bare-operating-system/packages/bare-os-coreutils/src/mv.js

/**
 * Move/rename via copy + delete. Hyperdrive has no single-key rename across paths, so
 * directory trees and cross-location moves are duplicated then removed. A single regular
 * file to a new non-directory path uses a two-phase write: staging buffer bytes under a
 * unique **`.bare-os-mv-tmp.*`** name in the **resolved destination directory**, writing the final name,
 * removing the staging file, then unlinking the source — so a failed final write leaves
 * the source path intact (staging is best-effort removed).
 *
 * Documented limitations: cross-volume moves always copy+delete; EXDEV-style behavior is
 * implicit. Busy targets, partial copy failures, and union read-only trees surface as
 * generic errors from the VFS. Prefer same-directory renames for smallest blast radius.
 */
function mvStagingPathForTarget(ctx, target) {
  const raw =
    ctx.vfs && typeof ctx.vfs.resolveLogical === 'function'
      ? ctx.vfs.resolveLogical(target)
      : String(target || '')
  const trimmed = String(raw || '').replace(/\/+$/, '') || '/'
  const last = trimmed.lastIndexOf('/')
  const dir =
    last < 0 ? '/' : last === 0 ? '/' : trimmed.slice(0, last) || '/'
  const base =
    last < 0 ? trimmed : trimmed.slice(last + 1) || 'file'
  const tag =
    Date.now().toString(36) +
    '-' +
    Math.random().toString(36).slice(2, 10) +
    Math.random().toString(36).slice(2, 6)
  const name = '.bare-os-mv-tmp.' + tag + '.' + base
  return dir === '/' ? '/' + name : dir + '/' + name
}
async function mvCopyPath(ctx, from, to, recursive, followSymlink) {
  const st = await ctx.vfs.lstat(from)
  if (!st) return false
  if (st.type === 'symlink') {
    if (!followSymlink) {
      await ctx.vfs.symlink(await ctx.vfs.readlink(from), to)
      return true
    }
    const fst = await ctx.vfs.stat(from)
    if (fst.type === 'file') {
      const buf = await ctx.vfs.readFile(from)
      if (!buf) return false
      await ctx.vfs.writeFile(to, buf)
      return true
    }
    if (fst.type === 'directory') {
      if (!recursive) return false
      await ctx.vfs.mkdir(to, { recursive: true })
      const names = await ctx.vfs.readdir(from)
      for (const n of names) {
        if (n === '.bareos_empty') continue
        const f = from.replace(/\/+$/, '') + '/' + n
        const t = to.replace(/\/+$/, '') + '/' + n
        if (!(await mvCopyPath(ctx, f, t, true, followSymlink))) return false
      }
      return true
    }
    return false
  }
  if (st.type === 'file') {
    const buf = await ctx.vfs.readFile(from)
    if (!buf) return false
    await ctx.vfs.writeFile(to, buf)
    return true
  }
  if (st.type === 'directory') {
    if (!recursive) return false
    await ctx.vfs.mkdir(to, { recursive: true })
    const names = await ctx.vfs.readdir(from)
    for (const n of names) {
      if (n === '.bareos_empty') continue
      const f = from.replace(/\/+$/, '') + '/' + n
      const t = to.replace(/\/+$/, '') + '/' + n
      if (!(await mvCopyPath(ctx, f, t, true, followSymlink))) return false
    }
    return true
  }
  return false
}

async function run(ctx, argv) {
  let followSymlink = false
  const paths = []
  for (let i = 1; i < argv.length; i++) {
    const a = argv[i]
    if (a === '-L' || a === '--dereference') {
      followSymlink = true
      continue
    }
    if (a === '-P' || a === '--no-dereference') {
      followSymlink = false
      continue
    }
    if (a === '--') {
      paths.push(...argv.slice(i + 1))
      break
    }
    if (a.startsWith('-')) {
      ctx.console.error('mv: unsupported option ' + a)
      ctx.exitCode = 1
      return
    }
    paths.push(a)
  }
  if (paths.length < 2) {
    ctx.console.error('usage: mv [-L|-P] SOURCE... DEST')
    ctx.exitCode = 1
    return
  }
  const dest = paths.pop()
  const sources = paths
  let destIsDir = false
  try {
    const dst = await ctx.vfs.lstat(dest)
    destIsDir = !!(dst && dst.type === 'directory')
  } catch {
    destIsDir = false
  }
  if (sources.length > 1 && !destIsDir) {
    ctx.console.error('mv: target is not a directory')
    ctx.exitCode = 1
    return
  }
  for (const src of sources) {
    const base = src.replace(/\/+$/, '').split('/').pop() || src
    const target =
      destIsDir || sources.length > 1
        ? dest.replace(/\/+$/, '') + '/' + base
        : dest
    try {
      const st = await ctx.vfs.lstat(src)
      let followReg = st && st.type === 'file'
      if (!followReg && followSymlink && st && st.type === 'symlink') {
        const fs = await ctx.vfs.stat(src).catch(() => null)
        followReg = !!(fs && fs.type === 'file')
      }
      const singleFileToFile = sources.length === 1 && !destIsDir && followReg
      if (singleFileToFile) {
        const buf = await ctx.vfs.readFile(src)
        if (!buf) throw new Error('cannot read source')
        const stage = mvStagingPathForTarget(ctx, target)
        await ctx.vfs.writeFile(stage, buf)
        try {
          await ctx.vfs.writeFile(target, buf)
        } catch (e) {
          await ctx.vfs.unlink(stage).catch(() => {})
          throw e
        }
        await ctx.vfs.unlink(stage).catch(() => {})
        await ctx.vfs.unlink(src)
        continue
      }
      if (!(await mvCopyPath(ctx, src, target, true, followSymlink))) {
        throw new Error('cannot copy')
      }
      await ctx.vfs.rm(src, { recursive: true, force: true })
    } catch (e) {
      ctx.console.error('mv: ' + src + ': ' + ((e && e.message) || e))
      ctx.exitCode = 1
    }
  }
}