[libvirt] [PATCHv4 05/21] util: storage: Add helper to resolve relative path difference
Peter Krempa
pkrempa at redhat.com
Wed Jun 11 11:45:15 UTC 2014
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 7671730..773b208 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -1875,6 +1875,7 @@ virStorageFileGetLVMKey;
virStorageFileGetMetadataFromBuf;
virStorageFileGetMetadataFromFD;
virStorageFileGetMetadataInternal;
+virStorageFileGetRelativeBackingPath;
virStorageFileGetSCSIKey;
virStorageFileIsClusterFS;
virStorageFileParseChainIndex;
diff --git a/src/util/virstoragefile.c b/src/util/virstoragefile.c
index ef69bf3..ce1fc86 100644
--- a/src/util/virstoragefile.c
+++ b/src/util/virstoragefile.c
@@ -2123,3 +2123,80 @@ 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 8111f58..5cea929 100644
--- a/tests/virstoragetest.c
+++ b/tests/virstoragetest.c
@@ -588,6 +588,104 @@ 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)
@@ -596,6 +694,7 @@ mymain(void)
virCommandPtr cmd = NULL;
struct testChainData data;
struct testPathCanonicalizeData data3;
+ struct testPathRelativeBacking data4;
virStorageSourcePtr chain = NULL;
/* Prep some files with qemu-img; if that is not found on PATH, or
@@ -1136,6 +1235,53 @@ 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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