src/common/payload.hpp

   1 /*
   2  * Copyright (C) 2020 Jérémie Galarneau <jeremie.galarneau@efficios.com>
   3  *
   4  * SPDX-License-Identifier: LGPL-2.1-only
   5  *
   6  */
   7
   8 #ifndef LTTNG_PAYLOAD_H
   9 #define LTTNG_PAYLOAD_H
  10
  11 #include <common/dynamic-buffer.hpp>
  12 #include <common/dynamic-array.hpp>
  13 #include <common/fd-handle.hpp>
  14
  15 /*
  16  * An lttng_payload encompasses the 'data' (bytes) and any passed file
  17  * descriptors as part of a message between liblttng-ctl and the session
  18  * daemon.
  19  */
  20 struct lttng_payload {
  21         struct lttng_dynamic_buffer buffer;
  22         /* private */
  23         struct lttng_dynamic_pointer_array _fd_handles;
  24 };
  25
  26 /*
  27  * Initialize a payload. This performs no allocation and is meant
  28  * to be used instead of zero-ing the payload structure.
  29  */
  30 void lttng_payload_init(struct lttng_payload *payload);
  31
  32 /* Copy a payload. */
  33 int lttng_payload_copy(const struct lttng_payload *src_payload,
  34                 struct lttng_payload *dst_payload);
  35
  36 /* Release any memory and references held by the payload. */
  37 void lttng_payload_reset(struct lttng_payload *payload);
  38
  39 /*
  40  * Empty the contents of a payload, releasing all references held.
  41  * This should be used to put a payload in a re-usable state.
  42  *
  43  * lttng_payload_reset must still be called on an lttng_payload to
  44  * free all allocated memory.
  45  */
  46 void lttng_payload_clear(struct lttng_payload *payload);
  47
  48 /**
  49  * Add an fd to the payload.
  50  * The payload acquires a reference to the fd_handle.
  51  *
  52  * @payload     Payload instance
  53  * @fd_handle   File descriptor handle to add to the payload
  54  *
  55  * Returns 0 on success, -1 on allocation error.
  56  */
  57 int lttng_payload_push_fd_handle(struct lttng_payload *payload,
  58                 struct fd_handle *fd_handle);
  59
  60 #endif /* LTTNG_PAYLOAD_H */