5:30 p.m.
Previously, no one was using virStorageFileGetMetadata, and for good
reason - it couldn't support root-squash NFS. Change the signature
and make it useful to future patches, including enhancing the metadata
to recursively track the entire chain.
* src/util/storage_file.h (_virStorageFileMetadata): Add field.
(virStorageFileGetMetadata): Alter signature.
* src/util/storage_file.c (virStorageFileGetMetadata): Rewrite.
(virStorageFileGetMetadataRecurse): New function.
(virStorageFileFreeMetadata): Handle recursion.
---
v3: warn rather than error when not returning NULL; inline one
more bit of functionality regarding probing when format unknown
src/util/storage_file.c | 95 +++++++++++++++++++++++++++++++++++++++----------
src/util/storage_file.h | 18 ++++++----
2 files changed, 88 insertions(+), 25 deletions(-)
diff --git a/src/util/storage_file.c b/src/util/storage_file.c
index 0d8cb86..68c7605 100644
--- a/src/util/storage_file.c
+++ b/src/util/storage_file.c
@@ -40,6 +40,7 @@
#include "logging.h"
#include "virfile.h"
#include "c-ctype.h"
+#include "virhash.h"
#define VIR_FROM_THIS VIR_FROM_STORAGE
@@ -839,7 +840,7 @@ virStorageFileProbeFormat(const char *path)
*
* Extract metadata about the storage volume with the specified
* image format. If image format is VIR_STORAGE_FILE_AUTO, it
- * will probe to automatically identify the format.
+ * will probe to automatically identify the format. Does not recurse.
*
* Callers are advised never to use VIR_STORAGE_FILE_AUTO as a
* format, since a malicious guest can turn a raw file into any
@@ -909,12 +910,69 @@ cleanup:
return ret;
}
+/* Recursive workhorse for virStorageFileGetMetadata. */
+static virStorageFileMetadataPtr
+virStorageFileGetMetadataRecurse(const char *path, int format,
+ uid_t uid, gid_t gid,
+ bool allow_probe, virHashTablePtr cycle)
+{
+ int fd;
+ virStorageFileMetadataPtr ret = NULL;
+
+ if (virHashLookup(cycle, path)) {
+ virReportError(VIR_ERR_INTERNAL_ERROR,
+ _("backing store for %s is self-referential"),
+ path);
+ return NULL;
+ }
+ if (virHashAddEntry(cycle, path, (void *)1) < 0)
+ return NULL;
+
+ if ((fd = virFileOpenAs(path, O_RDONLY, 0, uid, gid, 0)) < 0) {
+ virReportSystemError(-fd, _("cannot open file '%s'"), path);
+ return NULL;
+ }
+
+ if (VIR_ALLOC(ret) < 0) {
+ virReportOOMError();
+ VIR_FORCE_CLOSE(fd);
+ return NULL;
+ }
+ if (virStorageFileGetMetadataFromFD(path, fd, format, ret) < 0) {
+ virStorageFileFreeMetadata(ret);
+ VIR_FORCE_CLOSE(fd);
+ return NULL;
+ }
+
+ if (VIR_CLOSE(fd) < 0)
+ VIR_WARN("could not close file %s", path);
+
+ if (ret->backingStoreIsFile) {
+ if (ret->backingStoreFormat == VIR_STORAGE_FILE_AUTO && !allow_probe)
+ ret->backingStoreFormat = VIR_STORAGE_FILE_RAW;
+ else if (ret->backingStoreFormat == VIR_STORAGE_FILE_AUTO_SAFE)
+ ret->backingStoreFormat = VIR_STORAGE_FILE_AUTO;
+ format = ret->backingStoreFormat;
+ ret->backingMeta = virStorageFileGetMetadataRecurse(ret->backingStore,
+ format,
+ uid, gid,
+ allow_probe,
+ cycle);
+ }
+
+ return ret;
+}
+
/**
* virStorageFileGetMetadata:
*
* Extract metadata about the storage volume with the specified
* image format. If image format is VIR_STORAGE_FILE_AUTO, it
- * will probe to automatically identify the format.
+ * will probe to automatically identify the format. Recurses through
+ * the entire chain.
+ *
+ * Open files using UID and GID (or pass -1 for the current user/group).
+ * Treat any backing files without explicit type as raw, unless ALLOW_PROBE.
*
* Callers are advised never to use VIR_STORAGE_FILE_AUTO as a
* format, since a malicious guest can turn a raw file into any
@@ -922,27 +980,27 @@ cleanup:
*
* If the returned meta.backingStoreFormat is VIR_STORAGE_FILE_AUTO
* it indicates the image didn't specify an explicit format for its
- * backing store. Callers are advised against probing for the
- * backing store format in this case.
+ * backing store. Callers are advised against using ALLOW_PROBE, as
+ * it would probe the backing store format in this case.
*
- * Caller MUST free @meta after use via virStorageFileFreeMetadata.
+ * Caller MUST free result after use via virStorageFileFreeMetadata.
*/
-int
-virStorageFileGetMetadata(const char *path,
- int format,
- virStorageFileMetadata *meta)
+virStorageFileMetadataPtr
+virStorageFileGetMetadata(const char *path, int format,
+ uid_t uid, gid_t gid,
+ bool allow_probe)
{
- int fd, ret;
+ virHashTablePtr cycle = virHashCreate(5, NULL);
+ virStorageFileMetadataPtr ret;
- if ((fd = open(path, O_RDONLY)) < 0) {
- virReportSystemError(errno, _("cannot open file '%s'"), path);
- return -1;
- }
-
- ret = virStorageFileGetMetadataFromFD(path, fd, format, meta);
-
- VIR_FORCE_CLOSE(fd);
+ if (!cycle)
+ return NULL;
+ if (format <= VIR_STORAGE_FILE_NONE)
+ format = allow_probe ? VIR_STORAGE_FILE_AUTO : VIR_STORAGE_FILE_RAW;
+ ret = virStorageFileGetMetadataRecurse(path, format, uid, gid,
+ allow_probe, cycle);
+ virHashFree(cycle);
return ret;
}
@@ -957,6 +1015,7 @@ virStorageFileFreeMetadata(virStorageFileMetadata *meta)
if (!meta)
return;
+ virStorageFileFreeMetadata(meta->backingMeta);
VIR_FREE(meta->backingStore);
VIR_FREE(meta);
}
diff --git a/src/util/storage_file.h b/src/util/storage_file.h
index 683ec73..18dea6a 100644
--- a/src/util/storage_file.h
+++ b/src/util/storage_file.h
@@ -50,13 +50,16 @@ enum virStorageFileFormat {
VIR_ENUM_DECL(virStorageFileFormat);
-typedef struct _virStorageFileMetadata {
+typedef struct _virStorageFileMetadata virStorageFileMetadata;
+typedef virStorageFileMetadata *virStorageFileMetadataPtr;
+struct _virStorageFileMetadata {
char *backingStore;
- int backingStoreFormat;
+ int backingStoreFormat; /* enum virStorageFileFormat */
bool backingStoreIsFile;
+ virStorageFileMetadataPtr backingMeta;
unsigned long long capacity;
bool encrypted;
-} virStorageFileMetadata;
+};
# ifndef DEV_BSIZE
# define DEV_BSIZE 512
@@ -66,15 +69,16 @@ int virStorageFileProbeFormat(const char *path);
int virStorageFileProbeFormatFromFD(const char *path,
int fd);
-int virStorageFileGetMetadata(const char *path,
- int format,
- virStorageFileMetadata *meta);
+virStorageFileMetadataPtr virStorageFileGetMetadata(const char *path,
+ int format,
+ uid_t uid, gid_t gid,
+ bool allow_probe);
int virStorageFileGetMetadataFromFD(const char *path,
int fd,
int format,
virStorageFileMetadata *meta);
-void virStorageFileFreeMetadata(virStorageFileMetadata *meta);
+void virStorageFileFreeMetadata(virStorageFileMetadataPtr meta);
int virStorageFileResize(const char *path, unsigned long long capacity);
--
1.7.11.7