#ifndef _OS_OVERFLOW_H
#define _OS_OVERFLOW_H
#include <sys/cdefs.h>
#define __OS_TYPE_CHECK(x, y) do { \
_Static_assert(__builtin_types_compatible_p(typeof(x),typeof(y)), \
"overflow arithmetic: incompatible types"); \
} while (0)
#define __os_add_overflow_func(T,U,V) _Generic((T), \
unsigned: __builtin_uadd_overflow, \
unsigned long: __builtin_uaddl_overflow, \
unsigned long long: __builtin_uaddll_overflow, \
int: __builtin_sadd_overflow, \
long: __builtin_saddl_overflow, \
long long: __builtin_saddll_overflow \
)(T,U,V)
#define __os_sub_overflow_func(T,U,V) _Generic((T), \
unsigned: __builtin_usub_overflow, \
unsigned long: __builtin_usubl_overflow, \
unsigned long long: __builtin_usubll_overflow, \
int: __builtin_ssub_overflow, \
long: __builtin_ssubl_overflow, \
long long: __builtin_ssubll_overflow \
)(T,U,V)
#define __os_mul_overflow_func(T,U,V) _Generic((T), \
unsigned: __builtin_umul_overflow, \
unsigned long: __builtin_umull_overflow, \
unsigned long long: __builtin_umulll_overflow, \
int: __builtin_smul_overflow, \
long: __builtin_smull_overflow, \
long long: __builtin_smulll_overflow \
)(T,U,V)
int __header_always_inline __attribute__((__warn_unused_result__))
__os_warn_unused(const int x)
{
return x;
}
#define os_add_overflow(a, b, res) __os_warn_unused(({ \
__OS_TYPE_CHECK((a), (b)); \
__OS_TYPE_CHECK((b), *(res)); \
__os_add_overflow_func((a), (b), (res)); \
}))
#define os_add3_overflow(a, b, c, res) __os_warn_unused(({ \
typeof(a) _tmp; \
int _s, _t; \
_s = os_add_overflow((a), (b), &_tmp); \
_t = os_add_overflow((c), _tmp, (res)); \
_s | _t; \
}))
#define os_sub_overflow(a, b, res) __os_warn_unused(({ \
__OS_TYPE_CHECK((a), (b)); \
__OS_TYPE_CHECK((b), *(res)); \
__os_sub_overflow_func((a), (b), (res)); \
}))
#define os_mul_overflow(a, b, res) __os_warn_unused(({ \
__OS_TYPE_CHECK((a), (b)); \
__OS_TYPE_CHECK((b), *(res)); \
__os_mul_overflow_func((a), (b), (res)); \
}))
#endif