# Test Case: 255-byte Filename

**Test ID**: TC123-long-filename  
**Category**: Boundary & Stress  
**Priority**: Medium  
**Regression**: None

## Objective

Verify exact `NAME_MAX` lookup, readdir name bytes, stat, and file content.

## Preconditions

- Complete `G7-MANUAL-SETUP.md`.
- Use the fixture's ASCII `LONG-NAME`; its byte count must be 255.

## Manual Steps

```sh
G7=/root/repo22-g7
FIX=$G7/fixtures
SRCROOT=$FIX/sources/boundaries
IMAGE=$FIX/images/boundaries.erofs
MNT=/mnt/repo22-g7-tc123
E=$G7/evidence/TC123
mkdir -p "$MNT" "$E"
long_name=$(cat "$FIX/LONG-NAME")
name_bytes=$(printf '%s' "$long_name" | wc -c | tr -d ' ')
printf 'name_bytes=%s\nname=%s\n' "$name_bytes" "$long_name" \
  | tee "$E/name.txt"
test "$name_bytes" -eq 255
unit=$(mdconfig -a -t vnode -f "$IMAGE")
mount -t erofs -o ro "/dev/$unit" "$MNT"
(cd "$SRCROOT" && find longname -type f -print | sort) > "$E/source.names"
(cd "$MNT" && find longname -type f -print | sort) > "$E/target.names"
cmp "$E/source.names" "$E/target.names"
test "$(wc -l < "$E/target.names" | tr -d ' ')" -eq 1
stat -f 'size=%z name=%N' "$MNT/longname/$long_name" | tee "$E/stat.txt"
cmp "$SRCROOT/longname/$long_name" "$MNT/longname/$long_name"
source_hash=$(sha256 -q "$SRCROOT/longname/$long_name")
target_hash=$(sha256 -q "$MNT/longname/$long_name")
printf 'source=%s\ntarget=%s\n' "$source_hash" "$target_hash" \
  | tee "$E/hashes.txt"
test "$source_hash" = "$target_hash"
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

- The filename is exactly 255 bytes and readdir returns that one exact name.
- Stat succeeds; source/mount `cmp` and SHA256 values match.
- No truncation, extra entry, panic, hang, or cleanup leak occurs.
