String equality checking wrong - only checks 4 bytes?

[martin-hughes]

I haven't had a chance to fully investigate yet, but consider the following ASL:

DefinitionBlock("", "DSDT", 1, "RSACPI", "StrEqual", 1) {
    Method(MAIN, 0, NotSerialized) {
        Local0 = "Hello"
        Local1 = "Hellp"

        Return(Local0 == Local1)
    }
}

This test should pass - remember that a zero result indicates success - but it actually doesn't.

From a bit of playing, the parser seems to think (with the logic the correct way around again)

• "Hello" == "Hellp"
• "Hello" == "Hell",
• "Hello" != "Help"

Which leads me to think it's only comparing the first 4 bytes (or possibly "integer-size" number of bytes)

[martin-hughes]

Ah I think there's a conflict in the spec.

Looking at the 6.4 version of the spec:
19.6.69. LEqual (Logical Equal) says "For strings and buffers, True is returned only if both lengths are the same and the result of a byte-wise compare indicates exact equality"
(Version 6.6 of the spec has a similar statement)

But also in section 20:
DefLEqual := LequalOp Operand Operand, plus
Operand := TermArg => Integer

I can see you've gone for the section 20 one in the code, but that doesn't feel quite right - are you sure we shouldn't be doing the "proper" string comparison?