126159 - Integer not always converted to integer correctly

Status: VERIFIED FIXED

(Core :: JavaScript Engine, defect)

Description

[Steven Don]

I use the SpiderMonkey engine in a project of my own. I have found that some
values specified as integers, although stored correctly, are incorrectly
converted by JS_ValueToInt32 (and possibly others as well).

JavaScript:
  const WHITE=0xFFFFFF;
  CallCFunction (WHITE);

C:
  #define WHITE 0xFFFFFF
  int i;
  JS_ValueToInt32 (cx, *vp, &b);
  if (i == WHITE)
  {
    printf ("OK!");
  } else {
    printf ("0x%08X", i);
  }

Output:
  0x01000000

Perhaps JS_ValueToInt32 should first check JSVAL_IS_INT. That would also
eliminate the conversion to double and other operations, thereby increasing
performance.

Comment 1

[Steven Don]

The &b is a typo and should be &i, obviously.

Comment 2

[Phil Schwartau]

cc'ing Brendan on this one - 

Comment 3

[Brendan Eich [:brendan]]

JS_ValueToInt32 is an old API entry point, deprecated in favor of
JS_ValueToECMAInt32.  If you can use the latter, please do so.

I agree that js_ValueToInt32 in jsnum.c should have an early out for int-tagged
jsvals, patch coming up.  I trust doing so will not break anyone using this old
API -- it is an incompatible change, however!  Presumably, anyone using it was
not counting on the buggy behavior Steven reports.

/be

Comment 4

[Brendan Eich [:brendan]]

Attachment: proposed fix

Let's try for 0.9.9, this is an easy one.

/be

Comment 5

[Mike Shaver (:shaver emeritus)]

Comment on attachment 70133 [details] [diff] [review]
proposed fix

r=shaver.

(If jband finds something I missed in _this_ one, I'm hanging up my spurs.)

Comment 6

[John Bandhauer]

Comment on attachment 70133 [details] [diff] [review]
proposed fix

sr=jband

Comment 7

[Brendan Eich [:brendan]]

Fixed.

Comment 8

[Phil Schwartau]

Marking Verified -