src/common/payload.h

   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.h>
  12 #include <common/dynamic-array.h>
  13 #include <common/fd-handle.h>
  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 LTTNG_HIDDEN
  31 void lttng_payload_init(struct lttng_payload *payload);
  32
  33 /* Copy a payload. */
  34 LTTNG_HIDDEN
  35 int lttng_payload_copy(const struct lttng_payload *src_payload,
  36                 struct lttng_payload *dst_payload);
  37
  38 /* Release any memory and references held by the payload. */
  39 LTTNG_HIDDEN
  40 void lttng_payload_reset(struct lttng_payload *payload);
  41
  42 /*
  43  * Empty the contents of a payload, releasing all references held.
  44  * This should be used to put a payload in a re-usable state.
  45  *
  46  * lttng_payload_reset must still be called on an lttng_payload to
  47  * free all allocated memory.
  48  */
  49 LTTNG_HIDDEN
  50 void lttng_payload_clear(struct lttng_payload *payload);
  51
  52 /**
  53  * Add an fd to the payload.
  54  * The payload acquires a reference to the fd_handle.
  55  *
  56  * @payload     Payload instance
  57  * @fd_handle   File descriptor handle to add to the payload
  58  *
  59  * Returns 0 on success, -1 on allocation error.
  60  */
  61 LTTNG_HIDDEN
  62 int lttng_payload_push_fd_handle(struct lttng_payload *payload,
  63                 struct fd_handle *fd_handle);
  64
  65 #endif /* LTTNG_PAYLOAD_H */