The virCommandNewArgs() method would free the virCommandPtr
if it failed to add the args. This meant errors reported in
virCommandAddArgSet() were lost. Simply removing the check
for errors from the constructor means they can be reported
correctly later

The virCommandAddEnvPassCommon() method failed to check for
errors before reallocating the cmd->env array, causing a
potential SEGV if cmd was NULL

The virCommandAddArgSet() method needs to validate that at
least 1 element in 'val's parameter is non-NULL, otherwise
code like

    cmd = virCommandNew(binary)
    virCommandAddAtg(cmd, "foo")

Would end up trying todo  execve("foo"), if binary was
NULL.

The virSetNonBlock() API only allows enabling non-blocking
operations. It doesn't allow turning blocking back on. Add
a new API to allow arbitrary toggling.

* src/libvirt_private.syms, src/util/util.h
  src/util/util.c: Add virSetBlocking

This is the part allowing to dynamically resize the debug log
buffer from it's default 64kB size. The buffer is now dynamically
allocated.
It adds a new API virLogSetBufferSize() which resizes the buffer
If passed a zero size, the buffer is deallocated and we do the small
optimization of not formatting messages which are not output anymore.
On the daemon side, it just adds a new option log_buffer_size to
libvirtd.conf and call virLogSetBufferSize() if needed
* src/util/logging.h src/util/logging.c src/libvirt_private.syms:
  make buffer dynamic and add virLogSetBufferSize() internal API
* daemon/libvirtd.conf: document the new log_buffer_size option
* daemon/libvirtd.c: read and use the new log_buffer_size option

Adding audit points showed that we were granting too much privilege
to qemu; it should not need any mknod rights to recreate any
devices.  On the other hand, lxc should have all device privileges.
The solution is adding a flag parameter.

This also lets us restrict write access to read-only disks.

* src/util/cgroup.h (virCgroup*Device*): Adjust prototypes.
* src/util/cgroup.c (virCgroupAllowDevice)
(virCgroupAllowDeviceMajor, virCgroupAllowDevicePath)
(virCgroupDenyDevice, virCgroupDenyDeviceMajor)
(virCgroupDenyDevicePath): Add parameter.
* src/qemu/qemu_driver.c (qemudDomainSaveFlag): Update clients.
* src/lxc/lxc_controller.c (lxcSetContainerResources): Likewise.
* src/qemu/qemu_cgroup.c: Likewise.
(qemuSetupDiskPathAllow): Also, honor read-only disks.

Although the cgroup device ACL controller path can be worked out
by researching the code, it is more efficient to include that
information directly in the audit message.

* src/util/cgroup.h (virCgroupPathOfController): New prototype.
* src/util/cgroup.c (virCgroupPathOfController): Export.
* src/libvirt_private.syms: Likewise.
* src/qemu/qemu_audit.c (qemuAuditCgroup): Use it.

I noticed these while testing 'make dist'.

Parsing ./../src/util/event.c
Function comment for virEventRegisterDefaultImpl lacks description of return value
Function comment for virEventRunDefaultImpl lacks description of return value
Parsing ./../src/util/virterror.c
Missing comment for function virSetErrorLogPriorityFunc

* src/util/event.c (virEventRegisterDefaultImpl)
(virEventRunDefaultImpl): Document return types.
* src/util/virterror.c (virSetErrorLogPriorityFunc): Provide docs.

On cygwin:

  CC        libvirt_util_la-cgroup.lo
util/cgroup.c: In function 'virCgroupKillRecursiveInternal':
util/cgroup.c:1458: warning: implicit declaration of function 'virCgroupNew' [-Wimplicit-function-declaration]

* src/util/cgroup.c (virCgroupKill): Don't build on platforms
where virCgroupNew is unsupported.

Apparently some signals found on Unix are not exposed, this led
to a compilation failure
* src/util/logging.c: make code related to each signal dependant
  upon the definition of that signal

When I use newest libvirt to save a domain, libvirtd will be deadlock.
Here is the output of gdb:
(gdb) thread 3
[Switching to thread 3 (Thread 0x7f972a1fc710 (LWP 30265))]#0  0x000000351fe0e034 in __lll_lock_wait () from /lib64/libpthread.so.0
(gdb) bt
    at qemu/qemu_driver.c:2074
    ret=0x7f972a1fbbe0) at remote.c:2273
(gdb) thread 7
[Switching to thread 7 (Thread 0x7f9730bcd710 (LWP 30261))]#0  0x000000351fe0e034 in __lll_lock_wait () from /lib64/libpthread.so.0
(gdb) bt
(gdb) p *(virMutexPtr)0x6fdd60
$2 = {lock = {__data = {__lock = 2, __count = 0, __owner = 30261, __nusers = 1, __kind = 0, __spins = 0, __list = {__prev = 0x0, __next = 0x0}},
    __size = "\002\000\000\000\000\000\000\000\065v\000\000\001", '\000' <repeats 26 times>, __align = 2}}
(gdb) p *(virMutexPtr)0x1a63ac0
$3 = {lock = {__data = {__lock = 2, __count = 0, __owner = 30265, __nusers = 1, __kind = 0, __spins = 0, __list = {__prev = 0x0, __next = 0x0}},
    __size = "\002\000\000\000\000\000\000\000\071v\000\000\001", '\000' <repeats 26 times>, __align = 2}}
(gdb) info threads
  7 Thread 0x7f9730bcd710 (LWP 30261)  0x000000351fe0e034 in __lll_lock_wait () from /lib64/libpthread.so.0
  6 Thread 0x7f972bfff710 (LWP 30262)  0x000000351fe0b43c in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  5 Thread 0x7f972b5fe710 (LWP 30263)  0x000000351fe0b43c in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  4 Thread 0x7f972abfd710 (LWP 30264)  0x000000351fe0b43c in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
* 3 Thread 0x7f972a1fc710 (LWP 30265)  0x000000351fe0e034 in __lll_lock_wait () from /lib64/libpthread.so.0
  2 Thread 0x7f97297fb710 (LWP 30266)  0x000000351fe0b43c in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
  1 Thread 0x7f9737aac800 (LWP 30260)  0x000000351fe0803d in pthread_join () from /lib64/libpthread.so.0

The reason is that we will try to lock some object in callback function, and we may call event API with locking the same object.
In the function virEventDispatchHandles(), we unlock eventLoop before calling callback function. I think we should
do the same thing in the function virEventCleanupTimeouts() and virEventCleanupHandles().
Signed-off-by: NWen Congyang <wency@cn.fujitsu.com>
Signed-off-by: NEric Blake <eblake@redhat.com>

Not all applications have an existing event loop they need
to integrate with. Forcing them to implement the libvirt
event loop integration APIs is an undue burden. This just
exposes our simple poll() based implementation for apps
to use. So instead of calling

   virEventRegister(....callbacks...)

The app would call

   virEventRegisterDefaultImpl()

And then have a thread somewhere calling

    static bool quit = false;
    ....
    while (!quit)
      virEventRunDefaultImpl()

* daemon/libvirtd.c, tools/console.c,
  tools/virsh.c: Convert to public event loop APIs
* include/libvirt/libvirt.h.in, src/libvirt_private.syms: Add
  virEventRegisterDefaultImpl and virEventRunDefaultImpl
* src/util/event.c: Implement virEventRegisterDefaultImpl
  and virEventRunDefaultImpl using poll() event loop
* src/util/event_poll.c: Add full error reporting
* src/util/virterror.c, include/libvirt/virterror.h: Add
  VIR_FROM_EVENTS

The event loop implementation is used by more than just the
daemon, so move it into the shared area.

* daemon/event.c, src/util/event_poll.c: Renamed
* daemon/event.h, src/util/event_poll.h: Renamed
* tools/Makefile.am, tools/console.c, tools/virsh.c: Update
  to use new virEventPoll APIs
* daemon/mdns.c, daemon/mdns.c, daemon/Makefile.am: Update
  to use new virEventPoll APIs

* src/util/logging.c: fix virLogDumpAllFD() to avoid snprintf, simplify
  the code and provide more useful signal descriptions. Also remove an
  unused variable.

Signed-off-by: NEric Blake <eblake@redhat.com>

virLogEmergencyDumpAll() allows to dump the content of the
debug buffer from within a signal handler. It saves to all
log file or stderr if none is found
* src/util/logging.h src/util/logging.c: add the new API
  and cleanup the old virLogDump code
* src/libvirt_private.syms: exports it as a private symbol

* src/util/logging.c: the start pointer need to wrap around too

Initially only the log actually written out by libvirt were
saved on the memory buffer, this patch forces all informations
including info and debug to be saved in memory too. This is
useful to get full data in case of crash.

In virFileOperation, the parent does a fallback to a non-fork
attempt if it detects that the child returned EACCES.  However,
the child was calling _exit(-EACCES), which does _not_ appear
as EACCES in the parent.

* src/util/util.c (virFileOperation): Correctly pass EACCES from
child to parent.

This fixes a possible crash of libvirtd during its startup. When qemu
driver reconnects to running domains, it iterates over all domain
objects in a hash. When reconnecting to an associated qemu monitor
fails and the domain is transient, it's immediately removed from the
hash. Despite the fact that it's explicitly forbidden to do so. If
libvirtd is lucky enough, virHashForEach will access random memory when
the callback finishes and the deamon will crash.

Since it's trivial to fix virHashForEach to allow removal of hash
entries while iterating through them, I went this way instead of fixing
qemuReconnectDomain callback (and possibly others) to avoid deleting the
entries.

Replace the 'Unknown failure' error message with something a
little bit more descriptive.

* src/util/virterror.c: Improve error message

The kill() function doesn't exist on Win32, so it needs to be
checked for at build time & code disabled in cgroups

* configure.ac: Check for kill()
* src/util/cgroup.c: Stub out virCGroupKill* functions
  when kill() isn't available

The virCgroupKill method kills all PIDs found in a cgroup

The virCgroupKillRecursively method does this recursively
for child cgroups.

The virCgroupKillPainfully method does a recursive kill
several times in a row until everything has really died

Relax the restriction that the hash table key must be a string
by allowing an arbitrary hash code generator + comparison func
to be provided

* util/hash.c, util/hash.h: Allow any pointer as a key
* internal.h: Include stdbool.h as standard.
* conf/domain_conf.c, conf/domain_conf.c,
  conf/nwfilter_params.c, nwfilter/nwfilter_gentech_driver.c,
  nwfilter/nwfilter_gentech_driver.h, nwfilter/nwfilter_learnipaddr.c,
  qemu/qemu_command.c, qemu/qemu_driver.c,
  qemu/qemu_process.c, uml/uml_driver.c,
  xen/xm_internal.c: s/char */void */ in hash callbacks

Since the deallocator is passed into the constructor of
a hash table it is not desirable to pass it into each
function again. Remove it from all functions, but provide
a virHashSteal to allow a item to be removed from a hash
table without deleteing it.

* src/util/hash.c, src/util/hash.h: Remove deallocator
  param from all functions. Add virHashSteal
* src/libvirt_private.syms: Add virHashSteal
* src/conf/domain_conf.c, src/conf/nwfilter_params.c,
  src/nwfilter/nwfilter_learnipaddr.c,
  src/qemu/qemu_command.c, src/xen/xm_internal.c: Update
  for changed hash API

Replace wrong "set" by correct "seek" in error message.
Signed-off-by: NPhilipp Hahn <hahn@univention.de>

* src/util/cgroup.c (virCgroupAllowDevicePath)
(virCgroupDenyDevicePath): Don't fail with EINVAL for
non-devices.
* src/qemu/qemu_driver.c (qemudDomainSaveFlag): Update caller.
* src/qemu/qemu_cgroup.c (qemuSetupDiskPathAllow)
(qemuSetupChardevCgroup, qemuSetupHostUsbDeviceCgroup)
(qemuSetupCgroup, qemuTeardownDiskPathDeny): Likewise.

valgrind warns:

==21079== Syscall param rt_sigaction(act->sa_mask) points to uninitialised byte(s)
==21079==    at 0x329840F63E: __libc_sigaction (sigaction.c:67)
==21079==    by 0x4E5A8E7: __virExec (util.c:661)

Regression introduced in commit ab07533e.  Technically, sa_mask
shouldn't affect operation if sa_flags selects sa_handler, and
sa_handler selects SIG_IGN, but better safe than sorry.

* src/util/util.c (__virExec): Supply missing sigemptyset.

Remove the <stdbool.h> header from all source files / headers
and just put it into internal.h

* src/internal.h: Add <stdbool.h>

The virFileAbsPath was not taking into account the '/' directory
separator when allocating memory for combining cwd + path. Convert
to use virAsprintf to avoid this type of bug completely.

* src/util/util.c: Convert virFileAbsPath to use virAsprintf

Current code does an IFF_UP on a 8021Qbh interface immediately after a port
profile set. This is ok in most cases except when its the migration prepare
stage. During migration we want to postpone IFF_UP'ing the interface on the
destination host until the source host has disassociated the interface.
This patch moves IFF_UP of the interface to the final stage of migration.
The motivation for this change is to postpone any addr registrations on the
destination host until the source host has done the addr deregistrations.

While at it, for symmetry with associate move ifDown of a 8021Qbh interface
to before disassociate

Done mechanically with:
$ git grep -l '\bDEBUG0\? *(' | xargs -L1 sed -i 's/\bDEBUG0\? *(/VIR_&/'

followed by manual deletion of qemudDebug in daemon/libvirtd.c, along
with a single 'make syntax-check' fallout in the same file, and the
actual deletion in src/util/logging.h.

* src/util/logging.h (DEBUG, DEBUG0): Delete.
* daemon/libvirtd.h (qemudDebug): Likewise.
* global: Change remaining clients over to VIR_DEBUG counterpart.

Two-argument free functions are uncommon; match the style elsewhere
by caching the callback at creation.

* src/util/hash.h (virHashCreate, virHashFree): Move deallocator
argument to creation.
* cfg.mk (useless_free_options): Add virHashFree.
* src/util/hash.c (_virHashTable): Track deallocator.
(virHashCreate, virHashFree): Update to new signature.
* src/conf/domain_conf.c (virDomainObjListDeinit)
(virDomainObjListInit, virDomainDiskDefForeachPath)
(virDomainSnapshotObjListDeinit, virDomainSnapshotObjListInit):
Update callers.
* src/conf/nwfilter_params.c (virNWFilterHashTableFree)
(virNWFilterHashTableCreate): Likewise.
* src/conf/nwfilter_conf.c (virNWFilterTriggerVMFilterRebuild):
Likewise.
* src/cpu/cpu_generic.c (genericHashFeatures, genericBaseline):
Likewise.
* src/xen/xm_internal.c (xenXMOpen, xenXMClose): Likewise.
* src/nwfilter/nwfilter_learnipaddr.c (virNWFilterLearnInit)
(virNWFilterLearnShutdown): Likewise.
* src/qemu/qemu_command.c (qemuDomainPCIAddressSetCreate)
(qemuDomainPCIAddressSetFree): Likewise.
* src/qemu/qemu_process.c (qemuProcessWaitForMonitor): Likewise.

Two regressions:
Commit df1011ca broke builds for systems that lack devmapper
(non-Linux, as well as Linux with ./autogen.sh --without-libvirtd
and without the libraries present).
Commit ce6fd650 broke cross-compilation, due to a gnulib bug.

* .gnulib: Update to latest, for cross-compilation fix.
* src/util/util.c (virIsDevMapperDevice): Provide stub for
platforms not using storage driver.
* configure.ac (devmapper): Arrange to define HAVE_LIBDEVMAPPER_H.
devmapper issue reported by Wen Congyang.

The only difference between these 2 functions is that one errors
out when the entry is already present while the other modifies
the existing entry. Add an helper function with a boolean argument
indicating whether existing entries should be updated or not, and
use this helper in both functions.

The code in virHashUpdateEntry and virHashAddEntry is really
similar. However, the latter rebalances the hash table when
one of its buckets contains too many elements while the former
does not. Fix this discrepancy.

* src/util/hash.c (virHashGrow) [DEBUG_GROW]: Use modern logging.
Reported by Christophe Fergeau.

Followup to commit 17e19add, and would have prevented the bug
independently fixed in commit 76c57a7c.

* src/util/logging.c (virLogMessage): Preserve errno, since
logging should be as unintrusive as possible.