When we added the default USB controller into domain XML, we efficiently
broke migration to older versions of libvirt that didn't support USB
controllers at all (0.9.4 and earlier) even for domains that don't use
anything that the older libvirt can't provide. We still want to present
the default USB controller in any XML seen by a user/app but we can
safely remove it from the domain XML used during migration. If we are
migrating to a new enough libvirt, it will add the controller XML back,
while older libvirt won't be confused with it although it will still
tell qemu to create the controller.

Similar approach can be used in the future whenever we find out we
always enabled some kind of device without properly advertising it in
domain XML.

Always use appropriate qemuDomain{,Def}Format wrapper since it may do
some additional magic based on the flags.

Commit 4c82f09e added a capability check for qemu per-device io
throttling, but only applied it to domain startup.  As mentioned
in the previous commit (98cec052), the user can still get an 'internal
error' message during a hotplug attempt, when the monitor command
doesn't exist.  It is confusing to allow tuning on inactive domains
only to then be rejected when starting the domain.

* src/qemu/qemu_driver.c (qemuDomainSetBlockIoTune): Reject
offline tuning if online can't match it.

If you have a qemu build that lacks the blockio tune monitor command,
then this command:

$ virsh blkdeviotune rhel6u2 hda --total_bytes_sec 1000
error: Unable to change block I/O throttle
error: internal error Unexpected error

fails as expected (well, the error message is lousy), but the next
dumpxml shows that the domain was modified anyway.  Worse, that means
if you save the domain then restore it, the restore will likely fail
due to throttling being unsupported, even though no throttling should
even be active because the monitor command failed in the first place.

* src/qemu/qemu_driver.c (qemuDomainSetBlockIoTune): Check for
error before making modification permanent.

These two functions are called from main() on all platforms, and
always return success on platforms that don't support libnl. They
still log an error message, though, which doesn't make sense - they
should just be NOPs on those platforms. (Per a suggestion during
review, I've turned the logs into debug messages rather than removing
them completely).

Error: STRING_NULL:
/libvirt/src/node_device/node_device_linux_sysfs.c:80:
string_null_argument: Function "saferead" does not terminate string "*buf".
/libvirt/src/util/util.c:101:
string_null_argument: Function "read" fills array "*buf" with a non-terminated string.
/libvirt/src/node_device/node_device_linux_sysfs.c:87:
string_null: Passing unterminated string "buf" to a function expecting a null-terminated string.

Error: STRING_NULL:
/libvirt/src/util/uuid.c:273:
string_null_argument: Function "getDMISystemUUID" does not terminate string "*dmiuuid".
/libvirt/src/util/uuid.c:241:
string_null_argument: Function "saferead" fills array "*uuid" with a non-terminated string.
/libvirt/src/util/util.c:101:
string_null_argument: Function "read" fills array "*buf" with a non-terminated string.
/libvirt/src/util/uuid.c:274:
string_null: Passing unterminated string "dmiuuid" to a function expecting a null-terminated string.
/libvirt/src/util/uuid.c:138:
var_assign_parm: Assigning: "cur" = "uuidstr". They now point to the same thing.
/libvirt/src/util/uuid.c:164:
string_null_sink_loop: Searching for null termination in an unterminated array "cur".

Error: RESOURCE_LEAK:
/libvirt/src/qemu/qemu_driver.c:6968:
alloc_fn: Calling allocation function "calloc".
/libvirt/src/qemu/qemu_driver.c:6968:
var_assign: Assigning: "nodeset" =  storage returned from "calloc(1UL, 1UL)".
/libvirt/src/qemu/qemu_driver.c:6977:
noescape: Variable "nodeset" is not freed or pointed-to in function "virTypedParameterAssign".
/libvirt/src/qemu/qemu_driver.c:6997:
leaked_storage: Variable "nodeset" going out of scope leaks the storage it points to.

Error: RESOURCE_LEAK:
/libvirt/src/vmx/vmx.c:2431:
alloc_fn: Calling allocation function "calloc".
/libvirt/src/vmx/vmx.c:2431:
var_assign: Assigning: "networkName" =  storage returned from "calloc(1UL, 1UL)".
/libvirt/src/vmx/vmx.c:2495:
leaked_storage: Variable "networkName" going out of scope leaks the storage it points to.

Error: RESOURCE_LEAK:
/builddir/build/BUILD/libvirt-0.9.10/src/nodeinfo.c:629: alloc_fn: Calling allocation function "fopen".
/builddir/build/BUILD/libvirt-0.9.10/src/nodeinfo.c:629: var_assign: Assigning: "cpuinfo" =  storage returned from "fopen("/proc/cpuinfo", "r")".
/builddir/build/BUILD/libvirt-0.9.10/src/nodeinfo.c:638: leaked_storage: Variable "cpuinfo" going out of scope leaks the storage it points to.

Error: RESOURCE_LEAK:
/builddir/build/BUILD/libvirt-0.9.10/src/test/test_driver.c:1041: alloc_arg: Calling allocation function "virXPathNodeSet" on "devs".
/builddir/build/BUILD/libvirt-0.9.10/src/util/xml.c:621: alloc_arg: "virAllocN" allocates memory that is stored into "*list".
/builddir/build/BUILD/libvirt-0.9.10/src/util/memory.c:129: alloc_fn: Storage is returned from allocation function "calloc".
/builddir/build/BUILD/libvirt-0.9.10/src/util/memory.c:129: var_assign: Assigning: "*((void **)ptrptr)" = "calloc(count, size)".
/builddir/build/BUILD/libvirt-0.9.10/src/util/xml.c:625: noescape: Variable "*list" is not freed or pointed-to in function "memcpy".
/builddir/build/BUILD/libvirt-0.9.10/src/test/test_driver.c:1098: leaked_storage: Variable "devs" going out of scope leaks the storage it points to.

Coverity logs:

Error: RESOURCE_LEAK:
/builddir/build/BUILD/libvirt-0.9.10/src/xen/xen_inotify.c:103: alloc_fn: Calling allocation function "xenDaemonLookupByUUID".
/builddir/build/BUILD/libvirt-0.9.10/src/xen/xend_internal.c:2534: alloc_fn: Storage is returned from allocation function "virGetDomain".
/builddir/build/BUILD/libvirt-0.9.10/src/datatypes.c:191: alloc_arg: "virAlloc" allocates memory that is stored into "ret".
/builddir/build/BUILD/libvirt-0.9.10/src/util/memory.c:101: alloc_fn: Storage is returned from allocation function "calloc".
/builddir/build/BUILD/libvirt-0.9.10/src/util/memory.c:101: var_assign: Assigning: "*((void **)ptrptr)" = "calloc(1UL, size)".
/builddir/build/BUILD/libvirt-0.9.10/src/datatypes.c:210: return_alloc: Returning allocated memory "ret".
/builddir/build/BUILD/libvirt-0.9.10/src/xen/xend_internal.c:2534: var_assign: Assigning: "ret" = "virGetDomain(conn, name, uuid)".
/builddir/build/BUILD/libvirt-0.9.10/src/xen/xend_internal.c:2541: return_alloc: Returning allocated memory "ret".
/builddir/build/BUILD/libvirt-0.9.10/src/xen/xen_inotify.c:103: var_assign: Assigning: "dom" =  storage returned from "xenDaemonLookupByUUID(conn, rawuuid)".
/builddir/build/BUILD/libvirt-0.9.10/src/xen/xen_inotify.c:126: leaked_storage: Variable "dom" going out of scope leaks the storage it points to.

Error: RESOURCE_LEAK:
/builddir/build/BUILD/libvirt-0.9.10/src/xen/xen_hypervisor.c:2742: alloc_fn: Calling allocation function "fopen".
/builddir/build/BUILD/libvirt-0.9.10/src/xen/xen_hypervisor.c:2742: var_assign: Assigning: "cpuinfo" =  storage returned from "fopen("/proc/cpuinfo", "r")".
/builddir/build/BUILD/libvirt-0.9.10/src/xen/xen_hypervisor.c:2763: noescape: Variable "cpuinfo" is not freed or pointed-to in function "xenHypervisorMakeCapabilitiesInternal".
/builddir/build/BUILD/libvirt-0.9.10/src/xen/xen_hypervisor.c:2574:45: noescape: "xenHypervisorMakeCapabilitiesInternal" does not free or save its pointer parameter "cpuinfo".
/builddir/build/BUILD/libvirt-0.9.10/src/xen/xen_hypervisor.c:2768: leaked_storage: Variable "cpuinfo" going out of scope leaks the storage it points to.

Error: RESOURCE_LEAK:
/builddir/build/BUILD/libvirt-0.9.10/src/xen/xen_hypervisor.c:2752: alloc_fn: Calling allocation function "fopen".
/builddir/build/BUILD/libvirt-0.9.10/src/xen/xen_hypervisor.c:2752: var_assign: Assigning: "capabilities" =  storage returned from "fopen("/sys/hypervisor/properties/capabilities", "r")".
/builddir/build/BUILD/libvirt-0.9.10/src/xen/xen_hypervisor.c:2763: noescape: Variable "capabilities" is not freed or pointed-to in function "xenHypervisorMakeCapabilitiesInternal".
/builddir/build/BUILD/libvirt-0.9.10/src/xen/xen_hypervisor.c:2574:60: noescape: "xenHypervisorMakeCapabilitiesInternal" does not free or save its pointer parameter "capabilities".
/builddir/build/BUILD/libvirt-0.9.10/src/xen/xen_hypervisor.c:2768: leaked_storage: Variable "capabilities" going out of scope leaks the storage it points to.

Coverity logs:

Error: RESOURCE_LEAK:
/builddir/build/BUILD/libvirt-0.9.10/src/phyp/phyp_driver.c:523: alloc_fn: Calling allocation function "fopen".
/builddir/build/BUILD/libvirt-0.9.10/src/phyp/phyp_driver.c:523: var_assign: Assigning: "fd" =  storage returned from "fopen(local_file, "rb")".
/builddir/build/BUILD/libvirt-0.9.10/src/phyp/phyp_driver.c:540: noescape: Variable "fd" is not freed or pointed-to in function "fread".
/builddir/build/BUILD/libvirt-0.9.10/src/phyp/phyp_driver.c:542: noescape: Variable "fd" is not freed or pointed-to in function "feof".
/builddir/build/BUILD/libvirt-0.9.10/src/phyp/phyp_driver.c:575: leaked_storage: Variable "fd" going out of scope leaks the storage it points to.
/builddir/build/BUILD/libvirt-0.9.10/src/phyp/phyp_driver.c:585: leaked_storage: Variable "fd" going out of scope leaks the storage it points to.

Error: RESOURCE_LEAK:
/builddir/build/BUILD/libvirt-0.9.10/src/phyp/phyp_driver.c:2088: alloc_fn: Calling allocation function "phypVolumeLookupByName".
/builddir/build/BUILD/libvirt-0.9.10/src/phyp/phyp_driver.c:2026: alloc_fn: Storage is returned from allocation function "virGetStorageVol".
/builddir/build/BUILD/libvirt-0.9.10/src/datatypes.c:724: alloc_arg: "virAlloc" allocates memory that is stored into "ret".
/builddir/build/BUILD/libvirt-0.9.10/src/util/memory.c:101: alloc_fn: Storage is returned from allocation function "calloc".
/builddir/build/BUILD/libvirt-0.9.10/src/util/memory.c:101: var_assign: Assigning: "*((void **)ptrptr)" = "calloc(1UL, size)".
/builddir/build/BUILD/libvirt-0.9.10/src/datatypes.c:753: return_alloc: Returning allocated memory "ret".
/builddir/build/BUILD/libvirt-0.9.10/src/phyp/phyp_driver.c:2026: var_assign: Assigning: "vol" = "virGetStorageVol(pool->conn, pool->name, volname, key)".
/builddir/build/BUILD/libvirt-0.9.10/src/phyp/phyp_driver.c:2030: return_alloc: Returning allocated memory "vol".
/builddir/build/BUILD/libvirt-0.9.10/src/phyp/phyp_driver.c:2088: leaked_storage: Failing to save storage allocated by "phypVolumeLookupByName(pool, voldef->name)" leaks it.

Error: RESOURCE_LEAK:
/builddir/build/BUILD/libvirt-0.9.10/src/phyp/phyp_driver.c:2725: alloc_fn: Calling allocation function "phypGetStoragePoolLookUpByUUID".
/builddir/build/BUILD/libvirt-0.9.10/src/phyp/phyp_driver.c:2689: alloc_fn: Storage is returned from allocation function "virGetStoragePool".
/builddir/build/BUILD/libvirt-0.9.10/src/datatypes.c:592: alloc_arg: "virAlloc" allocates memory that is stored into "ret".
/builddir/build/BUILD/libvirt-0.9.10/src/util/memory.c:101: alloc_fn: Storage is returned from allocation function "calloc".
/builddir/build/BUILD/libvirt-0.9.10/src/util/memory.c:101: var_assign: Assigning: "*((void **)ptrptr)" = "calloc(1UL, size)".
/builddir/build/BUILD/libvirt-0.9.10/src/datatypes.c:610: return_alloc: Returning allocated memory "ret".
/builddir/build/BUILD/libvirt-0.9.10/src/phyp/phyp_driver.c:2689: var_assign: Assigning: "sp" = "virGetStoragePool(conn, pools[i], uuid)".
/builddir/build/BUILD/libvirt-0.9.10/src/phyp/phyp_driver.c:2694: return_alloc: Returning allocated memory "sp".
/builddir/build/BUILD/libvirt-0.9.10/src/phyp/phyp_driver.c:2725: leaked_storage: Failing to save storage allocated by "phypGetStoragePoolLookUpByUUID(conn, def->uuid)" leaks it.

Error: RESOURCE_LEAK:
/builddir/build/BUILD/libvirt-0.9.10/src/phyp/phyp_driver.c:2719: alloc_fn: Calling allocation function "phypStoragePoolLookupByName".
/builddir/build/BUILD/libvirt-0.9.10/src/phyp/phyp_driver.c:2254: alloc_fn: Storage is returned from allocation function "virGetStoragePool".
/builddir/build/BUILD/libvirt-0.9.10/src/datatypes.c:592: alloc_arg: "virAlloc" allocates memory that is stored into "ret".
/builddir/build/BUILD/libvirt-0.9.10/src/util/memory.c:101: alloc_fn: Storage is returned from allocation function "calloc".
/builddir/build/BUILD/libvirt-0.9.10/src/util/memory.c:101: var_assign: Assigning: "*((void **)ptrptr)" = "calloc(1UL, size)".
/builddir/build/BUILD/libvirt-0.9.10/src/datatypes.c:610: return_alloc: Returning allocated memory "ret".
/builddir/build/BUILD/libvirt-0.9.10/src/phyp/phyp_driver.c:2254: return_alloc_fn: Directly returning storage allocated by "virGetStoragePool".
/builddir/build/BUILD/libvirt-0.9.10/src/phyp/phyp_driver.c:2719: leaked_storage: Failing to save storage allocated by "phypStoragePoolLookupByName(conn, def->name)" leaks it.

Error: RESOURCE_LEAK:
/builddir/build/BUILD/libvirt-0.9.10/src/phyp/phyp_driver.c:2270: alloc_fn: Calling allocation function "phypStoragePoolLookupByName".
/builddir/build/BUILD/libvirt-0.9.10/src/phyp/phyp_driver.c:2254: alloc_fn: Storage is returned from allocation function "virGetStoragePool".
/builddir/build/BUILD/libvirt-0.9.10/src/datatypes.c:592: alloc_arg: "virAlloc" allocates memory that is stored into "ret".
/builddir/build/BUILD/libvirt-0.9.10/src/util/memory.c:101: alloc_fn: Storage is returned from allocation function "calloc".
/builddir/build/BUILD/libvirt-0.9.10/src/util/memory.c:101: var_assign: Assigning: "*((void **)ptrptr)" = "calloc(1UL, size)".
/builddir/build/BUILD/libvirt-0.9.10/src/datatypes.c:610: return_alloc: Returning allocated memory "ret".
/builddir/build/BUILD/libvirt-0.9.10/src/phyp/phyp_driver.c:2254: return_alloc_fn: Directly returning storage allocated by "virGetStoragePool".
/builddir/build/BUILD/libvirt-0.9.10/src/phyp/phyp_driver.c:2270: var_assign: Assigning: "sp" =  storage returned from "phypStoragePoolLookupByName(vol->conn, vol->pool)".
/builddir/build/BUILD/libvirt-0.9.10/src/phyp/phyp_driver.c:2324: leaked_storage: Variable "sp" going out of scope leaks the storage it points to.
/builddir/build/BUILD/libvirt-0.9.10/src/phyp/phyp_driver.c:2327: leaked_storage: Variable "sp" going out of scope leaks the storage it points t

On 32-bit platforms, gcc warns that the comparison between a long
and (ULLONG_MAX/1024/1024) is always false; throwing in a type
conversion shuts up the warning.

* src/qemu/qemu_monitor.c (qemuMonitorBlockJob): Shut gcc up.

configure.ac: check for libnl-3 in addition to libnl-1

src/Makefile.am: link against libnl when needed

src/util/virnetlink.c:
support libnl3 api.  To minimize impact on code flow, wrap the
differences under the virNetlink* namespace.

Unfortunately libnl3 moves netlink/msg.h to
/usr/include/libnl3/netlink/msg.h, so the LIBNL_CFLAGS need to be added
to a bunch of places where they weren't needed with libnl1.
Signed-off-by: NSerge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: NEric Blake <eblake@redhat.com>

Add function virJSONValueObjectKeysNumber, virJSONValueObjectGetKey
and virJSONValueObjectGetValue, which allow you to iterate over all
fields of json object: you can get number of fields and then get
name and value, stored in field with that name by index.
Signed-off-by: NDmitry Guryanov <dguryanov@parallels.com>

qemuDomainNetsRestart indents with 3 spaces.

This patch is to correct it.
Signed-off-by: NLi Zhang <zhlcindy@linux.vnet.ibm.com>

The code uses long long for pid_t now.
It fails on mingw64 without this change.

Fix a few more places where pid_t is printed with wrong type

The ATTRIBUTE_NONNULL(m) macro normally resolves to the gcc builtin
__attribute__((__nonnull__(m))). The effect of this in gcc is
unfortunately only to make gcc believe that "m" can never possibly be
NULL, *not* to add in any checks to guarantee that it isn't ever NULL
(i.e. it is an optimization aid, *not* something to verify code
correctness.) - see the following gcc bug report for more details:

  http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17308

Static source analyzers such as clang and coverity apparently can use
ATTRIBUTE_NONNULL(), though, to detect dead code (in the case that the
arg really is guaranteed non-NULL), as well as situations where an
obviously NULL arg is given to the function.

https://bugzilla.redhat.com/show_bug.cgi?id=815270 is a good example
of a bug caused by erroneous application of ATTRIBUTE_NONNULL().
Several people spent a long time staring at this code and not finding
the problem, because the problem wasn't in the function itself, but in
the prototype that specified ATTRIBUTE_NONNULL() for an arg that
actually *wasn't* always non-NULL, and caused a segv when dereferenced
(even though the code that dereferenced the pointer was inside an if()
that checked for a NULL pointer, that code was optimized out by gcc).

There may be some very small gain to be had from the optimizations
that can be inferred from ATTRIBUTE_NONNULL(), but it seems safer to
err on the side of generating code that behaves as expected, while
turning on the attribute for static analyzers.

Once lxcContainerSetStdio is invoked, logging will not work as
expected in libvirt_lxc. So make sure this is the last thing to
be called, in particular after setting the security process label

The virLogSetFromEnv call was done too late in startup to
catch many log messages (eg from security driver initialization).
To assist debugging also explicitly log the security details
at startup

The driver->securityDriverName field may be NULL, if automatic
probing is used to determine security driver. This meant that
unless selinux was explicitly requested in lxc.conf, it was
not being sent to the libvirt_lxc process.

The driver->securityManager field is guaranteed non-NULL, since
there will always be the 'none' security driver present if
nothing else exists. So use that to set the driver name for
libvirt_lxc
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

Currently the libvirt_lxc process uses VIR_DOMAIN_XML_INACTIVE
when loading the XML for the container. This means it loses
any dynamic data such as the, just allocated, SELinux label.

Further there is an inconsistency in the libvirt LXC driver
whereby it saves the live config XML and then later overwrites
the file with the live status XML instead. Add a comment about
this for future reference.

* src/lxc/lxc_controller.c: Remove VIR_DOMAIN_XML_INACTIVE
  when loading XML
* src/lxc/lxc_driver.c: Add comment about inconsistent
  config file formats
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

Signed-off-by: NJosh Durgin <josh.durgin@dreamhost.com>

This works with newer qemu that doesn't allow escaping spaces.
It's backwards compatible as well.
Signed-off-by: NJosh Durgin <josh.durgin@dreamhost.com>

In fact, the 'tapfd' is always NULL, the function 'virNetDevTapCreate()' hasn't
assign 'fd' to 'tapfd', when the function 'virNetDevSetMAC()' is failed then
goto 'error' label, finally, the VIR_FORCE_CLOSE() will deref a NULL 'tapfd'.

* util/virnetdevtap.c (virNetDevTapCreateInBridgePort): fix a NULL pointer derefing.

* How to reproduce?

$ cat > /tmp/net.xml <<EOF
<network>
  <name>test</name>
  <forward mode='nat'/>
  <bridge name='br1' stp='off' delay='1' />
  <mac address='00:00:00:00:00:00'/>
  <ip address='192.168.100.1' netmask='255.255.255.0'>
    <dhcp>
      <range start='192.168.100.2' end='192.168.100.254' />
    </dhcp>
  </ip>
</network>
EOF

$ virsh net-define /tmp/net.xml

$ virsh net-start test
error: Failed to start network brTest
error: End of file while reading data: Input/output error
Signed-off-by: NAlex Jia <ajia@redhat.com>

The previous storage patch missed an instance affected by the struct
member rename.  It also had some botched whitespace detected by
'make check'.

* src/storage/storage_backend_iscsi.c
(virStorageBackendISCSIFindPoolSources): Adjust to new struct.
* src/conf/storage_conf.c (virStoragePoolSourceFormat): Fix
indentation.

It doesn't break out the "for" loop even if duplicate pool is
found, and thus the "matchpool" could be overriden as NULL again
if there is different pool afterwards.

To address the problem in libvirt-user list:

https://www.redhat.com/archives/libvirt-users/2012-April/msg00150.html

The current storage pools for NFS and iSCSI only require one host to
connect to. Future storage pools like RBD and Sheepdog will require
multiple hosts.

This patch allows multiple source hosts and rewrites the current
storage drivers.
Signed-off-by: NWido den Hollander <wido@widodh.nl>

When libvirtd is started, we create "libvirt/qemu" directories under
hugetlbfs mount point. Only the "qemu" subdirectory is chowned to qemu
user and "libvirt" remains owned by root. If umask was too restrictive
when libvirtd started, qemu user may lose access to "qemu"
subdirectory. Let's explicitly grant search permissions to "libvirt"
directory for all users.

Currently, qemu GA is not providing 'desc' field for errors like
we are used to from qemu monitor. Therefore, we fall back to this
general 'unknown error' string. However, GA is reporting 'class' which
is not perfect, but much more helpful than generic error string.
Thus we should fall back to class firstly and if even no class
is presented, then we can fall back to that generic string.

Before this patch:
virsh # dompmsuspend --target mem f16
error: Domain f16 could not be suspended
error: internal error unable to execute QEMU command
'guest-suspend-ram': unknown QEMU command error

After this patch:
virsh # dompmsuspend --target mem f16
error: Domain f16 could not be suspended
error: internal error unable to execute QEMU command
'guest-suspend-ram': The command has not been found

More bug extermination in the category of:

Error: CHECKED_RETURN:

/libvirt/src/conf/network_conf.c:595:
check_return: Calling function "virAsprintf" without checking return value (as is done elsewhere 515 out of 543 times).

/libvirt/src/qemu/qemu_process.c:2780:
unchecked_value: No check of the return value of "virAsprintf(&msg, "was paused (%s)", virDomainPausedReasonTypeToString(reason))".

/libvirt/tests/commandtest.c:809:
check_return: Calling function "setsid" without checking return value (as is done elsewhere 4 out of 5 times).

/libvirt/tests/commandtest.c:830:
unchecked_value: No check of the return value of "virTestGetDebug()".

/libvirt/tests/commandtest.c:831:
check_return: Calling function "virTestGetVerbose" without checking return value (as is done elsewhere 41 out of 42 times).

/libvirt/tests/commandtest.c:833:
check_return: Calling function "virInitialize" without checking return value (as is done elsewhere 18 out of 21 times).


One note about the error in commandtest line 809: setsid() seems to fail when running the test -- could be removed ?

With RHEL 6.2, virDomainBlockPull(dom, dev, bandwidth, 0) has a race
with non-zero bandwidth: there is a window between the block_stream
and block_job_set_speed monitor commands where an unlimited amount
of data was let through, defeating the point of a throttle.

This race was first identified in commit a9d3495e, and libvirt was
able to reduce the size of the window for that race.  In the meantime,
the qemu developers decided to fix things properly; per this message:
https://lists.gnu.org/archive/html/qemu-devel/2012-04/msg03793.html
the fix will be in qemu 1.1, and changes block-job-set-speed to use
a different parameter name, as well as adding a new optional parameter
to block-stream, which eliminates the race altogether.

Since our documentation already mentioned that we can refuse a non-zero
bandwidth for some hypervisors, I think the best solution is to do
just that for RHEL 6.2 qemu, so that the race is obvious to the user
(anyone using stock RHEL 6.2 binaries won't have this patch, and anyone
building their own libvirt with this patch for RHEL can also rebuild
qemu to get the modern semantics, so it is no real loss in behavior).

Meanwhile the code must be fixed to honor actual qemu 1.1 naming.
Rename the parameter to 'modern', since the naming difference now
covers more than just 'async' block-job-cancel.  And while at it,
fix an unchecked integer overflow.

* src/qemu/qemu_monitor.h (enum BLOCK_JOB_CMD): Drop unused value,
rename enum to match conventions.
* src/qemu/qemu_monitor.c (qemuMonitorBlockJob): Reflect enum rename.
* src/qemu_qemu_monitor_json.h (qemuMonitorJSONBlockJob): Likewise.
* src/qemu/qemu_monitor_json.c (qemuMonitorJSONBlockJob): Likewise,
and support difference between RHEL 6.2 and qemu 1.1 block pull.
* src/qemu/qemu_driver.c (qemuDomainBlockJobImpl): Reject
bandwidth during pull with too-old qemu.
* src/libvirt.c (virDomainBlockPull, virDomainBlockRebase):
Document this.

Error: UNINIT:
/libvirt/src/lxc/lxc_driver.c:1412:
var_decl: Declaring variable "fd" without initializer.
/libvirt/src/lxc/lxc_driver.c:1460:
uninit_use_in_call: Using uninitialized value "fd" when calling "virFileClose".
/libvirt/src/util/virfile.c:50:
read_parm: Reading a parameter value.

Error: DEADCODE:
/libvirt/src/lxc/lxc_controller.c:960:
dead_error_condition: On this path, the condition "ret == 4" cannot be true.
/libvirt/src/lxc/lxc_controller.c:959:
at_most: After this line, the value of "ret" is at most -1.
/libvirt/src/lxc/lxc_controller.c:959:
new_values: Noticing condition "ret < 0".
/libvirt/src/lxc/lxc_controller.c:961:
dead_error_line: Execution cannot reach this statement "continue;".

Error: UNINIT:
/libvirt/src/lxc/lxc_controller.c:1104:
var_decl: Declaring variable "consoles" without initializer.
/libvirt/src/lxc/lxc_controller.c:1237:
uninit_use: Using uninitialized value "consoles".

QEMU binary is called several times when we probe different kinds of
capabilities the binary supports. This patch introduces new common
helper so that all probes use a consistent way of invoking qemu.

https://bugzilla.redhat.com/show_bug.cgi?id=816662 pointed out
that attempting 'virsh blockpull' on an offline domain gave a
misleading error message about qemu lacking support for the
operation, even when qemu was specifically updated to support it.
The real problem is that we have several capabilities that are
only determined when starting a domain, and therefore are still
clear when first working with an inactive domain (namely, any
capability set by qemuMonitorJSONCheckCommands).

While this patch was able to hoist an existing check in one of the
three culprits, it had to add redundant checks in the other two
places (because you always have to check for an active domain after
obtaining a VM job lock, but the capability bits were being checked
prior to obtaining the job lock).

Someday it would be nice to patch libvirt to cache the set of
capabilities per qemu binary (as determined by inode and timestamp),
rather than re-probing the binary every time a domain is started,
and to teach the cache how to query the monitor during the one
time the probe is made rather than having to wait until a guest
is started; then, a capability probe would succeed even for offline
guests because it just refers to the cache, and the single check for
an active domain after grabbing the job lock would be sufficient.
But since that will involve a lot more coding, I'm happy to go
with this simpler solution for an immediate solution.

* src/qemu/qemu_driver.c (qemuDomainPMSuspendForDuration)
(qemuDomainSnapshotCreateXML, qemuDomainBlockJobImpl): Check for
offline state before checking an online-only cap.

Below patch fixes the following coverity findings

Error: OVERRUN_STATIC:
/libvirt/src/qemu/qemu_command.c:152:
overrun-buffer-val: Overrunning static array "net->mac" of size 6 bytes by passing it as an argument to a function which indexes it at byte position 15.
/libvirt/src/util/virnetdevmacvlan.c:948:
access_dbuff_const: Calling "virNetDevMacVLanVPortProfileRegisterCallback" indexes array "macaddress" at byte position 15.
/libvirt/src/util/virnetdevmacvlan.c:773:
access_dbuff_const: Calling "memcpy" indexes array "macaddress" with index "16UL" at byte position 15.

Error: OVERRUN_STATIC:
/libvirt/src/qemu/qemu_migration.c:2744:
overrun-buffer-val: Overrunning static array "net->mac" of size 6 bytes by passing it as an argument to a function which indexes it at byte position 15.
/libvirt/src/util/virnetdevmacvlan.c:773:
access_dbuff_const: Calling "memcpy" indexes array "macaddress" with index "16UL" at byte position 15.

Error: OVERRUN_STATIC:
/libvirt/src/qemu/qemu_driver.c:435:
overrun-buffer-val: Overrunning static array "net->mac" of size 6 bytes by passing it as an argument to a function which indexes it at byte position 15.
/libvirt/src/util/virnetdevmacvlan.c:1036:
access_dbuff_const: Calling "virNetDevMacVLanVPortProfileRegisterCallback" indexes array "macaddress" at byte position 15.
/libvirt/src/util/virnetdevmacvlan.c:773:
access_dbuff_const: Calling "memcpy" indexes array "macaddress" with index "16UL" at byte position 15.