File Explorer

1// check to see if a bin is allowed to be overwritten2// either rejects or resolves to nothing.  return value not relevant.3const isWindows = require('./is-windows.js')4const binTarget = require('./bin-target.js')5const { resolve, dirname, sep } = require('path')6const readCmdShim = require('read-cmd-shim')7const { readlink } = require('fs/promises')8 9const checkBin = async ({ bin, path, top, global, force }) => {10  // always ok to clobber when forced11  // always ok to clobber local bins, or when forced12  if (force || !global || !top) {13    return14  }15 16  // ok, need to make sure, then17  const target = resolve(binTarget({ path, top }), bin)18  path = resolve(path)19  return isWindows ? checkShim({ target, path }) : checkLink({ target, path })20}21 22// only enoent is allowed.  anything else is a problem.23const handleReadLinkError = async ({ er, target }) =>24  er.code === 'ENOENT' ? null25  : failEEXIST({ target })26 27const checkLink = async ({ target, path }) => {28  const current = await readlink(target)29    .catch(er => handleReadLinkError({ er, target }))30 31  if (!current) {32    return33  }34 35  const resolved = resolve(dirname(target), current)36 37  const resolvedLower = resolved.toLowerCase()38  const pathLower = path.toLowerCase()39  if (resolvedLower !== pathLower && !resolvedLower.startsWith(pathLower + sep)) {40    return failEEXIST({ target })41  }42}43 44const handleReadCmdShimError = ({ er, target }) =>45  er.code === 'ENOENT' ? null46  : failEEXIST({ target })47 48const failEEXIST = ({ target }) =>49  Promise.reject(Object.assign(new Error('EEXIST: file already exists'), {50    path: target,51    code: 'EEXIST',52  }))53 54const checkShim = async ({ target, path }) => {55  const shims = [56    target,57    target + '.cmd',58    target + '.ps1',59  ]60  await Promise.all(shims.map(async shim => {61    const current = await readCmdShim(shim)62      .catch(er => handleReadCmdShimError({ er, target: shim }))63 64    if (!current) {65      return66    }67 68    const resolved = resolve(dirname(shim), current.replace(/\\/g, '/'))69 70    const resolvedLower = resolved.toLowerCase()71    const pathLower = path.toLowerCase()72    if (resolvedLower !== pathLower && !resolvedLower.startsWith(pathLower + sep)) {73      return failEEXIST({ target: shim })74    }75  }))76}77 78module.exports = checkBin79