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no-op commit to note that the example given in the previous commit is

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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
This commit is contained in:
Dag-Erling Smørgrav 2010-08-15 14:55:32 +00:00
parent 1035d74025
commit b6fbd4d50d
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=211338
1 changed files with 1 additions and 1 deletions
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lib/libutil/expand_number.c
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@ -66,7 +66,7 @@ expand_number(const char *buf, uint64_t *num)
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)) {