add fs.mkstemp (lib_uv recently landed uv_fs_mkstemp #21)

[kaizhu256]

Is your feature request related to a problem? Please describe.
Please describe the problem you are trying to solve.
i have a build-system (in debian-docker under windows) that async-updates files w/ multiple child_processes doing fs.writeFile, fs.unlink, fs.link.
there are occasional race-conditions (i can't discern how) where one child_process writing to a file while another child_process unlinking-and-hardlinking ends up with file unlinked.

Describe the solution you'd like
Please describe the desired behavior.
mkstemp would make file-writes "atomic" by writing to tmpfile and then "atomically" rename it to destination. this might resolve the race condition from my multiple child_processes and allow the final hardlink to succeed.

ideal solution of atomic file-write with mkstemp:

/*jslint browser, node*/
/*global os*/
function fsWriteFileWithMkdirpAtomic(pathname, data, onError) {
/*
 * this file with async-atomically write <data> to <pathname> with auto mkdir -p
 */
 let fs;
 let path;
 let throwOnError;
 throwOnError = function (err) {
 /*
 * this function will throw <err> if exists
 * we typically want program to crash on <err> in ci/build use-case
 */
 if (err) {
 throw err;
 }
 };
 try {
 fs = require("fs");
 path = require("path");
 // win32-compat
 pathname = path.resolve(pathname);
 } catch (ignore) {
 // do nothing in browser-env
 onError();
 return;
 }
 fs.mkstemp(os.tmpdir(), function (err, tmpfile) {
 throwOnError(err);
 fs.writeFile(tmpfile, data, function (err) {
 throwOnError(err);
 // fs.rename attempt #1
 fs.rename(tmpfile, pathname, function (err) {
 if (!err) {
 onError();
 return;
 }
 // mkdir -p
 fs.mkdirp(path.dirname(pathname), {
 recursive: true
 }, function (ignore) {
 // fs.rename attempt #2
 fs.rename(tmpfile, pathname, function (err) {
 throwOnError(err);
 onError();
 });
 });
 });
 });
 });
}
fsWriteFileWithMkdirpAtomic("aa/bb/cc/dd/foo", "hello world", function () {
 console.log("successfully wrote file atomically with no race-condition");
});

Describe alternatives you've considered
Please describe alternative solutions or features you have considered.

• use a random generator to create tmpfile in os.tmpdir(), which is not idead for obvious reasons.
• or use fs.mkdtemp and deal with cleaninup tmpdir after atomic-write, which again, not ideal.

[targos]

Work in progress: #33549

[kaizhu256]

Cool thx. Closing this as duplicate