In order to do that, virNodeSuspendSupportsTargetPMUtils() and virSystemdPMSupportTarget() are created even when pm-utils and dbus are compiled out, respectively, but in that case returning -2 meaning "unavailable" (this return code was already used for unavailability before). Error is reported in virNodeSuspendSupportsTarget() only if both functions returned -2, otherwise the error (or success) is properly propagated up the stack. Signed-off-by: Martin Kletzander <mkletzan(a)redhat.com&gt; --- Notes: v1: https://www.redhat.com/archives/libvir-list/2014-April/msg00550.html This is a build-breaker if building --without-dbus due to dbus_message_unref being called unconditionally. However, I'm not pushing it as such. I haven't followed the suggestion of return codes -1, 0 and 1 because there is already a -2 used for unavailability and these return codes are used in other parts of the code for similar reasons as well (e.g. storage driver). src/util/virnodesuspend.c | 22 ++++++++++++++++++---- src/util/virsystemd.c | 11 ++++++++++- 2 files changed, 28 insertions(+), 5 deletions(-) diff --git a/src/util/virnodesuspend.c b/src/util/virnodesuspend.c index 59b84ef..60b86ee 100644 --- a/src/util/virnodesuspend.c +++ b/src/util/virnodesuspend.c @@ -1,6 +1,7 @@ /* * virnodesuspend.c: Support for suspending a node (host machine) * + * Copyright (C) 2014 Red Hat, Inc. * Copyright (C) 2011 Srivatsa S. Bhat <srivatsa.bhat(a)linux.vnet.ibm.com&gt; * * This library is free software; you can redistribute it and/or @@ -267,7 +268,14 @@ virNodeSuspendSupportsTargetPMUtils(unsigned int target, bool *supported) virCommandFree(cmd); return ret; } -#endif +#else /* ! WITH_PM_UTILS */ +static int +virNodeSuspendSupportsTargetPMUtils(unsigned int target ATTRIBUTE_UNUSED, + bool *supported ATTRIBUTE_UNUSED) +{ + return -2; +} +#endif /* ! WITH_PM_UTILS */ static int virNodeSuspendSupportsTargetSystemd(unsigned int target, bool *supported) @@ -313,10 +321,16 @@ virNodeSuspendSupportsTarget(unsigned int target, bool *supported) int ret; ret = virNodeSuspendSupportsTargetSystemd(target, supported); -#ifdef WITH_PM_UTILS - if (ret < 0) + + /* If just unavailable, try other options */ + if (ret == -2) ret = virNodeSuspendSupportsTargetPMUtils(target, supported); -#endif + + /* If still unavailable, then report error */ + if (ret == -2) { + virReportError(VIR_ERR_INTERNAL_ERROR, "%s", + _("Cannot probe for supported suspend types")); + } return ret; } diff --git a/src/util/virsystemd.c b/src/util/virsystemd.c index e9ca564..e67956f 100644 --- a/src/util/virsystemd.c +++ b/src/util/virsystemd.c @@ -1,7 +1,7 @@ /* * virsystemd.c: helpers for using systemd APIs * - * Copyright (C) 2013 Red Hat, Inc. + * Copyright (C) 2013, 2014 Red Hat, Inc. * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public @@ -326,6 +326,7 @@ virSystemdNotifyStartup(void) #endif } +#ifdef WITH_SYSTEMD_DAEMON static int virSystemdPMSupportTarget(const char *methodName, bool *result) { @@ -369,6 +370,14 @@ virSystemdPMSupportTarget(const char *methodName, bool *result) return ret; } +#else /* ! WITH_SYSTEMD_DAEMON */ +static int +virSystemdPMSupportTarget(const char *methodName ATTRIBUTE_UNUSED, + bool *result ATTRIBUTE_UNUSED) +{ + return -2; +} +#endif /* ! WITH_SYSTEMD_DAEMON */ int virSystemdCanSuspend(bool *result) { -- 1.9.2