shared: add NM_PTRARRAY_LEN() utility macro

I used to use g_strv_length ((char **) p) instead, but that feels
ugly because it g_strv_length() is not designed to operate on
arbitrary pointer arrays.

2 files changed, 93 insertions, 0 deletions

diff --git a/libnm-core/tests/test-general.c b/libnm-core/tests/test-general.c
index 0f65e8f6ae..0d6cb5322d 100644
--- a/libnm-core/tests/test-general.c
+++ b/libnm-core/tests/test-general.c
@@ -4655,6 +4655,81 @@ test_nm_utils_strstrdictkey (void)
 
 /*****************************************************************************/
 
+static guint
+_g_strv_length (gconstpointer arr)
+{
+	return arr ? g_strv_length ((char **) arr) : 0;
+}
+
+static void
+test_nm_ptrarray_len (void)
+{
+#define _PTRARRAY_cmp(len, arr) \
+	G_STMT_START { \
+		g_assert_cmpint (len, ==, NM_PTRARRAY_LEN (arr)); \
+		g_assert_cmpint (len, ==, _g_strv_length (arr)); \
+	} G_STMT_END
+#define _PTRARRAY_LEN0(T) \
+	G_STMT_START { \
+		T **vnull = NULL; \
+		T *const*vnull1 = NULL; \
+		T *const*const vnull2 = NULL; \
+		T *v0[] = { NULL }; \
+		T *const*v01 = v0; \
+		T *const*const v02 = v0; \
+		T **const v03 = v0; \
+		\
+		_PTRARRAY_cmp (0, vnull); \
+		_PTRARRAY_cmp (0, vnull1); \
+		_PTRARRAY_cmp (0, vnull2); \
+		_PTRARRAY_cmp (0, v0); \
+		_PTRARRAY_cmp (0, v01); \
+		_PTRARRAY_cmp (0, v02); \
+		_PTRARRAY_cmp (0, v03); \
+	} G_STMT_END
+
+	_PTRARRAY_LEN0 (char);
+	_PTRARRAY_LEN0 (const char);
+	_PTRARRAY_LEN0 (int);
+	_PTRARRAY_LEN0 (const int);
+	_PTRARRAY_LEN0 (void *);
+	_PTRARRAY_LEN0 (void);
+	_PTRARRAY_LEN0 (const void);
+
+#define _PTRARRAY_LENn(T) \
+	G_STMT_START { \
+		T x[5] = { 0 }; \
+		\
+		T *v1[] = { &x[0], NULL }; \
+		T *const*v11 = v1; \
+		T *const*const v12 = v1; \
+		T **const v13 = v1; \
+		\
+		T *v2[] = { &x[0], &x[1], NULL }; \
+		T *const*v21 = v2; \
+		T *const*const v22 = v2; \
+		T **const v23 = v2; \
+		\
+		_PTRARRAY_cmp (1, v1); \
+		_PTRARRAY_cmp (1, v11); \
+		_PTRARRAY_cmp (1, v12); \
+		_PTRARRAY_cmp (1, v13); \
+		\
+		_PTRARRAY_cmp (2, v2); \
+		_PTRARRAY_cmp (2, v21); \
+		_PTRARRAY_cmp (2, v22); \
+		_PTRARRAY_cmp (2, v23); \
+	} G_STMT_END
+
+	_PTRARRAY_LENn (char);
+	_PTRARRAY_LENn (const char);
+	_PTRARRAY_LENn (int);
+	_PTRARRAY_LENn (const int);
+	_PTRARRAY_LENn (void *);
+}
+
+/*****************************************************************************/
+
 static void
 test_nm_utils_dns_option_validate_do (char *option, gboolean ipv6, const NMUtilsDNSOptionDesc *descs,
                                       gboolean exp_result, char *exp_name, gboolean exp_value)
@@ -5716,6 +5791,7 @@ int main (int argc, char **argv)
 	g_test_add_func ("/core/general/_glib_compat_g_hash_table_get_keys_as_array", test_g_hash_table_get_keys_as_array);
 	g_test_add_func ("/core/general/_nm_utils_ptrarray_find_binary_search", test_nm_utils_ptrarray_find_binary_search);
 	g_test_add_func ("/core/general/_nm_utils_strstrdictkey", test_nm_utils_strstrdictkey);
+	g_test_add_func ("/core/general/nm_ptrarray_len", test_nm_ptrarray_len);
 
 	g_test_add_func ("/core/general/_nm_utils_dns_option_validate", test_nm_utils_dns_option_validate);
 	g_test_add_func ("/core/general/_nm_utils_dns_option_find_idx", test_nm_utils_dns_option_find_idx);
diff --git a/shared/nm-utils/nm-macros-internal.h b/shared/nm-utils/nm-macros-internal.h
index f362968f58..eaf8b9e54d 100644
--- a/shared/nm-utils/nm-macros-internal.h
+++ b/shared/nm-utils/nm-macros-internal.h
@@ -209,6 +209,23 @@ NM_G_ERROR_MSG (GError *error)
 /* macro to return strlen() of a compile time string. */
 #define NM_STRLEN(str)     ( sizeof ("" str) - 1 )
 
+/* returns the length of a NULL terminated array of pointers,
+ * like g_strv_length() does. The difference is:
+ *  - it operats on arrays of pointers (of any kind, requiring no cast).
+ *  - it accepts NULL to return zero. */
+#define NM_PTRARRAY_LEN(array) \
+	({ \
+		typeof (*(array)) *const _array = (array); \
+		gsize _n = 0; \
+		\
+		if (_array) { \
+			_nm_unused typeof (*(_array[0])) *_array_check = _array[0]; \
+			while (_array[_n]) \
+				_n++; \
+		} \
+		_n; \
+	})
+
 /* Note: @value is only evaluated when *out_val is present.
  * Thus,
  *    NM_SET_OUT (out_str, g_strdup ("hallo"));