fs: use w flag for writeFileSync with utf8 encoding when flag not specified

[MuriloKakazu]

PR #49884 seems to have accidentally changed the behavior for fs.writeFileSync with utf-8 encoding when the file does not exist, as compared to previous node versions.

On a low level, it seems we are not passing the O_CREAT flag to uvlib anymore.

Examples:

In node 16.16.0: ✅

❯ nvm use 16.16 Now using node v16.16.0 (npm v8.11.0) ❯ node Welcome to Node.js v16.16.0. Type ".help" for more information. > fs.writeFileSync('./test.txt', 'test',{encoding: 'utf8'}); undefined > fs.readFileSync('./test.txt'); <Buffer 74 65 73 74> 

In node 21.2.0: ✅

❯ nvm use 21.2 Now using node v21.2.0 (npm v10.2.3) ❯ node Welcome to Node.js v21.2.0. Type ".help" for more information. > fs.writeFileSync('./test.txt', 'test',{encoding: 'utf8'}); undefined > fs.readFileSync('./test.txt'); <Buffer 74 65 73 74> 

In node 21.3.0 (currently latest): ❌

❯ nvm use 21.3 Now using node v21.3.0 (npm v10.2.4) ❯ node Welcome to Node.js v21.3.0. Type ".help" for more information. > fs.writeFileSync('./test.txt', 'test',{encoding: 'utf8'}); Uncaught Error: ENOENT: no such file or directory, open './test.txt' at Object.writeFileSync (node:fs:2352:20){errno: -2, code: 'ENOENT', syscall: 'open', path: './test.txt' } 

Currently, a workaround for 21.3.0 is to pass the w flag (which includes O_CREAT) explicitly when calling writeFileSync. e.g:

fs.writeFileSync('./test.txt', 'test',{encoding: 'utf8', flag: 'w'}); --> works fs.writeFileSync('./test.txt', 'test',{encoding: 'utf8'}); --> does not work 

This PR will just set the w flag back as the default value when it is not specified, so its the same behavior from previous node versions.

Fixes#50989

[anonrig]

Can you add a test?

[MuriloKakazu]

@anonrig Done :)

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/56038/

[chenrui333]

Works for me. Thanks for the quick turnaround!

Homebrew/homebrew-core#156024

[bricss]

It would be great to get this fixed asap with semver patch release at least 👮

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/56046/

[nodejs-github-bot]

Commit Queue failed

- Loading data for nodejs/node/pull/50990 ✔ Done loading data for nodejs/node/pull/50990 ----------------------------------- PR info ------------------------------------ Title fs: use w flag for writeFileSync with utf8 encoding when flag not specified (#50990) Author Murilo Kakazu (@MuriloKakazu, first-time contributor) Branch MuriloKakazu:fix/default-flag-fs-write-file-sync -> nodejs:main Labels fs, author ready, needs-ci Commits 2 - fs: use default w flag for writeFileSync with utf8 encoding - fs: add tests for writeFileSync with no flag Committers 1 - Murilo Kakazu PR-URL: https://github.com/nodejs/node/pull/50990 Reviewed-By: Luigi Pinca Reviewed-By: Yagiz Nizipli ------------------------------ Generated metadata ------------------------------ PR-URL: https://github.com/nodejs/node/pull/50990 Reviewed-By: Luigi Pinca Reviewed-By: Yagiz Nizipli -------------------------------------------------------------------------------- ℹ This PR was created on Fri, 01 Dec 2023 07:05:02 GMT ✔ Approvals: 2 ✔ - Luigi Pinca (@lpinca): https://github.com/nodejs/node/pull/50990#pullrequestreview-1760486535 ✔ - Yagiz Nizipli (@anonrig) (TSC): https://github.com/nodejs/node/pull/50990#pullrequestreview-1760934016 ✔ Last GitHub CI successful ℹ Last Full PR CI on 2023-12-02T18:04:37Z: https://ci.nodejs.org/job/node-test-pull-request/56046/ - Querying data for job/node-test-pull-request/56046/ ✔ Last Jenkins CI successful -------------------------------------------------------------------------------- ✔ No git cherry-pick in progress ✔ No git am in progress ✔ No git rebase in progress -------------------------------------------------------------------------------- - Bringing origin/main up to date... From https://github.com/nodejs/node * branch main -> FETCH_HEAD ✔ origin/main is now up-to-date - Downloading patch for 50990 From https://github.com/nodejs/node * branch refs/pull/50990/merge -> FETCH_HEAD ✔ Fetched commits as 23031d9b0a56..aaa4edda7d2e -------------------------------------------------------------------------------- Auto-merging lib/fs.js [main 2fba1f3a18] fs: use default w flag for writeFileSync with utf8 encoding Author: Murilo Kakazu Date: Fri Dec 1 03:45:10 2023 -0300 1 file changed, 3 insertions(+), 3 deletions(-) [main 934e830937] fs: add tests for writeFileSync with no flag Author: Murilo Kakazu Date: Fri Dec 1 13:46:14 2023 -0300 1 file changed, 16 insertions(+) ✔ Patches applied There are 2 commits in the PR. Attempting autorebase. Rebasing (2/4) 
Executing: git node land --amend --yes
 --------------------------------- New Message ----------------------------------
 fs: use default w flag for writeFileSync with utf8 encoding
PR-URL: #50990
 Reviewed-By: Luigi Pinca [email protected]
 Reviewed-By: Yagiz Nizipli [email protected]
[detached HEAD 7d6cf7982e] fs: use default w flag for writeFileSync with utf8 encoding
 Author: Murilo Kakazu [email protected]
 Date: Fri Dec 1 03:45:10 2023 -0300
 1 file changed, 3 insertions(+), 3 deletions(-)
 Rebasing (3/4)
 Rebasing (4/4)
Executing: git node land --amend --yes
 --------------------------------- New Message ----------------------------------
 fs: add tests for writeFileSync with no flag
PR-URL: #50990
 Reviewed-By: Luigi Pinca [email protected]
 Reviewed-By: Yagiz Nizipli [email protected]
[detached HEAD 5220933a12] fs: add tests for writeFileSync with no flag
 Author: Murilo Kakazu [email protected]
 Date: Fri Dec 1 13:46:14 2023 -0300
 1 file changed, 16 insertions(+)
Successfully rebased and updated refs/heads/main.
ℹ Add commit-queue-squash label to land the PR as one commit, or commit-queue-rebase to land as separate commits.

https://github.com/nodejs/node/actions/runs/7075388656

[nodejs-github-bot]

Landed in 7bfb087