debugging with -dbg libraries

I am having a problem getting openssl to verify a signature that I generated from a smartcard. I decided to step through the openssl code to see what it’s actually doing when I call RSA_verify()… but I didn’t feel like rebuilding openssl.

apt-get install libssl-dbg

… this installs some files under /usr/lib/debug/usr/lib. A path that I have never seen before. I was unable to get anywhere with LD_*_PATH variables, then I found some reference that I should make this the gdb debug file directory.

    $ gdb
    (gdb) set debug-file-directory /usr/lib/debug

… this gives gdb access to the files that seem to have the debug info. Then I add my breakpoint and run…

    (gdb) b RSA_verify
    ...

    (gdb) run
    ...

    (gdb) l
    147     rsa_sign.c: No such file or directory.
    in rsa_sign.c

… that makes sense, I don’t have the source for openssl (yet).

    apt-get source openssl

Now I can tell gdb where to find it …

    (gdb) dir /home/bart/tmp/openssl-0.9.8e/crypto/rsa/

Finally, gdb knows where it is.

    (gdb) l
    147             {
    148             int i,ret=0,sigtype;
    149             unsigned char *s;
    150             X509_SIG *sig=NULL;
    151     
    152             if (siglen != (unsigned int)RSA_size(rsa))
    153                     {
    154                     RSAerr(RSA_F_RSA_VERIFY,RSA_R_WRONG_SIGNATURE_LENGTH);
    155                     return(0);
    156                     }

oooh… yucky indenting. :)