#!/usr/bin/env python3"""Coverage of --append and --append-verify at depth. --append assumes each destination file is a prefix of the (longer) source andtransfers only the bytes past the existing size; it does NOT re-check the dataalready present, and it never touches a file that is already the same size orlarger. --append-verify works the same way but folds the existing data into thewhole-file checksum, so a transfer whose result fails verification is re-sentwith a normal --inplace pass. Exercise both on files >=3 levels deep.""" import os from rsyncfns import (    FROMDIR, TODIR,    assert_same, forced_protocol, make_tree, rmtree, run_rsync, test_fail,    walk_files,) src = FROMDIRdeep = os.path.join('d1', 'd2', 'd3', 'f3')  def seed_source():    rmtree(src)    make_tree(src, depth=3, data=True, data_size=8192)    return [p.relative_to(src) for p in walk_files(src)]  def dest_prefix(rels, *, corrupt=False, frac=0.5):    """Build a destination holding the first `frac` of each source file (a    valid prefix), optionally corrupting the deep file's leading bytes."""    rmtree(TODIR)    for rel in rels:        dst = TODIR / rel        dst.parent.mkdir(parents=True, exist_ok=True)        full = (src / rel).read_bytes()        dst.write_bytes(full[: int(len(full) * frac)])    if corrupt:        p = TODIR / deep        bad = bytearray(p.read_bytes())        bad[0:64] = b'\x00' * 64        p.write_bytes(bytes(bad))  # --- --append completes truncated destinations at every level ---------------rels = seed_source()dest_prefix(rels)run_rsync('-a', '--append', f'{src}/', f'{TODIR}/')for rel in rels:    assert_same(TODIR / rel, src / rel, label=f'append {rel}') # The split between non-verifying --append and verifying --append-verify only# exists at protocol >= 30; at protocol 29 plain --append still verifies, so# skip the distinguishing sub-cases there.proto = forced_protocol()if proto is not None and proto < 30:    print(f"append: protocol {proto} -- skipping the --append/--append-verify "          "split (verifying-append behaviour predates the protocol-30 split)")else:    # plain --append trusts a corrupted prefix (leaves it wrong)    dest_prefix(rels, corrupt=True)    run_rsync('-a', '--append', f'{src}/', f'{TODIR}/')    if (TODIR / deep).read_bytes() == (src / deep).read_bytes():        test_fail("plain --append unexpectedly repaired a corrupted prefix "                  "(it should append only and trust the existing data)")     # --append-verify detects the bad prefix and re-sends the whole file    dest_prefix(rels, corrupt=True)    run_rsync('-a', '--append-verify', f'{src}/', f'{TODIR}/')    assert_same(TODIR / deep, src / deep, label='append-verify deep') print("append: tail-only completion at depth; append-verify repairs prefix")