Request for sponsor: 4421494 infinite loop while parsing double literal

[Joe Darcy]

Dmitry Nadezhin wrote:
> http://bugs.sun.com/view_bug.do?bug_id=4421494
> https://bugs.openjdk.java.net/show_bug.cgi?id=100119
>
> Summary: This old bug report says that Double.parseDouble(s) hangs for 
> decimal strings
> in range (Double.MIN_NORMAL-0.5*Double.MIN_VALUE,Double.MIN), and returns
> incorrect result for decimal string 
> Double.MIN_NORMAL-0.5*Double.MIN_VALUE.
>
> This is because current code in FloatingDecimal.doubleValue() incorrectly
> defines the condition when nextDown(dValue) - dValue == 
> -0.5*ulp(dValue). The
> current code considers that these are all numbers 2^n which are 
> represented as
> normal doubles, and nexDown(dValue) - dValue == -1.0*ulp(dValue) for 
> other
> doubles (subnormal or not 2-powers).
> However, this is not correct for dValue == Double.MIN_VALUE, because
> nextDown(Double.MIN_NORMAL) - Double.MIN_NORMAL == 
> -1.0*ulp(Double.MIN_NORMAL).
>
> The suggested change
> -                    if ( (bigIntNBits == 1) && (bigIntExp > -expBias) ){
> +                    if ( (bigIntNBits == 1) && (bigIntExp > 
> -expBias+1) ){
> redefines the condition so that dValue == Double.MIN_NORMAL doesn't 
> satisfy it.
>
> -Dima

Hello.

Thank you for the proposed fix; that certainly sounds like a plausible 
cause of the problem.

I'm a bit swamped now, but I'll try to look at verifying the fix and 
sponsoring getting it back into the JDK within the next few weeks.

-Joe