Commit Graph

34 Commits

Author SHA1 Message Date
Kostiantyn Kostiuk 9f34101db0 qga-vss: Use dynamic linking for GLib
The current GLib version implements the DllMain function. DllMain is also
present in the provider.cpp code. So in the case of static linking, the
DllMain redefinition error occurs. For now, just switch to dynamic linking
and revert this patch when the issue will be solved.

See Glib issue for more details https://gitlab.gnome.org/GNOME/glib/-/issues/692

Signed-off-by: Kostiantyn Kostiuk <konstantin@daynix.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-03-06 11:41:54 +01:00
Paolo Bonzini 588a19fa9d meson: convert dummy Windows qga/qemu-ga target
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-08-21 06:30:12 -04:00
Marc-André Lureau 328ec32d7d meson: add msi generation
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-08-21 06:30:12 -04:00
Marc-André Lureau 7272fc7268 meson: convert vss-win32
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-08-21 06:30:12 -04:00
Basil Salman 917ebcb170 qga-win: Fix QGA VSS Provider service stop failure
On one hand "guest-fsfreeze-freeze" command, "COM+ System Application service" is
stopped, on the other hand "guest-fsfreeze-thaw" stops QGA VSS Provider service from
"COM+ Application Admin Catalog".
Invoking a series of freeze and thaw commands may result in QGA failing to stop
VSS Provider service as "COM+ System Application service" is stopped, which can
cause some delay in qga response.
In this commit StopService function was changed and VSS Provider service is now
stopped using Winsvc library API.

BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1549425

Signed-off-by: Basil Salman <bsalman@redhat.com>
Signed-off-by: Basil Salman <basil@daynix.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
2020-07-13 17:13:14 -05:00
Sameeh Jubran b2413df833 qga-win: Handle VSS_E_PROVIDER_ALREADY_REGISTERED error
This patch handles the case where VSS Provider is already registered,
where in such case qga uninstalls the provider and registers it again.

Signed-off-by: Sameeh Jubran <sjubran@redhat.com>
Signed-off-by: Basil Salman <basil@daynix.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
2020-03-24 11:32:19 -05:00
Paolo Bonzini db5adeaa84 build-sys: clean up flags included in the linker command line
Some of the CFLAGS that are discovered during configure, for example
compiler warnings, are being included on the linker command line because
QEMU_CFLAGS is added to it.  Other flags, such as the -m32, appear twice
because they are included in both QEMU_CFLAGS and LDFLAGS.  All this
leads to confusion with respect to what goes in which Makefile variables
(and we have plenty).

So, introduce QEMU_LDFLAGS for flags discovered by configure, following
the lead of QEMU_CFLAGS, and stop adding to it:

1) options that are already in CFLAGS, for example "-g"

2) duplicate options

At the same time, options that _are_ needed by both compiler and linker
must now be added to both QEMU_CFLAGS and QEMU_LDFLAGS, which is clearer.
This is mostly -fsanitize options.  For now, --extra-cflags has this behavior
(but --extra-cxxflags does not).

Meson will not include CFLAGS on the linker command line, do the same in our
build system as well.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-01-24 20:59:17 +01:00
Markus Armbruster a8b991b52d Clean up ill-advised or unusual header guards
Leading underscores are ill-advised because such identifiers are
reserved.  Trailing underscores are merely ugly.  Strip both.

Our header guards commonly end in _H.  Normalize the exceptions.

Done with scripts/clean-header-guards.pl.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20190315145123.28030-7-armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
[Changes to slirp/ dropped, as we're about to spin it off]
2019-05-13 08:58:55 +02:00
Michael Roth 40cebc5811 qga-win: fix VSS build breakage due to unintended gnu99 C++ flag
Commit 7be41675f7 set -std=gnu99 for C code via QEMU_CFLAGS. Currently
we generate a "custom" QEMU_CXXFLAGS for VSS DLL C++ build by
filtering out some options from QEMU_CFLAGS and adding some others.
Since we don't filter out -std=gnu99 currently this breaks builds when
VSS support is enabled.

We could keep the existing approach, filter out -std=gnu99 from
QEMU_CFLAGS, and add -std=gnu++98, like configure currently does for
QEMU_CXXFLAGS, but as it turns out our resulting QEMU_CXXFLAGS would
be exactly what configure already generates, just with these filtered
out:

  -fstack-protector-all -fstack-protector-strong

and these added:

  -Wno-unknown-pragmas -Wno-delete-non-virtual-dtor

So fix the issue by re-using configure-generated QEMU_CXXFLAGS and
just handling these specific changes.

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
2019-03-18 10:24:20 -05:00
Michael Roth 82a58d270c qga-win: include glib when building VSS DLL
Commit 3ebee3b191 defined assert() as g_assert(), but when we build
the VSS DLL component of QGA (to handle fsfreeze) we do not include
glib, which results in breakage when building with VSS support enabled.

Fix this by including glib (along with the -lintl and -lws2_32
dependencies it brings).

Since the VSS DLL is built statically, this introduces an additional
dependency on static glib and supporting libs for the mingw environment
(possibly why we didn't include glib originally), but VSS support
already has very specific prerequisites so it shouldn't affect too many
build environments.

Since the VSS DLL code does use qemu/osdep.h, this should also help
avoid future breakages and possibly allow for some clean ups in current
VSS code.

Suggested-by: Daniel P. Berrangé <berrange@redhat.com>
Cc: Daniel P. Berrangé <berrange@redhat.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
2019-03-18 10:24:20 -05:00
Chen Hanxiao 0692b03ee1 qga-win: add support for qmp_guest_fsfreeze_freeze_list
This patch add support for freeze specified fs.

The valid mountpoints list member are [1]:

  The path of a mounted folder, for example, Y:\MountX\
  A drive letter, for example, D:\
  A volume GUID path of the form \\?\Volume{GUID}\,
      where GUID identifies the volume
  A UNC path that specifies a remote file share,
      for example, \\Clusterx\Share1\

[1] https://docs.microsoft.com/en-us/windows/desktop/api/vsbackup/nf-vsbackup-ivssbackupcomponents-addtosnapshotset

Cc: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Chen Hanxiao <chenhanxiao@gmail.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
2018-10-30 16:48:49 -05:00
Michael Roth 8cedc80555 qga-win: fix error-handling in getNameByStringSID()
In one case we misconstrue a BOOL return as an HRESULT, and in the
other case we don't check the BOOL return from LookupAccountSidW()
before extracting the HRESULT from GetLastError(). Both can lead to
getNameByStringSID() misreporting an error.

Reported-by: Chen Hanxiao <chenhanxiao@gmail.com>
Suggested-by: Tomáš Golembiovský <tgolembi@redhat.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
2017-10-26 20:01:32 -05:00
Chen Hanxiao 4d80d20fe1 qga-win: don't hang if vss hold writes timeout
When VM is in a heavy IO, if the command "guest-fsfreeze-freeze"
is executed, VSS may timeout when trying to hold writes.

Inside guest, Event ID 12298(VSS_ERROR_HOLD_WRITES_TIMEOUT)
is logged in the Event Viewer.

At that time, if we call AbortBackup, qga may hang forever.

This patch will solve this issue.

Cc: Michael Roth <mdroth@linux.vnet.ibm.com>
Cc: Tomoki Sekiyama <tomoki.sekiyama@gmail.com>

Signed-off-by: Chen Hanxiao <chenhanxiao@gmail.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
2017-10-25 17:12:26 -05:00
Daniel Rempel 009f38d985 qga-win: fix installation on localized windows
Bug: https://bugzilla.redhat.com/show_bug.cgi?id=1357789
Replace hardcoded user and group names ("Administrators", "SYSTEM") with the ones acquired from system. Windows uses localized strings for these names and it may cause the installation to fail.
Windows has Well-known SIDs for "Administrators" group and "SYSTEM" user so they were used to identify required users and groups.
Well-known SIDs: https://support.microsoft.com/en-us/help/243330/well-known-security-identifiers-in-windows-operating-systems

Signed-off-by: Daniel Rempel <daniel@daynix.com>
Signed-off-by: Sameeh Jubran <sjubran@redhat.com>
Reviewed-by: Sameeh Jubran <sameeh@daynix.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
2017-07-17 18:51:14 -05:00
Sameeh Jubran 1529605337 qga-win: Fix Event Viewer errors caused by qemu-ga
When the command "guest-fsfreeze-freeze" is executed it causes
the VSS service to log the error below in the Event Viewer. This
error is caused by an issue in the function "CommitSnapshots" in
provider.cpp:

* When VSS_TIMEOUT_MSEC expires the funtion returns E_ABORT. This causes
the error #12293.

|event id|                           error                               |
* 12293  : Volume Shadow Copy Service error: Error calling a routine on a
           Shadow Copy Provider {00000000-0000-0000-0000-000000000000}.
           Routine details CommitSnapshots [hr = 0x80004004, Operation
           aborted.

Signed-off-by: Sameeh Jubran <sameeh@daynix.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
2017-04-26 23:56:47 -05:00
Sameeh Jubran 94d81ae896 qga-win: Fix a bug where qemu-ga service is stuck during stop operation
After triggering a freeze command without any following thaw command,
qemu-ga will not respond to stop operation. This behaviour is wanted on Linux
as there is no time limit for a freeze command and we want to prevent
quitting in the middle of freeze, on the other hand on Windows the time
limit for freeze is 10 seconds, so we should wait for the timeout, thaw
the file system and quit.

Signed-off-by: Sameeh Jubran <sameeh@daynix.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
2017-04-26 23:56:47 -05:00
Sameeh Jubran f342cc93ec qemu-ga: Make QGA VSS provider service run only when needed
Currently the service runs in background on boot even though it is not
needed and once it is running it never stops. The service needs to be
running only during freeze operation and it should be stopped after
executing thaw.

Signed-off-by: Sameeh Jubran <sameeh@daynix.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
2017-04-26 23:56:46 -05:00
Peter Maydell 0bdb12c7c5 rules.mak: quiet-command: Split command name and args to print
The quiet-command make rule currently takes two arguments:
the command and arguments to run, and a string to print if
the V flag is not set (ie we are not being verbose).
By convention, the string printed is of the form
"  NAME   some args". Unfortunately to get nicely lined up
output all the strings have to agree about what column the
arguments should start in, which means that if we add a
new quiet-command usage which wants a slightly longer CMD
name then we either put up with misalignment or change
every quiet-command string.

Split the quiet-mode string into two, the "NAME" and
the "same args" part, and use printf(1) to format the
string automatically. This means we only need to change
one place if we want to support a longer maximum name.

In particular, we can now print 7-character names lined
up properly (they are needed for the OSX "SETTOOL" invocation).

Change all the uses of quiet-command to the new syntax.
(Any which are missed or inadvertently reintroduced
via later merges will result in slightly misformatted
quiet output rather than disaster.)

A few places in the pc-bios/ makefiles are updated to use
"BUILD", "SIGN" and "STRIP" rather than "Building",
"Signing" and "Stripping" for consistency and to keep them
below 7 characters. Module .mo links now print "LD" rather
than the nonstandard "LD -r".

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 1475598441-27908-1-git-send-email-peter.maydell@linaro.org
2016-10-06 12:11:51 +01:00
Markus Armbruster 121d07125b Clean up header guards that don't match their file name
Header guard symbols should match their file name to make guard
collisions less likely.  Offenders found with
scripts/clean-header-guards.pl -vn.

Cleaned up with scripts/clean-header-guards.pl, followed by some
renaming of new guard symbols picked by the script to better ones.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Richard Henderson <rth@twiddle.net>
2016-07-12 16:19:16 +02:00
Markus Armbruster a9c94277f0 Use #include "..." for our own headers, <...> for others
Tracked down with an ugly, brittle and probably buggy Perl script.

Also move includes converted to <...> up so they get included before
ours where that's obviously okay.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Tested-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Richard Henderson <rth@twiddle.net>
2016-07-12 16:19:16 +02:00
Markus Armbruster c80f6e9caa Clean up includes some more
Manually drop redundant includes that scripts/clean-includes misses,
e.g. because they're hidden in generator programs, or they use the
wrong kind of delimiter.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-03-22 22:20:16 +01:00
Michael Roth e55eb806db qga: fix w32 breakage due to missing osdep.h includes
requester.h relied on qemu/compiler.h definitions to
handle GCC_FMT_ATTR() stub, but this include was removed as part
of scripted clean-ups via 30456d5:

  all: Clean up includes

under the assumption that all C files would have included it via
qemu/osdep.h at that point. requester.cpp was likely missed
due to C++ files requiring manual/special handling as well as
VSS build options needing to be enabled to trigger build failures.

Fix this by including qemu/osdep.h. That in turn pulls in a
macro from qapi/error.h that conflicts with a struct field name
in requester.h, so fix that as well by renaming the field.

While we're at it, fix up provider.cpp/install.cpp to include
osdep.h as well.

Cc: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
2016-02-25 10:54:32 -06:00
Peter Maydell 30456d5ba3 all: Clean up includes
Clean up includes so that osdep.h is included first and headers
which it implies are not included manually.

This commit was created with scripts/clean-includes.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
2016-02-23 12:43:05 +00:00
Markus Armbruster 1e9b65bb1b error: On abort, report where the error was created
This is particularly useful when we abort in error_propagate(),
because there the stack backtrace doesn't lead to where the error was
created.  Looks like this:

    Unexpected error in parse_block_error_action() at .../qemu/blockdev.c:322:
    qemu-system-x86_64: -drive if=none,werror=foo: 'foo' invalid write error action
    Aborted (core dumped)

Note: to get this example output, I monkey-patched drive_new() to pass
&error_abort to blockdev_init().

To keep the error handling boiler plate from growing even more, all
error_setFOO() become macros expanding into error_setFOO_internal()
with additional __FILE__, __LINE__, __func__ arguments.  Not exactly
pretty, but it works.

The macro trickery breaks down when you take the address of an
error_setFOO().  Fortunately, we do that in just one place: qemu-ga's
Windows VSS provider and requester DLL wants to call
error_setg_win32() through a function pointer "to avoid linking glib
to the DLL".  Use error_setg_win32_internal() there.  The use of the
function pointer is already wrapped in a macro, so the churn isn't
bad.

Code size increases by some 35KiB for me (0.7%).  Tolerable.  Could be
less if we passed relative rather than absolute source file names to
the compiler, or forwent reporting __func__.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
2015-09-10 13:48:06 +02:00
Markus Armbruster 08e6464035 qga/vss-win32: Document the DLL requires non-null errp
requester.cpp uses this pattern to receive an error and pass it on to
the caller (err_is_set() macro peeled off for clarity):

    ... code that may set errset->errp ...
    if (errset->errp && *errset->errp) {
        ... handle error ...
    }

This breaks when errset->errp is null.  As far as I can tell, it
currently isn't, so this is merely fragile, not actually broken.

The robust way to do this is to receive the error in a local variable,
then propagate it up, like this:

    Error *err = NULL;

    ... code that may set err ...
    if (err)
        ... handle error ...
        error_propagate(errset->errp, err);
    }

See also commit 5e54769, 0f230bf, a903f40.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
2015-09-10 13:48:06 +02:00
Markus Armbruster e7cf59e847 qga: Clean up unnecessarily dirty casts
qga_vss_fsfreeze() casts error_set_win32() from

    void (*)(Error **, int, ErrorClass, const char *, ...)

to

    void (*)(void **, int, int, const char *, ...)

The result is later called.  Since the two types are not compatible,
the call is undefined behavior.  It works in practice anyway.

However, there's no real need for trickery here.  Clean it up as
follows:

* Declare struct Error, and fix the first parameter.

* Switch to error_setg_win32().  This gets rid of the troublesome
  ErrorClass parameter.  Requires converting error_setg_win32() from
  macro to function, but that's trivially easy, because this is the
  only user of error_set_win32().

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
2015-09-10 13:48:06 +02:00
Joseph Hindin 420957a598 qga: fitering out -fstack-protector-strong
configure script may add -fstack-protector-strong option instead
of -fstack-protector-all, depending on availability ( see
commit 63678e17c ). Both options have to by filtered out for
qga-vss.dll, otherwise MinGW cross-compilation fails at linking
stage.

Signed-off-by: Joseph Hindin <jhindin@daynix.com>
Message-Id: <1427906337-20805-2-git-send-email-jhindin@daynix.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-04-02 15:57:27 +02:00
Tomoki Sekiyama 9854202b57 vss-win32: Fix build with mingw64-headers-3.1.0
In mingw64-headers-3.1.0, definition of _com_issue_error() is added, which
conflicts with definition in install.cpp. This adds version checking for
mingw headers to disable the definition when the headers>=3.1 is used.

Signed-off-by: Tomoki Sekiyama <tomoki.sekiyama@hds.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
2014-04-07 14:39:19 -05:00
Tomoki Sekiyama d9e1f574cb qga: vss-win32: Fix interference with snapshot deletion by other VSS request
When a VSS requester such as vshadow.exe or diskshadow.exe requests to
delete snapshots, qemu-ga VSS provider's DeleteSnapshots() is also called
and returns E_NOTIMPL, that makes the deletion fail.
To avoid this issue, return S_OK and set values that represent no snapshots
are deleted by qemu-ga VSS provider.

Signed-off-by: Tomoki Sekiyama <tomoki.sekiyama@hds.com>
Reviewed-by: Gal Hammer <ghammer@redhat.com>
Reviewed-by: Yan Vugenfirer <yvugenfi@redhat.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
2014-02-23 13:11:52 -06:00
Tomoki Sekiyama ff8adbcfdb qga: vss-win32: Fix interference with snapshot creation by other VSS requesters
When a VSS requester such as vshadow.exe or diskshadow.exe requests to
create disk snapshots, Windows may choose qemu-ga VSS provider if it is
only provider registered on the system. However, because it provides only a
function to freeze the filesystem, the snapshotting fails.

This patch adds a check into CQGAVssProvider::IsVolumeSupported() to reject
the request from other VSS requesters, so that the other provider is chosen.

The check of requester is done by confirming event channels between
qemu-ga's requester and provider established. To ensure that the events are
initialized when CQGAVssProvider::IsVolumeSupported() is called, it moves
the initialization earlier.

Signed-off-by: Tomoki Sekiyama <tomoki.sekiyama@hds.com>
Reviewed-by: Gal Hammer <ghammer@redhat.com>
Reviewed-by: Yan Vugenfirer <yvugenfi@redhat.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
2014-02-23 13:11:26 -06:00
Tomoki Sekiyama 4c1b8f1e83 qga: vss-win32: Use NULL as an invalid pointer for OpenEvent and CreateEvent
OpenEvent and CreateEvent WinAPI return NULL when failed to open/create
events handles, instead of INVALID_HANDLE_VALUE (although their return
types are HANDLE).
This replaces INVALID_HANDLE_VALUE related to event handles with NULL.

Signed-off-by: Tomoki Sekiyama <tomoki.sekiyama@hds.com>
Reviewed-by: Gal Hammer <ghammer@redhat.com>
Reviewed-by: Yan Vugenfirer <yvugenfi@redhat.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
2014-02-23 13:10:20 -06:00
Tomoki Sekiyama bca4bf1028 qemu-ga: vss-win32: Install VSS provider COM+ application service
Currently, qemu-ga for Windows fails to execute guset-fsfreeze-freeze when
no user is logging in to Windows, with an error message:
  {"error":{"class":"GenericError",
            "desc":"failed to add C:\\ to snapshotset:  (error: 8004230f)"}}

To enable guest-fsfreeze-freeze/thaw without logging in users, this installs
a service to execute qemu-ga VSS provider COM+ application that has full
access privileges to the local system. The service will automatically be
removed when the COM+ application is deregistered.

This patch replaces ICOMAdminCatalog interface with ICOMAdminCatalog2
interface that contains CreateServiceForApplication() method in addition.

Signed-off-by: Tomoki Sekiyama <tomoki.sekiyama@hds.com>
Reviewed-by: Gal Hammer <ghammer@redhat.com>
Reviewed-by: Yan Vugenfirer <yvugenfi@redhat.com>
Tested-by: Yan Vugenfirer <yvugenfi@redhat.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
2013-11-22 15:14:05 -06:00
Stefan Weil ba1c293109 qga: Fix compilation for old versions of MinGW
While MinGW-w64 can compile the qga code, MinGW from Debian lenny
(gcc-mingw32 4.4.2-3) shows these errors:

In file included from qga/vss-win32.c:17:
qga/vss-win32/requester.h:31:
 error: expected »=«, »,«, »;«, »asm« or »__attribute__« before »requester_init«
qga/vss-win32/requester.h:32:
 error: expected »=«, »,«, »;«, »asm« or »__attribute__« before »requester_deinit«

The macro STDAPI is unknown, so add the missing include file which
defines it.

Signed-off-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
2013-11-13 15:59:06 +04:00
Tomoki Sekiyama b39297aedf qemu-ga: Add Windows VSS provider and requester as DLL
Adds VSS provider and requester as a qga-vss.dll, which is loaded by
Windows VSS service as well as by qemu-ga.

"provider.cpp" implements a basic stub of a software VSS provider.
Currently, this module only relays a frozen event from VSS service to the
agent, and thaw event from the agent to VSS service, to block VSS process
to keep the system frozen while snapshots are taken at the host.

To register the provider to the guest system as COM+ application, the type
library (.tlb) for qga-vss.dll is required. To build it from COM IDL (.idl),
VisualC++, MIDL and stdole2.tlb in Windows SDK are required. This patch also
adds pre-compiled .tlb file in the repository in order to enable
cross-compile qemu-ga.exe for Windows with VSS support.

"requester.cpp" provides the VSS requester to kick the VSS snapshot process.
Qemu-ga.exe works without the DLL, although fsfreeze features are disabled.

These functions are only supported in Windows 2003 or later. In older
systems, fsfreeze features are disabled.

In several versions of Windows which don't support attribute
VSS_VOLSNAP_ATTR_NO_AUTORECOVERY, DoSnapshotSet fails with error
VSS_E_OBJECT_NOT_FOUND. In this patch, we just ignore this error.
To solve this fundamentally, we need a framework to handle mount writable
snapshot on guests, which is required by VSS auto-recovery feature
(cleanup phase after a snapshot is taken).

Signed-off-by: Tomoki Sekiyama <tomoki.sekiyama@hds.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
2013-09-09 14:17:57 -05:00