diff options
| author | eadler <eadler@NetBSD.org> | 2018-03-10 09:44:47 +0000 |
|---|---|---|
| committer | eadler <eadler@NetBSD.org> | 2018-03-10 09:44:47 +0000 |
| commit | bb8d31f415a9cfc59beda6fb21e02dbae38b9af1 (patch) | |
| tree | e4b729d2e8dc63e10e4cb31adf802bd0d4858ab4 /lib/libm/src | |
| parent | c2fc4f5d1e80e95d0660d4f5d0ef19c6d5b50722 (diff) | |
Fix signed overflow in atan2
As a component of atan2(y, x), the case of x == 1.0 is farmed out to
atan(y). The current implementation of this comparison is vulnerable
to signed integer underflow (that is, undefined behavior), and it's
performed in a somewhat more complicated way than it need be. Change
it to not be quite so cute, rather directly comparing the high/low
bits of x to the specific IEEE-754 bit pattern that encodes 1.0.
ok martin@ pgoyette@ maya@
obtained from FreeBSD
Diffstat (limited to 'lib/libm/src')
| -rw-r--r-- | lib/libm/src/e_atan2.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/lib/libm/src/e_atan2.c b/lib/libm/src/e_atan2.c index 08d8f06da3a..c2a91547692 100644 --- a/lib/libm/src/e_atan2.c +++ b/lib/libm/src/e_atan2.c @@ -12,7 +12,7 @@ #include <sys/cdefs.h> #if defined(LIBM_SCCS) && !defined(lint) -__RCSID("$NetBSD: e_atan2.c,v 1.12 2002/05/26 22:01:48 wiz Exp $"); +__RCSID("$NetBSD: e_atan2.c,v 1.13 2018/03/10 09:44:47 eadler Exp $"); #endif /* __ieee754_atan2(y,x) @@ -67,7 +67,7 @@ __ieee754_atan2(double y, double x) if(((ix|((lx|-lx)>>31))>0x7ff00000)|| ((iy|((ly|-ly)>>31))>0x7ff00000)) /* x or y is NaN */ return x+y; - if(((hx-0x3ff00000)|lx)==0) return atan(y); /* x=1.0 */ + if(hx==0x3ff00000&&lx==0) return atan(y); /* x=1.0 */ m = ((hy>>31)&1)|((hx>>30)&2); /* 2*sign(x)+sign(y) */ /* when y = 0 */ |
