From 5a2f5f00f3444590bb1b237f55836f07edc9bef5 Mon Sep 17 00:00:00 2001
From: =?utf8?q?J=C3=A9r=C3=A9mie=20Galarneau?=
 <jeremie.galarneau@efficios.com>
Date: Fri, 19 Jun 2020 18:54:58 -0400
Subject: [PATCH] common: add lttng_payload_view fd count accessor and buffer
 init
MIME-Version: 1.0
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Allow the initialization of a payload view from a subset of a dynamic
buffer (echoing the lttng_buffer_view API) and add an accessor for the
fd count property.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: I647e955b625230010a8789df88f93cf19487ce58
---
 src/common/payload-view.c | 36 ++++++++++++++++++++++++++++++++++++
 src/common/payload-view.h | 29 ++++++++++++++++++++++++++++-
 2 files changed, 64 insertions(+), 1 deletion(-)

diff --git a/src/common/payload-view.c b/src/common/payload-view.c
index fdfef6150..f15fa8447 100644
--- a/src/common/payload-view.c
+++ b/src/common/payload-view.c
@@ -5,6 +5,7 @@
  *
  */
 
+#include <common/dynamic-array.h>
 #include <common/buffer-view.h>
 #include "payload-view.h"
 #include "payload.h"
@@ -46,6 +47,41 @@ struct lttng_payload_view lttng_payload_view_from_dynamic_buffer(
 	};
 }
 
+LTTNG_HIDDEN
+struct lttng_payload_view lttng_payload_view_from_buffer_view(
+		const struct lttng_buffer_view *view, size_t offset,
+		ptrdiff_t len)
+{
+	return (struct lttng_payload_view) {
+		.buffer = lttng_buffer_view_from_view(
+			view, offset, len)
+	};
+}
+
+LTTNG_HIDDEN
+int lttng_payload_view_get_fd_count(struct lttng_payload_view *payload_view)
+{
+	int ret;
+	size_t position;
+
+	if (!payload_view) {
+		ret = -1;
+		goto end;
+	}
+
+	ret = lttng_dynamic_array_get_count(&payload_view->_fds);
+	if (ret < 0) {
+		goto end;
+	}
+
+	position = payload_view->_iterator.p_fds_position ?
+			*payload_view->_iterator.p_fds_position :
+			payload_view->_iterator.fds_position;
+	ret = ret - (int) position;
+end:
+	return ret;
+}
+
 LTTNG_HIDDEN
 int lttng_payload_view_pop_fd(struct lttng_payload_view *view)
 {
diff --git a/src/common/payload-view.h b/src/common/payload-view.h
index f125e8890..c7501bcda 100644
--- a/src/common/payload-view.h
+++ b/src/common/payload-view.h
@@ -87,7 +87,7 @@ struct lttng_payload_view lttng_payload_view_from_view(
  * from an existing dynamic buffer.
  *
  * @src		Source dynamic buffer to reference
- * @offset	Offset to apply to the payload's buffer
+ * @offset	Offset to apply to the dynamic buffer
  * @len		Length of the buffer contents to reference. Passing -1 will
  *		cause the payload view to reference the whole payload from the
  *		offset provided.
@@ -96,6 +96,33 @@ LTTNG_HIDDEN
 struct lttng_payload_view lttng_payload_view_from_dynamic_buffer(
 		const struct lttng_dynamic_buffer *buffer, size_t offset,
 		ptrdiff_t len);
+/**
+ *
+ * Return a payload view referencing a subset of a dynamic buffer.
+ *
+ * Meant as an adapter for code paths that need to create a payload view
+ * from an existing buffer view.
+ *
+ * @src		Source buffer view to reference
+ * @offset	Offset to apply to the buffer view
+ * @len		Length of the buffer contents to reference. Passing -1 will
+ *		cause the payload view to reference the whole payload from the
+ *		offset provided.
+ */
+LTTNG_HIDDEN
+struct lttng_payload_view lttng_payload_view_from_buffer_view(
+		const struct lttng_buffer_view *view, size_t offset,
+		ptrdiff_t len);
+
+/**
+ * Get the number of file descriptors left in a payload view.
+ *
+ * @payload	Payload instance
+ *
+ * Returns the number of file descriptors left on success, -1 on error.
+ */
+LTTNG_HIDDEN
+int lttng_payload_view_get_fd_count(struct lttng_payload_view *payload_view);
 
 /**
  * Pop an fd from a payload view.
-- 
2.34.1