+43 -7
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@@ -719,13 +719,18 @@ class TestVerifyAndFlip:
source = self._src("cmpd")
dest = self._dst("cmpd")
rdst = self._dst("cmpd_r")
# Pin the mtime so rsync's size+mtime quick-check (and FastSync's
# default) matches deterministically across a second boundary.
OLD = 1_500_000_000
with open(os.path.join(source, "f.txt"), "wb") as fh:
fh.write(b"basis-content\n")
os.utime(os.path.join(source, "f.txt"), (OLD, OLD))
# rsync resolves --compare-dest relative to the destination dir; its
# basis file sits at the transfer-relative path.
os.makedirs(os.path.join(rdst, "basis"), exist_ok=True)
with open(os.path.join(rdst, "basis", "f.txt"), "wb") as fh:
fh.write(b"basis-content\n")
os.utime(os.path.join(rdst, "basis", "f.txt"), (OLD, OLD))
rs = _rsync(["-a", "--compare-dest=basis", source + "/", rdst + "/"])
assert rs.returncode == 0, rs.stderr
assert not os.path.exists(os.path.join(rdst, "f.txt")), \
@@ -738,6 +743,7 @@ class TestVerifyAndFlip:
os.makedirs(basis, exist_ok=True)
with open(os.path.join(basis, "f.txt"), "wb") as fh:
fh.write(b"basis-content\n")
os.utime(os.path.join(basis, "f.txt"), (OLD, OLD))
received = get_dest_received_dir(dest, source)
result, _ = run_client(source, dest,
flags=["--compare-dest=basis", "--incremental"],
@@ -751,14 +757,17 @@ class TestVerifyAndFlip:
def test_link_dest_hardlinks_matches_rsync(self, shared_server):
source = self._src("linkd")
dest = self._dst("linkd")
OLD = 1_500_000_000
with open(os.path.join(source, "f.txt"), "wb") as fh:
fh.write(b"link-basis-content\n")
os.utime(os.path.join(source, "f.txt"), (OLD, OLD))
rel = os.path.abspath(source).lstrip(os.sep)
basis = os.path.join(dest, "basis", rel)
os.makedirs(basis, exist_ok=True)
basis_file = os.path.join(basis, "f.txt")
with open(basis_file, "wb") as fh:
fh.write(b"link-basis-content\n")
os.utime(basis_file, (OLD, OLD))
received = get_dest_received_dir(dest, source)
result, _ = run_client(source, dest,
flags=["--link-dest=basis", "--incremental"],
@@ -771,12 +780,11 @@ class TestVerifyAndFlip:
@requires_rsync
def test_basis_dir_size_only_content_residual(self, shared_server):
"""Documented residual (RSYNC_COMPAT.md basis-dir rows): FastSync
xxHash-verifies a basis hit, while rsync's `--size-only` quick check
trusts the size alone. With a same-size, different-content basis,
rsync links/copies the wrong basis content while FastSync transfers the
source. This test pins both observed behaviors (FastSync is stricter,
so the rows are reclassified Divergent)."""
"""rsync parity (default): a basis hit is decided by the metadata
quick-check alone. With `--size-only`, a same-size, different-content
basis is trusted, so rsync links the basis content and FastSync must now
do the same instead of xxHash-verifying it. `--verify-basis` restores
the stricter content equality (covered by the differential test)."""
source = self._src("basissz")
rdest = self._dst("basissz_r")
fdest = self._dst("basissz_f")
@@ -806,9 +814,37 @@ class TestVerifyAndFlip:
flags=["-a", "--size-only", "--link-dest=basis", "--incremental"],
port=shared_server.port)
assert result.returncode == 0, result.stderr[:300]
with open(os.path.join(received, "f.txt"), "rb") as fh:
assert fh.read() == b"BBBB\n", \
"FastSync must trust the metadata quick-check exactly like rsync"
@requires_rsync
def test_verify_basis_restores_content_check(self, shared_server):
"""FastSync-only `--verify-basis`: a same-size, same-mtime basis with
different content is rejected by the whole-file digest, so the source is
transferred instead of installing the wrong basis bytes. The default
(no flag) installs the basis content, matching rsync."""
source = self._src("vbasis")
fdest = self._dst("vbasis_f")
with open(os.path.join(source, "f.txt"), "wb") as fh:
fh.write(b"AAAA\n")
OLD = 1_400_000_000
os.utime(os.path.join(source, "f.txt"), (OLD, OLD))
rel = os.path.abspath(source).lstrip(os.sep)
basis = os.path.join(fdest, "basis", rel)
os.makedirs(basis, exist_ok=True)
with open(os.path.join(basis, "f.txt"), "wb") as fh:
fh.write(b"BBBB\n")
os.utime(os.path.join(basis, "f.txt"), (OLD, OLD))
received = get_dest_received_dir(fdest, source)
result, _ = run_client(source, fdest,
flags=["-a", "--link-dest=basis", "--incremental",
"--verify-basis"],
port=shared_server.port)
assert result.returncode == 0, result.stderr[:300]
with open(os.path.join(received, "f.txt"), "rb") as fh:
assert fh.read() == b"AAAA\n", \
"FastSync must verify the basis content and transfer the source"
"--verify-basis must reject the same-size/different-content basis"
class TestIgnoreExistingShortCircuit: