Each backing store of a given disk is associated with a unique index
(which is also formatted in domain XML) for easier addressing of any
particular backing store. With this patch, any backing store can be
addressed by its disk target and the index. For example, "vdc[4]"
addresses the backing store with index equal to 4 of the disk identified
by "vdc" target. Such shorthand can be used in any API in place for a
backing file path:
virsh blockcommit domain vda --base vda[3] --top vda[2]
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
To avoid having the root of a backing chain present twice in the list we
need to invert the working of virStorageFileGetMetadataRecurse.
Until now the recursive worker created a new backing chain element from
the name and other information passed as arguments. This required us to
pass the data of the parent in a deconstructed way and the worker
created a new entry for the parent.
This patch converts this function so that it just fills in metadata
about the parent and creates a backing chain element from those. This
removes the duplication of the first element.
To avoid breaking the test suite, virstoragetest now calls a wrapper
that creates the parent structure explicitly and pre-fills it with the
test data with same function signature as previously used.
Add the required fields that are missing from the new structure that
will allow us to switch the storage file metadata code entirely to the
new structure.
Add "relPath" and "relDir" and the raw backing store name. Also allow
creating linked lists of virStorageSourcePtrs to express backing chains.
Remove the obsolete field replaced by data in "path".
The testsuite requires tweaking as the name of the backing file is now
stored one layer deeper in the backing chain linked list.
As for the previous patch, this change is needed to achieve
compatibility with all the existing code, where we expect a fully
qualified path of local files to be present.
To allow future change of virStorageFileMetadata to virStorageSource we
need to store a full path in the "path" variable as rest of the code
expects it to be a full path. Rename the "path" field to "relPath" to
keep tracking the info but allowing a real "path" field.
Domain snapshots should only permit an external snapshot into
a storage format that permits a backing chain, since the new
snapshot file necessarily must be backed by the existing file.
The C code for the qemu driver is a little bit stricter in
currently enforcing only qcow2 or qed, but at the XML parser
level, including virt-xml-validate, it is fairly easy to
enforce that a user can't request a 'raw' external snapshot.
* docs/schemas/storagecommon.rng (storageFormat): Split out...
(storageFormatBacking): ...new sublist.
* docs/schemas/domainsnapshot.rng (disksnapshotdriver): Use new
type.
* src/util/virstoragefile.h (virStorageFileFormat): Rearrange for
easier code management.
* src/util/virstoragefile.c (virStorageFileFormat, fileTypeInfo):
Likewise.
* src/conf/snapshot_conf.c (virDomainSnapshotDiskDefParseXML): Use
new marker to limit selection of formats.
Signed-off-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
Another field no longer needed, getting us one step closer to
merging virStorageFileMetadata and virStorageSource.
* src/util/virstoragefile.h (_virStorageFileMetadata): Drop
field.
* src/util/virstoragefile.c (virStorageFileGetMetadataInternal)
(virStorageFileGetMetadataFromFDInternal): Alter signature.
(virStorageFileFreeMetadata, virStorageFileGetMetadataFromBuf)
(virStorageFileGetMetadataFromFD): Adjust clients.
* tests/virstoragetest.c (_testFileData, testStorageChain)
(mymain): Simplify test.
Signed-off-by: Eric Blake <eblake@redhat.com>
The original chain lookup code had to pass in the starting name,
because it was not available in the chain. But now that we have
added fields to the struct, this parameter is redundant.
* src/util/virstoragefile.h (virStorageFileChainLookup): Alter
signature.
* src/util/virstoragefile.c (virStorageFileChainLookup): Adjust
handling of top of chain.
* src/qemu/qemu_driver.c (qemuDomainBlockCommit): Adjust caller.
* tests/virstoragetest.c (testStorageLookup, mymain): Likewise.
Signed-off-by: Eric Blake <eblake@redhat.com>
Drop another redundant field from virStorageFileMetadata.
* src/util/virstoragefile.h (_virStorageFileMetadata): Drop
field.
* src/util/virstoragefile.c
(virStorageFileGetMetadataFromFDInternal)
(virStorageFileGetMetadataFromFD)
(virStorageFileGetMetadataRecurse): Adjust callers.
* tests/virstoragetest.c (_testFileData, testStorageChain)
(mymain): Simplify test.
Signed-off-by: Eric Blake <eblake@redhat.com>
A couple pieces of virStorageFileMetadata are used only while
collecting information about the chain, and don't need to
live permanently in the struct. This patch refactors external
callers to collect the information separately, so that the
next patch can remove the fields.
* src/util/virstoragefile.h (virStorageFileGetMetadataFromBuf):
Alter signature.
* src/util/virstoragefile.c (virStorageFileGetMetadataInternal):
Likewise.
(virStorageFileGetMetadataFromFDInternal): Adjust callers.
* src/storage/storage_backend_fs.c (virStorageBackendProbeTarget):
Likewise.
* src/storage/storage_backend_gluster.c
(virStorageBackendGlusterRefreshVol): Likewise.
Signed-off-by: Eric Blake <eblake@redhat.com>
Finally starting to prune away some of the old fields that have
been made redundant by the new fields, on my way towards directly
reusing virStorageSource.
* src/util/virstoragefile.h (_virStorageFileMetadata): Drop
field.
* src/util/virstoragefile.c (virStorageFileGetMetadataInternal)
(virStorageFileChainLookup): Adjust callers.
* tests/virstoragetest.c (_testFileData, testStorageChain)
(mymain): Simplify test.
Signed-off-by: Eric Blake <eblake@redhat.com>
Deciding if a user string represents a local file instead of a
network path is an operation worth exposing directly, particularly
since the next patch will be removing a redundant variable that
was caching the information.
* src/util/virstoragefile.h (virStorageIsFile): New declaration.
* src/util/virstoragefile.c (virBackingStoreIsFile): Rename...
(virStorageIsFile): ...export, and allow NULL input.
(virStorageFileGetMetadataInternal)
(virStorageFileGetMetadataRecurse, virStorageFileGetMetadata):
Update callers.
* src/conf/domain_conf.c (virDomainDiskDefForeachPath): Use it.
* src/storage/storage_backend_fs.c (virStorageBackendProbeTarget):
Likewise.
* src/libvirt_private.syms (virstoragefile.h): Export function.
Signed-off-by: Eric Blake <eblake@redhat.com>
The current use of virStorageFileMetadata is awkward; to learn
some of the information about a child node, you have to read
fields in the parent node. This does not lend itself well to
modifying backing chains (whether inserting a new node in the
chain, or consolidating existing nodes); better would be to
learn about a child node directly in that node. This patch
sets up some new fields which contain redundant information,
although not necessarily in the final desired state for the
new fields (see the next patch for actual tests of what is there
now). Then later patches will do any refactoring necessary to
get the fields to their desired states, and update clients to
get the information from the new fields, so we can finally
delete the fields that are tracking information about the wrong
node.
More concretely, compare these three example backing chains:
good <- one
missing <- two
gluster://server/vol/img <- three
Pre-patch, querying the chains gives:
{ .backingStore = "/path/to/good",
.backingStoreRaw = "good",
.backingStoreIsFile = true,
.backingStoreFormat = VIR_STORAGE_FILE_RAW,
.backingMeta = {
.backingStore = NULL,
.backingStoreRaw = NULL,
.backingStoreIsFile = false,
.backingMeta = NULL,
}
}
{ .backingStore = NULL,
.backingStoreRaw = "missing",
.backingStoreIsFile = false,
.backingStoreFormat = VIR_STORAGE_FILE_NONE,
.backingMeta = NULL,
}
{ .backingStore = "gluster://server/vol/img",
.backingStoreRaw = NULL,
.backingStoreIsFile = false,
.backingStoreFormat = VIR_STORAGE_FILE_RAW,
.backingMeta = NULL,
}
Deciding whether to ignore a missing backing file (as in virsh
vol-dumpxml) or report an error (as in security manager sVirt
labeling) requires reading multiple fields. Plus, the format
is hard-coded to treat all network protocols as end-of-the-chain,
as if they were raw. By the end of this patch series, the goal
is to instead represent these three situations as:
{ .path = "one",
.canonPath = "/path/to/one",
.type = VIR_STORAGE_TYPE_FILE,
.format = VIR_STORAGE_FILE_QCOW2,
.backingStoreRaw = "good",
.backingMeta = {
.path = "good",
.canonPath = "/path/to/good",
.type = VIR_STORAGE_TYPE_FILE,
.format = VIR_STORAGE_FILE_RAW,
.backingStoreRaw = NULL,
.backingMeta = NULL,
}
}
{ .path = "two",
.canonPath = "/path/to/two",
.type = VIR_STORAGE_TYPE_FILE,
.format = VIR_STORAGE_FILE_QCOW2,
.backingStoreRaw = "missing",
.backingMeta = NULL,
}
{ .path = "three",
.canonPath = "/path/to/three",
.type = VIR_STORAGE_TYPE_FILE,
.format = VIR_STORAGE_FILE_QCOW2,
.backingStoreRaw = "gluster://server/vol/img",
.backingMeta = {
.path = "gluster://server/vol/img",
.canonPath = "gluster://server/vol/img",
.type = VIR_STORAGE_TYPE_NETWORK,
.format = VIR_STORAGE_FILE_RAW,
.backingStoreRaw = NULL,
.backingMeta = NULL,
}
}
or, for the second file, maybe also allowing:
{ .path = "two",
.canonPath = "/path/to/two",
.type = VIR_STORAGE_TYPE_FILE,
.format = VIR_STORAGE_FILE_QCOW2,
.backingStoreRaw = "missing",
.backingMeta = {
.path = "missing",
.canonPath = NULL,
.type = VIR_STORAGE_TYPE_NONE,
.format = VIR_STORAGE_FILE_NONE,
.backingStoreRaw = NULL,
.backingMeta = NULL,
}
}
* src/util/virstoragefile.h (_virStorageFileMetadata): Add
path, canonPath, relDir, type, and format fields. Reorder
existing fields, and add lots of comments.
* src/util/virstoragefile.c (virStorageFileFreeMetadata): Clean
new fields.
(virStorageFileGetMetadataInternal)
(virStorageFileGetMetadataFromFDInternal): Start populating new
fields.
Signed-off-by: Eric Blake <eblake@redhat.com>
Now that we store all metadata about a storage image in a
virStorageSource struct let's use it also to store information needed by
the storage driver to access and do operations on the files.
I noticed that the apparmor code could request metadata even
for a cdrom with no media, which would cause a memory leak of
the hash table used to look for loops in the backing chain.
But even before that, we blindly dereferenced the path for
printing a debug statement, so it is just better to enforce
that this is only used on non-NULL names.
* src/util/virstoragefile.c (virStorageFileGetMetadata): Assume
non-NULL path.
* src/util/virstoragefile.h: Annotate this.
* src/security/virt-aa-helper.c (get_files): Fix caller.
Signed-off-by: Eric Blake <eblake@redhat.com>
Right now, virStorageFileMetadata tracks bool backingStoreIsFile
for whether the backing string specified in metadata can be
resolved as a file (covering both block and regular file
resources) or is treated as a network protocol. But when
merging this struct with virStorageSource, it will be easier
to just actually track which type of resource it is, as well
as have a reserved value for the case where the resource type
is unknown (or had an error during probing).
* src/util/virstoragefile.h (virStorageType): Add a placeholder
value, swap order to match similar public enum.
* src/util/virstoragefile.c (virStorage): Update string mapping.
* src/conf/domain_conf.c (virDomainDiskSourceParse)
(virDomainDiskDefParseXML, virDomainDiskDefFormat)
(virDomainDiskSourceFormat): Adjust clients.
* src/conf/snapshot_conf.c (virDomainSnapshotDiskDefParseXML):
Likewise.
* src/qemu/qemu_driver.c
(qemuDomainSnapshotPrepareDiskExternalBackingInactive)
(qemuDomainSnapshotPrepareDiskExternalOverlayActive)
(qemuDomainSnapshotPrepareDiskExternalOverlayInactive)
(qemuDomainSnapshotPrepareDiskInternal)
(qemuDomainSnapshotCreateSingleDiskActive): Likewise.
* src/qemu/qemu_command.c (qemuGetDriveSourceString): Likewise.
Signed-off-by: Eric Blake <eblake@redhat.com>
A future patch will merge virStorageFileMetadata and virStorageSource,
but I found it easier to do if both structs use the same information
for tracking whether a source file needs encryption keys.
* src/util/virstoragefile.h (_virStorageFileMetadata): Prepare
full encryption struct instead of just a bool.
* src/storage/storage_backend_fs.c (virStorageBackendProbeTarget):
Use transfer semantics.
* src/storage/storage_backend_gluster.c
(virStorageBackendGlusterRefreshVol): Likewise.
* src/util/virstoragefile.c (virStorageFileGetMetadataInternal):
Populate struct.
(virStorageFileFreeMetadata): Adjust clients.
* tests/virstoragetest.c (testStorageChain): Likewise.
Signed-off-by: Eric Blake <eblake@redhat.com>
One of the features of qcow2 is that a wrapper file can have
more capacity than its backing file from the guest's perspective;
what's more, sparse files make tracking allocation of both
the active and backing file worthwhile. As such, it makes
more sense to show allocation numbers for each file in a chain,
and not just the top-level file. This sets up the fields for
the tracking, although it does not modify XML to display any
new information.
* src/util/virstoragefile.h (_virStorageSource): Add fields.
* src/conf/storage_conf.h (_virStorageVolDef): Drop redundant
fields.
* src/storage/storage_backend.c (virStorageBackendCreateBlockFrom)
(createRawFile, virStorageBackendCreateQemuImgCmd)
(virStorageBackendCreateQcowCreate): Update clients.
* src/storage/storage_driver.c (storageVolDelete)
(storageVolCreateXML, storageVolCreateXMLFrom, storageVolResize)
(storageVolWipeInternal, storageVolGetInfo): Likewise.
* src/storage/storage_backend_fs.c (virStorageBackendProbeTarget)
(virStorageBackendFileSystemRefresh)
(virStorageBackendFileSystemVolResize)
(virStorageBackendFileSystemVolRefresh): Likewise.
* src/storage/storage_backend_logical.c
(virStorageBackendLogicalMakeVol)
(virStorageBackendLogicalCreateVol): Likewise.
* src/storage/storage_backend_scsi.c
(virStorageBackendSCSINewLun): Likewise.
* src/storage/storage_backend_mpath.c
(virStorageBackendMpathNewVol): Likewise.
* src/storage/storage_backend_rbd.c
(volStorageBackendRBDRefreshVolInfo)
(virStorageBackendRBDCreateImage): Likewise.
* src/storage/storage_backend_disk.c
(virStorageBackendDiskMakeDataVol)
(virStorageBackendDiskCreateVol): Likewise.
* src/storage/storage_backend_sheepdog.c
(virStorageBackendSheepdogBuildVol)
(virStorageBackendSheepdogParseVdiList): Likewise.
* src/storage/storage_backend_gluster.c
(virStorageBackendGlusterRefreshVol): Likewise.
* src/conf/storage_conf.c (virStorageVolDefFormat)
(virStorageVolDefParseXML): Likewise.
* src/test/test_driver.c (testOpenVolumesForPool)
(testStorageVolCreateXML, testStorageVolCreateXMLFrom)
(testStorageVolDelete, testStorageVolGetInfo): Likewise.
* src/esx/esx_storage_backend_iscsi.c (esxStorageVolGetXMLDesc):
Likewise.
* src/esx/esx_storage_backend_vmfs.c (esxStorageVolGetXMLDesc)
(esxStorageVolCreateXML): Likewise.
* src/parallels/parallels_driver.c (parallelsAddHddByVolume):
Likewise.
* src/parallels/parallels_storage.c (parallelsDiskDescParseNode)
(parallelsStorageVolDefineXML, parallelsStorageVolCreateXMLFrom)
(parallelsStorageVolDefRemove, parallelsStorageVolGetInfo):
Likewise.
* src/vbox/vbox_tmpl.c (vboxStorageVolCreateXML)
(vboxStorageVolGetXMLDesc): Likewise.
* tests/storagebackendsheepdogtest.c (test_vdi_list_parser):
Likewise.
* src/phyp/phyp_driver.c (phypStorageVolCreateXML): Likewise.
Another step towards unification of structures. While we might
not expose everything in XML via domain disk as we do for
storage volume pointer, both places want to deal with (at least
part of) the backing chain; therefore, moving towards a single
struct usable from both contexts will make the backing chain
code more reusable.
* src/conf/storage_conf.h (_virStoragePerms)
(virStorageTimestamps): Move...
* src/util/virstoragefile.h: ...here.
(_virStorageSource): Add more fields.
* src/util/virstoragefile.c (virStorageSourceClear): Clean
additional fields.
Signed-off-by: Eric Blake <eblake@redhat.com>
Move some functions out of domain_conf for use in the next
patch where snapshot starts to directly use structs in
virstoragefile.
* src/conf/domain_conf.c (virDomainDiskDefFree)
(virDomainDiskSourcePoolDefParse): Adjust callers.
(virDomainDiskSourceDefClear, virDomainDiskSourcePoolDefFree)
(virDomainDiskAuthClear): Move...
* src/util/virstoragefile.c (virStorageSourceClear)
(virStorageSourcePoolDefFree, virStorageSourceAuthClear): ...and
rename.
* src/conf/domain_conf.h (virDomainDiskAuthClear): Drop
declaration.
* src/qemu/qemu_conf.c (qemuTranslateDiskSourcePool): Adjust
caller.
* src/util/virstoragefile.h: Declare them.
* src/libvirt_private.syms (virstoragefile.h): Export them.
Signed-off-by: Eric Blake <eblake@redhat.com>
The code in virstoragefile.c is getting more complex as I
consolidate backing chain handling code. But for the setuid
virt-login-shell, we don't need to crawl backing chains. It's
easier to audit things for setuid security if there are fewer
files involved, so this patch moves the one function that
virFileOpen() was actually relying on to also live in virfile.c.
* src/util/virstoragefile.c (virStorageFileIsSharedFS)
(virStorageFileIsSharedFSType): Move...
* src/util/virfile.c (virFileIsSharedFS, virFileIsSharedFSType):
...to here, and rename.
(virFileOpenAs): Update caller.
* src/security/security_selinux.c
(virSecuritySELinuxSetFileconHelper)
(virSecuritySELinuxSetSecurityAllLabel)
(virSecuritySELinuxRestoreSecurityImageLabelInt): Likewise.
* src/security/security_dac.c
(virSecurityDACRestoreSecurityImageLabelInt): Likewise.
* src/qemu/qemu_driver.c (qemuOpenFileAs): Likewise.
* src/qemu/qemu_migration.c (qemuMigrationIsSafe): Likewise.
* src/util/virstoragefile.h: Adjust declarations.
* src/util/virfile.h: Likewise.
* src/libvirt_private.syms (virfile.h, virstoragefile.h): Move
symbols as appropriate.
Signed-off-by: Eric Blake <eblake@redhat.com>
With this patch, all information related to a host resource in
a storage file backing chain now lives in util/virstoragefile.h.
The next step will be to consolidate various places that have
been tracking backing chain details to all use a common struct.
The changes to tools/Makefile.am were made necessary by the
fact that virstorageencryption includes uses of libxml, and is
now pulled in by inclusion from virstoragefile.h. No
additional libraries are linked into the final image, and in
comparison, the build of the setuid library in src/Makefile.am
already was using LIBXML_CFLAGS via AM_CFLAGS.
* src/conf/domain_conf.h (virDomainDiskSourceDef): Move...
* src/util/virstoragefile.h (virStorageSource): ...and rename.
* src/conf/domain_conf.c (virDomainDiskSourceDefClear)
(virDomainDiskAuthClear): Adjust clients.
* tools/Makefile.am (virt_login_shell_CFLAGS)
(virt_host_validate_CFLAGS): Add libxml headers.
Signed-off-by: Eric Blake <eblake@redhat.com>
This one is a relatively easy move. We don't ever convert the
enum to or from strings (it is inferred from other elements in
the xml, rather than directly represented).
* src/conf/domain_conf.h (virDomainDiskSecretType): Move...
* src/util/virstoragefile.h (virStorageSecreteType): ...and
rename.
* src/conf/domain_conf.c (virDomainDiskSecretType): Drop unused
enum conversion.
(virDomainDiskAuthClear, virDomainDiskDefParseXML)
(virDomainDiskDefFormat): Adjust clients.
* src/qemu/qemu_command.c (qemuGetSecretString): Likewise.
* src/qemu/qemu_conf.c (qemuTranslateDiskSourcePoolAuth):
Likewise.
Signed-off-by: Eric Blake <eblake@redhat.com>
Another struct being moved to util. This one doesn't have as
much use yet, thankfully.
* src/conf/domain_conf.h (virDomainDiskSourcePoolMode)
(virDomainDiskSourcePoolDef): Move...
* src/util/virstoragefile.h (virStorageSourcePoolMode)
(virStorageSourcePoolDef): ...and rename.
* src/conf/domain_conf.c (virDomainDiskSourcePoolDefFree)
(virDomainDiskSourceDefClear, virDomainDiskSourcePoolDefParse)
(virDomainDiskDefParseXML, virDomainDiskSourceDefParse)
(virDomainDiskSourceDefFormatInternal)
(virDomainDiskDefForeachPath, virDomainDiskSourceIsBlockType):
Adjust clients.
* src/qemu/qemu_conf.c (qemuTranslateDiskSourcePool): Likewise.
* src/libvirt_private.syms (domain_conf.h): Move symbols...
(virstoragefile.h): ...as appropriate.
Signed-off-by: Eric Blake <eblake@redhat.com>
This gets rid of another stat() per volume, as well as cutting
bytes read in half, when populating the volumes of a directory
pool during a pool refresh. Not to mention that it provides an
interface that can let gluster pools also probe file types.
* src/util/virstoragefile.h (virStorageFileProbeFormatFromFD):
Delete.
(virStorageFileProbeFormatFromBuf): New prototype.
(VIR_STORAGE_MAX_HEADER): New constant, based on...
* src/util/virstoragefile.c (STORAGE_MAX_HEAD): ...old name.
(vmdk4GetBackingStore, virStorageFileGetMetadataInternal)
(virStorageFileProbeFormat): Adjust clients.
(virStorageFileProbeFormatFromFD): Delete.
(virStorageFileProbeFormatFromBuf): Export.
* src/storage/storage_backend_fs.c (virStorageBackendProbeTarget):
Adjust client.
* src/libvirt_private.syms (virstoragefile.h): Adjust exports.
Signed-off-by: Eric Blake <eblake@redhat.com>
Future patches will want to learn metadata about a file using
a buffer that was already parsed in order to probe the file's
format. Rather than reopening and re-reading the file, it makes
sense to separate getting file contents from actually parsing
those contents.
* src/util/virstoragefile.c (virStorageFileGetMetadataFromBuf)
(virStorageFileGetMetadataFromFDInternal): New functions.
(virStorageFileGetMetadataInternal): Hoist fstat() and read() into
callers.
(virStorageFileGetMetadataFromFD)
(virStorageFileGetMetadataRecurse): Rework clients.
* src/util/virstoragefile.h (virStorageFileGetMetadataFromBuf):
New prototype.
* src/libvirt_private.syms (virstoragefile.h): Export it.
Signed-off-by: Eric Blake <eblake@redhat.com>
This should resolve:
https://bugzilla.redhat.com/show_bug.cgi?id=1012085
libvirt previously recognized NFS, GFS2, OCFS2, and AFS filesystems as
"shared", and thus eligible for exceptions to certain rules/actions
about chowning image files before handing them off to a guest. This
patch widens the definition of "shared filesystem" to include SMB and
CIFS filesystems (aka "Windows file sharing"); both of these use the
same protocol, but different drivers so there are different magic
numbers for each.
*src/util/virstoragefile.c: Add a helper function to get
the first name of missing backing files, if the name is NULL,
it means the diskchain is not broken.
*src/qemu/qemu_domain.c: qemuDiskChainCheckBroken(disk) to
check if its chain is broken
It's not used anywhere except for the switch in
virStorageBackendCreateQemuImgOpts, where leaving it in causes
a dead code coverity warning and omitting it breaks compilation
because of unhandled enum value.
Introduced by 6298f74.
Detect qcow2 images with version 3 in the image header as
VIR_STORAGE_FILE_QCOW2.
These images have a feature bitfield, with just one feature supported
so far: lazy_refcounts.
The header length changed too, moving the location of the backing
format name.
The document for "vol-resize" says the new capacity will be sparse
unless "--allocate" is specified, however, the "--allocate" flag
is never implemented. This implements the "--allocate" flag for
fs backend's raw type volume, based on posix_fallocate and the
syscall SYS_fallocate.
POSIX says that both basename() and dirname() may return static
storage (aka they need not be thread-safe); and that they may but
not must modify their input argument. Furthermore, <libgen.h>
is not available on all platforms. For these reasons, you should
never use these functions in a multi-threaded library.
Gnulib instead recommends a way to avoid the portability nightmare:
gnulib's "dirname.h" provides useful thread-safe counterparts. The
obvious dir_name() and base_name() are GPL (because they malloc(),
but call exit() on failure) so we can't use them; but the LGPL
variants mdir_name() (malloc's or returns NULL) and last_component
(always points into the incoming string without modifying it,
differing from basename semantics only on corner cases like the
empty string that we shouldn't be hitting in the first place) are
already in use in libvirt. This finishes the swap over to the safe
functions.
* cfg.mk (sc_prohibit_libgen): New rule.
* src/util/vircgroup.c: Fix offenders.
* src/parallels/parallels_storage.c (parallelsPoolAddByDomain):
Likewise.
* src/parallels/parallels_network.c (parallelsGetBridgedNetInfo):
Likewise.
* src/node_device/node_device_udev.c (udevProcessSCSIHost)
(udevProcessSCSIDevice): Likewise.
* src/storage/storage_backend_disk.c
(virStorageBackendDiskDeleteVol): Likewise.
* src/util/virpci.c (virPCIGetDeviceAddressFromSysfsLink):
Likewise.
* src/util/virstoragefile.h (_virStorageFileMetadata): Avoid false
positive.
Signed-off-by: Eric Blake <eblake@redhat.com>
If you have a qcow2 file /path1/to/file pointed to by symlink
/path2/symlink, and pass qemu /path2/symlink, then qemu treats
a relative backing file in the qcow2 metadata as being relative
to /path2, not /path1/to. Yes, this means that it is possible
to create a qcow2 file where the choice of WHICH directory and
symlink you access its contents from will then determine WHICH
backing file (if any) you actually find; the results can be
rather screwy, but we have to match what qemu does.
Libvirt and qemu default to creating absolute backing file
names, so most users don't hit this. But at least VDSM uses
symlinks and relative backing names alongside the
--reuse-external flags to libvirt snapshot operations, with the
result that libvirt was failing to follow the intended chain of
backing files, and then backing files were not granted the
necessary sVirt permissions to be opened by qemu.
See https://bugzilla.redhat.com/show_bug.cgi?id=903248 for
more gory details. This fixes a regression introduced in
commit 8250783.
I tested this patch by creating the following chain:
ls /home/eblake/Downloads/Fedora.iso # raw file for base
cd /var/lib/libvirt/images
qemu-img create -f qcow2 \
-obacking_file=/home/eblake/Downloads/Fedora.iso,backing_fmt=raw one
mkdir sub
cd sub
ln -s ../one onelink
qemu-img create -f qcow2 \
-obacking_file=../sub/onelink,backing_fmt=qcow2 two
mv two ..
ln -s ../two twolink
qemu-img create -f qcow2 \
-obacking_file=../sub/twolink,backing_fmt=qcow2 three
mv three ..
ln -s ../three threelink
then pointing my domain at /var/lib/libvirt/images/sub/threelink.
Prior to this patch, I got complaints about missing backing
files; afterwards, I was able to verify that the backing chain
(and hence DAC and SELinux relabels) of the entire chain worked.
* src/util/virstoragefile.h (_virStorageFileMetadata): Add
directory member.
* src/util/virstoragefile.c (absolutePathFromBaseFile): Drop,
replaced by...
(virFindBackingFile): ...better function.
(virStorageFileGetMetadataInternal): Add an argument.
(virStorageFileGetMetadataFromFD, virStorageFileChainLookup)
(virStorageFileGetMetadata): Update callers.
QEMU is fully capable of handling VDI images and we just refuse to
work with them. As qemu-img knows and supports this, there should be
no problem with this addition.
This is of course, just basic functionality, without searching for any
backing files, etc.
