ovn-nbctl: Initialize arguments to avoid compilation warnings.

Output arguments for parse_priority() and dhcp_options_get() may not be
initialized when either function returns an error.

This causes compilation warnings for GCC 6.3.x regarding use of
uninitialized variable use and null-pointer-arithmetic.

Fix this by initializing priority_p* value to 0 for priority_parse()
when an error occurs during parsing.

For dhcp_options_get() set *dhcp_opts_p = dhcp_opts regardless as
dhcp_opts will be equal to NULL when an error occurs within the function
anyhow.

Cc: Jakub Sitnicki <[email protected]>
Fixes: 3844c85 ("ovn-nbctl: Don't die in dhcp_options_get()."
Fixes: bc8223d ("ovn-nbctl: Don't die in parse_priority().")
Signed-off-by: Ian Stokes <[email protected]>
Signed-off-by: Ben Pfaff <[email protected]>
Acked-by: Jakub Sitnicki <[email protected]>

ovn/utilities/ovn-nbctl.c

@@ -1879,6 +1879,9 @@ parse_priority(const char *arg, int64_t *priority_p)
     int64_t priority;
     if (!ovs_scan(arg, "%"SCNd64, &priority)
         || priority < 0 || priority > 32767) {
+        /* Priority_p could be uninitialized as no valid priority was
+         * input, initialize it to a valid value of 0 before returning */
+        *priority_p = 0;
         return xasprintf("%s: priority must in range 0...32767", arg);
     }
     *priority_p = priority;
@@ -3043,10 +3046,11 @@ dhcp_options_get(struct ctl_context *ctx, const char *id, bool must_exist,
         dhcp_opts = nbrec_dhcp_options_get_for_uuid(ctx->idl, &dhcp_opts_uuid);
     }
 
+    *dhcp_opts_p = dhcp_opts;
     if (!dhcp_opts && must_exist) {
         return xasprintf("%s: dhcp options UUID not found", id);
     }
-    *dhcp_opts_p = dhcp_opts;
+
     return NULL;
 }