Don’t try reading from pipes or special file descriptors

[thecrypticace]

Fixes #19420

[coderabbitai]

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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[coderabbitai]

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.

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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.

[coderabbitai]

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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