util: storage: Allow checking whether virStorageFileCreate is supported

Add virStorageFileSupportsCreate which allows silent check whether
virStorageFileCreate is implemented.
Signed-off-by: NPeter Krempa <pkrempa@redhat.com>
Reviewed-by: NJán Tomko <jtomko@redhat.com>

src/libvirt_private.syms

@@ -2994,6 +2994,7 @@ virStorageFileReportBrokenChain;
 virStorageFileResize;
 virStorageFileStat;
 virStorageFileSupportsAccess;
+virStorageFileSupportsCreate;
 virStorageFileSupportsSecurityDriver;
 virStorageFileUnlink;
 virStorageIsFile;

src/util/virstoragefile.c

@@ -4505,6 +4505,26 @@ virStorageFileSupportsAccess(const virStorageSource *src)
 }
 
 
+/**
+ * virStorageFileSupportsCreate:
+ * @src: a storage file structure
+ *
+ * Check if the storage driver supports creating storage described by @src
+ * via virStorageFileCreate.
+ */
+int
+virStorageFileSupportsCreate(const virStorageSource *src)
+{
+    virStorageFileBackendPtr backend;
+    int rv;
+
+    if ((rv = virStorageFileGetBackendForSupportCheck(src, &backend)) < 1)
+        return rv;
+
+    return backend->storageFileCreate ? 1 : 0;
+}
+
+
 void
 virStorageFileDeinit(virStorageSourcePtr src)
 {

src/util/virstoragefile.h

@@ -532,6 +532,7 @@ int virStorageFileChown(const virStorageSource *src, uid_t uid, gid_t gid);
 
 int virStorageFileSupportsSecurityDriver(const virStorageSource *src);
 int virStorageFileSupportsAccess(const virStorageSource *src);
+int virStorageFileSupportsCreate(const virStorageSource *src);
 
 int virStorageFileGetMetadata(virStorageSourcePtr src,
                               uid_t uid, gid_t gid,