fs: fix writeFile[Sync] for non-seekable files

Completely disables the use of positioned writes at
writeFile and writeFileSync, which allows it to work
with non-seekable files.

Fixes: #31926

PR-URL: #32006
Reviewed-By: Anna Henningsen <anna@addaleax.net>

lib/fs.js

@@ -1248,9 +1248,9 @@ function futimesSync(fd, atime, mtime) {
  handleErrorFromBinding(ctx);
 }
 
-function writeAll(fd, isUserFd, buffer, offset, length, position, callback) {
+function writeAll(fd, isUserFd, buffer, offset, length, callback) {
  // write(fd, buffer, offset, length, position, callback)
- fs.write(fd, buffer, offset, length, position, (writeErr, written) => {
+ fs.write(fd, buffer, offset, length, null, (writeErr, written) => {
  if (writeErr) {
  if (isUserFd) {
  callback(writeErr);
@@ -1268,10 +1268,7 @@ function writeAll(fd, isUserFd, buffer, offset, length, position, callback) {
  } else {
  offset += written;
  length -= written;
- if (position !== null) {
- position += written;
- }
- writeAll(fd, isUserFd, buffer, offset, length, position, callback);
+ writeAll(fd, isUserFd, buffer, offset, length, callback);
  }
  });
 }
@@ -1288,7 +1285,7 @@ function writeFile(path, data, options, callback) {
 
  if (isFd(path)) {
  const isUserFd = true;
- writeAll(path, isUserFd, data, 0, data.byteLength, null, callback);
+ writeAll(path, isUserFd, data, 0, data.byteLength, callback);
  return;
  }
 
@@ -1297,8 +1294,7 @@ function writeFile(path, data, options, callback) {
  callback(openErr);
  } else {
  const isUserFd = false;
- const position = /a/.test(flag) ? null : 0;
- writeAll(fd, isUserFd, data, 0, data.byteLength, position, callback);
+ writeAll(fd, isUserFd, data, 0, data.byteLength, callback);
  }
  });
 }
@@ -1318,15 +1314,11 @@ function writeFileSync(path, data, options) {
 
  let offset = 0;
  let length = data.byteLength;
- let position = (/a/.test(flag) || isUserFd) ? null : 0;
  try {
  while (length > 0) {
- const written = fs.writeSync(fd, data, offset, length, position);
+ const written = fs.writeSync(fd, data, offset, length);
  offset += written;
  length -= written;
- if (position !== null) {
- position += written;
- }
  }
  } finally {
  if (!isUserFd) fs.closeSync(fd);