1) bcode.c and bn_check() call bn_check(BN_zero(f));
https://github.com/openbsd/src/blob/master/usr.bin/dc/bcode.c#L389 https://github.com/openbsd/src/blob/master/usr.bin/dc/bcode.c#L807 https://github.com/openbsd/src/blob/master/usr.bin/dc/bcode.c#L891 2) mem.c is a function https://github.com/openbsd/src/blob/master/usr.bin/dc/mem.c#L92 void bn_check(int x) \ { if (x == 0) err(1, "big number failure %lx", ERR_get_error()); } 3) dc uses macro from libcrypto/bn/bn.h https://github.com/openbsd/src/blob/master/lib/libcrypto/bn/bn.h#L335 #define BN_zero_ex(a) \ do { \ BIGNUM *_tmp_bn = (a); \ _tmp_bn->top = 0; \ _tmp_bn->neg = 0; \ } while(0) #ifdef OPENSSL_NO_DEPRECATED #define BN_zero(a) BN_zero_ex(a) #else #define BN_zero(a) (BN_set_word((a),0)) #endif Summing up: if OPENSSL_NO_DEPRECATED is defined, then the bn_check(int x) will be called with: do { \ BIGNUM *_tmp_bn = (a); \ _tmp_bn->top = 0; \ _tmp_bn->neg = 0; \ } Best regards, Daniel
