Is this posible/reachabe code?

[juanarbol]

• Node.js Version: current
• OS: any
• Scope (install, code, runtime, meta, other?):
• Module (and version) (if relevant): current

// src/node_os.cc:133
static void GetFreeMemory(const FunctionCallbackInfo<Value>& args) {
  double amount = uv_get_free_memory();
  if (amount < 0) // This
    return;
  args.GetReturnValue().Set(amount);
}

Is it possible to have amount < 0 ? Based on libuv codebase (at least on LINUX), the free mem (also total mem) is taken from /proc/meminfo, based on that, is it possible to have a negative amount?

[gireeshpunathil]

@juanarbol - may be this, for example? https://github.com/libuv/libuv/blob/2ab3dc1567d67924b634be6f478d25f4528ce574/src/unix/darwin.c#L101

[juanarbol]

Yeap, I think it is a possible "non-positive amount", in that case, don't you think that we should provide a better error handling on the implementation? I mean, at least use CHECK_GT or something like that...

I don't know, this is just a proposal because I don't know why we are dealing with invalid amount in this way.

[gireeshpunathil]

don't you think that we should provide a better error handling on the implementation?

@juanarbol - makes sense to me! but throw an exception that carries the original libuv error message, with a doc update, instead of CHECK_GT?

[juanarbol]

Yeap, it is a better approach, I think that:

if (amount < 0) {
  return uv_err_name(amount);
}

But amm... the free memory method is void so that won't work, and I don't know how to throw an exception with a given FunctionCallbackInfo

[gireeshpunathil]

here is a recent PR which did a similar thing: you need to:

• get the error message from libuv,
• compose a full exception message with that,
• define a new error type if need be, in src/node_errors.h
• and throw

https://github.com/nodejs/node/pull/32344/files#diff-853c968290ed44d71c73689242b1fab4R648-R661

/cc @addaleax for a better suggestion!

[bnoordhuis]

Is it possible to have amount < 0?

No, because the return type of uv_get_free_memory() is uint64_t, i.e, an unsigned value. Those are always >= 0.

[juanarbol]

Thanks for the support! I'm closing this issue now.