# Test Case: Empty File Read

**Test ID**: TC120-empty-file  
**Category**: Boundary & Stress  
**Priority**: Medium  
**Regression**: None

## Objective

Verify exact zero-length inode, EOF, seek, hash, and close behavior.

## Preconditions

- Complete `G7-MANUAL-SETUP.md`.
- Load the exact G7 KLD by full path.
- Verify the guest copy of `SOURCE-SHA256SUMS` before mounting.

## Manual Steps

```sh
G7=/root/repo22-g7
FIX=$G7/fixtures
SRC=$FIX/sources/boundaries/empty.bin
IMAGE=$FIX/images/boundaries.erofs
MNT=/mnt/repo22-g7-tc120
E=$G7/evidence/TC120
mkdir -p "$MNT" "$E"
unit=$(mdconfig -a -t vnode -f "$IMAGE")
printf 'md=%s\n' "$unit" | tee "$E/provider.txt"
mount -t erofs -o ro "/dev/$unit" "$MNT"
stat -f 'size=%z mode=%Sp name=%N' "$SRC" "$MNT/empty.bin" \
  | tee "$E/stat.txt"
source_hash=$(sha256 -q "$SRC")
target_hash=$(sha256 -q "$MNT/empty.bin")
printf 'source=%s\ntarget=%s\n' "$source_hash" "$target_hash" \
  | tee "$E/hashes.txt"
test "$source_hash" = "$target_hash"
cmp "$SRC" "$MNT/empty.bin"
"$G7/g7_probe" empty "$MNT/empty.bin" | tee "$E/probe.txt"
umount "$MNT"
mdconfig -d -u "${unit#md}"
test -z "$(mount -p | awk -v m="$MNT" '$2 == m { print }')"
test -z "$(mdconfig -l | tr ' ' '\n' | grep -x "$unit")"
```

## PASS Gate

- Both sizes are exactly 0 and both SHA256 values are the empty-file hash.
- `cmp` exits 0.
- The probe reports `read_bytes=0`, both seek offsets 0, and exit 0.
- The exact mount and md provider are absent after cleanup.

Any kernel panic, trap, hang, or unexpected EROFS dmesg error is KFAIL and
requires an issue report without changing `src`.
