bare-operating-system/packages/bare-os-booter/lib/git-fs-adapter.js

/**
 * Node fs.promises-shaped adapter over ctx.vfs for isomorphic-git.
 * Empty directories are represented by a hidden marker file (filtered from readdir).
 * Stat/lstat return Node-like objects (mtime/ctime, mtimeMs/ctimeMs, mode, dev, ino, uid, gid)
 * because isomorphic-git normalizeStats() requires them for the index.
 */

import path from 'path'

const MARKER = '.bareos_empty'

function err(code, message) {
  const e = new Error(message || code)
  // @ts-ignore
  e.code = code
  return e
}

/** Default Unix mode bits isomorphic-git expects for Git trees (see normalizeMode in upstream). */
const MODE_FILE = 0o100644
const MODE_DIR = 0o040755
const MODE_SYMLINK = 0o120000

/**
 * Node fs.Stats-shaped object for isomorphic-git (normalizeStats reads mtime/ctime and numeric ids).
 */
export class VfsGitStats {
  /**
   * @param {'file' | 'directory' | 'symlink'} type
   * @param {number} [size]
   * @param {{ mtimeMs?: number, ctimeMs?: number, mode?: number, dev?: number, ino?: number, uid?: number, gid?: number }} [opts]
   */
  constructor(type, size = 0, opts = {}) {
    this.type = type
    this.size = size
    const ms = typeof opts.mtimeMs === 'number' ? opts.mtimeMs : Date.now()
    this.mtimeMs = ms
    this.ctimeMs = typeof opts.ctimeMs === 'number' ? opts.ctimeMs : ms
    this.atimeMs = ms
    this.birthtimeMs = this.ctimeMs
    this.mtime = new Date(this.mtimeMs)
    this.ctime = new Date(this.ctimeMs)
    this.atime = this.mtime
    this.birthtime = this.ctime
    this.dev = opts.dev ?? 0
    this.ino = opts.ino ?? 0
    this.mode = opts.mode ?? (type === 'directory' ? MODE_DIR : type === 'symlink' ? MODE_SYMLINK : MODE_FILE)
    this.uid = opts.uid ?? 0
    this.gid = opts.gid ?? 0
    this.blocks = 0
    this.blksize = 4096
    this.nlink = 1
    this.rdev = 0
  }

  isFile() {
    return this.type === 'file'
  }

  isDirectory() {
    return this.type === 'directory'
  }

  isSymbolicLink() {
    return this.type === 'symlink'
  }
}

/**
 * Map vfs lstat/stat result to Stats or throw ENOENT.
 * @param {Record<string, unknown> | null} st
 */
function toStats(st) {
  if (!st) throw err('ENOENT', 'ENOENT')
  const ts = {
    mtimeMs: typeof st.mtimeMs === 'number' ? st.mtimeMs : undefined,
    ctimeMs: typeof st.ctimeMs === 'number' ? st.ctimeMs : undefined,
    mode: typeof st.mode === 'number' ? st.mode : undefined
  }
  if (st.type === 'file') return new VfsGitStats('file', Number(st.size) || 0, ts)
  if (st.type === 'directory') return new VfsGitStats('directory', 0, ts)
  if (st.type === 'symlink')
    return new VfsGitStats('symlink', Number(st.size) || 0, ts)
  throw err('ENOENT', 'ENOENT')
}

/**
 * @param {{ readFile: Function, writeFile: Function, unlink: Function, readdir: Function, stat: Function, lstat: Function, readlink: Function, symlink: Function }} vfs
 */
export function createGitFsFromVfs(vfs) {
  async function rawReaddir(p) {
    return vfs.readdir(p)
  }

  async function readDirFiltered(p) {
    const names = await rawReaddir(p)
    return names.filter((n) => n !== MARKER)
  }

  async function stat(p) {
    const st = await vfs.stat(p)
    return toStats(st)
  }

  async function lstat(p) {
    const st = await vfs.lstat(p)
    return toStats(st)
  }

  async function readFile(p, opts = {}) {
    const buf = await vfs.readFile(p)
    if (buf == null) throw err('ENOENT', 'ENOENT')
    const u8 = buf instanceof Uint8Array ? buf : new Uint8Array(buf)
    if (opts.encoding === 'utf8' || opts.encoding === 'utf-8') {
      return Buffer.from(u8).toString('utf8')
    }
    return Buffer.from(u8)
  }

  async function writeFile(p, data, _opts = {}) {
    const body =
      typeof data === 'string'
        ? Buffer.from(data, 'utf8')
        : data instanceof Buffer
          ? data
          : Buffer.from(data)
    await vfs.writeFile(p, body)
  }

  async function unlink(p) {
    try {
      await vfs.unlink(p)
    } catch (e) {
      if (e && e.code === 'ENOENT') throw e
      throw e
    }
  }

  async function mkdir(p, options = {}) {
    const recursive = Boolean(options.recursive)
    const norm = path.posix.normalize(p)
    if (norm === '/' || norm === '') return

    try {
      const s = await stat(norm)
      if (s.isDirectory()) return
      if (s.isFile()) throw err('EEXIST', 'EEXIST')
    } catch (e) {
      if (e.code !== 'ENOENT') throw e
      const parent = path.posix.dirname(norm)
      if (parent !== norm && parent !== '/' && parent !== '') {
        try {
          const ps = await stat(parent)
          if (!ps.isDirectory()) throw err('ENOTDIR', 'ENOTDIR')
        } catch (pe) {
          if (pe.code === 'ENOENT') {
            if (recursive) await mkdir(parent, { recursive: true })
            else throw err('ENOENT', 'ENOENT')
          } else throw pe
        }
      }
      const markerPath = path.posix.join(norm, MARKER)
      await vfs.writeFile(markerPath, Buffer.alloc(0))
    }
  }

  async function rmdir(p, opts = {}) {
    if (opts.recursive) {
      await rm(p, { recursive: true, force: true })
      return
    }
    const names = await readDirFiltered(p)
    if (names.length) throw err('ENOTEMPTY', 'ENOTEMPTY')
    const markerPath = path.posix.join(p, MARKER)
    try {
      await vfs.unlink(markerPath)
    } catch (e) {
      if (e && e.code !== 'ENOENT') throw e
    }
  }

  async function rm(p, opts = {}) {
    const recursive = Boolean(opts.recursive)
    const force = Boolean(opts.force)
    let st
    try {
      st = await lstat(p)
    } catch (e) {
      if (e.code === 'ENOENT' && force) return
      throw e
    }
    if (st.isSymbolicLink() || st.isFile()) {
      await unlink(p)
      return
    }
    if (!st.isDirectory()) {
      await unlink(p)
      return
    }
    if (!recursive) {
      await rmdir(p, {})
      return
    }
    const children = await rawReaddir(p)
    for (const name of children) {
      const full = path.posix.join(p, name)
      await rm(full, { recursive: true, force: true })
    }
    try {
      await vfs.unlink(path.posix.join(p, MARKER))
    } catch {
      /* */
    }
    try {
      await rmdir(p, {})
    } catch (e) {
      if (e.code !== 'ENOENT' && e.code !== 'ENOTEMPTY') throw e
    }
  }

  async function readdir(p) {
    try {
      await stat(p)
    } catch (e) {
      if (e.code === 'ENOENT') return null
      throw e
    }
    return readDirFiltered(p)
  }

  async function readlink(p) {
    return vfs.readlink(p)
  }

  async function symlink(target, p) {
    return vfs.symlink(target, p)
  }

  async function chmod(p, mode) {
    if (typeof vfs.chmod === 'function') {
      await vfs.chmod(p, mode)
    }
  }

  const promises = {
    readFile,
    writeFile,
    unlink,
    mkdir,
    rmdir,
    rm,
    stat,
    lstat,
    readdir,
    readlink,
    symlink,
    chmod
  }

  return { promises }
}