add timestamp to error_report()

[Issue]
When we offer a customer support service and a problem happens
in a customer's system, we try to understand the problem by
comparing what the customer reports with message logs of the
customer's system.

In this case, we often need to know when the problem happens.

But, currently, there is no timestamp in qemu's error messages.
Therefore, we may not be able to understand the problem based on
error messages.

[Solution]
Add a timestamp to qemu's error message logged by
error_report() with g_time_val_to_iso8601().

Signed-off-by: Seiji Aguchi <seiji.aguchi@hds.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>

include/qemu/error-report.h

@@ -14,6 +14,7 @@
 #define QEMU_ERROR_H
 
 #include <stdarg.h>
+#include <stdbool.h>
 #include "qemu/compiler.h"
 
 typedef struct Location {
@@ -40,5 +41,6 @@ void error_print_loc(void);
 void error_set_progname(const char *argv0);
 void error_report(const char *fmt, ...) GCC_FMT_ATTR(1, 2);
 const char *error_get_progname(void);
+extern bool enable_timestamp_msg;
 
 #endif

qemu-options.hx

@@ -3100,6 +3100,17 @@ property must be set.  These objects are placed in the
 '/objects' path.
 ETEXI
 
+DEF("msg", HAS_ARG, QEMU_OPTION_msg,
+    "-msg timestamp[=on|off]\n"
+    "                change the format of messages\n"
+    "                on|off controls leading timestamps (default:on)\n",
+    QEMU_ARCH_ALL)
+STEXI
+@item -msg timestamp[=on|off]
+@findex -msg
+prepend a timestamp to each log message.(default:on)
+ETEXI
+
 HXCOMM This is the last statement. Insert new options before this line!
 STEXI
 @end table

util/qemu-error.c

@@ -196,6 +196,7 @@ void error_print_loc(void)
     }
 }
 
+bool enable_timestamp_msg;
 /*
  * Print an error message to current monitor if we have one, else to stderr.
  * Format arguments like sprintf().  The result should not contain
@@ -206,6 +207,15 @@ void error_print_loc(void)
 void error_report(const char *fmt, ...)
 {
     va_list ap;
+    GTimeVal tv;
+    gchar *timestr;
+
+    if (enable_timestamp_msg) {
+        g_get_current_time(&tv);
+        timestr = g_time_val_to_iso8601(&tv);
+        error_printf("%s ", timestr);
+        g_free(timestr);
+    }
 
     error_print_loc();
     va_start(ap, fmt);

vl.c

@@ -516,6 +516,18 @@ static QemuOptsList qemu_realtime_opts = {
     },
 };
 
+static QemuOptsList qemu_msg_opts = {
+    .name = "msg",
+    .head = QTAILQ_HEAD_INITIALIZER(qemu_msg_opts.head),
+    .desc = {
+        {
+            .name = "timestamp",
+            .type = QEMU_OPT_BOOL,
+        },
+        { /* end of list */ }
+    },
+};
+
 /**
  * Get machine options
  *
@@ -1503,6 +1515,12 @@ static void configure_realtime(QemuOpts *opts)
     }
 }
 
+
+static void configure_msg(QemuOpts *opts)
+{
+    enable_timestamp_msg = qemu_opt_get_bool(opts, "timestamp", true);
+}
+
 /***********************************************************/
 /* USB devices */
 
@@ -2942,6 +2960,7 @@ int main(int argc, char **argv, char **envp)
     qemu_add_opts(&qemu_object_opts);
     qemu_add_opts(&qemu_tpmdev_opts);
     qemu_add_opts(&qemu_realtime_opts);
+    qemu_add_opts(&qemu_msg_opts);
 
     runstate_init();
 
@@ -3838,6 +3857,13 @@ int main(int argc, char **argv, char **envp)
                 }
                 configure_realtime(opts);
                 break;
+            case QEMU_OPTION_msg:
+                opts = qemu_opts_parse(qemu_find_opts("msg"), optarg, 0);
+                if (!opts) {
+                    exit(1);
+                }
+                configure_msg(opts);
+                break;
             default:
                 os_parse_cmd_args(popt->index, optarg);
             }