payload: use fd_handle instead of raw file descriptors

[lttng-tools.git] / src / common / payload-view.h

diff --git a/src/common/payload-view.h b/src/common/payload-view.h
index f125e8890bf9e2d207f9a9d0a7cd32c05dfb4da7..a07c0be003c7e9638c0ab8af0f1bd0f0cb6e6326 100644 (file)
--- a/src/common/payload-view.h
+++ b/src/common/payload-view.h
@@ -12,6 +12,7 @@
 #include <common/dynamic-array.h>
 
 struct lttng_payload;
+struct fd_handle;
 
 /*
  * An lttng_payload_view references a payload and allows code to share
@@ -21,22 +22,23 @@ struct lttng_payload;
  * payload view) is modified.
  *
  * While a payload view does not allow users to modify the underlying bytes
- * of the payload, it can be used to 'pop' file descriptors using an iterator
- * belonging to the top-level payload view.
+ * of the payload, it can be used to 'pop' file descriptor handles using an
+ * iterator belonging to the top-level payload view.
  *
  * Hence, a payload view created from a        payload or a dynamic buffer contains
- * an implicit file descriptor iterator. Any payload view created from another
- * payload view will share the same underlying file descriptor iterator.
+ * an implicit file descriptor handle iterator. Any payload view created from
+ * another payload view will share the same underlying file descriptor handle
+ * iterator.
  *
- * The rationale for this is that a payload is never consumed directly, it
- * must be consumed through a payload view.
+ * The rationale for this is that a payload is never consumed directly, it must
+ * be consumed through a payload view.
  *
  * Typically, a payload view will be used to rebuild a previously serialized
  * object hierarchy. Sharing an underlying iterator allows aggregate objects
  * to provide a restricted view of the payload to their members, which will
- * report the number of bytes consumed and `pop` the file descriptors they
+ * report the number of bytes consumed and `pop` the file descriptor handle they
  * should own. In return, those objects can create an even narrower view for
- * their children, allowing them to also consume file descriptors.
+ * their children, allowing them to also consume file descriptor handles.
  *
  * Note that a payload view never assumes any ownership of the underlying
  * payload.
@@ -44,10 +46,10 @@ struct lttng_payload;
 struct lttng_payload_view {
        struct lttng_buffer_view buffer;
        /* private */
-       const struct lttng_dynamic_array _fds;
+       const struct lttng_dynamic_pointer_array _fd_handles;
        struct {
-               size_t *p_fds_position;
-               size_t fds_position;
+               size_t *p_fd_handles_position;
+               size_t fd_handles_position;
        } _iterator;
 };
 
@@ -87,7 +89,7 @@ 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.
@@ -96,16 +98,61 @@ 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);
 
 /**
- * Pop an fd from a payload view.
- * No ownership of the file descriptor is assumed by the payload.
+ * Return a payload view referencing a subset of the memory referenced by a raw
+ * pointer.
+ *
+ * @src                Source buffer to reference
+ * @offset     Offset to apply to the source memory buffer
+ * @len                Length of the memory contents to reference.
+ *
+ * Note that a payload view never assumes the ownership of the memory it
+ * references.
+ */
+LTTNG_HIDDEN
+struct lttng_payload_view lttng_payload_view_init_from_buffer(
+               const char *src, size_t offset, ptrdiff_t len);
+
+/**
+ * Get the number of file descriptor handles left in a payload view.
+ *
+ * @payload    Payload instance
+ *
+ * Returns the number of file descriptor handles left on success, -1 on error.
+ */
+LTTNG_HIDDEN
+int lttng_payload_view_get_fd_handle_count(
+               struct lttng_payload_view *payload_view);
+
+/**
+ * Pop an fd handle from a payload view.
+ *
+ * A reference to the returned fd_handle is acquired on behalf of the caller.
  *
  * @payload    Payload instance
  *
- * Returns a file descriptor on success, -1 on error.
+ * Returns an fd_handle on success, -1 on error.
  */
 LTTNG_HIDDEN
-int lttng_payload_view_pop_fd(struct lttng_payload_view *payload_view);
+struct fd_handle *lttng_payload_view_pop_fd_handle(
+               struct lttng_payload_view *payload_view);
 
 #endif /* LTTNG_PAYLOAD_VIEW_H */