Merge pull request #4845 from t-ikegami/mpz_crash_fix

tannewt · web-flow · commit a25872dcb3e4 · 2021-06-02T08:28:24.000-07:00
Fix bit_length() method to work with zero-valued mpz integer.
diff --git a/py/mpz.h b/py/mpz.h
@@ -142,6 +142,9 @@ static inline size_t mpz_max_num_bits(const mpz_t *z) {
     return z->len * MPZ_DIG_SIZE;
 }
 static inline size_t mpz_num_bits(const mpz_t *z) {
+    if (mpz_is_zero(z)) {
+        return 0;
+    }
     size_t last_bits = (8 * (sizeof(long) - sizeof(mpz_dig_t))) - __builtin_clzl(z->dig[z->len - 1]);
     return z->len * MPZ_DIG_SIZE + last_bits;
 }

Original file line number	Diff line number	Diff line change
`@@ -142,6 +142,9 @@ static inline size_t mpz_max_num_bits(const mpz_t *z) {`
`142`	`142`	`return z->len * MPZ_DIG_SIZE;`
`143`	`143`	`}`
`144`	`144`	`static inline size_t mpz_num_bits(const mpz_t *z) {`
	`145`	`+ if (mpz_is_zero(z)) {`
	`146`	`+ return 0;`
	`147`	`+ }`
`145`	`148`	`size_t last_bits = (8 * (sizeof(long) - sizeof(mpz_dig_t))) - __builtin_clzl(z->dig[z->len - 1]);`
`146`	`149`	`return z->len * MPZ_DIG_SIZE + last_bits;`
`147`	`150`	`}`