hmp: Allow for error message hints on HMP
Commits 7216ae3d and d2828429 disabled some error message hints,
all because a change to use modern error reporting meant that the
hint would be output prior to the actual error. Fix this by making
hints a first-class member of Error.
For example, we are now back to the pleasant:
$ qemu-system-x86_64 --nodefaults -S --vnc :0 --chardev null,id=,
qemu-system-x86_64: --chardev null,id=,: Parameter 'id' expects an identifier
Identifiers consist of letters, digits, '-', '.', '_', starting with a letter.
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1441901956-21991-1-git-send-email-eblake@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
diff --git a/include/qapi/error.h b/include/qapi/error.h
index 426d5ea..d7878c3 100644
--- a/include/qapi/error.h
+++ b/include/qapi/error.h
@@ -155,6 +155,13 @@
*/
void error_propagate(Error **dst_errp, Error *local_err);
+/**
+ * Append a printf-style human-readable explanation to an existing error.
+ * May be called multiple times, and safe if @errp is NULL.
+ */
+void error_append_hint(Error **errp, const char *fmt, ...)
+ GCC_FMT_ATTR(2, 3);
+
/*
* Convenience function to report open() failure.
*/
diff --git a/qdev-monitor.c b/qdev-monitor.c
index f9e2d62..0bf7f83 100644
--- a/qdev-monitor.c
+++ b/qdev-monitor.c
@@ -289,37 +289,35 @@
return dev;
}
-#if 0 /* conversion from qerror_report() to error_set() broke their use */
-static void qbus_list_bus(DeviceState *dev)
+static void qbus_list_bus(DeviceState *dev, Error **errp)
{
BusState *child;
const char *sep = " ";
- error_printf("child buses at \"%s\":",
- dev->id ? dev->id : object_get_typename(OBJECT(dev)));
+ error_append_hint(errp, "child buses at \"%s\":",
+ dev->id ? dev->id : object_get_typename(OBJECT(dev)));
QLIST_FOREACH(child, &dev->child_bus, sibling) {
- error_printf("%s\"%s\"", sep, child->name);
+ error_append_hint(errp, "%s\"%s\"", sep, child->name);
sep = ", ";
}
- error_printf("\n");
}
-static void qbus_list_dev(BusState *bus)
+static void qbus_list_dev(BusState *bus, Error **errp)
{
BusChild *kid;
const char *sep = " ";
- error_printf("devices at \"%s\":", bus->name);
+ error_append_hint(errp, "devices at \"%s\":", bus->name);
QTAILQ_FOREACH(kid, &bus->children, sibling) {
DeviceState *dev = kid->child;
- error_printf("%s\"%s\"", sep, object_get_typename(OBJECT(dev)));
- if (dev->id)
- error_printf("/\"%s\"", dev->id);
+ error_append_hint(errp, "%s\"%s\"", sep,
+ object_get_typename(OBJECT(dev)));
+ if (dev->id) {
+ error_append_hint(errp, "/\"%s\"", dev->id);
+ }
sep = ", ";
}
- error_printf("\n");
}
-#endif
static BusState *qbus_find_bus(DeviceState *dev, char *elem)
{
@@ -461,11 +459,7 @@
if (!dev) {
error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND,
"Device '%s' not found", elem);
-#if 0 /* conversion from qerror_report() to error_set() broke this: */
- if (!monitor_cur_is_qmp()) {
- qbus_list_dev(bus);
- }
-#endif
+ qbus_list_dev(bus, errp);
return NULL;
}
@@ -483,11 +477,7 @@
if (dev->num_child_bus) {
error_setg(errp, "Device '%s' has multiple child buses",
elem);
-#if 0 /* conversion from qerror_report() to error_set() broke this: */
- if (!monitor_cur_is_qmp()) {
- qbus_list_bus(dev);
- }
-#endif
+ qbus_list_bus(dev, errp);
} else {
error_setg(errp, "Device '%s' has no child bus", elem);
}
@@ -503,11 +493,7 @@
bus = qbus_find_bus(dev, elem);
if (!bus) {
error_setg(errp, "Bus '%s' not found", elem);
-#if 0 /* conversion from qerror_report() to error_set() broke this: */
- if (!monitor_cur_is_qmp()) {
- qbus_list_bus(dev);
- }
-#endif
+ qbus_list_bus(dev, errp);
return NULL;
}
}
diff --git a/util/error.c b/util/error.c
index cdb726c..9dd474f 100644
--- a/util/error.c
+++ b/util/error.c
@@ -20,6 +20,7 @@
ErrorClass err_class;
const char *src, *func;
int line;
+ GString *hint;
};
Error *error_abort;
@@ -115,6 +116,28 @@
"Could not open '%s'", filename);
}
+void error_append_hint(Error **errp, const char *fmt, ...)
+{
+ va_list ap;
+ int saved_errno = errno;
+ Error *err;
+
+ if (!errp) {
+ return;
+ }
+ err = *errp;
+ assert(err && errp != &error_abort);
+
+ if (!err->hint) {
+ err->hint = g_string_new(NULL);
+ }
+ va_start(ap, fmt);
+ g_string_append_vprintf(err->hint, fmt, ap);
+ va_end(ap);
+
+ errno = saved_errno;
+}
+
#ifdef _WIN32
void error_setg_win32_internal(Error **errp,
@@ -151,6 +174,9 @@
err_new = g_malloc0(sizeof(*err));
err_new->msg = g_strdup(err->msg);
err_new->err_class = err->err_class;
+ if (err->hint) {
+ err_new->hint = g_string_new(err->hint->str);
+ }
return err_new;
}
@@ -168,6 +194,9 @@
void error_report_err(Error *err)
{
error_report("%s", error_get_pretty(err));
+ if (err->hint) {
+ error_printf_unless_qmp("%s\n", err->hint->str);
+ }
error_free(err);
}
@@ -175,6 +204,9 @@
{
if (err) {
g_free(err->msg);
+ if (err->hint) {
+ g_string_free(err->hint, true);
+ }
g_free(err);
}
}
diff --git a/util/qemu-option.c b/util/qemu-option.c
index b1fb57c..a50ecea 100644
--- a/util/qemu-option.c
+++ b/util/qemu-option.c
@@ -205,10 +205,8 @@
break;
default:
error_setg(errp, QERR_INVALID_PARAMETER_VALUE, name, "a size");
-#if 0 /* conversion from qerror_report() to error_set() broke this: */
- error_printf_unless_qmp("You may use k, M, G or T suffixes for "
- "kilobytes, megabytes, gigabytes and terabytes.\n");
-#endif
+ error_append_hint(errp, "You may use k, M, G or T suffixes for "
+ "kilobytes, megabytes, gigabytes and terabytes.");
return;
}
} else {
@@ -648,9 +646,8 @@
if (!id_wellformed(id)) {
error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "id",
"an identifier");
-#if 0 /* conversion from qerror_report() to error_set() broke this: */
- error_printf_unless_qmp("Identifiers consist of letters, digits, '-', '.', '_', starting with a letter.\n");
-#endif
+ error_append_hint(errp, "Identifiers consist of letters, digits, "
+ "'-', '.', '_', starting with a letter.");
return NULL;
}
opts = qemu_opts_find(list, id);
