rz_types_overflow.h

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#ifndef RZ_TYPES_OVERFLOW_H
#define RZ_TYPES_OVERFLOW_H
 
#include <rz_types.h>
 
// TODO: Use CLANG/GCC builtins if available: __builtin_mul_overflow
 
// ADD
// if ((x > 0) && (a > INT_MAX - x)) /* `a + x` would overflow */;
// if ((x < 0) && (a < INT_MIN - x)) /* `a + x` would underflow */;
#define SZT_ADD_OVFCHK(x, y)  ((SIZE_MAX - (x)) < (y))
#define SSZT_ADD_OVFCHK(a, x) ((((x) > 0) && ((a) > SSIZE_MAX - (x))) || (((x) < 0) && (a) < SSIZE_MIN - (x)))
#define UT64_ADD_OVFCHK(x, y) ((UT64_MAX - (x)) < (y))
#define ST64_ADD_OVFCHK(a, x) ((((x) > 0) && ((a) > ST64_MAX - (x))) || (((x) < 0) && (a) < ST64_MIN - (x)))
#define UT32_ADD_OVFCHK(x, y) ((UT32_MAX - (x)) < (y))
#define ST32_ADD_OVFCHK(a, x) ((((x) > 0) && ((a) > ST32_MAX - (x))) || (((x) < 0) && (a) < ST32_MIN - (x)))
#define UT16_ADD_OVFCHK(x, y) ((UT16_MAX - (x)) < (y))
#define ST16_ADD_OVFCHK(a, b) ((((b) > 0) && ((a) > ST16_MAX - (b))) || (((b) < 0) && ((a) < ST16_MIN - (b))))
#define UT8_ADD_OVFCHK(x, y)  ((UT8_MAX - (x)) < (y))
#define ST8_ADD_OVFCHK(a, x)  ((((x) > 0) && ((a) > ST8_MAX - (x))) || ((x) < 0 && (a) < ST8_MIN - (x)))
 
// SUB
// if ((x < 0) && (a > INT_MAX + x)) /* `a - x` would overflow */;
// if ((x > 0) && (a < INT_MIN + x)) /* `a - x` would underflow */;
#define SZT_SUB_OVFCHK(a, b)  SZT_ADD_OVFCHK(a, -(b))
#define SSZT_SUB_OVFCHK(a, b) SSZT_ADD_OVFCHK(a, -(b))
#define UT64_SUB_OVFCHK(a, b) UT64_ADD_OVFCHK(a, -(b))
#define ST64_SUB_OVFCHK(a, b) ST64_ADD_OVFCHK(a, -(b))
#define UT32_SUB_OVFCHK(a, b) UT32_ADD_OVFCHK(a, -(b))
#define ST32_SUB_OVFCHK(a, b) ST32_ADD_OVFCHK(a, -(b))
#define UT16_SUB_OVFCHK(a, b) UT16_ADD_OVFCHK(a, -(b))
#define ST16_SUB_OVFCHK(a, b) ST16_ADD_OVFCHK(a, -(b))
#define UT8_SUB_OVFCHK(a, b)  UT8_ADD_OVFCHK(a, -(b))
#define ST8_SUB_OVFCHK(a, b)  ST8_ADD_OVFCHK(a, -(b))
 
// MUL
#define UNSIGNED_MUL_OVERFLOW_CHECK(overflow_name, type_base, type_min, type_max) \
    static inline bool overflow_name(type_base a, type_base b) { \
        return (a > 0 && b > 0 && a > type_max / b); \
    }
 
#define SIGNED_MUL_OVERFLOW_CHECK(overflow_name, type_base, type_min, type_max) \
    static inline bool overflow_name(type_base a, type_base b) { \
        if (a > 0) { \
            if (b > 0) { \
                return a > type_max / b; \
            } \
            return b < type_min / a; \
        } \
        if (b > 0) { \
            return a < type_min / b; \
        } \
        return a && b < type_max / a; \
    }
 
#define SIGNED_DIV_OVERFLOW_CHECK(overflow_name, type_base, type_mid, type_max) \
    static inline bool overflow_name(type_base a, type_base b) { \
        return (!b || (a == type_mid && b == type_max)); \
    }
#define UNSIGNED_DIV_OVERFLOW_CHECK(overflow_name, type_base, type_min, type_max) \
    static inline bool overflow_name(type_base a, type_base b) { \
        (void)a; \
        return !b; \
    }
 
SIGNED_DIV_OVERFLOW_CHECK(ST8_DIV_OVFCHK, ut8, UT8_GT0, UT8_MAX)
SIGNED_DIV_OVERFLOW_CHECK(ST16_DIV_OVFCHK, ut16, UT16_GT0, UT16_MAX)
SIGNED_DIV_OVERFLOW_CHECK(ST32_DIV_OVFCHK, ut32, UT32_GT0, UT32_MAX)
SIGNED_DIV_OVERFLOW_CHECK(ST64_DIV_OVFCHK, ut64, UT64_GT0, UT64_MAX)
UNSIGNED_DIV_OVERFLOW_CHECK(UT8_DIV_OVFCHK, ut8, UT8_MIN, UT8_MAX)
UNSIGNED_DIV_OVERFLOW_CHECK(UT16_DIV_OVFCHK, ut16, UT16_MIN, UT16_MAX)
UNSIGNED_DIV_OVERFLOW_CHECK(UT32_DIV_OVFCHK, ut32, UT32_MIN, UT32_MAX)
UNSIGNED_DIV_OVERFLOW_CHECK(UT64_DIV_OVFCHK, ut64, UT64_MIN, UT64_MAX)
// TODO: Windows doesn't have ssize_t, and we don't need this check yet
// SIGNED_MUL_OVERFLOW_CHECK(SSZT_MUL_OVFCHK, ssize_t, SSZT_MIN, SSZT_MAX)
SIGNED_MUL_OVERFLOW_CHECK(ST8_MUL_OVFCHK, st8, ST8_MIN, ST8_MAX)
SIGNED_MUL_OVERFLOW_CHECK(ST16_MUL_OVFCHK, st16, ST16_MIN, ST16_MAX)
SIGNED_MUL_OVERFLOW_CHECK(ST32_MUL_OVFCHK, st32, ST32_MIN, ST32_MAX)
SIGNED_MUL_OVERFLOW_CHECK(ST64_MUL_OVFCHK, st64, ST64_MIN, ST64_MAX)
UNSIGNED_MUL_OVERFLOW_CHECK(SZT_MUL_OVFCHK, size_t, SZT_MIN, SZT_MAX)
UNSIGNED_MUL_OVERFLOW_CHECK(UT8_MUL_OVFCHK, ut8, UT8_MIN, UT8_MAX)
UNSIGNED_MUL_OVERFLOW_CHECK(UT16_MUL_OVFCHK, ut16, UT16_MIN, UT16_MAX)
UNSIGNED_MUL_OVERFLOW_CHECK(UT32_MUL_OVFCHK, ut32, UT32_MIN, UT32_MAX)
UNSIGNED_MUL_OVERFLOW_CHECK(UT64_MUL_OVFCHK, ut64, UT64_MIN, UT64_MAX)
 
#endif