nstdlib-nightly/lib/internal/fs/cp/cp-sync.mjs

Node.js standard library converted to runtime-agnostic ES modules.

// Source: https://github.com/nodejs/node/blob/65eff1eb/lib/internal/fs/cp/cp-sync.js

import * as fsBinding from "nstdlib/stub/binding/fs";
import { isSrcSubdir } from "nstdlib/lib/internal/fs/cp/cp";
import { codes as __codes__ } from "nstdlib/lib/internal/errors";
import { os as __os__ } from "nstdlib/stub/binding/constants";
import {
  chmodSync,
  copyFileSync,
  lstatSync,
  mkdirSync,
  opendirSync,
  readlinkSync,
  statSync,
  symlinkSync,
  unlinkSync,
  utimesSync,
} from "nstdlib/lib/fs";
import { dirname, isAbsolute, join, resolve } from "nstdlib/lib/path";
import { isPromise } from "nstdlib/lib/util/types";
import * as __hoisted_internal_assert__ from "nstdlib/lib/internal/assert";

// This file is a modified version of the fs-extra's copySync method.

const {
  ERR_FS_CP_EEXIST,
  ERR_FS_CP_EINVAL,
  ERR_FS_CP_SYMLINK_TO_SUBDIRECTORY,
  ERR_INVALID_RETURN_VALUE,
} = __codes__;

const {
  errno: { EEXIST, EINVAL },
} = __os__;

function cpSyncFn(src, dest, opts) {
  // Warn about using preserveTimestamps on 32-bit node
  if (opts.preserveTimestamps && process.arch === "ia32") {
    const warning =
      "Using the preserveTimestamps option in 32-bit " +
      "node is not recommended";
    process.emitWarning(warning, "TimestampPrecisionWarning");
  }
  if (opts.filter) {
    const shouldCopy = opts.filter(src, dest);
    if (isPromise(shouldCopy)) {
      throw new ERR_INVALID_RETURN_VALUE("boolean", "filter", shouldCopy);
    }
    if (!shouldCopy) return;
  }

  fsBinding.cpSyncCheckPaths(src, dest, opts.dereference, opts.recursive);

  return getStats(src, dest, opts);
}

function getStats(src, dest, opts) {
  // TODO(@anonrig): Avoid making two stat calls.
  const statSyncFn = opts.dereference ? statSync : lstatSync;
  const srcStat = statSyncFn(src);
  const destStat = statSyncFn(dest, { bigint: true, throwIfNoEntry: false });

  if (srcStat.isDirectory() && opts.recursive) {
    return onDir(srcStat, destStat, src, dest, opts);
  } else if (
    srcStat.isFile() ||
    srcStat.isCharacterDevice() ||
    srcStat.isBlockDevice()
  ) {
    return onFile(srcStat, destStat, src, dest, opts);
  } else if (srcStat.isSymbolicLink()) {
    return onLink(destStat, src, dest, opts.verbatimSymlinks);
  }

  // It is not possible to get here because all possible cases are handled above.
  const assert = __hoisted_internal_assert__;
  assert.fail("Unreachable code");
}

function onFile(srcStat, destStat, src, dest, opts) {
  if (!destStat) return copyFile(srcStat, src, dest, opts);
  return mayCopyFile(srcStat, src, dest, opts);
}

// TODO(@anonrig): Move this function to C++.
function mayCopyFile(srcStat, src, dest, opts) {
  if (opts.force) {
    unlinkSync(dest);
    return copyFile(srcStat, src, dest, opts);
  } else if (opts.errorOnExist) {
    throw new ERR_FS_CP_EEXIST({
      message: `${dest} already exists`,
      path: dest,
      syscall: "cp",
      errno: EEXIST,
      code: "EEXIST",
    });
  }
}

function copyFile(srcStat, src, dest, opts) {
  copyFileSync(src, dest, opts.mode);
  if (opts.preserveTimestamps) handleTimestamps(srcStat.mode, src, dest);
  return setDestMode(dest, srcStat.mode);
}

function handleTimestamps(srcMode, src, dest) {
  // Make sure the file is writable before setting the timestamp
  // otherwise open fails with EPERM when invoked with 'r+'
  // (through utimes call)
  if (fileIsNotWritable(srcMode)) makeFileWritable(dest, srcMode);
  return setDestTimestamps(src, dest);
}

function fileIsNotWritable(srcMode) {
  return (srcMode & 0o200) === 0;
}

function makeFileWritable(dest, srcMode) {
  return setDestMode(dest, srcMode | 0o200);
}

function setDestMode(dest, srcMode) {
  return chmodSync(dest, srcMode);
}

function setDestTimestamps(src, dest) {
  // The initial srcStat.atime cannot be trusted
  // because it is modified by the read(2) system call
  // (See https://nodejs.org/api/fs.html#fs_stat_time_values)
  const updatedSrcStat = statSync(src);
  return utimesSync(dest, updatedSrcStat.atime, updatedSrcStat.mtime);
}

// TODO(@anonrig): Move this function to C++.
function onDir(srcStat, destStat, src, dest, opts) {
  if (!destStat) return mkDirAndCopy(srcStat.mode, src, dest, opts);
  return copyDir(src, dest, opts);
}

function mkDirAndCopy(srcMode, src, dest, opts) {
  mkdirSync(dest);
  copyDir(src, dest, opts);
  return setDestMode(dest, srcMode);
}

// TODO(@anonrig): Move this function to C++.
function copyDir(src, dest, opts) {
  const dir = opendirSync(src);

  try {
    let dirent;

    while ((dirent = dir.readSync()) !== null) {
      const { name } = dirent;
      const srcItem = join(src, name);
      const destItem = join(dest, name);
      let shouldCopy = true;

      if (opts.filter) {
        shouldCopy = opts.filter(srcItem, destItem);
        if (isPromise(shouldCopy)) {
          throw new ERR_INVALID_RETURN_VALUE("boolean", "filter", shouldCopy);
        }
      }

      if (shouldCopy) {
        getStats(srcItem, destItem, opts);
      }
    }
  } finally {
    dir.closeSync();
  }
}

// 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);
  }
  if (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);
  return symlinkSync(resolvedSrc, dest);
}

export { cpSyncFn };