Set errno for atan2 underflow (bug 16349)

["Joseph S. Myers" <joseph at codesourcery dot com>]

This patch fixes bug 16349, missing errno setting for atan2 underflow,
by adding appropriate checks to the existing wrappers.  (As in other
cases, the __kernel_standard support for calling matherr is considered
to be for existing code expecting existing rules for what's considered
an error, even if those don't correspond to a general logical scheme
for what counts as what kind of error, so __set_errno calls are added
directly without any changes to __kernel_standard.)

Tested x86_64 and x86.

(auto-libm-test-out diffs omitted below.)

2014-03-25  Joseph Myers  <joseph@codesourcery.com>

	[BZ #16349]
	* math/w_atan2.c: Include <errno.h>.
	(__atan2): Set errno for result underflowing to zero.
	* math/w_atan2f.c: Include <errno.h>.
	(__atan2f): Set errno for result underflowing to zero.
	* math/w_atan2l.c: Include <errno.h>.
	(__atan2l): Set errno for result underflowing to zero.
	* math/auto-libm-test-in: Don't allow missing errno for some atan2
	tests.
	* math/auto-libm-test-out: Regenerated.

diff --git a/math/auto-libm-test-in b/math/auto-libm-test-in
index 7c80192..7ef6b81 100644
--- a/math/auto-libm-test-in
+++ b/math/auto-libm-test-in
@@ -157,13 +157,12 @@ atan2 -min -max
 atan2 min_subnorm -max
 atan2 -min_subnorm -max
 # Bug 15319: underflow exception may be missing.
-# Bug 16349: errno setting may be missing.
 atan2 1 max missing-underflow
 atan2 -1 max missing-underflow
-atan2 min max missing-underflow missing-errno
-atan2 -min max missing-underflow missing-errno
-atan2 min_subnorm max missing-underflow missing-errno
-atan2 -min_subnorm max missing-underflow missing-errno
+atan2 min max missing-underflow
+atan2 -min max missing-underflow
+atan2 min_subnorm max missing-underflow
+atan2 -min_subnorm max missing-underflow
 
 atanh 0
 atanh -0
diff --git a/math/w_atan2.c b/math/w_atan2.c
index efbf0b3..c56d7b6 100644
--- a/math/w_atan2.c
+++ b/math/w_atan2.c
@@ -20,6 +20,7 @@
  * wrapper atan2(y,x)
  */
 
+#include <errno.h>
 #include <math.h>
 #include <math_private.h>
 
@@ -27,10 +28,15 @@
 double
 __atan2 (double y, double x)
 {
+  double z;
+
   if (__builtin_expect (x == 0.0 && y == 0.0, 0) && _LIB_VERSION == _SVID_)
     return __kernel_standard (y, x, 3); /* atan2(+-0,+-0) */
 
-  return __ieee754_atan2 (y, x);
+  z = __ieee754_atan2 (y, x);
+  if (__glibc_unlikely (z == 0.0 && y != 0.0 && __finite (x)))
+    __set_errno (ERANGE);
+  return z;
 }
 weak_alias (__atan2, atan2)
 #ifdef NO_LONG_DOUBLE
diff --git a/math/w_atan2f.c b/math/w_atan2f.c
index 6967540..e4e90fc 100644
--- a/math/w_atan2f.c
+++ b/math/w_atan2f.c
@@ -20,6 +20,7 @@
  * wrapper atan2f(y,x)
  */
 
+#include <errno.h>
 #include <math.h>
 #include <math_private.h>
 
@@ -27,9 +28,14 @@
 float
 __atan2f (float y, float x)
 {
+  float z;
+
   if (__builtin_expect (x == 0.0f && y == 0.0f, 0) && _LIB_VERSION == _SVID_)
     return __kernel_standard_f (y, x, 103); /* atan2(+-0,+-0) */
 
-  return __ieee754_atan2f (y, x);
+  z = __ieee754_atan2f (y, x);
+  if (__glibc_unlikely (z == 0.0f && y != 0.0f && __finitef (x)))
+    __set_errno (ERANGE);
+  return z;
 }
 weak_alias (__atan2f, atan2f)
diff --git a/math/w_atan2l.c b/math/w_atan2l.c
index f1de1d1..d6498ae 100644
--- a/math/w_atan2l.c
+++ b/math/w_atan2l.c
@@ -20,6 +20,7 @@
  * wrapper atan2l(y,x)
  */
 
+#include <errno.h>
 #include <math.h>
 #include <math_private.h>
 
@@ -27,9 +28,14 @@
 long double
 __atan2l (long double y, long double x)
 {
+  long double z;
+
   if (__builtin_expect (x == 0.0L && y == 0.0L, 0) && _LIB_VERSION == _SVID_)
     return __kernel_standard_l (y, x, 203); /* atan2(+-0,+-0) */
 
-  return __ieee754_atan2l (y, x);
+  z = __ieee754_atan2l (y, x);
+  if (__glibc_unlikely (z == 0.0L && y != 0.0L && __finitel (x)))
+    __set_errno (ERANGE);
+  return z;
 }
 weak_alias (__atan2l, atan2l)

-- 
Joseph S. Myers
joseph@codesourcery.com