output_formatter: improve error message

In some environments, these error messages are triggered often, without
being actual errors (client send command to Director and closes the
connection. In this case, the Director can't send the result back to the
client and issues this error).
With this patch, a debug message is issued instead of an error message.

Also instead of always stating, that the message might be too long,
it now checks the message size. Short messages are also show in the
output.

src/lib/output_formatter.c

@@ -2,7 +2,7 @@
    BAREOS® - Backup Archiving REcovery Open Sourced
 
    Copyright (C) 2016-2016 Planets Communications B.V.
-   Copyright (C) 2015-2016 Bareos GmbH & Co. KG
+   Copyright (C) 2015-2017 Bareos GmbH & Co. KG
 
    This program is Free Software; you can redistribute it and/or
    modify it under the terms of version three of the GNU Affero General Public
@@ -603,9 +603,19 @@ bool OUTPUT_FORMATTER::process_text_buffer()
    if (string_length > 0) {
       retval = send_func(send_ctx, result_message_plain->c_str());
       if (!retval) {
-         error_msg.bsprintf("Failed to send message. Maybe result message to long?\n"
-                            "Message length = %lld\n", string_length);
-         Emsg0(M_ERROR, 0, error_msg.c_str());
+         /*
+          * If send failed, include short messages in error messages.
+          * As messages can get quite long, don't show long messages.
+          */
+         error_msg.bsprintf("Failed to send message (length=%lld). ", string_length);
+         if (string_length < max_message_length_shown_in_error) {
+            error_msg.strcat("Message: ");
+            error_msg.strcat(result_message_plain->c_str());
+            error_msg.strcat("\n");
+         } else {
+            error_msg.strcat("Maybe result message to long?\n");
+         }
+         Dmsg0(100, error_msg.c_str());
       }
       result_message_plain->strcpy("");
    }
@@ -817,9 +827,19 @@ void OUTPUT_FORMATTER::json_finalize_result(bool result)
        * send json string, on failure, send json error message
        */
       if (!send_func(send_ctx, string)) {
-         error_msg.bsprintf("Failed to send result as json. Maybe result message to long?\n"
-                            "Message length = %lld\n", string_length);
-         Emsg0(M_ERROR, 0, error_msg.c_str());
+         /*
+          * If send failed, include short messages in error messages.
+          * As messages can get quite long, don't show long messages.
+          */
+         error_msg.bsprintf("Failed to send json message (length=%lld). ", string_length);
+         if (string_length < max_message_length_shown_in_error) {
+            error_msg.strcat("Message: ");
+            error_msg.strcat(string);
+            error_msg.strcat("\n");
+         } else {
+            error_msg.strcat("Maybe result message to long?\n");
+         }
+         Dmsg0(100, error_msg.c_str());
          json_send_error_message(error_msg.c_str());
       }
       free(string);

src/lib/output_formatter.h

@@ -2,7 +2,7 @@
    BAREOS® - Backup Archiving REcovery Open Sourced
 
    Copyright (C) 2016-2016 Planets Communications B.V.
-   Copyright (C) 2015-2016 Bareos GmbH & Co. KG
+   Copyright (C) 2015-2017 Bareos GmbH & Co. KG
 
    This program is Free Software; you can redistribute it and/or
    modify it under the terms of version three of the GNU Affero General Public
@@ -117,6 +117,7 @@ class OUTPUT_FORMATTER : public SMARTALLOC {
    alist *filters;
    char *hidden_columns;
    POOL_MEM *result_message_plain;
+   static const unsigned int max_message_length_shown_in_error = 1024;
 #if HAVE_JANSSON
    json_t *result_json;
    alist *result_stack_json;