[PATCHv2 10/16] storage: remember relative names in backing chain

[Eric Blake <eblake@xxxxxxxxxx>]

In order to search for a backing file name as literally present
in a chain, we need to remember if the chain had relative names.
Also, searching for absolute names is easier if we only have
to canonicalize once, rather than on every iteration.

* src/util/storage_file.h (_virStorageFileMetadata): Add field.
* src/util/storage_file.c (virStorageFileGetMetadataFromBuf):
(virStorageFileFreeMetadata): Manage it
(absolutePathFromBaseFile): Store absolute names in canonical form.
---
 src/util/storage_file.c | 28 ++++++++++++++++++++--------
 src/util/storage_file.h |  3 ++-
 2 files changed, 22 insertions(+), 9 deletions(-)

diff --git a/src/util/storage_file.c b/src/util/storage_file.c
index 5387f1e..6f299c0 100644
--- a/src/util/storage_file.c
+++ b/src/util/storage_file.c
@@ -28,6 +28,7 @@
 #include <sys/stat.h>
 #include <unistd.h>
 #include <fcntl.h>
+#include <stdlib.h>
 #ifdef __linux__
 # if HAVE_LINUX_MAGIC_H
 #  include <linux/magic.h>
@@ -531,18 +532,22 @@ static char *
 absolutePathFromBaseFile(const char *base_file, const char *path)
 {
     char *res;
+    char *tmp;
     size_t d_len = dir_len (base_file);

     /* If path is already absolute, or if dirname(base_file) is ".",
        just return a copy of path.  */
     if (*path == '/' || d_len == 0)
-        return strdup(path);
+        return canonicalize_file_name(path);

     /* Ensure that the following cast-to-int is valid.  */
     if (d_len > INT_MAX)
         return NULL;

-    ignore_value(virAsprintf(&res, "%.*s/%s", (int) d_len, base_file, path));
+    if (virAsprintf(&tmp, "%.*s/%s", (int) d_len, base_file, path) < 0)
+        return NULL;
+    res = canonicalize_file_name(tmp);
+    VIR_FREE(tmp);
     return res;
 }

@@ -698,17 +703,23 @@ virStorageFileGetMetadataFromBuf(int format,

         meta->backingStoreIsFile = false;
         if (backing != NULL) {
+            meta->backingStore = strdup(backing);
+            if (meta->backingStore == NULL) {
+                virReportOOMError();
+                VIR_FREE(backing);
+                return -1;
+            }
             if (virBackingStoreIsFile(backing)) {
                 meta->backingStoreIsFile = true;
+                meta->backingStoreRaw = meta->backingStore;
                 meta->backingStore = absolutePathFromBaseFile(path, backing);
-            } else {
-                meta->backingStore = strdup(backing);
+                if (meta->backingStore == NULL) {
+                    virReportOOMError();
+                    VIR_FREE(backing);
+                    return -1;
+                }
             }
             VIR_FREE(backing);
-            if (meta->backingStore == NULL) {
-                virReportOOMError();
-                return -1;
-            }
             meta->backingStoreFormat = backingFormat;
         } else {
             meta->backingStore = NULL;
@@ -1012,6 +1023,7 @@ virStorageFileFreeMetadata(virStorageFileMetadata *meta)

     virStorageFileFreeMetadata(meta->backingMeta);
     VIR_FREE(meta->backingStore);
+    VIR_FREE(meta->backingStoreRaw);
     VIR_FREE(meta);
 }

diff --git a/src/util/storage_file.h b/src/util/storage_file.h
index 9a60451..685fcb8 100644
--- a/src/util/storage_file.h
+++ b/src/util/storage_file.h
@@ -53,7 +53,8 @@ VIR_ENUM_DECL(virStorageFileFormat);
 typedef struct _virStorageFileMetadata virStorageFileMetadata;
 typedef virStorageFileMetadata *virStorageFileMetadataPtr;
 struct _virStorageFileMetadata {
-    char *backingStore;
+    char *backingStore; /* Canonical name (absolute file, or protocol) */
+    char *backingStoreRaw; /* If file, original name, possibly relative */
     int backingStoreFormat; /* enum virStorageFileFormat */
     bool backingStoreIsFile;
     virStorageFileMetadataPtr backingMeta;
-- 
1.7.11.7

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