core-lightning/common/overflows.h
Rusty Russell 888774e2ad overflows: helpers for integer assignment overflows.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2021-07-20 13:28:38 -04:00

44 lines
834 B
C

#ifndef LIGHTNING_COMMON_OVERFLOWS_H
#define LIGHTNING_COMMON_OVERFLOWS_H
#include "config.h"
#include <ccan/short_types/short_types.h>
static inline bool add_overflows_size_t(uint64_t a, uint64_t b)
{
return (size_t)a != a || (size_t)b != b || (a + b) < (size_t)a;
}
static inline bool add_overflows_u64(uint64_t a, uint64_t b)
{
return (a + b) < a;
}
static inline bool mul_overflows_u64(uint64_t a, uint64_t b)
{
uint64_t ret;
if (a == 0)
return false;
ret = a * b;
return (ret / a != b);
}
static inline bool assign_overflow_u8(u8 *dst, uint64_t v)
{
*dst = v;
return *dst == v;
}
static inline bool assign_overflow_u16(u16 *dst, uint64_t v)
{
*dst = v;
return *dst == v;
}
static inline bool assign_overflow_u32(u32 *dst, uint64_t v)
{
*dst = v;
return *dst == v;
}
#endif /* LIGHTNING_COMMON_OVERFLOWS_H */