From mboxrd@z Thu Jan 1 00:00:00 1970 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 From: Markus Armbruster 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> Subject: [Qemu-devel] [PATCH v3 10/14] qga: Clean up fragile use of error_is_set() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: pbonzini@redhat.com, mdroth@linux.vnet.ibm.com, lcapitulino@redhat.com 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; } -- 1.8.1.4