From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51688) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZYuOF-0002Fm-N0 for qemu-devel@nongnu.org; Mon, 07 Sep 2015 07:15:13 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZYuOB-00057K-Df for qemu-devel@nongnu.org; Mon, 07 Sep 2015 07:15:11 -0400 Received: from mx1.redhat.com ([209.132.183.28]:42092) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZYuOB-000555-4u for qemu-devel@nongnu.org; Mon, 07 Sep 2015 07:15:07 -0400 References: <1440002082-16249-1-git-send-email-eblake@redhat.com> From: Paolo Bonzini Message-ID: <55ED71B6.7040607@redhat.com> Date: Mon, 7 Sep 2015 13:15:02 +0200 MIME-Version: 1.0 In-Reply-To: <1440002082-16249-1-git-send-email-eblake@redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v3] hmp: Allow for error message hints on HMP List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eric Blake , qemu-devel@nongnu.org Cc: armbru@redhat.com, stefanha@redhat.com, afaerber@suse.de On 19/08/2015 18:34, Eric Blake wrote: > 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 > --- > > v3: don't crash when freeing error without hint [Eric] > v2: use GString instead of rolling our own O(n^2) string concast [Paolo] > > include/qapi/error.h | 7 +++++++ > qdev-monitor.c | 42 ++++++++++++++---------------------------- > util/error.c | 32 ++++++++++++++++++++++++++++++++ > util/qemu-option.c | 11 ++++------- > 4 files changed, 57 insertions(+), 35 deletions(-) > > diff --git a/include/qapi/error.h b/include/qapi/error.h > index f44c451..00daea3 100644 > --- a/include/qapi/error.h > +++ b/include/qapi/error.h > @@ -67,6 +67,13 @@ void error_set_win32(Error **errp, int win32_err, ErrorClass err_class, > */ > void error_setg_file_open(Error **errp, int os_errno, const char *filename); > > +/** > + * 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); > + > /* > * Get the error class of an error object. > */ > 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 @@ static Object *qdev_get_peripheral_anon(void) > 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 @@ static BusState *qbus_find(const char *path, Error **errp) > 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 @@ static BusState *qbus_find(const char *path, Error **errp) > 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 @@ static BusState *qbus_find(const char *path, Error **errp) > 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 14f4351..df5d640 100644 > --- a/util/error.c > +++ b/util/error.c > @@ -18,6 +18,7 @@ struct Error > { > char *msg; > ErrorClass err_class; > + GString *hint; > }; > > Error *error_abort; > @@ -91,6 +92,28 @@ void error_setg_file_open(Error **errp, int os_errno, const char *filename) > error_setg_errno(errp, os_errno, "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_set_win32(Error **errp, int win32_err, ErrorClass err_class, > @@ -138,6 +161,9 @@ Error *error_copy(const Error *err) > 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; > } > @@ -155,6 +181,9 @@ const char *error_get_pretty(Error *err) > 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); > } > > @@ -162,6 +191,9 @@ void error_free(Error *err) > { > 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 efe9d27..03201ad 100644 > --- a/util/qemu-option.c > +++ b/util/qemu-option.c > @@ -200,10 +200,8 @@ void parse_option_size(const char *name, const char *value, > 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 { > @@ -643,9 +641,8 @@ QemuOpts *qemu_opts_create(QemuOptsList *list, const char *id, > 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); > Reviewed-by: Paolo Bonzini