[Libguestfs] [PATCH hivex 19/19] lib: node_add_child: Handle li-records as intermediate notes (RHBZ#987463).
Richard W.M. Jones
rjones at redhat.com
Thu Jul 25 10:39:01 UTC 2013
From: "Richard W.M. Jones" <rjones at redhat.com>
This commit implements adding a child to a registry key that uses
li-records for intermediate nodes.
---
lib/write.c | 139 +++++++++++++++++++++++++++++++++++++++++++++++++-----------
1 file changed, 114 insertions(+), 25 deletions(-)
diff --git a/lib/write.c b/lib/write.c
index 371b1ab..076cf8c 100644
--- a/lib/write.c
+++ b/lib/write.c
@@ -385,6 +385,57 @@ insert_lf_record (hive_h *h, size_t old_offs, size_t posn,
return new_offs;
}
+/* Insert node into existing li-record at position. Pretty much the
+ * same as insert_lf_record above, but the record layout is a bit
+ * different.
+ */
+static size_t
+insert_li_record (hive_h *h, size_t old_offs, size_t posn,
+ const char *name, hive_node_h node)
+{
+ assert (IS_VALID_BLOCK (h, old_offs));
+ assert (BLOCK_ID_EQ (h, old_offs, "li"));
+
+ struct ntreg_ri_record *old_li =
+ (struct ntreg_ri_record *) ((char *) h->addr + old_offs);
+ size_t nr_offsets = le16toh (old_li->nr_offsets);
+
+ nr_offsets++; /* in new record ... */
+
+ size_t seg_len = sizeof (struct ntreg_ri_record) + (nr_offsets-1) * 4;
+
+ /* Copy the old_li->id in case it moves during allocate_block. */
+ char id[2];
+ memcpy (id, old_li->id, sizeof id);
+
+ size_t new_offs = allocate_block (h, seg_len, id);
+ if (new_offs == 0)
+ return 0;
+
+ /* old_li could have been invalidated by allocate_block. */
+ old_li = (struct ntreg_ri_record *) ((char *) h->addr + old_offs);
+
+ struct ntreg_ri_record *new_li =
+ (struct ntreg_ri_record *) ((char *) h->addr + new_offs);
+ new_li->nr_offsets = htole16 (nr_offsets);
+
+ /* Copy the offsets until we reach posn, insert the new offset
+ * there, then copy the remaining offsets.
+ */
+ size_t i;
+ for (i = 0; i < posn; ++i)
+ new_li->offset[i] = old_li->offset[i];
+
+ new_li->offset[i] = htole32 (node - 0x1000);
+
+ for (i = posn+1; i < nr_offsets; ++i)
+ new_li->offset[i] = old_li->offset[i-1];
+
+ /* Old block is unused, return new block. */
+ mark_block_unused (h, old_offs);
+ return new_offs;
+}
+
/* Compare name with name in nk-record. */
static int
compare_name_with_nk_name (hive_h *h, const char *name, hive_node_h nk_offs)
@@ -407,19 +458,34 @@ compare_name_with_nk_name (hive_h *h, const char *name, hive_node_h nk_offs)
return r;
}
+/* See comment about keeping things sorted in hivex_node_add_child. */
static int
insert_subkey (hive_h *h, const char *name,
size_t parent, size_t nkoffset, size_t *blocks)
{
size_t old_offs = 0, new_offs = 0;
- size_t i, j;
+ size_t i, j = SIZE_MAX;
struct ntreg_lf_record *old_lf = NULL;
+ struct ntreg_ri_record *old_li = NULL;
- /* Find lf/lh key name just after the one we are inserting. */
+ /* The caller already dealt with the no subkeys case, so this should
+ * be true.
+ */
+ assert (blocks[0] != 0);
+
+ /* Find the intermediate block which contains a link to the key that
+ * is just after the one we are inserting. This intermediate block
+ * might be an lf/lh-record or an li-record (but it won't be a
+ * ri-record so we can ignore those). The lf/lh- and li-records
+ * have different formats. If we cannot find the key after, then we
+ * end up at the final block and we have to insert the new key at
+ * the end.
+ */
for (i = 0; blocks[i] != 0; ++i) {
if (BLOCK_ID_EQ (h, blocks[i], "lf") || BLOCK_ID_EQ (h, blocks[i], "lh")) {
old_offs = blocks[i];
old_lf = (struct ntreg_lf_record *) ((char *) h->addr + old_offs);
+ old_li = NULL;
for (j = 0; j < le16toh (old_lf->nr_keys); ++j) {
hive_node_h nk_offs = le32toh (old_lf->keys[j].offset);
nk_offs += 0x1000;
@@ -427,39 +493,62 @@ insert_subkey (hive_h *h, const char *name,
goto insert_it;
}
}
+ else if (BLOCK_ID_EQ (h, blocks[i], "li")) {
+ old_offs = blocks[i];
+ old_lf = NULL;
+ old_li = (struct ntreg_ri_record *) ((char *) h->addr + old_offs);
+ for (j = 0; j < le16toh (old_li->nr_offsets); ++j) {
+ hive_node_h nk_offs = le32toh (old_li->offset[j]);
+ nk_offs += 0x1000;
+ if (compare_name_with_nk_name (h, name, nk_offs) < 0)
+ goto insert_it;
+ }
+ }
}
- /* Insert it at the end.
- * old_offs points to the last lf record, set j.
- */
- assert (old_offs != 0); /* should never happen if nr_subkeys > 0 */
- j = le16toh (old_lf->nr_keys);
+ /* To insert it at the end, we fall through here. */
+ assert (j != SIZE_MAX);
- /* Insert it. */
insert_it:
- DEBUG (2, "insert key in existing lh-record at 0x%zx, posn %zu",
- old_offs, j);
+ /* Verify that the search worked. */
+ assert (old_lf || old_li);
+ assert (!(old_lf && old_li));
- new_offs = insert_lf_record (h, old_offs, j, name, nkoffset);
- if (new_offs == 0)
- return -1;
+ if (old_lf) {
+ DEBUG (2, "insert key in existing lf/lh-record at 0x%zx, posn %zu",
+ old_offs, j);
- DEBUG (2, "new lh-record at 0x%zx", new_offs);
+ new_offs = insert_lf_record (h, old_offs, j, name, nkoffset);
+ if (new_offs == 0)
+ return -1;
+
+ DEBUG (2, "new lf/lh-record at 0x%zx", new_offs);
+ }
+ else /* old_li */ {
+ DEBUG (2, "insert key in existing li-record at 0x%zx, posn %zu",
+ old_offs, j);
+
+ new_offs = insert_li_record (h, old_offs, j, name, nkoffset);
+ if (new_offs == 0)
+ return -1;
+
+ DEBUG (2, "new li-record at 0x%zx", new_offs);
+ }
/* Recalculate pointers that could have been invalidated by
- * previous call to allocate_block (via new_lh_record).
+ * previous call to allocate_block (via new_{lf,li}_record).
*/
struct ntreg_nk_record *parent_nk =
(struct ntreg_nk_record *) ((char *) h->addr + parent);
- /* If the lf/lh-record was directly referenced by the parent nk,
- * then update the parent nk.
+ /* Since the lf/lh/li-record has moved, now we have to find the old
+ * reference to it and update it. It might be referenced directly
+ * from the parent_nk->subkey_lf, or it might be referenced
+ * indirectly from some ri-record in blocks[]. Since we can update
+ * either of these in-place, we don't need to do this recursively.
*/
if (le32toh (parent_nk->subkey_lf) + 0x1000 == old_offs)
parent_nk->subkey_lf = htole32 (new_offs - 0x1000);
- /* Else we have to look for the intermediate ri-record and update
- * that in-place.
- */
else {
for (i = 0; blocks[i] != 0; ++i) {
if (BLOCK_ID_EQ (h, blocks[i], "ri")) {
@@ -548,11 +637,11 @@ hivex_node_add_child (hive_h *h, hive_node_h parent, const char *name)
* Windows won't see the subkey _and_ Windows will corrupt the hive
* itself when it modifies or saves it.
*
- * So use get_children() to get a list of intermediate
- * lf/lh-records. get_children() returns these in reading order
- * (which is sorted), so we look for the lf/lh-records in sequence
- * until we find the key name just after the one we are inserting,
- * and we insert the subkey just before it.
+ * So use get_children() to get a list of intermediate records.
+ * get_children() returns these in reading order (which is sorted),
+ * so we look for the lf/lh/li-records in sequence until we find the
+ * key name just after the one we are inserting, and we insert the
+ * subkey just before it.
*
* The only other case is the no-subkeys case, where we have to
* create a brand new lh-record.
--
1.8.3.1
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