numpy.lib.machar: replace 'while 1' loops with 'for _ in max_iter'

If there are bugs in the scalar objects, the 'while 1' loops can potentially
run forever, so we make sure they only go at most 1000 times.

1 files changed, 25 insertions, 8 deletions

diff --git a/numpy/lib/machar.py b/numpy/lib/machar.py
index 443fef83b..e66583774 100644
--- a/numpy/lib/machar.py
+++ b/numpy/lib/machar.py
@@ -58,6 +58,7 @@ class MachAr(object):
           float_to_str - convert array float to str
           title        - description of used floating point numbers
         """
+        max_iter = range(1000)
         one = float_conv(1)
         two = one + one
         zero = one - one
@@ -65,41 +66,49 @@ class MachAr(object):
         # Do we really need to do this?  Aren't they 2 and 2.0?
         # Determine ibeta and beta
         a = one
-        while 1:
+        for _ in max_iter:
             a = a + a
             temp = a + one
             temp1 = temp - a
             if any(temp1 - one != zero):
                 break
+        else:
+            raise RuntimeError
         b = one
-        while 1:
+        for _ in max_iter:
             b = b + b
             temp = a + b
             itemp = int_conv(temp-a)
             if any(itemp != 0):
                 break
+        else:
+            raise RuntimeError
         ibeta = itemp
         beta = float_conv(ibeta)
 
         # Determine it and irnd
         it = -1
         b = one
-        while 1:
+        for _ in max_iter:
             it = it + 1
             b = b * beta
             temp = b + one
             temp1 = temp - b
             if any(temp1 - one != zero):
                 break
+        else:
+            raise RuntimeError
 
         betah = beta / two
         a = one
-        while 1:
+        for _ in max_iter:
             a = a + a
             temp = a + one
             temp1 = temp - a
             if any(temp1 - one != zero):
                 break
+        else:
+            raise RuntimeError
         temp = a + betah
         irnd = 0
         if any(temp-a != zero):
@@ -116,7 +125,7 @@ class MachAr(object):
         for i in range(negep):
             a = a * betain
         b = a
-        while 1:
+        for _ in max_iter:
             temp = one - a
             if any(temp-one != zero):
                 break
@@ -126,6 +135,8 @@ class MachAr(object):
             if negep < 0:
                 raise RuntimeError, "could not determine machine tolerance " \
                                     "for 'negep', locals() -> %s" % (locals())
+        else:
+            raise RuntimeError
         negep = -negep
         epsneg = a
 
@@ -133,12 +144,14 @@ class MachAr(object):
         machep = - it - 3
         a = b
 
-        while 1:
+        for _ in max_iter:
             temp = one + a
             if any(temp-one != zero):
                 break
             a = a * beta
             machep = machep + 1
+        else:
+            raise RuntimeError
         eps = a
 
         # Determine ngrd
@@ -153,7 +166,7 @@ class MachAr(object):
         z = betain
         t = one + eps
         nxres = 0
-        while 1:
+        for _ in max_iter:
             y = z
             z = y*y
             a = z*one # Check here for underflow
@@ -165,6 +178,8 @@ class MachAr(object):
                 break
             i = i + 1
             k = k + k
+        else:
+            raise RuntimeError
         if ibeta != 10:
             iexp = i + 1
             mx = k + k
@@ -177,7 +192,7 @@ class MachAr(object):
             mx = iz + iz - 1
 
         # Determine minexp and xmin
-        while 1:
+        for _ in max_iter:
             xmin = y
             y = y * betain
             a = y * one
@@ -191,6 +206,8 @@ class MachAr(object):
                     break
             else:
                 break
+        else:
+            raise RuntimeError
         minexp = -k
 
         # Determine maxexp, xmax