Function getPathsForPermissionCheck

src/utils/fsOperations.ts:288–382

(inputPath: string)

 * @returns An array of absolute paths to check permissions for
 */
export function getPathsForPermissionCheck(inputPath: string): string[] {
  // Expand tilde notation defensively - tools should do this in getPath(),
  // but we normalize here as defense in depth for permission checking
  let path = inputPath
  if (path === '~') {
    path = homedir().normalize('NFC')
  } else if (path.startsWith('~/')) {
    path = nodePath.join(homedir().normalize('NFC'), path.slice(2))
  }

  const pathSet = new Set<string>()
  const fsImpl = getFsImplementation()

  // Always check the original path
  pathSet.add(path)

  // Block UNC paths before any filesystem access to prevent network
  // requests (DNS/SMB) during validation on Windows
  if (path.startsWith('//') || path.startsWith('\\\\')) {
    return Array.from(pathSet)
  }

  // Follow the symlink chain, collecting ALL intermediate targets
  // This handles cases like: test.txt -> /etc/passwd -> /private/etc/passwd
  // We want to check all three paths, not just test.txt and /private/etc/passwd
  try {
    let currentPath = path
    const visited = new Set<string>()
    const maxDepth = 40 // Prevent runaway loops, matches typical SYMLOOP_MAX

    for (let depth = 0; depth < maxDepth; depth++) {
      // Prevent infinite loops from circular symlinks
      if (visited.has(currentPath)) {
        break
      }
      visited.add(currentPath)

      if (!fsImpl.existsSync(currentPath)) {
        // Path doesn't exist (new file case). existsSync follows symlinks,
        // so this is also reached for DANGLING symlinks (link entry exists,
        // target doesn't). Resolve symlinks in the path and its ancestors
        // so permission checks see the real destination. Without this,
        // `./data -> /etc/cron.d/` (live parent symlink) or
        // `./evil.txt -> ~/.ssh/authorized_keys2` (dangling file symlink)
        // would allow writes that escape the working directory.
        if (currentPath === path) {
          const resolved = resolveDeepestExistingAncestorSync(fsImpl, path)
          if (resolved !== undefined) {
            pathSet.add(resolved)
          }
        }
        break
      }

      const stats = fsImpl.lstatSync(currentPath)

      // Skip special file types that can cause issues
      if (