Function resolveSafePath

packages/agent-core/src/services/fs/fsPathSafety.ts:38–74

(
  cwd: string,
  inputPath: string,
)

}

export async function resolveSafePath(
  cwd: string,
  inputPath: string,
): Promise<PathSafetyResult> {

  if (inputPath === '' || inputPath === '/') {
    throw new FsPathEscapesError(inputPath, 'empty');
  }

  if (path.isAbsolute(inputPath)) {
    throw new FsPathEscapesError(inputPath, 'absolute');
  }

  const segments = inputPath.split(/[/\\]+/);
  if (segments.some((s) => s === '..')) {
    throw new FsPathEscapesError(inputPath, 'dotdot_segment');
  }

  const realCwd = await fs.realpath(cwd);

  const candidate = path.resolve(realCwd, inputPath);

  const resolved = await realpathLongestExistingPrefix(candidate);

  if (!isInsideOrEqual(resolved, realCwd)) {

    const reason: FsPathEscapesError['reason'] = isInsideOrEqual(candidate, realCwd)
      ? 'symlink_outside_cwd'
      : 'resolved_outside_cwd';
    throw new FsPathEscapesError(inputPath, reason, resolved);
  }

  return {
    absolute: resolved,
    relative: toPosixRelative(realCwd, resolved),
  };
}

function isInsideOrEqual(child: string, parent: string): boolean {
  const rel = path.relative(parent, child);