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-rw-r--r--tests/unit/test-xs-node.c871
1 files changed, 871 insertions, 0 deletions
diff --git a/tests/unit/test-xs-node.c b/tests/unit/test-xs-node.c
new file mode 100644
index 0000000000..b80d10ff98
--- /dev/null
+++ b/tests/unit/test-xs-node.c
@@ -0,0 +1,871 @@
+/*
+ * QEMU XenStore XsNode testing
+ *
+ * Copyright © 2023 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "qemu/module.h"
+
+static int nr_xs_nodes;
+static GList *xs_node_list;
+
+#define XS_NODE_UNIT_TEST
+
+/*
+ * We don't need the core Xen definitions. And we *do* want to be able
+ * to run the unit tests even on architectures that Xen doesn't support
+ * (because life's too short to bother doing otherwise, and test coverage
+ * doesn't hurt).
+ */
+#define __XEN_PUBLIC_XEN_H__
+typedef unsigned long xen_pfn_t;
+
+#include "hw/i386/kvm/xenstore_impl.c"
+
+#define DOMID_QEMU 0
+#define DOMID_GUEST 1
+
+static void dump_ref(const char *name, XsNode *n, int indent)
+{
+    int i;
+
+    if (!indent && name) {
+        printf("%s:\n", name);
+    }
+
+    for (i = 0; i < indent; i++) {
+        printf(" ");
+    }
+
+    printf("->%p(%d, '%s'): '%.*s'%s%s\n", n, n->ref, n->name,
+           (int)(n->content ? n->content->len : strlen("<empty>")),
+           n->content ? (char *)n->content->data : "<empty>",
+           n->modified_in_tx ? " MODIFIED" : "",
+           n->deleted_in_tx ? " DELETED" : "");
+
+    if (n->children) {
+        g_hash_table_foreach(n->children, (void *)dump_ref,
+                             GINT_TO_POINTER(indent + 2));
+    }
+}
+
+/* This doesn't happen in qemu but we want to make valgrind happy */
+static void xs_impl_delete(XenstoreImplState *s, bool last)
+{
+    int err;
+
+    xs_impl_reset_watches(s, DOMID_GUEST);
+    g_assert(!s->nr_domu_watches);
+
+    err = xs_impl_rm(s, DOMID_QEMU, XBT_NULL, "/local");
+    g_assert(!err);
+    g_assert(s->nr_nodes == 1);
+
+    g_hash_table_unref(s->watches);
+    g_hash_table_unref(s->transactions);
+    xs_node_unref(s->root);
+    g_free(s);
+
+    if (!last) {
+        return;
+    }
+
+    if (xs_node_list) {
+        GList *l;
+        for (l = xs_node_list; l; l = l->next) {
+            XsNode *n = l->data;
+            printf("Remaining node at %p name %s ref %u\n", n, n->name,
+                   n->ref);
+        }
+    }
+    g_assert(!nr_xs_nodes);
+}
+
+struct compare_walk {
+    char path[XENSTORE_ABS_PATH_MAX + 1];
+    XsNode *parent_2;
+    bool compare_ok;
+};
+
+
+static bool compare_perms(GList *p1, GList *p2)
+{
+    while (p1) {
+        if (!p2 || g_strcmp0(p1->data, p2->data)) {
+            return false;
+        }
+        p1 = p1->next;
+        p2 = p2->next;
+    }
+    return (p2 == NULL);
+}
+
+static bool compare_content(GByteArray *c1, GByteArray *c2)
+{
+    size_t len1 = 0, len2 = 0;
+
+    if (c1) {
+        len1 = c1->len;
+    }
+    if (c2) {
+        len2 = c2->len;
+    }
+    if (len1 != len2) {
+        return false;
+    }
+
+    if (!len1) {
+        return true;
+    }
+
+    return !memcmp(c1->data, c2->data, len1);
+}
+
+static void compare_child(gpointer, gpointer, gpointer);
+
+static void compare_nodes(struct compare_walk *cw, XsNode *n1, XsNode *n2)
+{
+    int nr_children1 = 0, nr_children2 = 0;
+
+    if (n1->children) {
+        nr_children1 = g_hash_table_size(n1->children);
+    }
+    if (n2->children) {
+        nr_children2 = g_hash_table_size(n2->children);
+    }
+
+    if (n1->ref != n2->ref ||
+        n1->deleted_in_tx != n2->deleted_in_tx ||
+        n1->modified_in_tx != n2->modified_in_tx ||
+        !compare_perms(n1->perms, n2->perms) ||
+        !compare_content(n1->content, n2->content) ||
+        nr_children1 != nr_children2) {
+        cw->compare_ok = false;
+        printf("Compare failure on '%s'\n", cw->path);
+    }
+
+    if (nr_children1) {
+        XsNode *oldparent = cw->parent_2;
+        cw->parent_2 = n2;
+        g_hash_table_foreach(n1->children, compare_child, cw);
+
+        cw->parent_2 = oldparent;
+    }
+}
+
+static void compare_child(gpointer key, gpointer val, gpointer opaque)
+{
+    struct compare_walk *cw = opaque;
+    char *childname = key;
+    XsNode *child1 = val;
+    XsNode *child2 = g_hash_table_lookup(cw->parent_2->children, childname);
+    int pathlen = strlen(cw->path);
+
+    if (!child2) {
+        cw->compare_ok = false;
+        printf("Child '%s' does not exist under '%s'\n", childname, cw->path);
+        return;
+    }
+
+    strncat(cw->path, "/", sizeof(cw->path) - 1);
+    strncat(cw->path, childname, sizeof(cw->path) - 1);
+
+    compare_nodes(cw, child1, child2);
+    cw->path[pathlen] = '\0';
+}
+
+static bool compare_trees(XsNode *n1, XsNode *n2)
+{
+    struct compare_walk cw;
+
+    cw.path[0] = '\0';
+    cw.parent_2 = n2;
+    cw.compare_ok = true;
+
+    if (!n1 || !n2) {
+        return false;
+    }
+
+    compare_nodes(&cw, n1, n2);
+    return cw.compare_ok;
+}
+
+static void compare_tx(gpointer key, gpointer val, gpointer opaque)
+{
+    XenstoreImplState *s2 = opaque;
+    XsTransaction *t1 = val, *t2;
+    unsigned int tx_id = GPOINTER_TO_INT(key);
+
+    t2 = g_hash_table_lookup(s2->transactions, key);
+    g_assert(t2);
+
+    g_assert(t1->tx_id == tx_id);
+    g_assert(t2->tx_id == tx_id);
+    g_assert(t1->base_tx == t2->base_tx);
+    g_assert(t1->dom_id == t2->dom_id);
+    if (!compare_trees(t1->root, t2->root)) {
+        printf("Comparison failure in TX %u after serdes:\n", tx_id);
+        dump_ref("Original", t1->root, 0);
+        dump_ref("Deserialised", t2->root, 0);
+        g_assert(0);
+    }
+    g_assert(t1->nr_nodes == t2->nr_nodes);
+}
+
+static int write_str(XenstoreImplState *s, unsigned int dom_id,
+                          unsigned int tx_id, const char *path,
+                          const char *content)
+{
+    GByteArray *d = g_byte_array_new();
+    int err;
+
+    g_byte_array_append(d, (void *)content, strlen(content));
+    err = xs_impl_write(s, dom_id, tx_id, path, d);
+    g_byte_array_unref(d);
+    return err;
+}
+
+static void watch_cb(void *_str, const char *path, const char *token)
+{
+    GString *str = _str;
+
+    g_string_append(str, path);
+    g_string_append(str, token);
+}
+
+static void check_serdes(XenstoreImplState *s)
+{
+    XenstoreImplState *s2 = xs_impl_create(DOMID_GUEST);
+    GByteArray *bytes = xs_impl_serialize(s);
+    int nr_transactions1, nr_transactions2;
+    int ret;
+
+    ret = xs_impl_deserialize(s2, bytes, DOMID_GUEST, watch_cb, NULL);
+    g_assert(!ret);
+
+    g_byte_array_unref(bytes);
+
+    g_assert(s->last_tx == s2->last_tx);
+    g_assert(s->root_tx == s2->root_tx);
+
+    if (!compare_trees(s->root, s2->root)) {
+        printf("Comparison failure in main tree after serdes:\n");
+        dump_ref("Original", s->root, 0);
+        dump_ref("Deserialised", s2->root, 0);
+        g_assert(0);
+    }
+
+    nr_transactions1 = g_hash_table_size(s->transactions);
+    nr_transactions2 = g_hash_table_size(s2->transactions);
+    g_assert(nr_transactions1 == nr_transactions2);
+
+    g_hash_table_foreach(s->transactions, compare_tx, s2);
+
+    g_assert(s->nr_domu_watches == s2->nr_domu_watches);
+    g_assert(s->nr_domu_transactions == s2->nr_domu_transactions);
+    g_assert(s->nr_nodes == s2->nr_nodes);
+    xs_impl_delete(s2, false);
+}
+
+static XenstoreImplState *setup(void)
+{
+   XenstoreImplState *s = xs_impl_create(DOMID_GUEST);
+   char *abspath;
+   GList *perms;
+   int err;
+
+   abspath = g_strdup_printf("/local/domain/%u", DOMID_GUEST);
+
+   err = write_str(s, DOMID_QEMU, XBT_NULL, abspath, "");
+   g_assert(!err);
+   g_assert(s->nr_nodes == 4);
+
+   perms = g_list_append(NULL, g_strdup_printf("n%u", DOMID_QEMU));
+   perms = g_list_append(perms, g_strdup_printf("r%u", DOMID_GUEST));
+
+   err = xs_impl_set_perms(s, DOMID_QEMU, XBT_NULL, abspath, perms);
+   g_assert(!err);
+
+   g_list_free_full(perms, g_free);
+   g_free(abspath);
+
+   abspath = g_strdup_printf("/local/domain/%u/some", DOMID_GUEST);
+
+   err = write_str(s, DOMID_QEMU, XBT_NULL, abspath, "");
+   g_assert(!err);
+   g_assert(s->nr_nodes == 5);
+
+   perms = g_list_append(NULL, g_strdup_printf("n%u", DOMID_GUEST));
+
+   err = xs_impl_set_perms(s, DOMID_QEMU, XBT_NULL, abspath, perms);
+   g_assert(!err);
+
+   g_list_free_full(perms, g_free);
+   g_free(abspath);
+
+   return s;
+}
+
+static void test_xs_node_simple(void)
+{
+    GByteArray *data = g_byte_array_new();
+    XenstoreImplState *s = setup();
+    GString *guest_watches = g_string_new(NULL);
+    GString *qemu_watches = g_string_new(NULL);
+    GList *items = NULL;
+    XsNode *old_root;
+    uint64_t gencnt;
+    int err;
+
+    g_assert(s);
+
+    err = xs_impl_watch(s, DOMID_GUEST, "some", "guestwatch",
+                        watch_cb, guest_watches);
+    g_assert(!err);
+    g_assert(guest_watches->len == strlen("someguestwatch"));
+    g_assert(!strcmp(guest_watches->str, "someguestwatch"));
+    g_string_truncate(guest_watches, 0);
+
+    err = xs_impl_watch(s, 0, "/local/domain/1/some", "qemuwatch",
+                        watch_cb, qemu_watches);
+    g_assert(!err);
+    g_assert(qemu_watches->len == strlen("/local/domain/1/someqemuwatch"));
+    g_assert(!strcmp(qemu_watches->str, "/local/domain/1/someqemuwatch"));
+    g_string_truncate(qemu_watches, 0);
+
+    /* Read gives ENOENT when it should */
+    err = xs_impl_read(s, DOMID_GUEST, XBT_NULL, "foo", data);
+    g_assert(err == ENOENT);
+
+    /* Write works */
+    err = write_str(s, DOMID_GUEST, XBT_NULL, "some/relative/path",
+                    "something");
+    g_assert(s->nr_nodes == 7);
+    g_assert(!err);
+    g_assert(!strcmp(guest_watches->str,
+                     "some/relative/pathguestwatch"));
+    g_assert(!strcmp(qemu_watches->str,
+                     "/local/domain/1/some/relative/pathqemuwatch"));
+
+    g_string_truncate(qemu_watches, 0);
+    g_string_truncate(guest_watches, 0);
+    xs_impl_reset_watches(s, 0);
+
+    /* Read gives back what we wrote */
+    err = xs_impl_read(s, DOMID_GUEST, XBT_NULL, "some/relative/path", data);
+    g_assert(!err);
+    g_assert(data->len == strlen("something"));
+    g_assert(!memcmp(data->data, "something", data->len));
+
+    /* Even if we use an abolute path */
+    g_byte_array_set_size(data, 0);
+    err = xs_impl_read(s, DOMID_GUEST, XBT_NULL,
+                       "/local/domain/1/some/relative/path", data);
+    g_assert(!err);
+    g_assert(data->len == strlen("something"));
+
+    g_assert(!qemu_watches->len);
+    g_assert(!guest_watches->len);
+    /* Keep a copy, to force COW mode */
+    old_root = xs_node_ref(s->root);
+
+    /* Write somewhere we aren't allowed, in COW mode */
+    err = write_str(s, DOMID_GUEST, XBT_NULL, "/local/domain/badplace",
+                    "moredata");
+    g_assert(err == EACCES);
+    g_assert(s->nr_nodes == 7);
+
+    /* Write works again */
+    err = write_str(s, DOMID_GUEST, XBT_NULL,
+                    "/local/domain/1/some/relative/path2",
+                    "something else");
+    g_assert(!err);
+    g_assert(s->nr_nodes == 8);
+    g_assert(!qemu_watches->len);
+    g_assert(!strcmp(guest_watches->str, "some/relative/path2guestwatch"));
+    g_string_truncate(guest_watches, 0);
+
+    /* Overwrite an existing node */
+    err = write_str(s, DOMID_GUEST, XBT_NULL, "some/relative/path",
+                    "another thing");
+    g_assert(!err);
+    g_assert(s->nr_nodes == 8);
+    g_assert(!qemu_watches->len);
+    g_assert(!strcmp(guest_watches->str, "some/relative/pathguestwatch"));
+    g_string_truncate(guest_watches, 0);
+
+    /* We can list the two files we wrote */
+    err = xs_impl_directory(s, DOMID_GUEST, XBT_NULL, "some/relative", &gencnt,
+                            &items);
+    g_assert(!err);
+    g_assert(items);
+    g_assert(gencnt == 2);
+    g_assert(!strcmp(items->data, "path"));
+    g_assert(items->next);
+    g_assert(!strcmp(items->next->data, "path2"));
+    g_assert(!items->next->next);
+    g_list_free_full(items, g_free);
+
+    err = xs_impl_unwatch(s, DOMID_GUEST, "some", "guestwatch",
+                          watch_cb, guest_watches);
+    g_assert(!err);
+
+    err = xs_impl_unwatch(s, DOMID_GUEST, "some", "guestwatch",
+                          watch_cb, guest_watches);
+    g_assert(err == ENOENT);
+
+    err = xs_impl_watch(s, DOMID_GUEST, "some/relative/path2", "watchp2",
+                        watch_cb, guest_watches);
+    g_assert(!err);
+    g_assert(guest_watches->len == strlen("some/relative/path2watchp2"));
+    g_assert(!strcmp(guest_watches->str, "some/relative/path2watchp2"));
+    g_string_truncate(guest_watches, 0);
+
+    err = xs_impl_watch(s, DOMID_GUEST, "/local/domain/1/some/relative",
+                        "watchrel", watch_cb, guest_watches);
+    g_assert(!err);
+    g_assert(guest_watches->len ==
+             strlen("/local/domain/1/some/relativewatchrel"));
+    g_assert(!strcmp(guest_watches->str,
+                     "/local/domain/1/some/relativewatchrel"));
+    g_string_truncate(guest_watches, 0);
+
+    /* Write somewhere else which already existed */
+    err = write_str(s, DOMID_GUEST, XBT_NULL, "some/relative", "moredata");
+    g_assert(!err);
+    g_assert(s->nr_nodes == 8);
+
+    /* Write somewhere we aren't allowed */
+    err = write_str(s, DOMID_GUEST, XBT_NULL, "/local/domain/badplace",
+                    "moredata");
+    g_assert(err == EACCES);
+
+    g_assert(!strcmp(guest_watches->str,
+                     "/local/domain/1/some/relativewatchrel"));
+    g_string_truncate(guest_watches, 0);
+
+    g_byte_array_set_size(data, 0);
+    err = xs_impl_read(s, DOMID_GUEST, XBT_NULL, "some/relative", data);
+    g_assert(!err);
+    g_assert(data->len == strlen("moredata"));
+    g_assert(!memcmp(data->data, "moredata", data->len));
+
+    /* Overwrite existing data */
+    err = write_str(s, DOMID_GUEST, XBT_NULL, "some/relative", "otherdata");
+    g_assert(!err);
+    g_string_truncate(guest_watches, 0);
+
+    g_byte_array_set_size(data, 0);
+    err = xs_impl_read(s, DOMID_GUEST, XBT_NULL, "some/relative", data);
+    g_assert(!err);
+    g_assert(data->len == strlen("otherdata"));
+    g_assert(!memcmp(data->data, "otherdata", data->len));
+
+    /* Remove the subtree */
+    err = xs_impl_rm(s, DOMID_GUEST, XBT_NULL, "some/relative");
+    g_assert(!err);
+    g_assert(s->nr_nodes == 5);
+
+    /* Each watch fires with the least specific relevant path */
+    g_assert(strstr(guest_watches->str,
+                    "some/relative/path2watchp2"));
+    g_assert(strstr(guest_watches->str,
+                    "/local/domain/1/some/relativewatchrel"));
+    g_string_truncate(guest_watches, 0);
+
+    g_byte_array_set_size(data, 0);
+    err = xs_impl_read(s, DOMID_GUEST, XBT_NULL, "some/relative", data);
+    g_assert(err == ENOENT);
+    g_byte_array_unref(data);
+
+    xs_impl_reset_watches(s, DOMID_GUEST);
+    g_string_free(qemu_watches, true);
+    g_string_free(guest_watches, true);
+    xs_node_unref(old_root);
+    xs_impl_delete(s, true);
+}
+
+
+static void do_test_xs_node_tx(bool fail, bool commit)
+{
+    XenstoreImplState *s = setup();
+    GString *watches = g_string_new(NULL);
+    GByteArray *data = g_byte_array_new();
+    unsigned int tx_id = XBT_NULL;
+    int err;
+
+    g_assert(s);
+
+    /* Set a watch */
+    err = xs_impl_watch(s, DOMID_GUEST, "some", "watch",
+                        watch_cb, watches);
+    g_assert(!err);
+    g_assert(watches->len == strlen("somewatch"));
+    g_assert(!strcmp(watches->str, "somewatch"));
+    g_string_truncate(watches, 0);
+
+    /* Write something */
+    err = write_str(s, DOMID_GUEST, XBT_NULL, "some/relative/path",
+                    "something");
+    g_assert(s->nr_nodes == 7);
+    g_assert(!err);
+    g_assert(!strcmp(watches->str,
+                     "some/relative/pathwatch"));
+    g_string_truncate(watches, 0);
+
+    /* Create a transaction */
+    err = xs_impl_transaction_start(s, DOMID_GUEST, &tx_id);
+    g_assert(!err);
+
+    if (fail) {
+        /* Write something else in the root */
+        err = write_str(s, DOMID_GUEST, XBT_NULL, "some/relative/path",
+                        "another thing");
+        g_assert(!err);
+        g_assert(s->nr_nodes == 7);
+        g_assert(!strcmp(watches->str,
+                         "some/relative/pathwatch"));
+        g_string_truncate(watches, 0);
+    }
+
+    g_assert(!watches->len);
+
+    /* Perform a write in the transaction */
+    err = write_str(s, DOMID_GUEST, tx_id, "some/relative/path",
+                    "something else");
+    g_assert(!err);
+    g_assert(s->nr_nodes == 7);
+    g_assert(!watches->len);
+
+    err = xs_impl_read(s, DOMID_GUEST, XBT_NULL, "some/relative/path", data);
+    g_assert(!err);
+    if (fail) {
+        g_assert(data->len == strlen("another thing"));
+        g_assert(!memcmp(data->data, "another thing", data->len));
+    } else {
+        g_assert(data->len == strlen("something"));
+        g_assert(!memcmp(data->data, "something", data->len));
+    }
+    g_byte_array_set_size(data, 0);
+
+    err = xs_impl_read(s, DOMID_GUEST, tx_id, "some/relative/path", data);
+    g_assert(!err);
+    g_assert(data->len == strlen("something else"));
+    g_assert(!memcmp(data->data, "something else", data->len));
+    g_byte_array_set_size(data, 0);
+
+    check_serdes(s);
+
+    /* Attempt to commit the transaction */
+    err = xs_impl_transaction_end(s, DOMID_GUEST, tx_id, commit);
+    if (commit && fail) {
+        g_assert(err == EAGAIN);
+    } else {
+        g_assert(!err);
+    }
+    if (commit && !fail) {
+        g_assert(!strcmp(watches->str,
+                         "some/relative/pathwatch"));
+        g_string_truncate(watches, 0);
+    } else {
+       g_assert(!watches->len);
+    }
+    g_assert(s->nr_nodes == 7);
+
+    check_serdes(s);
+
+    err = xs_impl_unwatch(s, DOMID_GUEST, "some", "watch",
+                        watch_cb, watches);
+    g_assert(!err);
+
+    err = xs_impl_read(s, DOMID_GUEST, XBT_NULL, "some/relative/path", data);
+    g_assert(!err);
+    if (fail) {
+        g_assert(data->len == strlen("another thing"));
+        g_assert(!memcmp(data->data, "another thing", data->len));
+    } else if (commit) {
+        g_assert(data->len == strlen("something else"));
+        g_assert(!memcmp(data->data, "something else", data->len));
+    } else {
+        g_assert(data->len == strlen("something"));
+        g_assert(!memcmp(data->data, "something", data->len));
+    }
+    g_byte_array_unref(data);
+    g_string_free(watches, true);
+    xs_impl_delete(s, true);
+}
+
+static void test_xs_node_tx_fail(void)
+{
+    do_test_xs_node_tx(true, true);
+}
+
+static void test_xs_node_tx_abort(void)
+{
+    do_test_xs_node_tx(false, false);
+    do_test_xs_node_tx(true, false);
+}
+static void test_xs_node_tx_succeed(void)
+{
+    do_test_xs_node_tx(false, true);
+}
+
+static void test_xs_node_tx_rm(void)
+{
+    XenstoreImplState *s = setup();
+    GString *watches = g_string_new(NULL);
+    GByteArray *data = g_byte_array_new();
+    unsigned int tx_id = XBT_NULL;
+    int err;
+
+    g_assert(s);
+
+    /* Set a watch */
+    err = xs_impl_watch(s, DOMID_GUEST, "some", "watch",
+                        watch_cb, watches);
+    g_assert(!err);
+    g_assert(watches->len == strlen("somewatch"));
+    g_assert(!strcmp(watches->str, "somewatch"));
+    g_string_truncate(watches, 0);
+
+    /* Write something */
+    err = write_str(s, DOMID_GUEST, XBT_NULL, "some/deep/dark/relative/path",
+                    "something");
+    g_assert(!err);
+    g_assert(s->nr_nodes == 9);
+    g_assert(!strcmp(watches->str,
+                     "some/deep/dark/relative/pathwatch"));
+    g_string_truncate(watches, 0);
+
+    /* Create a transaction */
+    err = xs_impl_transaction_start(s, DOMID_GUEST, &tx_id);
+    g_assert(!err);
+
+    /* Delete the tree in the transaction */
+    err = xs_impl_rm(s, DOMID_GUEST, tx_id, "some/deep/dark");
+    g_assert(!err);
+    g_assert(s->nr_nodes == 9);
+    g_assert(!watches->len);
+
+    err = xs_impl_read(s, DOMID_GUEST, XBT_NULL, "some/deep/dark/relative/path",
+                       data);
+    g_assert(!err);
+    g_assert(data->len == strlen("something"));
+    g_assert(!memcmp(data->data, "something", data->len));
+    g_byte_array_set_size(data, 0);
+
+    check_serdes(s);
+
+    /* Commit the transaction */
+    err = xs_impl_transaction_end(s, DOMID_GUEST, tx_id, true);
+    g_assert(!err);
+    g_assert(s->nr_nodes == 6);
+
+    g_assert(!strcmp(watches->str, "some/deep/darkwatch"));
+    g_string_truncate(watches, 0);
+
+    /* Now the node is gone */
+    err = xs_impl_read(s, DOMID_GUEST, XBT_NULL, "some/deep/dark/relative/path",
+                       data);
+    g_assert(err == ENOENT);
+    g_byte_array_unref(data);
+
+    err = xs_impl_unwatch(s, DOMID_GUEST, "some", "watch",
+                        watch_cb, watches);
+    g_assert(!err);
+
+    g_string_free(watches, true);
+    xs_impl_delete(s, true);
+}
+
+static void test_xs_node_tx_resurrect(void)
+{
+    XenstoreImplState *s = setup();
+    GString *watches = g_string_new(NULL);
+    GByteArray *data = g_byte_array_new();
+    unsigned int tx_id = XBT_NULL;
+    int err;
+
+    g_assert(s);
+
+    /* Write something */
+    err = write_str(s, DOMID_GUEST, XBT_NULL, "some/deep/dark/relative/path",
+                    "something");
+    g_assert(!err);
+    g_assert(s->nr_nodes == 9);
+
+    /* Another node to remain shared */
+    err = write_str(s, DOMID_GUEST, XBT_NULL, "some/place/safe", "keepme");
+    g_assert(!err);
+    g_assert(s->nr_nodes == 11);
+
+    /* This node will be wiped and resurrected */
+    err = write_str(s, DOMID_GUEST, XBT_NULL, "some/deep/dark",
+                    "foo");
+    g_assert(!err);
+    g_assert(s->nr_nodes == 11);
+
+    /* Set a watch */
+    err = xs_impl_watch(s, DOMID_GUEST, "some", "watch",
+                        watch_cb, watches);
+    g_assert(!err);
+    g_assert(watches->len == strlen("somewatch"));
+    g_assert(!strcmp(watches->str, "somewatch"));
+    g_string_truncate(watches, 0);
+
+    /* Create a transaction */
+    err = xs_impl_transaction_start(s, DOMID_GUEST, &tx_id);
+    g_assert(!err);
+
+    /* Delete the tree in the transaction */
+    err = xs_impl_rm(s, DOMID_GUEST, tx_id, "some/deep");
+    g_assert(!err);
+    g_assert(s->nr_nodes == 11);
+    g_assert(!watches->len);
+
+    /* Resurrect part of it */
+    err = write_str(s, DOMID_GUEST, tx_id, "some/deep/dark/different/path",
+                    "something");
+    g_assert(!err);
+    g_assert(s->nr_nodes == 11);
+
+    check_serdes(s);
+
+    /* Commit the transaction */
+    err = xs_impl_transaction_end(s, DOMID_GUEST, tx_id, true);
+    g_assert(!err);
+    g_assert(s->nr_nodes == 11);
+
+    check_serdes(s);
+
+    /* lost data */
+    g_assert(strstr(watches->str, "some/deep/dark/different/pathwatch"));
+    /* topmost deleted */
+    g_assert(strstr(watches->str, "some/deep/dark/relativewatch"));
+    /* lost data */
+    g_assert(strstr(watches->str, "some/deep/darkwatch"));
+
+    g_string_truncate(watches, 0);
+
+    /* Now the node is gone */
+    err = xs_impl_read(s, DOMID_GUEST, XBT_NULL, "some/deep/dark/relative/path",
+                       data);
+    g_assert(err == ENOENT);
+    g_byte_array_unref(data);
+
+    check_serdes(s);
+
+    err = xs_impl_unwatch(s, DOMID_GUEST, "some", "watch",
+                        watch_cb, watches);
+    g_assert(!err);
+
+    g_string_free(watches, true);
+    xs_impl_delete(s, true);
+}
+
+static void test_xs_node_tx_resurrect2(void)
+{
+    XenstoreImplState *s = setup();
+    GString *watches = g_string_new(NULL);
+    GByteArray *data = g_byte_array_new();
+    unsigned int tx_id = XBT_NULL;
+    int err;
+
+    g_assert(s);
+
+    /* Write something */
+    err = write_str(s, DOMID_GUEST, XBT_NULL, "some/deep/dark/relative/path",
+                    "something");
+    g_assert(!err);
+    g_assert(s->nr_nodes == 9);
+
+    /* Another node to remain shared */
+    err = write_str(s, DOMID_GUEST, XBT_NULL, "some/place/safe", "keepme");
+    g_assert(!err);
+    g_assert(s->nr_nodes == 11);
+
+    /* This node will be wiped and resurrected */
+    err = write_str(s, DOMID_GUEST, XBT_NULL, "some/deep/dark",
+                    "foo");
+    g_assert(!err);
+    g_assert(s->nr_nodes == 11);
+
+    /* Set a watch */
+    err = xs_impl_watch(s, DOMID_GUEST, "some", "watch",
+                        watch_cb, watches);
+    g_assert(!err);
+    g_assert(watches->len == strlen("somewatch"));
+    g_assert(!strcmp(watches->str, "somewatch"));
+    g_string_truncate(watches, 0);
+
+    /* Create a transaction */
+    err = xs_impl_transaction_start(s, DOMID_GUEST, &tx_id);
+    g_assert(!err);
+
+    /* Delete the tree in the transaction */
+    err = xs_impl_rm(s, DOMID_GUEST, tx_id, "some/deep");
+    g_assert(!err);
+    g_assert(s->nr_nodes == 11);
+    g_assert(!watches->len);
+
+    /* Resurrect part of it */
+    err = write_str(s, DOMID_GUEST, tx_id, "some/deep/dark/relative/path",
+                    "something");
+    g_assert(!err);
+    g_assert(s->nr_nodes == 11);
+
+    check_serdes(s);
+
+    /* Commit the transaction */
+    err = xs_impl_transaction_end(s, DOMID_GUEST, tx_id, true);
+    g_assert(!err);
+    g_assert(s->nr_nodes == 11);
+
+    check_serdes(s);
+
+    /* lost data */
+    g_assert(strstr(watches->str, "some/deep/dark/relative/pathwatch"));
+    /* lost data */
+    g_assert(strstr(watches->str, "some/deep/darkwatch"));
+
+    g_string_truncate(watches, 0);
+
+    /* Now the node is gone */
+    err = xs_impl_read(s, DOMID_GUEST, XBT_NULL, "some/deep/dark/relative/path",
+                       data);
+    g_assert(!err);
+    g_assert(data->len == strlen("something"));
+    g_assert(!memcmp(data->data, "something", data->len));
+
+    g_byte_array_unref(data);
+
+    check_serdes(s);
+
+    err = xs_impl_unwatch(s, DOMID_GUEST, "some", "watch",
+                        watch_cb, watches);
+    g_assert(!err);
+
+    g_string_free(watches, true);
+    xs_impl_delete(s, true);
+}
+
+int main(int argc, char **argv)
+{
+    g_test_init(&argc, &argv, NULL);
+    module_call_init(MODULE_INIT_QOM);
+
+    g_test_add_func("/xs_node/simple", test_xs_node_simple);
+    g_test_add_func("/xs_node/tx_abort", test_xs_node_tx_abort);
+    g_test_add_func("/xs_node/tx_fail", test_xs_node_tx_fail);
+    g_test_add_func("/xs_node/tx_succeed", test_xs_node_tx_succeed);
+    g_test_add_func("/xs_node/tx_rm", test_xs_node_tx_rm);
+    g_test_add_func("/xs_node/tx_resurrect", test_xs_node_tx_resurrect);
+    g_test_add_func("/xs_node/tx_resurrect2", test_xs_node_tx_resurrect2);
+
+    return g_test_run();
+}