From patchwork Fri May 2 11:26:38 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Markus Armbruster X-Patchwork-Id: 344925 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 52EE7140137 for ; Fri, 2 May 2014 21:27:47 +1000 (EST) Received: from localhost ([::1]:43263 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WgBd2-000230-W6 for incoming@patchwork.ozlabs.org; Fri, 02 May 2014 07:27:45 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49983) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WgBcL-0000pq-BU for qemu-devel@nongnu.org; Fri, 02 May 2014 07:27:07 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WgBcC-0007Xg-63 for qemu-devel@nongnu.org; Fri, 02 May 2014 07:27:01 -0400 Received: from mx1.redhat.com ([209.132.183.28]:63815) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WgBcB-0007XI-UZ for qemu-devel@nongnu.org; Fri, 02 May 2014 07:26:52 -0400 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s42BQoS7015483 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Fri, 2 May 2014 07:26:50 -0400 Received: from blackfin.pond.sub.org (ovpn-116-44.ams2.redhat.com [10.36.116.44]) by int-mx01.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id s42BQlOe007688 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Fri, 2 May 2014 07:26:49 -0400 Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id E9C23200DB; Fri, 2 May 2014 13:26:43 +0200 (CEST) From: Markus Armbruster To: qemu-devel@nongnu.org Date: Fri, 2 May 2014 13:26:38 +0200 Message-Id: <1399030002-27222-11-git-send-email-armbru@redhat.com> In-Reply-To: <1399030002-27222-1-git-send-email-armbru@redhat.com> References: <1399030002-27222-1-git-send-email-armbru@redhat.com> X-Scanned-By: MIMEDefang 2.67 on 10.5.11.11 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 209.132.183.28 Cc: pbonzini@redhat.com, mdroth@linux.vnet.ibm.com, lcapitulino@redhat.com Subject: [Qemu-devel] [PATCH v3 10/14] qga: Clean up fragile use of error_is_set() X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Using error_is_set(ERRP) to find out whether a function failed is either wrong, fragile, or unnecessarily opaque. It's wrong when ERRP may be null, because errors go undetected when it is. It's fragile when proving ERRP non-null involves a non-local argument. Else, it's unnecessarily opaque (see commit 84d18f0). The error_is_set(errp) in the guest agent command handler functions are merely fragile, because all chall chains (do_qmp_dispatch() via the generated marshalling functions) pass a non-null errp argument. Make the code more robust and more obviously correct: receive the error in a local variable, then propagate it through the parameter. Signed-off-by: Markus Armbruster Reviewed-by: Eric Blake Reviewed-by: Michael Roth --- qga/commands-posix.c | 22 ++++++++++++++++------ qga/commands-win32.c | 38 ++++++++++++++++++++++++-------------- 2 files changed, 40 insertions(+), 20 deletions(-) diff --git a/qga/commands-posix.c b/qga/commands-posix.c index 6af974f..34ddba0 100644 --- a/qga/commands-posix.c +++ b/qga/commands-posix.c @@ -1067,8 +1067,11 @@ out: void qmp_guest_suspend_disk(Error **errp) { - bios_supports_mode("pm-is-supported", "--hibernate", "disk", errp); - if (error_is_set(errp)) { + Error *local_err = NULL; + + bios_supports_mode("pm-is-supported", "--hibernate", "disk", &local_err); + if (local_err) { + error_propagate(errp, local_err); return; } @@ -1077,8 +1080,11 @@ void qmp_guest_suspend_disk(Error **errp) void qmp_guest_suspend_ram(Error **errp) { - bios_supports_mode("pm-is-supported", "--suspend", "mem", errp); - if (error_is_set(errp)) { + Error *local_err = NULL; + + bios_supports_mode("pm-is-supported", "--suspend", "mem", &local_err); + if (local_err) { + error_propagate(errp, local_err); return; } @@ -1087,8 +1093,12 @@ void qmp_guest_suspend_ram(Error **errp) void qmp_guest_suspend_hybrid(Error **errp) { - bios_supports_mode("pm-is-supported", "--suspend-hybrid", NULL, errp); - if (error_is_set(errp)) { + Error *local_err = NULL; + + bios_supports_mode("pm-is-supported", "--suspend-hybrid", NULL, + &local_err); + if (local_err) { + error_propagate(errp, local_err); return; } diff --git a/qga/commands-win32.c b/qga/commands-win32.c index d0d8504..3483c0d 100644 --- a/qga/commands-win32.c +++ b/qga/commands-win32.c @@ -87,6 +87,7 @@ static void execute_async(DWORD WINAPI (*func)(LPVOID), LPVOID opaque, void qmp_guest_shutdown(bool has_mode, const char *mode, Error **errp) { + Error *local_err = NULL; UINT shutdown_flag = EWX_FORCE; slog("guest-shutdown called, mode: %s", mode); @@ -105,8 +106,9 @@ void qmp_guest_shutdown(bool has_mode, const char *mode, Error **errp) /* Request a shutdown privilege, but try to shut down the system anyway. */ - acquire_privilege(SE_SHUTDOWN_NAME, errp); - if (error_is_set(errp)) { + acquire_privilege(SE_SHUTDOWN_NAME, &local_err); + if (local_err) { + error_propagate(errp, local_err); return; } @@ -191,14 +193,16 @@ int64_t qmp_guest_fsfreeze_freeze(Error **errp) /* cannot risk guest agent blocking itself on a write in this state */ ga_set_frozen(ga_state); - qga_vss_fsfreeze(&i, errp, true); - if (error_is_set(errp)) { + qga_vss_fsfreeze(&i, &local_err, true); + if (local_err) { + error_propagate(errp, local_err); goto error; } return i; error: + local_err = NULL; qmp_guest_fsfreeze_thaw(&local_err); if (local_err) { g_debug("cleanup thaw: %s", error_get_pretty(local_err)); @@ -313,28 +317,32 @@ static DWORD WINAPI do_suspend(LPVOID opaque) void qmp_guest_suspend_disk(Error **errp) { + Error *local_err = NULL; GuestSuspendMode *mode = g_malloc(sizeof(GuestSuspendMode)); *mode = GUEST_SUSPEND_MODE_DISK; - check_suspend_mode(*mode, errp); - acquire_privilege(SE_SHUTDOWN_NAME, errp); - execute_async(do_suspend, mode, errp); + check_suspend_mode(*mode, &local_err); + acquire_privilege(SE_SHUTDOWN_NAME, &local_err); + execute_async(do_suspend, mode, &local_err); - if (error_is_set(errp)) { + if (local_err) { + error_propagate(errp, local_err); g_free(mode); } } void qmp_guest_suspend_ram(Error **errp) { + Error *local_err = NULL; GuestSuspendMode *mode = g_malloc(sizeof(GuestSuspendMode)); *mode = GUEST_SUSPEND_MODE_RAM; - check_suspend_mode(*mode, errp); - acquire_privilege(SE_SHUTDOWN_NAME, errp); - execute_async(do_suspend, mode, errp); + check_suspend_mode(*mode, &local_err); + acquire_privilege(SE_SHUTDOWN_NAME, &local_err); + execute_async(do_suspend, mode, &local_err); - if (error_is_set(errp)) { + if (local_err) { + error_propagate(errp, local_err); g_free(mode); } } @@ -375,6 +383,7 @@ int64_t qmp_guest_get_time(Error **errp) void qmp_guest_set_time(bool has_time, int64_t time_ns, Error **errp) { + Error *local_err = NULL; SYSTEMTIME ts; FILETIME tf; LONGLONG time; @@ -406,8 +415,9 @@ void qmp_guest_set_time(bool has_time, int64_t time_ns, Error **errp) } } - acquire_privilege(SE_SYSTEMTIME_NAME, errp); - if (error_is_set(errp)) { + acquire_privilege(SE_SYSTEMTIME_NAME, &local_err); + if (local_err) { + error_propagate(errp, local_err); return; }