cmd/jwk: check return from jose_jwk_thp_buf() properly

jose_jwk_thp_buf() returns, on success, the number of
bytes written; otherwise, it returns SIZE_MAX.

We now check its return properly, from jcmd_jwk_thp(),
which is used by the CLI utility.

Signed-off-by: Sergio Correia <[email protected]>

Author: sergio-correia

cmd/jwk/thp.c

@@ -153,7 +153,7 @@ jcmd_jwk_thp(int argc, char *argv[])
             if (!opt.find && strcmp(opt.hash, a->name) != 0)
                 continue;
 
-            if (!jose_jwk_thp_buf(NULL, jwk, opt.hash, dec, sizeof(dec))) {
+            if (jose_jwk_thp_buf(NULL, jwk, opt.hash, dec, sizeof(dec)) == SIZE_MAX) {
                 fprintf(stderr, "Error making thumbprint!\n");
                 return EXIT_FAILURE;
             }