bignum: handle negative hex numbers

1 files changed, 11 insertions, 2 deletions

diff --git a/src/openssl.c b/src/openssl.c
index 0a444c8..66a6168 100644
--- a/src/openssl.c
+++ b/src/openssl.c
@@ -1686,6 +1686,7 @@ static BIGNUM *(checkbig)(lua_State *L, int index, _Bool *lvalue) {
         BIGNUM **bn;
         const char *str;
         size_t len;
+        _Bool neg, hex = 0;
 
         index = lua_absindex(L, index);
 
@@ -1697,11 +1698,19 @@ static BIGNUM *(checkbig)(lua_State *L, int index, _Bool *lvalue) {
 
                 luaL_argcheck(L, len > 0 && *str, index, "invalid big number string");
 
+                neg = (str[0] == '-');
+
+                if (str[neg] == '0' && (str[neg+1] == 'x' || str[neg+1] == 'X')) {
+                        hex = 1;
+                }
+
                 bn = prepsimple(L, BIGNUM_CLASS);
 
-                if (str[0] == '0' && (str[1] == 'x' || str[1] == 'X')) {
-                        if (!BN_hex2bn(bn, str+2))
+                if (hex) {
+                        if (!BN_hex2bn(bn, str+2+neg))
                                 auxL_error(L, auxL_EOPENSSL, "bignum");
+                        if (neg)
+                                BN_set_negative(*bn, 1);
                 } else {
                         if (!BN_dec2bn(bn, str))
                                 auxL_error(L, auxL_EOPENSSL, "bignum");