watch: strip watch flags from NODE_OPTIONS in child process

[marcopiraccini]

When NODE_OPTIONS contains --watch, the watch mode parent process spawns a child that inherits the same NODE_OPTIONS, causing the child to also enter watch mode and spawn another child, creating an infinite loop of process spawning.

This PR strips watch-related flags (--watch, --watch-path,--watch-preserve-output, --watch-kill-signal) from NODE_OPTIONS before passing the environment to the child process. This mirrors the existing logic that already strips these flags from process.execArgv.

Non-watch flags in NODE_OPTIONS (e.g., --max-old-space-size) are preserved.

To properly handle quoted strings and backslash escapes in NODE_OPTIONS values (e.g., --require "./path with --watch in name/f.js"), the C++ ParseNodeOptionsEnvVar tokenizer is exposed to JavaScript via a new internalBinding('options') method. This reuses the exact same parser that Node.js uses at startup, ensuring consistent behavior.

Fixes: #61740

This is actually similar to #61838 but more "surgical", it just avoid propagating watch flags.

[codecov]

Codecov Report

❌ Patch coverage is 81.81818% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.67%. Comparing base (3725bd2) to head (4cbc589).
⚠️ Report is 508 commits behind head on main.

Files with missing lines	Patch %	Lines
src/node_options.cc	80.00%	1 Missing and 3 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #62143      +/-   ##
==========================================
+ Coverage   89.65%   89.67%   +0.01%     
==========================================
  Files         676      713      +37     
  Lines      206543   224097   +17554     
  Branches    39547    42313    +2766     
==========================================
+ Hits       185184   200956   +15772     
- Misses      13480    14944    +1464     
- Partials     7879     8197     +318     

Files with missing lines	Coverage Δ
lib/internal/options.js	47.19% <100.00%> (+0.60%)	⬆️
src/node_options.cc	77.33% <80.00%> (+0.88%)	⬆️

... and 271 files with indirect coverage changes

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[Renegade334]

Ultimately, this sort of approach isn't robust enough.

$ mkdir 'test for --watch parsing'
$ echo 'console.log("hi!")' > 'test for --watch parsing/test.cjs'
$ NODE_OPTIONS='--require "./test for --watch parsing/test.cjs"' node -p 'process.env.NODE_OPTIONS.split(" ")'
hi!
[ '--require', '"./test', 'for', '--watch', 'parsing/test.cjs"' ]
                                  ^^^^^^^

I suspect this is going to need to interact with the options parser in some way.

[marcopiraccini]

Good catch.
Thinking about it, maybe adding a C++ binding that exposes ParseNodeOptionsEnvVar to JS would be more robust (being the same parser to interpret NODE_OPTIONS, in my undersanding) and then finltering out watch flags. Will amend this PR.

[marcopiraccini]

@Renegade334 PTAL

[Renegade334]

Oh, there's a test failing on macOS.

[marcopiraccini]

Oh, there's a test failing on macOS.

Because of --without-node-options for darwin. see:

node/.github/workflows/test-shared.yml

Line 167 in d179c7e

${{ endsWith(matrix.system, '-darwin') && '--arg withAmaro false --arg withLief false --arg withSQLite false --arg withFFI false --arg extraConfigFlags ''["--without-inspector" "--without-node-options"]'' \' || '\' }}

PTAL