Author: des
Date: Sun Aug 15 14:55:32 2010
New Revision: 211338
URL: http://svn.freebsd.org/changeset/base/211338
Log:
no-op commit to note that the example given in the previous commit is
a very bad one, since the shift does not actually overflow. This is
a better example (assuming uint64_t = unsigned long long):
~0LLU >> 9 = 0x7fffffffffffffLLU
~0LLU >> 9 << 10 = 0xfffffffffffffc00LLU
~0LLU >> 9 << 10 >> 10 = 0x3fffffffffffffLLU
Modified:
head/lib/libutil/expand_number.c
Modified: head/lib/libutil/expand_number.c
==============================================================================
--- head/lib/libutil/expand_number.c Sun Aug 15 14:50:03 2010
(r211337)
+++ head/lib/libutil/expand_number.c Sun Aug 15 14:55:32 2010
(r211338)
@@ -66,7 +66,7 @@ expand_number(const char *buf, uint64_t
return (0);
}
-#define SHIFT(n, b) \
+#define SHIFT(n, b) \
do { if (((n << b) >> b) != n) goto overflow; n <<= b; } while (0)
switch (tolower((unsigned char)*endptr)) {
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