Weed out extreme exponents in strtod.

Weed out extreme exponents in strtod.

If a decimal exponent is less than -309 return 0.0.
If a decimal exponent is greater than +324 return +infinity.

BUG=
TEST=

Committed: http://code.google.com/p/v8/source/detail?r=5623

[William Hesse, 2010-10-13 10:51:33]

In utils.h we have StrLength, which returns an int, not a size_t.  That is
needed by Vector's constructor.

Say 53-bit and 64-bit, not 53bit and 64bit.

I'm sure I have seen some sort of copy to a vector that ensures a trailing null.
 Or if you don't want that, then compute min(strlen(original), buffer_length).

http://codereview.chromium.org/3519017/diff/1/3
File test/cctest/test-strtod.cc (right):

http://codereview.chromium.org/3519017/diff/1/3#newcode19
test/cctest/test-strtod.cc:19: OS::StrNCpy(buffer, str, kBufferSize);
This doesn't guarantee a trailing null in buffer, so strlen call later on can be
bad.  Don't we have one that guarantees a trailing null?

What is the point of this copy?  Can Strtod modify the input buffer?  Is it just
to remove the constness?

Why doesn't Strtod take a Vector<const char> anyway?

http://codereview.chromium.org/3519017/diff/1/3#newcode188
test/cctest/test-strtod.cc:188: CHECK_EQ(17e307, StrtodChar("17", 307));
How about including right and left trim in these tests?

[Florian Loitsch, 2010-10-13 16:18:12]

http://codereview.chromium.org/3519017/diff/1/3
File test/cctest/test-strtod.cc (right):

http://codereview.chromium.org/3519017/diff/1/3#newcode19
test/cctest/test-strtod.cc:19: OS::StrNCpy(buffer, str, kBufferSize);
On 2010/10/13 10:51:33, William Hesse wrote:
> This doesn't guarantee a trailing null in buffer, so strlen call later on can
be
> bad.  Don't we have one that guarantees a trailing null?
> 
> What is the point of this copy?  Can Strtod modify the input buffer?  Is it
just
> to remove the constness?
> 
> Why doesn't Strtod take a Vector<const char> anyway?
done.
> 
> 
>

http://codereview.chromium.org/3519017/diff/1/3#newcode188
test/cctest/test-strtod.cc:188: CHECK_EQ(17e307, StrtodChar("17", 307));
On 2010/10/13 10:51:33, William Hesse wrote:
> How about including right and left trim in these tests?

Done.

[William Hesse, 2010-10-14 13:34:03]

LGTM.