Use correct flag to determine if V8 Sandboxing is enabled

[malshoff]

Electron switched to using v8's sandboxing feature as of V21. With this enabled, allocating a buffer using node::Buffer::New crashes the program, because it attempts to allocate memory outside of the allowed memory address range of the sandbox.

[23992:0508/184214.301:ERROR:node_bindings.cc(162)] Fatal error in V8: v8_ArrayBuffer_NewBackingStore When the V8 Sandbox is enabled, ArrayBuffer backing stores must be allocated inside the sandbox address space. Please use an appropriate ArrayBuffer::Allocator to allocate these buffers, or disable the sandbox.

Reproducing the issue is as simple as calling db.serialize() in Electron versions 30.0 and higher.

PR #1036 fixed this for electron versions until 30.x.x+, where this fix broke. Why this only broke in the most recent Electron versions, I'm not sure, but there were 2 issues:

• The flag being checked is rarely used, and also was not the proper one to use for determining if V8 sandboxing is enabled. That would be V8_ENABLE_SANDBOX . This is also the flag that Electron uses: https://github.com/electron/electron/blob/main/patches/node/support_v8_sandboxed_pointers.patch
• The conditions were illogical: "if sandboxing is enabled, use the allocation method that should violate sandboxing rules and crash the program". This never should never have worked, and yet it did until v30.

I tested the minimum repro with these changes inside of an Electron app, and it behaves as expected now. (#1372 )

[mceachen]

Thank you for doing this research!