Fixed memory leak and some -Werror=unused-result warnings

Signed-off-by: Joshua Gerrard <joshuagerrard+ompi-commit@protonmail.com>

AUTHORS

@@ -165,6 +165,7 @@ Josh Hursey, Indiana University, Oak Ridge National Laboratory, Los Alamos Natio
   jjhursey@open-mpi.org
 Joshua Gerrard
   enquiries@joshuagerrard.com
+  joshuagerrard+ompi-commit@protonmail.com
 Joshua Ladd, Mellanox
   jladd.mlnx@gmail.com
   joshual@mellanox.com

ompi/errhandler/errhandler_predefined.c

@@ -177,43 +177,84 @@ static void backend_fatal_aggregate(char *type,
                                     char *name, int *error_code,
                                     va_list arglist)
 {
-    char *arg, *prefix, *err_msg = "Unknown error";
-    bool err_msg_need_free = false;
+    char *arg = NULL, *prefix = NULL, *err_msg = NULL;
+    const char* const unknown_error_code = "Error code: %d (no associated error message)";
+    const char* const unknown_error = "Unknown error";
+    const char* const unknown_prefix = "[?:?]";
+
+    // these do not own what they point to; they're
+    // here to avoid repeating expressions such as
+    // (NULL == foo) ? unknown_foo : foo
+    const char* usable_prefix = unknown_prefix;
+    const char* usable_err_msg = unknown_error;
 
     arg = va_arg(arglist, char*);
     va_end(arglist);
 
-    asprintf(&prefix, "[%s:%d]", ompi_process_info.nodename,
-             (int) ompi_process_info.pid);
+    if (asprintf(&prefix, "[%s:%d]",
+                 ompi_process_info.nodename,
+                 (int) ompi_process_info.pid) == -1) {
+        prefix = NULL;
+        // non-fatal, we could still go on to give useful information here...
+        opal_output(0, "%s", "Could not write node and PID to prefix");
+        opal_output(0, "Node: %s", ompi_process_info.nodename);
+        opal_output(0, "PID: %d", (int) ompi_process_info.pid);
+    }
 
     if (NULL != error_code) {
         err_msg = ompi_mpi_errnum_get_string(*error_code);
         if (NULL == err_msg) {
-            err_msg_need_free = true;
-            asprintf(&err_msg, "Error code: %d (no associated error message)",
-                     *error_code);
+            if (asprintf(&err_msg, unknown_error_code,
+                         *error_code) == -1) {
+                err_msg = NULL;
+                opal_output(0, "%s", "Could not write to err_msg");
+                opal_output(0, unknown_error_code, *error_code);
+            }
         }
     }
 
+    usable_prefix  = (NULL == prefix)  ? unknown_prefix : prefix;
+    usable_err_msg = (NULL == err_msg) ? unknown_error  : err_msg;
+
     if (NULL != name) {
         opal_show_help("help-mpi-errors.txt",
-                       "mpi_errors_are_fatal", false,
-                       prefix, (NULL == arg) ? "" : "in",
+                       "mpi_errors_are_fatal",
+                       false,
+                       usable_prefix,
+                       (NULL == arg) ? "" : "in",
                        (NULL == arg) ? "" : arg,
-                       prefix, OMPI_PROC_MY_NAME->jobid, OMPI_PROC_MY_NAME->vpid,
-                       prefix, type, name, prefix, err_msg, prefix, type, prefix);
+                       usable_prefix,
+                       OMPI_PROC_MY_NAME->jobid,
+                       OMPI_PROC_MY_NAME->vpid,
+                       usable_prefix,
+                       type,
+                       name,
+                       usable_prefix,
+                       usable_err_msg,
+                       usable_prefix,
+                       type,
+                       usable_prefix);
     } else {
         opal_show_help("help-mpi-errors.txt",
-                       "mpi_errors_are_fatal unknown handle", false,
-                       prefix, (NULL == arg) ? "" : "in",
+                       "mpi_errors_are_fatal unknown handle",
+                       false,
+                       usable_prefix,
+                       (NULL == arg) ? "" : "in",
                        (NULL == arg) ? "" : arg,
-                       prefix, OMPI_PROC_MY_NAME->jobid, OMPI_PROC_MY_NAME->vpid,
-                       prefix, type, prefix, err_msg, prefix, type, prefix);
+                       usable_prefix,
+                       OMPI_PROC_MY_NAME->jobid,
+                       OMPI_PROC_MY_NAME->vpid,
+                       usable_prefix,
+                       type,
+                       usable_prefix,
+                       usable_err_msg,
+                       usable_prefix,
+                       type,
+                       usable_prefix);
     }
 
-    if (err_msg_need_free) {
-        free(err_msg);
-    }
+    free(prefix);
+    free(err_msg);
 }
 
 /*