free result of BN_bn2dec()

fixes issue #38

1 files changed, 21 insertions, 3 deletions

diff --git a/src/openssl.c b/src/openssl.c
index a5e1a52..8d1435a 100644
--- a/src/openssl.c
+++ b/src/openssl.c
@@ -1898,16 +1898,34 @@ static int bn__gc(lua_State *L) {
 } /* bn__gc() */
 
 
+static BIO *getbio(lua_State *);
+
 static int bn__tostring(lua_State *L) {
         BIGNUM *bn = checksimple(L, 1, BIGNUM_CLASS);
-        char *txt;
+        char *txt = NULL;
+        BIO *bio;
+        BUF_MEM *buf;
 
         if (!(txt = BN_bn2dec(bn)))
-                return auxL_error(L, auxL_EOPENSSL, "bignum:__tostring");
+                goto sslerr;
 
-        lua_pushstring(L, txt);
+        /* use GC-visible BIO as temporary buffer */
+        bio = getbio(L);
+
+        if (BIO_puts(bio, txt) < 0)
+                goto sslerr;
+
+        OPENSSL_free(txt);
+        txt = NULL;
+
+        BIO_get_mem_ptr(bio, &buf);
+        lua_pushlstring(L, buf->data, buf->length);
 
         return 1;
+sslerr:
+        OPENSSL_free(txt);
+
+        return auxL_error(L, auxL_EOPENSSL, "bignum:__tostring");
 } /* bn__tostring() */