Merge pull request #4427 from garlick/respond_error_0

libflux: handle flux_respond_error (errnum=0)

doc/man3/flux_respond.rst

@@ -51,7 +51,7 @@ building the payload using variable arguments with a format string in
 the style of jansson's ``json_pack()`` (used internally).
 
 ``flux_respond_error()`` returns an error response to the sender.
-*errnum* must be non-zero. If *errmsg* is non-NULL, an error string
+If *errnum* is zero, EINVAL is used.  If *errmsg* is non-NULL, an error string
 payload is included in the response. The error string may be used to
 provide a more detailed error message than can be conveyed via *errnum*.
 

src/common/libflux/response.c

@@ -315,8 +315,10 @@ int flux_respond_error (flux_t *h, const flux_msg_t *request,
 {
     flux_msg_t *msg = NULL;
 
-    if (!h || !request || errnum == 0)
+    if (!h || !request)
         goto inval;
+    if (errnum == 0)
+        errnum = EINVAL;
     if (flux_msg_is_noresponse (request))
         return 0;
     msg = flux_response_derive (request, errnum);

src/common/libflux/response.h

@@ -86,7 +86,8 @@ int flux_respond_raw (flux_t *h, const flux_msg_t *request,
                       const void *data, int len);
 
 /* Create an error response to the provided request message with optional
- * error string payload (if errstr is non-NULL).
+ * error string payload (if errstr is non-NULL).  If errnum is zero, EINVAL
+ * is substituted.
  */
 int flux_respond_error (flux_t *h, const flux_msg_t *request,
                         int errnum, const char *errstr);

src/common/libflux/test/response.c

@@ -19,11 +19,13 @@ int main (int argc, char *argv[])
 {
     flux_t *h;
     flux_msg_t *msg;
+    flux_msg_t *msg2;
     const char *topic, *s;
     const char *json_str = "{\"a\":42}";
     const void *d;
     const char data[] = "bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb";
     int l, len = strlen (data);
+    int errnum;
 
     plan (NO_PLAN);
 
@@ -168,6 +170,22 @@ int main (int argc, char *argv[])
         "flux_respond_error msg=NULL fails with EINVAL");
     flux_close (h);
 
+    /* errnum=0 */
+    h = loopback_create (0);
+    if (!h)
+        BAIL_OUT ("loopback_create");
+    msg = flux_request_encode ("foo", NULL);
+    if (!msg)
+        BAIL_OUT ("flux_request_encode failed");
+    ok (flux_respond_error (h, msg, 0, NULL) == 0,
+        "flux_respond_error errno=0 works");
+    msg2 = flux_recv (h, FLUX_MATCH_ANY, 0);
+    ok (flux_msg_get_errnum (msg2, &errnum) == 0 && errnum == EINVAL,
+        "and send a response message with errnum=EINVAL");
+    flux_msg_destroy (msg2);
+    flux_msg_destroy (msg);
+    flux_close (h);
+
     done_testing();
     return (0);
 }