limitInputPixels should probably be 53-bit integer

[AndrewJDR]

src/common.h and src/common.cc show that limitInputPixels is an int, but pixel counts can certainly exceed this (e.g. inputs for tile()) while still perhaps being worthy of some limiting, so ideally you could still set limits above 2^31 or 2^32.

[lovell]

This would require support for the BigInt data type, which was added to Node-API v6.

This means we'll need to wait until we drop support for Node.js 12, probably the forthcoming v0.31.0 release, then we can bump the minimum Node-API version from v5 to v6 (or v7) and consider adding this feature.

https://nodejs.org/dist/latest/docs/api/n-api.html#node-api-version-matrix

[AndrewJDR]

@lovell Isn't napi_create_int64() (since node v8.4.0) sufficient?

[lovell]

That would provide support for 53-bit integers, which is a wider range than 32-bit, but to support your request for 64-bit integers we'll need BigInt.

[AndrewJDR]

Ah, sure... 53-bit is more than sufficient for this purpose, in my opinion -- I can revise it.

[lovell]

Great, thanks for the update, this might be a good time to roll out the :why_not_both: meme! 😄

[AndrewJDR]

Oh, I should also mention -- if you pass a number >= 2^32 (or likely even >= 2^31, since it's signed under the hood) you'll get the Input image exceeds pixel limit error on images sized smaller than the number you passed. This was initially mystifying until I had a look at the code. And I didn't test for this, but I presume anything >= 2^31 overflows and you end up with some arbitrary number between -(2^31) ... 2^31. Anyhow, this is a long way of saying some type of overflow warning/error or documentation might be good, though it's less necessary once there is 53/64 bit support... I don't think many will run into it after that.