BSD imports in online GDB

Question

Trying to run cryptography example from.open ssl wiki
https://wiki.openssl.org/images/1/17/Evp-symmetric-encrypt.c

Errors:

/usr/bin/ld: /tmp/cc9IFOtb.o: in function `main':
main.c:(.text+0xb2): undefined reference to `BIO_dump_fp'
/usr/bin/ld: /tmp/cc9IFOtb.o: in function `handleErrors':
main.c:(.text+0x145): undefined reference to `ERR_print_errors_fp'

I added the header for BIO_dump_fp  explicitly
#include <openssl/bio.h>
I'm assuming it was already included by one of the other headers.

Is this because the functions are BSD?  Is there a way to make this work?

Answer 1

I was new to onlinegdb and did not understand how to link libraries. Once I found the "Extra Compiler Flags" in settings I could add -lssl and -lcrypto and compiled without issues.

Comments

Nice. Thank you for sharing the solution!

Answer 2

Can you just replace these functions with something standard?

It looks to me that BIO_dump_fp() takes a standard input and some character string and length. You could invent your own dump function that prints given amount of characters on the standard output.

Same for ERR_print_errors_fp(), replace it with something else, that has a similar purpose: print the error (check errno, or just print "cryptography error" for now, and you can fix it later after everything else works).