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Remove invalid left shifts of -1.

Browse source 
Bug: 24492248

Shifting sign bits left is considered undefined behavior, so we need to
switch these uses to unsigned equivalents. The time_t-related code is
updated relative to upstream sources.

Change-Id: I226e5a929a10f5c57dfcb90c748fdac34eb377c2
This commit is contained in:
Stephen Hines 2015-09-29 09:28:41 -07:00
parent 8b279eadd3
commit 23360cc498
2 changed files with 15 additions and 10 deletions
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2
libc/bionic/semaphore.cpp
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@ -80,7 +80,7 @@ static inline int SEMCOUNT_TO_VALUE(unsigned int sval) {
#define SEMCOUNT_ONE SEMCOUNT_FROM_VALUE(1)
// The value -1 as a sem->count bit-pattern.
#define SEMCOUNT_MINUS_ONE SEMCOUNT_FROM_VALUE(-1)
#define SEMCOUNT_MINUS_ONE SEMCOUNT_FROM_VALUE(~0U)
#define SEMCOUNT_DECREMENT(sval) (((sval) - (1U << SEMCOUNT_VALUE_SHIFT)) & SEMCOUNT_VALUE_MASK)
#define SEMCOUNT_INCREMENT(sval) (((sval) + (1U << SEMCOUNT_VALUE_SHIFT)) & SEMCOUNT_VALUE_MASK)

23
libc/tzcode/private.h
View file

@ -328,15 +328,20 @@ const char * scheck(const char * string, const char * format);
#define TYPE_SIGNED(type) (((type) -1) < 0)
#endif /* !defined TYPE_SIGNED */
/* The minimum and maximum finite time values. */
static time_t const time_t_min =
(TYPE_SIGNED(time_t)
? (time_t) -1 << (CHAR_BIT * sizeof (time_t) - 1)
: 0);
static time_t const time_t_max =
(TYPE_SIGNED(time_t)
? - (~ 0 < 0) - ((time_t) -1 << (CHAR_BIT * sizeof (time_t) - 1))
: -1);
#define TWOS_COMPLEMENT(t) ((t) ~ (t) 0 < 0)
/* Max and min values of the integer type T, of which only the bottom
* B bits are used, and where the highest-order used bit is considered
* to be a sign bit if T is signed. */
#define MAXVAL(t, b) \
((t) (((t) 1 << ((b) - 1 - TYPE_SIGNED(t))) \
- 1 + ((t) 1 << ((b) - 1 - TYPE_SIGNED(t)))))
#define MINVAL(t, b) \
((t) (TYPE_SIGNED(t) ? - TWOS_COMPLEMENT(t) - MAXVAL(t, b) : 0))
/* The minimum and maximum finite time values. This assumes no padding. */
static time_t const time_t_min = MINVAL(time_t, TYPE_BIT(time_t));
static time_t const time_t_max = MAXVAL(time_t, TYPE_BIT(time_t));
#ifndef INT_STRLEN_MAXIMUM
/*