Don’t try reading from pipes or special file descriptors #19421

thecrypticace · 2025-12-08T21:51:51Z

Fixes #19420

These can cause `fs.readFile()` to hang waiting for the file descriptor to be closed.

coderabbitai · 2025-12-08T21:53:46Z

Walkthrough

Adds a pre-check in the build utility to detect special file types (character devices or FIFOs) using fs.stat. If the target is a special file, the code skips reading existing contents to avoid hanging and proceeds to ensure the parent directory exists and write the file. For non-special files, the previous behavior remains: read current contents, skip writes when identical, then ensure directories and write. The public function signature is unchanged; changes are internal control flow and comments.

Pre-merge checks

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'Don't try reading from pipes or special file descriptors' clearly summarizes the main change addressing the hanging issue when outputting to special files like /dev/stdout.
Description check	✅ Passed	The description 'Fixes #19420' is related to the changeset, referencing the linked issue about the /dev/stdout hanging problem.
Linked Issues check	✅ Passed	The PR correctly implements a fix by detecting special files (character devices/FIFOs) and skipping the read operation to prevent hanging, directly addressing issue #19420's requirement that --output /dev/stdout should complete without hanging.
Out of Scope Changes check	✅ Passed	All changes are in-scope: the fs.stat pre-check in utils.ts targets the core issue, and the CHANGELOG.md entry documents the fix without introducing unrelated modifications.

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packages/@tailwindcss-cli/src/commands/build/utils.ts (1 hunks)

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packages/@tailwindcss-cli/src/commands/build/utils.ts

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GitHub Check: Linux / postcss
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Actionable comments posted: 1

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packages/@tailwindcss-cli/src/commands/build/utils.ts (1 hunks)

🔇 Additional comments (2)

packages/@tailwindcss-cli/src/commands/build/utils.ts (2)

16-17: Clear documentation of the fix.

The comment effectively explains why special files require different handling and prevents future regressions.

22-33: Conditional logic and write operations are correct.

The control flow properly skips reading for special files while preserving the optimization that avoids unnecessary writes for regular files when content is unchanged. Directory creation and file writing remain robust.

Note: This assessment assumes the critical issue with stat error handling (lines 18-21) is addressed.

packages/@tailwindcss-cli/src/commands/build/utils.ts

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Actionable comments posted: 0

🧹 Nitpick comments (1)

CHANGELOG.md (1)
27-27: Clarify scope to match the actual fix (pipes/char devices too).

The change handles more than just /dev/stdout. Consider wording it to reflect special files so users know FIFOs/char devices are covered.
- - CLI: Don't hang when output is `/dev/stdout` ([#19421](https://github.com/tailwindlabs/tailwindcss/pull/19421))
+ - CLI: Avoid hangs when output is `/dev/stdout` or another special file (FIFO/char device) ([#19421](https://github.com/tailwindlabs/tailwindcss/pull/19421))

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CHANGELOG.md (1 hunks)

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This PR contains the following updates: | Package | Change | Age | Confidence | |---|---|---|---| | [@tailwindcss/postcss](https://tailwindcss.com) ([source](https://github.com/tailwindlabs/tailwindcss/tree/HEAD/packages/@tailwindcss-postcss)) | [`4.1.17` -> `4.1.18`](https://renovatebot.com/diffs/npm/@tailwindcss%2fpostcss/4.1.17/4.1.18) | [![age](https://developer.mend.io/api/mc/badges/age/npm/@tailwindcss%2fpostcss/4.1.18?slim=true)](https://docs.renovatebot.com/merge-confidence/) | [![confidence](https://developer.mend.io/api/mc/badges/confidence/npm/@tailwindcss%2fpostcss/4.1.17/4.1.18?slim=true)](https://docs.renovatebot.com/merge-confidence/) | --- ### Release Notes <details> <summary>tailwindlabs/tailwindcss (@tailwindcss/postcss)</summary> ### [`v4.1.18`](https://github.com/tailwindlabs/tailwindcss/blob/HEAD/CHANGELOG.md#4118---2025-12-11) [Compare Source](tailwindlabs/tailwindcss@v4.1.17...v4.1.18) ##### Fixed - Ensure validation of `source(…)` happens relative to the file it is in ([#19274](tailwindlabs/tailwindcss#19274)) - Include filename and line numbers in CSS parse errors ([#19282](tailwindlabs/tailwindcss#19282)) - Skip comments in Ruby files when checking for class names ([#19243](tailwindlabs/tailwindcss#19243)) - Skip over arbitrary property utilities with a top-level `!` in the value ([#19243](tailwindlabs/tailwindcss#19243)) - Support environment API in `@tailwindcss/vite` ([#18970](tailwindlabs/tailwindcss#18970)) - Preserve case of theme keys from JS configs and plugins ([#19337](tailwindlabs/tailwindcss#19337)) - Write source maps correctly on the CLI when using `--watch` ([#19373](tailwindlabs/tailwindcss#19373)) - Handle special defaults (like `ringColor.DEFAULT`) in JS configs ([#19348](tailwindlabs/tailwindcss#19348)) - Improve backwards compatibility for `content` theme key from JS configs ([#19381](tailwindlabs/tailwindcss#19381)) - Upgrade: Handle `future` and `experimental` config keys ([#19344](tailwindlabs/tailwindcss#19344)) - Try to canonicalize any arbitrary utility to a bare value ([#19379](tailwindlabs/tailwindcss#19379)) - Validate candidates similarly to Oxide ([#19397](tailwindlabs/tailwindcss#19397)) - Canonicalization: combine `text-*` and `leading-*` classes ([#19396](tailwindlabs/tailwindcss#19396)) - Correctly handle duplicate CLI arguments ([#19416](tailwindlabs/tailwindcss#19416)) - Don’t emit color-mix fallback rules inside `@keyframes` ([#19419](tailwindlabs/tailwindcss#19419)) - CLI: Don't hang when output is `/dev/stdout` ([#19421](tailwindlabs/tailwindcss#19421)) </details> --- ### Configuration 📅 **Schedule**: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined). 🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied. ♻ **Rebasing**: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox. 🔕 **Ignore**: Close this PR and you won't be reminded about this update again. --- - [ ] If you want to rebase/retry this PR, check this box --- This PR has been generated by [Renovate Bot](https://github.com/renovatebot/renovate).  Reviewed-on: https://git.csmpro.ru/csmpro/mapban/pulls/74 Co-authored-by: Renovate Bot <[email protected]> Co-committed-by: Renovate Bot <[email protected]>

Don’t try reading from pipes or special file descriptors

eb59260

These can cause `fs.readFile()` to hang waiting for the file descriptor to be closed.

thecrypticace requested a review from a team as a code owner December 8, 2025 21:51

Update changelog

0c3e2f6

coderabbitai bot reviewed Dec 8, 2025

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packages/@tailwindcss-cli/src/commands/build/utils.ts Show resolved Hide resolved

thecrypticace added 2 commits December 8, 2025 16:55

Handle stat errors

47e71d5

Fix

fe4b1a1

coderabbitai bot reviewed Dec 8, 2025

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RobinMalfait approved these changes Dec 8, 2025

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thecrypticace merged commit 164194d into main Dec 8, 2025
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thecrypticace deleted the fix/issue-19420 branch December 8, 2025 22:04

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Don’t try reading from pipes or special file descriptors #19421

Don’t try reading from pipes or special file descriptors #19421

thecrypticace commented Dec 8, 2025

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Don’t try reading from pipes or special file descriptors #19421

Don’t try reading from pipes or special file descriptors #19421

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thecrypticace commented Dec 8, 2025

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coderabbitai bot commented Dec 8, 2025 •

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