Function truncateFileSync

packages/dofs/src/fs/writeFile.ts:848–918

(
  db: Database,
  path: string,
  size: number,
  now: () => number,
)

}

export function truncateFileSync(
  db: Database,
  path: string,
  size: number,
  now: () => number,
): void {
  const { path: canonical } = canonicalizePath(path);
  assertNotReadOnly(db, canonical);
  if (!Number.isInteger(size) || size < 0) {
    throw createWorkspaceError("EINVAL", `invalid truncate size: ${size}`, canonical);
  }
  const mtime = now();

  // Pending-create files truncate in-place on the path-keyed buffer.
  const pending = getPendingWriteBufferByPath(db, canonical);
  if (pending !== undefined) {
    if (size > pending.size) {
      ensureBufferCapacity(pending, size);
      pending.buf.fill(0, pending.size, size);
    }
    pending.size = size;
    pending.dirty = true;
    return;
  }

  const { inode, mode } = resolveFileInode(db, path);
  const buffered = getWriteBuffer(db, inode);

  if (buffered !== undefined) {
    hydrateBufferIfNeeded(db, inode, buffered);
    if (size > buffered.size) {
      ensureBufferCapacity(buffered, size);
      buffered.buf.fill(0, buffered.size, size);
    }
    buffered.size = size;
    buffered.dirty = true;
    return;
  }

  db.transactionSync(() => {
    const oldSize = fileSizeForInode(db, inode);
    if (oldSize === size) return;

    if (size === 0) {
      db.run("DELETE FROM vfs_chunks WHERE inode = ?", inode);
      const rev = incrementRev(db);
      db.run(
        "UPDATE vfs_nodes SET mode = ?, mtime = ?, rev = ?, size = 0, manifest_hash = NULL WHERE inode = ?",
        mode,
        mtime,
        rev,
        inode,
      );
      return;
    }

    applyChunkedInodeUpdate(
      db,