[PATCH v3 1/6] kernel-shark: Add KS_DOUBLE_SIZE macro

["Yordan Karadzhov (VMware)" <y.karadz@gmail.com>]

The macro is useful for resizing of dynamic arrays. It is currently
used to resize the Data stream descriptor array, owned by the session
context. We will later use the macro with the arrays of data fields and
plugin contexts.

Signed-off-by: Yordan Karadzhov (VMware) <y.karadz@gmail.com>
---
 src/libkshark-plugin.h    | 17 +++++++++++++++++
 src/libkshark.c           | 11 ++---------
 tests/libkshark-tests.cpp | 20 ++++++++++++++++++++
 3 files changed, 39 insertions(+), 9 deletions(-)

diff --git a/src/libkshark-plugin.h b/src/libkshark-plugin.h
index 1a642ad..4104357 100644
--- a/src/libkshark-plugin.h
+++ b/src/libkshark-plugin.h
@@ -346,6 +346,23 @@ int kshark_handle_dpi(struct kshark_data_stream *stream,
 int kshark_handle_all_dpis(struct kshark_data_stream *stream,
 			   enum kshark_plugin_actions  task_id);
 
+/** General purpose macro for resizing dynamic arrays. */
+#define KS_DOUBLE_SIZE(array, size)					\
+({									\
+	ssize_t __n = size;						\
+	bool __ok = false;						\
+	__typeof__(array) __tmp =					\
+		(__typeof__(array)) realloc(array,			\
+					    2 * __n * sizeof(*__tmp));	\
+	if (__tmp) {							\
+		memset(__tmp + __n, 0, __n * sizeof(*__tmp));		\
+		size = 2 * __n;						\
+		array = __tmp;						\
+		__ok = true;						\
+	}								\
+	__ok;								\
+})									\
+
 #ifdef __cplusplus
 }
 #endif // __cplusplus
diff --git a/src/libkshark.c b/src/libkshark.c
index 315c24f..0e2ce7a 100644
--- a/src/libkshark.c
+++ b/src/libkshark.c
@@ -234,16 +234,9 @@ int kshark_add_stream(struct kshark_context *kshark_ctx)
 
 	if (kshark_ctx->stream_info.next_free_stream_id ==
 	    kshark_ctx->stream_info.array_size) {
-		size_t new_size = 2 * kshark_ctx->stream_info.array_size;
-		struct kshark_data_stream **streams_tmp;
-
-		streams_tmp = realloc(kshark_ctx->stream,
-				      new_size * sizeof(*kshark_ctx->stream));
-		if (!streams_tmp)
+		if (!KS_DOUBLE_SIZE(kshark_ctx->stream,
+				    kshark_ctx->stream_info.array_size))
 			return -ENOMEM;
-
-		kshark_ctx->stream = streams_tmp;
-		kshark_ctx->stream_info.array_size = new_size;
 	}
 
 	stream = kshark_stream_alloc();
diff --git a/tests/libkshark-tests.cpp b/tests/libkshark-tests.cpp
index 27c1171..d0a3594 100644
--- a/tests/libkshark-tests.cpp
+++ b/tests/libkshark-tests.cpp
@@ -46,3 +46,23 @@ BOOST_AUTO_TEST_CASE(add_remove_streams)
 
 	kshark_close_all(kshark_ctx);
 }
+
+#define ARRAY_DEFAULT_SIZE	1000
+BOOST_AUTO_TEST_CASE(doule_size_macro)
+{
+	int i, n = ARRAY_DEFAULT_SIZE;
+	int *arr = (int *) malloc(n * sizeof(*arr));
+	bool ok;
+
+	for (i = 0; i < n; ++i)
+		arr[i] = i;
+
+	ok = KS_DOUBLE_SIZE(arr, n);
+	BOOST_CHECK_EQUAL(ok, true);
+	BOOST_CHECK_EQUAL(n, ARRAY_DEFAULT_SIZE * 2);
+
+	for (i = 0; i < ARRAY_DEFAULT_SIZE; ++i)
+		BOOST_CHECK_EQUAL(arr[i], i);
+	for (; i < n; ++i)
+		BOOST_CHECK_EQUAL(arr[i], 0);
+}
-- 
2.25.1