[v2,2/7] libsepol: add ebitmap_init_range

Commit Message

Christian Göttsche July 19, 2022, 3:30 p.m. UTC

Add an initializer for ebitmaps that sets all bits in a given range to
save node traversals for each bit to set, compared to calling
ebitmap_init() followed by iterating ebitmap_set_bit().

Signed-off-by: Christian Göttsche <[e-mail]>
---
v2:
  use braces for all if-else branches when used for at least one of them
---
 libsepol/include/sepol/policydb/ebitmap.h |  1 +
 libsepol/src/ebitmap.c                    | 49 +++++++++++++++++++++++
 libsepol/tests/test-ebitmap.c             | 32 +++++++++++++++
 3 files changed, 82 insertions(+)

Patch

diff --git a/libsepol/include/sepol/policydb/ebitmap.h b/libsepol/include/sepol/policydb/ebitmap.h
index 81d0c7a6..85b7ccfb 100644
--- a/libsepol/include/sepol/policydb/ebitmap.h
+++ b/libsepol/include/sepol/policydb/ebitmap.h
@@ -94,6 +94,7 @@  extern int ebitmap_contains(const ebitmap_t * e1, const ebitmap_t * e2);
 extern int ebitmap_match_any(const ebitmap_t *e1, const ebitmap_t *e2);
 extern int ebitmap_get_bit(const ebitmap_t * e, unsigned int bit);
 extern int ebitmap_set_bit(ebitmap_t * e, unsigned int bit, int value);
+extern int ebitmap_init_range(ebitmap_t * e, unsigned int minbit, unsigned int maxbit);
 extern unsigned int ebitmap_highest_set_bit(const ebitmap_t * e);
 extern void ebitmap_destroy(ebitmap_t * e);
 extern int ebitmap_read(ebitmap_t * e, void *fp);
diff --git a/libsepol/src/ebitmap.c b/libsepol/src/ebitmap.c
index bd98c0f8..0f9afd62 100644
--- a/libsepol/src/ebitmap.c
+++ b/libsepol/src/ebitmap.c
@@ -349,6 +349,55 @@  int ebitmap_set_bit(ebitmap_t * e, unsigned int bit, int value)
 	return 0;
 }
 
+int ebitmap_init_range(ebitmap_t * e, unsigned int minbit, unsigned int maxbit)
+{
+	ebitmap_node_t *new, *prev = NULL;
+	uint32_t minstartbit = minbit & ~(MAPSIZE - 1);
+	uint32_t maxstartbit = maxbit & ~(MAPSIZE - 1);
+	uint32_t minhighbit = minstartbit + MAPSIZE;
+	uint32_t maxhighbit = maxstartbit + MAPSIZE;
+	uint32_t startbit;
+	MAPTYPE mask;
+
+	ebitmap_init(e);
+
+	if (minbit > maxbit)
+		return -EINVAL;
+
+	if (minhighbit == 0 || maxhighbit == 0)
+		return -EOVERFLOW;
+
+	for (startbit = minstartbit; startbit <= maxstartbit; startbit += MAPSIZE) {
+		new = malloc(sizeof(ebitmap_node_t));
+		if (!new)
+			return -ENOMEM;
+
+		new->next = NULL;
+		new->startbit = startbit;
+
+		if (startbit != minstartbit && startbit != maxstartbit) {
+			new->map = ~((MAPTYPE)0);
+		} else if (startbit != maxstartbit) {
+			new->map = ~((MAPTYPE)0) << (minbit - startbit);
+		} else if (startbit != minstartbit) {
+			new->map = ~((MAPTYPE)0) >> (MAPSIZE - (maxbit - startbit + 1));
+		} else {
+			mask = ~((MAPTYPE)0) >> (MAPSIZE - (maxbit - minbit + 1));
+			new->map = (mask << (minbit - startbit));
+		}
+
+		if (prev)
+			prev->next = new;
+		else
+			e->node = new;
+		prev = new;
+	}
+
+	e->highbit = maxhighbit;
+
+	return 0;
+}
+
 unsigned int ebitmap_highest_set_bit(const ebitmap_t * e)
 {
 	const ebitmap_node_t *n;
diff --git a/libsepol/tests/test-ebitmap.c b/libsepol/tests/test-ebitmap.c
index fad5bd75..8774555e 100644
--- a/libsepol/tests/test-ebitmap.c
+++ b/libsepol/tests/test-ebitmap.c
@@ -253,6 +253,37 @@  static void test_ebitmap_set_and_get(void)
 	ebitmap_destroy(&e);
 }
 
+static void test_ebitmap_init_range(void)
+{
+	ebitmap_t e1, e2, e3, e4, e5, e6;
+
+	CU_ASSERT_EQUAL(ebitmap_init_range(&e1, 0, 0), 0);
+	CU_ASSERT_EQUAL(ebitmap_highest_set_bit(&e1), 0);
+	CU_ASSERT_EQUAL(ebitmap_cardinality(&e1), 1);
+
+	CU_ASSERT_EQUAL(ebitmap_init_range(&e2, 0, 5), 0);
+	CU_ASSERT_EQUAL(ebitmap_highest_set_bit(&e2), 5);
+	CU_ASSERT_EQUAL(ebitmap_cardinality(&e2), 6);
+
+	CU_ASSERT_EQUAL(ebitmap_init_range(&e3, 20, 100), 0);
+	CU_ASSERT_EQUAL(ebitmap_highest_set_bit(&e3), 100);
+	CU_ASSERT_EQUAL(ebitmap_cardinality(&e3), 81);
+
+	CU_ASSERT_EQUAL(ebitmap_init_range(&e4, 100, 400), 0);
+	CU_ASSERT_EQUAL(ebitmap_highest_set_bit(&e4), 400);
+	CU_ASSERT_EQUAL(ebitmap_cardinality(&e4), 301);
+
+	CU_ASSERT_EQUAL(ebitmap_init_range(&e5, 10, 5), -EINVAL);
+	CU_ASSERT_EQUAL(ebitmap_init_range(&e6, 0, UINT32_MAX), -EOVERFLOW);
+
+	ebitmap_destroy(&e6);
+	ebitmap_destroy(&e5);
+	ebitmap_destroy(&e4);
+	ebitmap_destroy(&e3);
+	ebitmap_destroy(&e2);
+	ebitmap_destroy(&e1);
+}
+
 static void test_ebitmap_or(void)
 {
 	ebitmap_t e1, e2, e3, e4;
@@ -1038,6 +1069,7 @@  int ebitmap_add_tests(CU_pSuite suite)
 	ADD_TEST(ebitmap_init_destroy);
 	ADD_TEST(ebitmap_cmp);
 	ADD_TEST(ebitmap_set_and_get);
+	ADD_TEST(ebitmap_init_range);
 	ADD_TEST(ebitmap_or);
 	ADD_TEST(ebitmap_and);
 	ADD_TEST(ebitmap_xor);