# Test Case: Write, Truncate, and Create Rejection

**Test ID**: TC063-setattr-write-reject
**Category**: Read-Only Enforcement
**Priority**: Critical

## Objective

Verify direct open-for-write, truncate, and create requests return EROFS and
leave the mounted tree unchanged.

## Procedure

Mount vfs/vfs-plain.erofs and run:

    sha256 /tmp/repo22-g3/mnt/testdir/file.txt > TC063-before.txt
    ./g3_vfs_probe expect-error open-rdwr \
      /tmp/repo22-g3/mnt/testdir/file.txt 30
    ./g3_vfs_probe expect-error truncate \
      /tmp/repo22-g3/mnt/testdir/file.txt 30
    ./g3_vfs_probe expect-error create \
      /tmp/repo22-g3/mnt/testdir/newfile.txt 30
    sha256 /tmp/repo22-g3/mnt/testdir/file.txt > TC063-after.txt
    cmp TC063-before.txt TC063-after.txt
    test ! -e /tmp/repo22-g3/mnt/testdir/newfile.txt

## Expected Results

All mutation syscalls report errno 30, the file hash is unchanged, and no new
entry exists. Record output and cleanup.