Messages in this thread | | | Date | Fri, 06 Jan 2006 07:42:48 +0100 | From | Eric Dumazet <> | Subject | Re: [PATCH] lib: Fix bug in int_sqrt() for 64 bit longs |
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Peter Williams a écrit : > The implementation of int_sqrt() assumes that longs have 32 bits. On > systems that have 64 bit longs this will result in gross errors when the > argument to the function is greater than 2^32 - 1 on such systems. I > doubt whether any such use is currently made of int_sqrt() but the > attached patch fixes the problem anyway. > > Signed-off-by: Peter Williams <pwil3058@bigpond.com.au> > > > ------------------------------------------------------------------------ > > Index: GIT-warnings/lib/int_sqrt.c > =================================================================== > --- GIT-warnings.orig/lib/int_sqrt.c 2005-10-25 13:55:22.000000000 +1000 > +++ GIT-warnings/lib/int_sqrt.c 2006-01-06 14:29:19.000000000 +1100 > @@ -15,7 +15,7 @@ unsigned long int_sqrt(unsigned long x) > op = x; > res = 0; > > - one = 1 << 30; > + one = 1 << (BITS_PER_LONG - 2); > while (one > op) > one >>= 2; >
Are you sure it works ?
I would have writen :
one = 1L << (BITS_PER_LONG - 2);
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