fix: skip native write for zero-length callback writeFile

[caneraltinbasak]

Description of Change

v8 built with V8_ENABLE_SANDBOX in Chromium. Every Buffer's bytes
must live inside the V8 memory cage, and pointers are cage-relative.
A zero-length buffer has no allocation in the cage, so Buffer::Data()
resolves to the cage base / an empty-store sentinel — an address
the kernel rejects when it's handed to write(2), even with len == 0

Plain Node, V8 sandbox off. Buffers come from Node's normal heap
allocator; an empty buffer yields an ordinary valid pointer, so
write(fd, ptr, 0) is a harmless no-op → returns 0.

Callback fs.writeFile()/writeAll() always issued a native
fs.write(fd, buffer, 0, 0, ...) syscall even when the data was empty.
On the Electron-based roHtmlWidget Node integration that zero-length
write returns "EFAULT: bad address in system call argument, write",
whereas it succeeds under the standalone roNodeJs runtime and under
fs/promises.writeFile().

Add a zero-length guard to writeAll() that skips the syscall and runs
the normal completion path (optional fsync, close the fd only when
writeFile() opened it, invoke callback(null)), matching the early
return already present in fs/promises.writeFile(). Non-empty writes,
validation, abort/signal handling and caller-owned fd semantics are
unchanged.

Checklist

• [ x] PR description included and stakeholders cc'd
• [ x] npm test passes
• [ x] tests are changed or added
• [ x] relevant documentation, tutorials, templates and examples are changed or added
• [ x] PR release notes describe the change in a way relevant to app developers, and are capitalized, punctuated, and past tense.

Release Notes

Notes:
Fixed an error(EFAULT) when Electron render process writes a file with zero length using fs.writeFile()

[Copilot]

Pull request overview

This PR addresses an Electron-specific failure mode in the callback-based fs.writeFile() path when writing zero-length data under V8 sandboxing, by skipping the underlying native write(2) syscall for length === 0 and completing via the normal success/flush/close path (aligning behavior with fs/promises.writeFile()).

Changes:

• Added a Node patch to short-circuit writeAll() for zero-length writes while preserving the usual completion behavior (optional fsync, close semantics, callback).
• Added renderer regression tests covering empty-string/empty-buffer writes, truncation, non-empty writes, and user-owned file descriptor behavior.
• Registered the new Node patch in patches/node/.patches.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
spec/node-spec.ts	Adds renderer regression coverage for callback fs.writeFile() zero-length writes and fd ownership behavior.
patches/node/fs_skip_native_write_for_zero-length_callback_writefile.patch	Updates Node’s writeAll() to skip the native write syscall when length === 0 and reuse a shared completion path.
patches/node/.patches	Includes the new patch in the Node patch application list.

[caneraltinbasak]

This is not the right fix. I've found the root cause of the problem, this was just a workaround.
I've filed https://issues.chromium.org/issues/527930354 to address the right issue and will send a patch upstream and add a temporary fix to our yocto build until my patch makes its way.