diff options
| -rw-r--r-- | git-compat-util.h | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/git-compat-util.h b/git-compat-util.h index af5af22680..061e33c774 100644 --- a/git-compat-util.h +++ b/git-compat-util.h @@ -96,6 +96,14 @@ #define unsigned_add_overflows(a, b) \ ((b) > maximum_unsigned_value_of_type(a) - (a)) +/* + * Returns true if the multiplication of "a" and "b" will + * overflow. The types of "a" and "b" must match and must be unsigned. + * Note that this macro evaluates "a" twice! + */ +#define unsigned_mult_overflows(a, b) \ + ((a) && (b) > maximum_unsigned_value_of_type(a) / (a)) + #ifdef __GNUC__ #define TYPEOF(x) (__typeof__(x)) #else @@ -698,6 +706,32 @@ extern void release_pack_memory(size_t); typedef void (*try_to_free_t)(size_t); extern try_to_free_t set_try_to_free_routine(try_to_free_t); +static inline size_t st_add(size_t a, size_t b) +{ + if (unsigned_add_overflows(a, b)) + die("size_t overflow: %"PRIuMAX" + %"PRIuMAX, + (uintmax_t)a, (uintmax_t)b); + return a + b; +} +#define st_add3(a,b,c) st_add((a),st_add((b),(c))) +#define st_add4(a,b,c,d) st_add((a),st_add3((b),(c),(d))) + +static inline size_t st_mult(size_t a, size_t b) +{ + if (unsigned_mult_overflows(a, b)) + die("size_t overflow: %"PRIuMAX" * %"PRIuMAX, + (uintmax_t)a, (uintmax_t)b); + return a * b; +} + +static inline size_t st_sub(size_t a, size_t b) +{ + if (a < b) + die("size_t underflow: %"PRIuMAX" - %"PRIuMAX, + (uintmax_t)a, (uintmax_t)b); + return a - b; +} + #ifdef HAVE_ALLOCA_H # include <alloca.h> # define xalloca(size) (alloca(size)) |