erofs-freebsd-out-tree/tests/TC115-unsupported-algorithm.md

Test Case: Future Compression Algorithm Rejection

Test ID: TC115-unsupported-algorithm Category: Error Handling Priority: High

Objective

Verify mount-time EOPNOTSUPP for a legal compressed image whose available_compr_algs field additionally advertises unknown bit 0x8000.

Fixture Qualification

work=$(mktemp -d /tmp/repo22-tc115.XXXXXX)
tests/prepare_error_fixtures.sh "$work/fixtures"
od -An -tx2 -j 1106 -N 2 "$work/fixtures/future-algorithm.erofs"
python3 tests/erofs_fixture.py inspect \
  "$work/fixtures/future-algorithm.erofs"
grep '^future-algorithm ' "$work/fixtures/fixture-evidence.txt"
wc -c "$work/fixtures/valid-lz4.erofs" \
  "$work/fixtures/future-algorithm.erofs"
sha256 -q "$work/fixtures/future-algorithm.erofs"

The mutator requires EROFS_FEATURE_INCOMPAT_COMPR_CFGS, asserts the old 16-bit field at absolute byte 1106, sets only future bit 0x8000, recomputes CRC32C, and preserves provider length.

FreeBSD Procedure

mkdir "$work/mnt"
unit=$(mdconfig -a -t vnode -f "$work/fixtures/future-algorithm.erofs")
set +e
mount -t erofs -o ro "/dev/$unit" "$work/mnt" \
  >"$work/mount.out" 2>"$work/mount.err"
status=$?
set -e
test "$status" -ne 0
set +e
truss -o "$work/mount.truss" mount -t erofs -o ro "/dev/$unit" \
  "$work/mnt" >/dev/null 2>&1
set -e
grep -E 'nmount.*ERR#45' "$work/mount.truss"
! mount -p | awk -v path="$work/mnt" '$2 == path { found=1 }
  END { exit found ? 0 : 1 }'
mdconfig -d -u "${unit#md}"

Expected Results

Mount returns errno 45 (EOPNOTSUPP), not checksum or media-size failure. No mount or md consumer remains.