Fix overflow check for parsing format strings

[dakersnar]

Fixes#67891

Limiting the precision to int.MaxValue ended up causing issues, so we are going to limit to 999_999_999 (9 digits) instead. As discussed in the above issue, that should be more than enough precision for every type we support and plan to support.

Do we need to update this article, or any other documentation? https://docs.microsoft.com/en-us/dotnet/standard/base-types/standard-numeric-format-strings

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Issue Details

---

Fixes #67891

Limiting the precision to int.MaxValue ended up causing issues, so we are going to limit to 999_999_999 (9 digits) instead. As discussed in the above issue, that should be more than enough precision for every type we support and plan to support.

Do we need to update this article, or any other documentation? https://docs.microsoft.com/en-us/dotnet/standard/base-types/standard-numeric-format-strings

Author:	dakersnar
Assignees:	-
Labels:	area-System.Numerics
Milestone:	-

[stephentoub]

Do we need to update this article, or any other documentation?

Yes, we should submit PRs to update the docs appropriately.

[stephentoub]

Does

runtime/src/libraries/Common/src/System/Globalization/FormatProvider.Number.cs

Lines 703 to 716 in 746fc5f

	// Fallback for symbol and any length digits. The digits value must be >= 0 && <= 99,
	// but it can begin with any number of 0s, and thus we may need to check more than two
	// digits. Further, for compat, we need to stop when we hit a null char.
	intn=0;
	inti=1;
	while((uint)i<(uint)format.Length&&char.IsAsciiDigit(format[i]))
	{
	inttemp=(n*10)+format[i++]-'0';
	if(temp<n)
	{
	thrownewFormatException(SR.Argument_BadFormatSpecifier);
	}
	n=temp;
	}

need to be updated, too?

[dakersnar]

@stephentoub yes, and probably this too https://source.dot.net/#System.Runtime.Numerics/System/Numerics/BigNumber.cs,858. I'll bundle those in.

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