Function onLink

lib/internal/fs/cp/cp-sync.js:189–237

(destStat, src, dest, verbatimSymlinks)

// TODO(@anonrig): Move this function to C++.
function onLink(destStat, src, dest, verbatimSymlinks) {
  let resolvedSrc = readlinkSync(src);
  if (!verbatimSymlinks && !isAbsolute(resolvedSrc)) {
    resolvedSrc = resolve(dirname(src), resolvedSrc);
  }
  if (!destStat) {
    return symlinkSync(resolvedSrc, dest);
  }
  let resolvedDest;
  try {
    resolvedDest = readlinkSync(dest);
  } catch (err) {
    // Dest exists and is a regular file or directory,
    // Windows may throw UNKNOWN error. If dest already exists,
    // fs throws error anyway, so no need to guard against it here.
    if (err.code === 'EINVAL' || err.code === 'UNKNOWN') {
      return symlinkSync(resolvedSrc, dest);
    }
    throw err;
  }
  if (!isAbsolute(resolvedDest)) {
    resolvedDest = resolve(dirname(dest), resolvedDest);
  }
  const srcIsDir = fsBinding.internalModuleStat(src) === 1;

  if (srcIsDir && isSrcSubdir(resolvedSrc, resolvedDest)) {
    throw new ERR_FS_CP_EINVAL({
      message: `cannot copy ${resolvedSrc} to a subdirectory of self ` +
          `${resolvedDest}`,
      path: dest,
      syscall: 'cp',
      errno: EINVAL,
      code: 'EINVAL',
    });
  }
  // Prevent copy if src is a subdir of dest since unlinking
  // dest in this case would result in removing src contents
  // and therefore a broken symlink would be created.
  if (statSync(dest).isDirectory() && isSrcSubdir(resolvedDest, resolvedSrc)) {
    throw new ERR_FS_CP_SYMLINK_TO_SUBDIRECTORY({
      message: `cannot overwrite ${resolvedDest} with ${resolvedSrc}`,
      path: dest,
      syscall: 'cp',
      errno: EINVAL,
      code: 'EINVAL',
    });
  }
  return copyLink(resolvedSrc, dest);
}

function copyLink(resolvedSrc, dest) {
  unlinkSync(dest);