writeFileSystemNodePermissions.js

import { chmod } from "fs"
import { permissionsToBinaryFlags } from "./internal/permissions.js"
import { assertAndNormalizeFileUrl } from "./assertAndNormalizeFileUrl.js"
import { urlToFileSystemPath } from "./urlToFileSystemPath.js"

export const writeFileSystemNodePermissions = async (source, permissions) => {
  const sourceUrl = assertAndNormalizeFileUrl(source)
  const sourcePath = urlToFileSystemPath(sourceUrl)

  let binaryFlags
  if (typeof permissions === "object") {
    permissions = {
      owner: {
        read: getPermissionOrComputeDefault("read", "owner", permissions),
        write: getPermissionOrComputeDefault("write", "owner", permissions),
        execute: getPermissionOrComputeDefault("execute", "owner", permissions),
      },
      group: {
        read: getPermissionOrComputeDefault("read", "group", permissions),
        write: getPermissionOrComputeDefault("write", "group", permissions),
        execute: getPermissionOrComputeDefault("execute", "group", permissions),
      },
      others: {
        read: getPermissionOrComputeDefault("read", "others", permissions),
        write: getPermissionOrComputeDefault("write", "others", permissions),
        execute: getPermissionOrComputeDefault("execute", "others", permissions),
      },
    }
    binaryFlags = permissionsToBinaryFlags(permissions)
  } else {
    binaryFlags = permissions
  }

  return chmodNaive(sourcePath, binaryFlags)
}

const chmodNaive = (fileSystemPath, binaryFlags) => {
  return new Promise((resolve, reject) => {
    chmod(fileSystemPath, binaryFlags, (error) => {
      if (error) {
        reject(error)
      } else {
        resolve()
      }
    })
  })
}

const actionLevels = { read: 0, write: 1, execute: 2 }
const subjectLevels = { others: 0, group: 1, owner: 2 }

const getPermissionOrComputeDefault = (action, subject, permissions) => {
  if (subject in permissions) {
    const subjectPermissions = permissions[subject]
    if (action in subjectPermissions) {
      return subjectPermissions[action]
    }

    const actionLevel = actionLevels[action]
    const actionFallback = Object.keys(actionLevels).find(
      (actionFallbackCandidate) =>
        actionLevels[actionFallbackCandidate] > actionLevel &&
        actionFallbackCandidate in subjectPermissions,
    )
    if (actionFallback) {
      return subjectPermissions[actionFallback]
    }
  }

  const subjectLevel = subjectLevels[subject]
  // do we have a subject with a stronger level (group or owner)
  // where we could read the action permission ?
  const subjectFallback = Object.keys(subjectLevels).find(
    (subjectFallbackCandidate) =>
      subjectLevels[subjectFallbackCandidate] > subjectLevel &&
      subjectFallbackCandidate in permissions,
  )
  if (subjectFallback) {
    const subjectPermissions = permissions[subjectFallback]
    return action in subjectPermissions
      ? subjectPermissions[action]
      : getPermissionOrComputeDefault(action, subjectFallback, permissions)
  }

  return false
}