HeimdalKerberos5library: The credential cache functions

# The credential cache functions

## Kerberos credential caches

krb5_ccache structure holds a Kerberos credential cache.

Heimdal support the follow types of credential caches:

- SCC Store the credential in a database
- FILE Store the credential in memory
- MEMORY Store the credential in memory
- API A credential cache server based solution for Mac OS X
- KCM A credential cache server based solution for all platforms

### Example

This is a minimalistic version of klist:

    #include <krb5.h>

    int
    main (int argc, char **argv)
    {
        krb5_context context;
        krb5_cc_cursor cursor;
        krb5_error_code ret;
        krb5_ccache id;
        krb5_creds creds;

        if (krb5_init_context (&context) != 0)
            errx(1, "krb5_context");

        ret = krb5_cc_default (context, &id);
        if (ret)
            krb5_err(context, 1, ret, "krb5_cc_default");

        ret = krb5_cc_start_seq_get(context, id, &cursor);
        if (ret)
            krb5_err(context, 1, ret, "krb5_cc_start_seq_get");

        while((ret = krb5_cc_next_cred(context, id, &cursor, &creds)) == 0){
            char *principal;

            krb5_unparse_name(context, creds.server, &principal);
            printf("principal: %s\\n", principal);
            free(principal);
            krb5_free_cred_contents (context, &creds);
        }
        ret = krb5_cc_end_seq_get(context, id, &cursor);
        if (ret)
            krb5_err(context, 1, ret, "krb5_cc_end_seq_get");

        krb5_cc_close(context, id);

        krb5_free_context(context);
        return 0;
    }