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Fix page_map corruption in hb_set_t during process(). 

If a process operation results in less pages then the current set has, it will likely corrupt the page_map since it overwrites page_map entries ahead of where it's processing. This fixes that problem by removing page_map entries that will be dropped. Then dropping orphaned pages and re-indexing retained pages.
This commit is contained in:
Garret Rieger 2020-01-28 13:55:31 -08:00 committed by Ebrahim Byagowi
parent eb7849a806
commit 2742c81624
2 changed files with 127 additions and 3 deletions
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51
src/hb-set.hh
View File

@ -450,6 +450,32 @@ struct hb_set_t
return true;
}
void compact (unsigned int length)
{
hb_hashmap_t<uint32_t, uint32_t> old_index_to_page_map_index;
for (unsigned int i = 0; i < length; i++) {
old_index_to_page_map_index.set (page_map[i].index, i);
}
compact_pages (old_index_to_page_map_index);
}
void compact_pages (const hb_hashmap_t<uint32_t, uint32_t>& old_index_to_page_map_index)
{
unsigned int write_index = 0;
for (unsigned int i = 0; i < pages.length; i++)
{
if (!old_index_to_page_map_index.has (i)) continue;
if (write_index < i)
pages[write_index] = pages[i];
page_map[old_index_to_page_map_index[i]].index = write_index;
write_index++;
}
}
template <typename Op>
void process (const Op& op, const hb_set_t *other)
{
@ -463,10 +489,22 @@ struct hb_set_t
unsigned int count = 0, newCount = 0;
unsigned int a = 0, b = 0;
unsigned int write_index = 0;
for (; a < na && b < nb; )
{
if (page_map[a].major == other->page_map[b].major)
{
if (!Op::passthru_left)
{
// Move page_map entries that we're keeping from the left side set
// to the front of the page_map vector. This isn't necessary if
// passthru_left is set since no left side pages will be removed
// in that case.
if (write_index < a)
page_map[write_index] = page_map[a];
write_index++;
}
count++;
a++;
b++;
@ -489,9 +527,16 @@ struct hb_set_t
if (Op::passthru_right)
count += nb - b;
if (count > pages.length)
if (!resize (count))
return;
if (!Op::passthru_left)
{
na = write_index;
next_page = write_index;
compact (write_index);
}
if (!resize (count))
return;
newCount = count;
/* Process in-place backward. */

79
test/api/test-set.c
View File

@ -135,6 +135,81 @@ test_set_basic (void)
// printf ("}\n");
// }
static void test_set_intersect_empty (void)
{
hb_set_t* a = hb_set_create ();
hb_set_add (a, 3585);
hb_set_add (a, 21333);
hb_set_add (a, 24405);
hb_set_t* b = hb_set_create();
hb_set_add (b, 21483);
hb_set_add (b, 24064);
hb_set_intersect (a, b);
g_assert (hb_set_is_empty (a));
hb_set_destroy (a);
hb_set_destroy (b);
a = hb_set_create ();
hb_set_add (a, 16777216);
b = hb_set_create();
hb_set_add (b, 0);
hb_set_intersect (a, b);
g_assert (hb_set_is_empty (a));
hb_set_destroy (a);
hb_set_destroy (b);
}
static void test_set_intersect_page_reduction (void)
{
hb_set_t* a = hb_set_create ();
hb_set_add (a, 3585);
hb_set_add (a, 21333);
hb_set_add (a, 24405);
hb_set_t* b = hb_set_create();
hb_set_add (b, 3585);
hb_set_add (b, 24405);
hb_set_intersect(a, b);
g_assert (hb_set_is_equal (a, b));
hb_set_destroy (a);
hb_set_destroy (b);
}
static void test_set_union (void)
{
hb_set_t* a = hb_set_create();
hb_set_add (a, 3585);
hb_set_add (a, 21333);
hb_set_add (a, 24405);
hb_set_t* b = hb_set_create();
hb_set_add (b, 21483);
hb_set_add (b, 24064);
hb_set_t* u = hb_set_create ();
hb_set_add (u, 3585);
hb_set_add (u, 21333);
hb_set_add (u, 21483);
hb_set_add (u, 24064);
hb_set_add (u, 24405);
hb_set_union(b, a);
g_assert (hb_set_is_equal (u, b));
hb_set_destroy (a);
hb_set_destroy (b);
hb_set_destroy (u);
}
static void
test_set_algebra (void)
{
@ -405,5 +480,9 @@ main (int argc, char **argv)
hb_test_add (test_set_iter);
hb_test_add (test_set_empty);
hb_test_add (test_set_intersect_empty);
hb_test_add (test_set_intersect_page_reduction);
hb_test_add (test_set_union);
return hb_test_run();
}