This patch introduces a function that will allow us to resolve a
relative difference between two elements of a disk backing chain. This
fucntion will be used to allow relative block commit and block pull
where we need to specify the new relative name of the image to qemu.
This patch also adds unit tests for the function to verify that it works
correctly.
---
src/libvirt_private.syms | 1 +
src/util/virstoragefile.c | 77 ++++++++++++++++++++++++
src/util/virstoragefile.h | 4 ++
tests/virstoragetest.c | 146 ++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 228 insertions(+)
diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index 4ed08ca..8d5df87 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -1884,6 +1884,7 @@ virStorageFileGetLVMKey;
virStorageFileGetMetadataFromBuf;
virStorageFileGetMetadataFromFD;
virStorageFileGetMetadataInternal;
+virStorageFileGetRelativeBackingPath;
virStorageFileGetSCSIKey;
virStorageFileIsClusterFS;
virStorageFileParseChainIndex;
diff --git a/src/util/virstoragefile.c b/src/util/virstoragefile.c
index efae692..ac3bcba 100644
--- a/src/util/virstoragefile.c
+++ b/src/util/virstoragefile.c
@@ -2130,3 +2130,80 @@ virStorageFileCanonicalizePath(const char *path,
return ret;
}
+
+
+static char *
+virStorageFileRemoveLastPathComponent(const char *path)
+{
+ char *tmp;
+ char *ret;
+
+ if (VIR_STRDUP(ret, path ? path : "") < 0)
+ return NULL;
+
+ if ((tmp = strrchr(ret, '/')))
+ tmp[1] = '\0';
+ else
+ ret[0] = '\0';
+
+ return ret;
+}
+
+
+/*
+ * virStorageFileGetRelativeBackingPath:
+ *
+ * Resolve relative path to be written to the overlay of @top image when
+ * collapsing the backing chain between @top and @base.
+ *
+ * Returns 0 on success; 1 if backing chain isn't relative and -1 on error.
+ */
+int
+virStorageFileGetRelativeBackingPath(virStorageSourcePtr top,
+ virStorageSourcePtr base,
+ char **relpath)
+{
+ virStorageSourcePtr next;
+ char *tmp = NULL;
+ char *path = NULL;
+ char ret = -1;
+
+ *relpath = NULL;
+
+ for (next = top; next; next = next->backingStore) {
+ if (!next->backingRelative || !next->relPath) {
+ ret = 1;
+ goto cleanup;
+ }
+
+ if (!(tmp = virStorageFileRemoveLastPathComponent(path)))
+ goto cleanup;
+
+ VIR_FREE(path);
+
+ if (virAsprintf(&path, "%s%s", tmp, next->relPath) < 0)
+ goto cleanup;
+
+ VIR_FREE(tmp);
+
+ if (next == base)
+ break;
+ }
+
+ if (next != base) {
+ virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+ _("failed to resolve relative backing name: "
+ "base image is not in backing chain"));
+ goto cleanup;
+ }
+
+ *relpath = path;
+ path = NULL;
+
+ ret = 0;
+
+ cleanup:
+ VIR_FREE(path);
+ VIR_FREE(tmp);
+ return ret;
+}
diff --git a/src/util/virstoragefile.h b/src/util/virstoragefile.h
index fd5c89e..ff8130d 100644
--- a/src/util/virstoragefile.h
+++ b/src/util/virstoragefile.h
@@ -333,4 +333,8 @@ char *virStorageFileCanonicalizePath(const char *path,
virStorageFileSimplifyPathReadlinkCallback cb,
void *cbdata);
+int virStorageFileGetRelativeBackingPath(virStorageSourcePtr from,
+ virStorageSourcePtr to,
+ char **relpath);
+
#endif /* __VIR_STORAGE_FILE_H__ */
diff --git a/tests/virstoragetest.c b/tests/virstoragetest.c
index 0bc4a42..72c7ca2 100644
--- a/tests/virstoragetest.c
+++ b/tests/virstoragetest.c
@@ -589,6 +589,104 @@ testPathCanonicalize(const void *args)
return ret;
}
+virStorageSource backingchain[12];
+
+static void
+testPathRelativePrepare(void)
+{
+ size_t i;
+
+ for (i = 0; i < ARRAY_CARDINALITY(backingchain); i++) {
+ if (i < ARRAY_CARDINALITY(backingchain) - 1)
+ backingchain[i].backingStore = &backingchain[i+1];
+ else
+ backingchain[i].backingStore = NULL;
+
+ backingchain[i].backingRelative = true;
+ }
+
+ /* normal relative backing chain */
+ backingchain[0].path = (char *) "/path/to/some/img";
+ backingchain[0].relPath = (char *) "/path/to/some/img";
+ backingchain[0].backingRelative = false;
+
+ backingchain[1].path = (char *) "/path/to/some/asdf";
+ backingchain[1].relPath = (char *) "asdf";
+
+ backingchain[2].path = (char *) "/path/to/some/test";
+ backingchain[2].relPath = (char *) "test";
+
+ backingchain[3].path = (char *) "/path/to/some/blah";
+ backingchain[3].relPath = (char *) "blah";
+
+ /* ovirt's backing chain */
+ backingchain[4].path = (char *) "/path/to/volume/image1";
+ backingchain[4].relPath = (char *) "/path/to/volume/image1";
+ backingchain[4].backingRelative = false;
+
+ backingchain[5].path = (char *) "/path/to/volume/image2";
+ backingchain[5].relPath = (char *) "../volume/image2";
+
+ backingchain[6].path = (char *) "/path/to/volume/image3";
+ backingchain[6].relPath = (char *) "../volume/image3";
+
+ backingchain[7].path = (char *) "/path/to/volume/image4";
+ backingchain[7].relPath = (char *) "../volume/image4";
+
+ /* some arbitrarily crazy backing chains */
+ backingchain[8].path = (char *) "/crazy/base/image";
+ backingchain[8].relPath = (char *) "/crazy/base/image";
+ backingchain[8].backingRelative = false;
+
+ backingchain[9].path = (char *) "/crazy/base/directory/stuff/volumes/garbage/image2";
+ backingchain[9].relPath = (char *) "directory/stuff/volumes/garbage/image2";
+
+ backingchain[10].path = (char *) "/crazy/base/directory/image3";
+ backingchain[10].relPath = (char *) "../../../image3";
+
+ backingchain[11].path = (char *) "/crazy/base/blah/image4";
+ backingchain[11].relPath = (char *) "../blah/image4";
+}
+
+
+struct testPathRelativeBacking
+{
+ virStorageSourcePtr top;
+ virStorageSourcePtr base;
+
+ const char *expect;
+};
+
+static int
+testPathRelative(const void *args)
+{
+ const struct testPathRelativeBacking *data = args;
+ char *actual = NULL;
+ int ret = -1;
+
+ if (virStorageFileGetRelativeBackingPath(data->top,
+ data->base,
+ &actual) < 0) {
+ fprintf(stderr, "relative backing path resolution failed\n");
+ goto cleanup;
+ }
+
+ if (STRNEQ_NULLABLE(data->expect, actual)) {
+ fprintf(stderr, "relative path resolution from '%s' to '%s': "
+ "expected '%s', got '%s'\n",
+ data->top->path, data->base->path,
+ NULLSTR(data->expect), NULLSTR(actual));
+ goto cleanup;
+ }
+
+ ret = 0;
+
+ cleanup:
+ VIR_FREE(actual);
+
+ return ret;
+}
+
static int
mymain(void)
@@ -598,6 +696,7 @@ mymain(void)
struct testChainData data;
struct testLookupData data2;
struct testPathCanonicalizeData data3;
+ struct testPathRelativeBacking data4;
virStorageSourcePtr chain = NULL;
virStorageSourcePtr chain2; /* short for chain->backingStore */
virStorageSourcePtr chain3; /* short for chain2->backingStore */
@@ -1180,6 +1279,53 @@ mymain(void)
TEST_PATH_CANONICALIZE(29, "/cycle", NULL);
TEST_PATH_CANONICALIZE(30, "/cycle2/link", NULL);
+#define TEST_RELATIVE_BACKING(id, TOP, BASE, EXPECT) \
+ do { \
+ data4.top = &TOP; \
+ data4.base = &BASE; \
+ data4.expect = EXPECT; \
+ if (virtTestRun("Path relative resolve " #id, \
+ testPathRelative, &data4) < 0) \
+ ret = -1; \
+ } while (0)
+
+ testPathRelativePrepare();
+
+ /* few negative tests first */
+
+ /* a non-relative image is in the backing chain span */
+ TEST_RELATIVE_BACKING(1, backingchain[0], backingchain[1], NULL);
+ TEST_RELATIVE_BACKING(2, backingchain[0], backingchain[2], NULL);
+ TEST_RELATIVE_BACKING(3, backingchain[0], backingchain[3], NULL);
+ TEST_RELATIVE_BACKING(4, backingchain[1], backingchain[5], NULL);
+
+ /* image is not in chain (specified backwards) */
+ TEST_RELATIVE_BACKING(5, backingchain[2], backingchain[1], NULL);
+
+ /* positive tests */
+ TEST_RELATIVE_BACKING(6, backingchain[1], backingchain[1], "asdf");
+ TEST_RELATIVE_BACKING(7, backingchain[1], backingchain[2], "test");
+ TEST_RELATIVE_BACKING(8, backingchain[1], backingchain[3], "blah");
+ TEST_RELATIVE_BACKING(9, backingchain[2], backingchain[2], "test");
+ TEST_RELATIVE_BACKING(10, backingchain[2], backingchain[3], "blah");
+ TEST_RELATIVE_BACKING(11, backingchain[3], backingchain[3], "blah");
+
+ /* oVirt spelling */
+ TEST_RELATIVE_BACKING(12, backingchain[5], backingchain[5], "../volume/image2");
+ TEST_RELATIVE_BACKING(13, backingchain[5], backingchain[6], "../volume/../volume/image3");
+ TEST_RELATIVE_BACKING(14, backingchain[5], backingchain[7], "../volume/../volume/../volume/image4");
+ TEST_RELATIVE_BACKING(15, backingchain[6], backingchain[6], "../volume/image3");
+ TEST_RELATIVE_BACKING(16, backingchain[6], backingchain[7], "../volume/../volume/image4");
+ TEST_RELATIVE_BACKING(17, backingchain[7], backingchain[7], "../volume/image4");
+
+ /* crazy spellings */
+ TEST_RELATIVE_BACKING(17, backingchain[9], backingchain[9], "directory/stuff/volumes/garbage/image2");
+ TEST_RELATIVE_BACKING(18, backingchain[9], backingchain[10], "directory/stuff/volumes/garbage/../../../image3");
+ TEST_RELATIVE_BACKING(19, backingchain[9], backingchain[11], "directory/stuff/volumes/garbage/../../../../blah/image4");
+ TEST_RELATIVE_BACKING(20, backingchain[10], backingchain[10], "../../../image3");
+ TEST_RELATIVE_BACKING(21, backingchain[10], backingchain[11], "../../../../blah/image4");
+ TEST_RELATIVE_BACKING(22, backingchain[11], backingchain[11], "../blah/image4");
+
cleanup:
/* Final cleanup */
virStorageSourceFree(chain);
--
1.9.3
--
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