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2015-09-10error: On abort, report where the error was createdMarkus Armbruster2-4/+7
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>
2015-09-10qga/vss-win32: Document the DLL requires non-null errpMarkus Armbruster2-2/+3
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>
2015-09-10qga: Clean up unnecessarily dirty castsMarkus Armbruster2-6/+7
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>
2015-04-02qga: fitering out -fstack-protector-strongJoseph Hindin1-1/+1
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>
2014-04-07vss-win32: Fix build with mingw64-headers-3.1.0Tomoki Sekiyama1-0/+3
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>
2014-02-23qga: vss-win32: Fix interference with snapshot deletion by other VSS requestTomoki Sekiyama1-1/+3
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>
2014-02-23qga: vss-win32: Fix interference with snapshot creation by other VSS requestersTomoki Sekiyama2-27/+36
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>
2014-02-23qga: vss-win32: Use NULL as an invalid pointer for OpenEvent and CreateEventTomoki Sekiyama2-17/+13
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>
2013-11-22qemu-ga: vss-win32: Install VSS provider COM+ application serviceTomoki Sekiyama1-6/+10
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>
2013-11-13qga: Fix compilation for old versions of MinGWStefan Weil1-0/+1
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>
2013-09-09qemu-ga: Add Windows VSS provider and requester as DLLTomoki Sekiyama9-0/+1715
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>