[christianaurichzm]

A snapshot builder script that reads globalThis.localStorage, sessionStorage or Storage aborts the build:

$ echo 'try { globalThis.localStorage } catch {}' > entry.js
$ node --snapshot-blob snapshot.blob --build-snapshot entry.js
Unknown external reference 0x5dfce95473e0.
<unresolved>

The webstorage binding never registers its C++ callbacks as external references, so once the getters load the binding the snapshot can't serialize the Storage template. Fixing only that is not enough for sessionStorage, because the Storage object itself can't be serialized either.

This registers the callbacks and makes creating localStorage or sessionStorage while building a snapshot throw ERR_NOT_SUPPORTED_IN_SNAPSHOT, like new Worker() does. lib/internal/webstorage.js also read --localstorage-file and the warning flag at load time, so a snapshot that touched localStorage ignored the file passed at run time and did not warn again. The options are now read in the getters, and the flag is reset when the snapshot is taken.

test/parallel/test-snapshot-webstorage.js covers both errors and the run-time case. It aborts without this change and passes with it.

#66740 adds a webstorage BindingData that is not serializable, so whichever of the two lands second will need to make it serializable. I haven't built them together yet.

Refs: #66740

[nodejs-github-bot]

Review requested:

• @nodejs/startup

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.49%. Comparing base (56da329) to head (df0e001).
⚠️ Report is 17 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #66884      +/-   ##
==========================================
- Coverage   90.51%   90.49%   -0.02%     
==========================================
  Files         797      797              
  Lines      278221   278399     +178     
  Branches    53463    53493      +30     
==========================================
+ Hits       251844   251951     +107     
- Misses      16763    16811      +48     
- Partials     9614     9637      +23     

Files with missing lines	Coverage Δ
lib/internal/webstorage.js	100.00% <100.00%> (ø)
src/node_external_reference.h	100.00% <ø> (ø)
src/node_webstorage.cc	78.71% <100.00%> (+1.07%)	⬆️

... and 42 files with indirect coverage changes

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