fix: correct throttle legacy resolution; add EXDEV temp-dir coverage

2026-09-22 14:06:26 +02:00
parent 1ffd4744c6
commit be20e836de
6 changed files with 146 additions and 14 deletions
@@ -0,0 +1,80 @@
+"""End-to-end coverage for the `--temp-dir` EXDEV (cross-filesystem) fallback.
+
+`file_to_disk_secure_impl` installs a completed temp file with `renameat(2)`;
+when the scratch dir lives on a different filesystem the rename fails with
+`EXDEV` and the engine retries with no scratch dir, writing the file directly in
+the destination directory (a non-atomic copy), matching rsync.
+
+The daemon receiver confines `--temp-dir` to the authorized receive root, so a
+genuine cross-fs scratch there would require an in-root mount point.  Bind/tmpfs
+mounting is not permitted in the CI container (no `CAP_SYS_ADMIN`, and
+unprivileged user namespaces are disabled), so this test reaches the exact same
+code path through the local `--read-batch` apply instead: it has no
+authorized-root confinement, so a relative `--temp-dir` that is a symlink to a
+tmpfs (`/dev/shm`) is accepted and the final install then crosses filesystems.
+"""
+import os
+import shutil
+import subprocess
+import sys
+
+import pytest
+
+sys.path.insert(0, os.path.dirname(__file__))
+from common import CLIENT_CMD, get_dest_received_dir
+
+TMPFS = "/dev/shm"
+
+
+def _run(args):
+    return subprocess.run(CLIENT_CMD + args, capture_output=True, text=True, timeout=180)
+
+
+def _read(path):
+    with open(path, "rb") as fh:
+        return fh.read()
+
+
+def test_read_batch_temp_dir_cross_filesystem_fallback(tmp_path):
+    if not os.path.isdir(TMPFS):
+        pytest.skip("no /dev/shm tmpfs available to force a cross-filesystem install")
+
+    source = tmp_path / "src"
+    dest = tmp_path / "dst"
+    source.mkdir()
+    dest.mkdir()
+    files = {
+        "payload.bin": bytes(range(256)) * 64,
+        "sub/nested.txt": b"nested exdev fallback\n" * 8,
+    }
+    for rel, data in files.items():
+        full = source / rel
+        full.parent.mkdir(parents=True, exist_ok=True)
+        full.write_bytes(data)
+
+    batch = tmp_path / "tree.batch"
+    r = _run(["--only-write-batch", str(batch), str(source)])
+    assert r.returncode == 0, (r.stdout, r.stderr)
+
+    # A cross-filesystem scratch dir, reached through a relative --temp-dir
+    # symlink (the local batch apply performs no authorized-root confinement).
+    scratch = os.path.join(TMPFS, "fastsync_exdev_%d" % os.getpid())
+    shutil.rmtree(scratch, ignore_errors=True)
+    os.makedirs(scratch)
+    os.symlink(scratch, dest / "scratch")
+    try:
+        assert os.stat(scratch).st_dev != os.stat(dest).st_dev, (
+            "scratch and destination share a filesystem; EXDEV cannot be exercised"
+        )
+        r = _run(["--read-batch", str(batch), str(dest), "--temp-dir=scratch"])
+        assert r.returncode == 0, (r.stdout, r.stderr)
+        # The engine must report the non-atomic cross-fs fallback rather than
+        # silently claiming an atomic install.
+        assert "different filesystem" in (r.stdout + r.stderr), (r.stdout, r.stderr)
+        # The tree is still byte-exact and the scratch dir is left clean.
+        received = get_dest_received_dir(str(dest), str(source))
+        for rel, data in files.items():
+            assert _read(os.path.join(received, rel)) == data, f"content mismatch for {rel}"
+        assert os.listdir(scratch) == [], "cross-fs temp file was not cleaned up"
+    finally:
+        shutil.rmtree(scratch, ignore_errors=True)