array: Add array_bsearch function

src/libstrongswan/collections/array.c

@@ -419,6 +419,56 @@ void array_sort(array_t *array, int (*cmp)(const void*,const void*,void*),
 	}
 }
 
+typedef struct {
+	/** the array */
+	array_t *array;
+	/** the key */
+	const void *key;
+	/** comparison function */
+	int (*cmp)(const void*,const void*);
+} bsearch_data_t;
+
+static int search_elements(const void *a, const void *b)
+{
+	bsearch_data_t *data = (bsearch_data_t*)a;
+
+	if (data->array->esize)
+	{
+		return data->cmp(data->key, b);
+	}
+	return data->cmp(data->key, *(void**)b);
+}
+
+int array_bsearch(array_t *array, const void *key,
+				  int (*cmp)(const void*,const void*), void *out)
+{
+	int idx = -1;
+
+	if (array)
+	{
+		bsearch_data_t data = {
+			.array = array,
+			.key = key,
+			.cmp = cmp,
+		};
+		void *start, *item;
+
+		start = array->data + get_size(array, array->head);
+
+		item = bsearch(&data, start, array->count, get_size(array, 1),
+					   search_elements);
+		if (item)
+		{
+			if (out)
+			{
+				memcpy(out, item, get_size(array, 1));
+			}
+			idx = (item - start) / get_size(array, 1);
+		}
+	}
+	return idx;
+}
+
 void array_invoke(array_t *array, array_callback_t cb, void *user)
 {
 	if (array)

src/libstrongswan/collections/array.h

@@ -185,6 +185,31 @@ bool array_remove(array_t *array, int idx, void *data);
 void array_sort(array_t *array, int (*cmp)(const void*,const void*,void*),
 				void *user);
 
+/**
+ * Binary search of a sorted array.
+ *
+ * The array should be sorted in ascending order according to the given
+ * comparison function.
+ *
+ * The comparison function must return an integer less than, equal to, or
+ * greater than zero if the first argument (the key) is considered to be
+ * respectively less than, equal to, or greater than the second.
+ *
+ * If there are multiple elements that match the key it is not specified which
+ * element is returned.
+ *
+ * The comparison function receives the key object and a pointer to an array
+ * element (esize != 0) or an actual pointer (esize = 0).
+ *
+ * @param array			array to search, or NULL
+ * @param key			key to search for
+ * @param cmp			comparison function
+ * @param data			data to copy element to, or NULL
+ * @return				index of the element if found, -1 if not
+ */
+int array_bsearch(array_t *array, const void *key,
+				  int (*cmp)(const void*,const void*), void *data);
+
 /**
  * Invoke a callback for all array members.
  *

src/libstrongswan/tests/suites/test_array.c

@@ -359,6 +359,67 @@ START_TEST(test_sort_ptr)
 }
 END_TEST
 
+static int comp_search_obj(const void *a, const void *b)
+{
+	return *(int*)a - *(int*)b;
+}
+
+START_TEST(test_bsearch_obj)
+{
+	array_t *array;
+	int x[] = { 3, 2, 1 };
+	int k, v;
+
+	array = array_create(sizeof(x[0]), 0);
+	array_insert(array, ARRAY_TAIL, &x[0]);
+	array_insert(array, ARRAY_TAIL, &x[1]);
+	array_insert(array, ARRAY_TAIL, &x[2]);
+
+	array_sort(array, (void*)comp_search_obj, NULL);
+
+	k = 0;
+	ck_assert_int_eq(array_bsearch(array, &k, comp_search_obj, &v), -1);
+	for (k = 1; k < 4; k++)
+	{
+		ck_assert_int_eq(array_bsearch(array, &k, comp_search_obj, &v), k-1);
+		ck_assert_int_eq(v, k);
+	}
+	k = 4;
+	ck_assert_int_eq(array_bsearch(array, &k, comp_search_obj, &v), -1);
+	array_destroy(array);
+}
+END_TEST
+
+static int comp_search_ptr(const void *a, const void *b)
+{
+	return strcmp(a, b);
+}
+
+START_TEST(test_bsearch_ptr)
+{
+	array_t *array;
+	char *x[] = {"c", "b", "a"};
+	char *v;
+
+	array = array_create(0, 0);
+	array_insert(array, ARRAY_TAIL, x[0]);
+	array_insert(array, ARRAY_TAIL, x[1]);
+	array_insert(array, ARRAY_TAIL, x[2]);
+
+	array_sort(array, (void*)comp_search_ptr, NULL);
+
+	ck_assert_int_eq(array_bsearch(array, "abc", comp_search_ptr, &v), -1);
+	ck_assert_int_eq(array_bsearch(array, "a", comp_search_ptr, &v), 0);
+	ck_assert_str_eq(v, "a");
+	ck_assert_int_eq(array_bsearch(array, "b", comp_search_ptr, &v), 1);
+	ck_assert_str_eq(v, "b");
+	ck_assert_int_eq(array_bsearch(array, "c", comp_search_ptr, &v), 2);
+	ck_assert_str_eq(v, "c");
+
+	array_destroy(array);
+}
+END_TEST
+
 static void invoke(void *data, int idx, void *user)
 {
 	int *y = user, *x = data;
@@ -454,6 +515,11 @@ Suite *array_suite_create()
 	tcase_add_test(tc, test_sort_ptr);
 	suite_add_tcase(s, tc);
 
+	tc = tcase_create("bsearch");
+	tcase_add_test(tc, test_bsearch_obj);
+	tcase_add_test(tc, test_bsearch_ptr);
+	suite_add_tcase(s, tc);
+
 	tc = tcase_create("invoke");
 	tcase_add_test(tc, test_invoke);
 	suite_add_tcase(s, tc);