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BSD imports in online GDB

+2 votes
asked Mar 2, 2023 by Mike Finch (300 points)

Trying to run cryptography example from.open ssl wiki


/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?

2 Answers

+2 votes
answered Mar 2, 2023 by Mike Finch (300 points)
Best answer
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.
commented Mar 2, 2023 by Peter Minarik (89,040 points)
Nice. Thank you for sharing the solution!
0 votes
answered Mar 2, 2023 by Peter Minarik (89,040 points)

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).

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