[libvirt] [PATCH 5/6] conf: tweak chain lookup internals

[Eric Blake]

Thanks to the testsuite, I feel quite confident that this rewrite
still gives the same results for all cases except for one, and
I can make the argument that _that_ case was a pre-existing bug.
When looking up relative names, the lookup is supposed to be
pegged to the directory that contains the parent qcow2 file.

* src/util/virstoragefile.c (virStorageFileChainLookup): Depend on
new rather than old fields.
* tests/virstoragetest.c (mymain): Adjust test to match fix.

Signed-off-by: Eric Blake <eblake at redhat.com>
---
 src/util/virstoragefile.c | 49 +++++++++++++++++++----------------------------
 tests/virstoragetest.c    |  3 +--
 2 files changed, 21 insertions(+), 31 deletions(-)

diff --git a/src/util/virstoragefile.c b/src/util/virstoragefile.c
index dcde9e5..e33f6ef 100644
--- a/src/util/virstoragefile.c
+++ b/src/util/virstoragefile.c
@@ -1544,48 +1544,39 @@ virStorageFileChainLookup(virStorageFileMetadataPtr chain,
                           const char **parent)
 {
     const char *start = chain->canonPath;
-    virStorageFileMetadataPtr owner;
     const char *tmp;
+    const char *parentDir = ".";
+    bool nameIsFile = virStorageIsFile(name);

     if (!parent)
         parent = &tmp;

     *parent = NULL;
-    if (name ? STREQ(start, name) || virFileLinkPointsTo(start, name) :
-        !chain->backingStore) {
-        if (meta)
-            *meta = chain;
-        return start;
-    }
-
-    owner = chain;
-    *parent = start;
-    while (owner) {
-        if (!owner->backingStore)
-            goto error;
+    while (chain) {
         if (!name) {
-            if (!owner->backingMeta ||
-                !owner->backingMeta->backingStore)
+            if (!chain->backingMeta)
                 break;
-        } else if (STREQ_NULLABLE(name, owner->backingStoreRaw) ||
-                   STREQ(name, owner->backingStore)) {
-            break;
-        } else if (virStorageIsFile(owner->backingStore)) {
-            int result = virFileRelLinkPointsTo(owner->directory, name,
-                                                owner->backingStore);
-            if (result < 0)
-                goto error;
-            if (result > 0)
+        } else {
+            if (STREQ(name, chain->path))
                 break;
+            if (nameIsFile && chain->type < VIR_STORAGE_TYPE_DIR) {
+                int result = virFileRelLinkPointsTo(parentDir, name,
+                                                    chain->canonPath);
+                if (result < 0)
+                    goto error;
+                if (result > 0)
+                    break;
+            }
         }
-        *parent = owner->backingStore;
-        owner = owner->backingMeta;
+        *parent = chain->canonPath;
+        parentDir = chain->relDir;
+        chain = chain->backingMeta;
     }
-    if (!owner)
+    if (!chain)
         goto error;
     if (meta)
-        *meta = owner->backingMeta;
-    return owner->backingStore;
+        *meta = chain;
+    return chain->canonPath;

  error:
     virReportError(VIR_ERR_INVALID_ARG,
diff --git a/tests/virstoragetest.c b/tests/virstoragetest.c
index 73bcb0b..37f41bd 100644
--- a/tests/virstoragetest.c
+++ b/tests/virstoragetest.c
@@ -927,8 +927,7 @@ mymain(void)
     TEST_LOOKUP(19, abswrap, chain->canonPath, chain, NULL);
     TEST_LOOKUP(20, "../qcow2", chain->backingStore, chain->backingMeta,
                 chain->canonPath);
-    TEST_LOOKUP(21, "qcow2", chain->backingStore, chain->backingMeta,
-                chain->canonPath);
+    TEST_LOOKUP(21, "qcow2", NULL, NULL, NULL);
     TEST_LOOKUP(22, absqcow2, chain->backingStore, chain->backingMeta,
                 chain->canonPath);
     TEST_LOOKUP(23, "raw", chain->backingMeta->backingStore,
-- 
1.9.0