src/common/buffer-view.hpp

   1 /*
   2  * Copyright (C) 2017 Jérémie Galarneau <jeremie.galarneau@efficios.com>
   3  *
   4  * SPDX-License-Identifier: LGPL-2.1-only
   5  *
   6  */
   7
   8 #ifndef LTTNG_BUFFER_VIEW_H
   9 #define LTTNG_BUFFER_VIEW_H
  10
  11 #include <common/macros.hpp>
  12
  13 #include <stdbool.h>
  14 #include <stddef.h>
  15 #include <stdint.h>
  16
  17 struct lttng_dynamic_buffer;
  18
  19 struct lttng_buffer_view {
  20         const char *data;
  21         size_t size;
  22 };
  23
  24 /**
  25  * Return a buffer view referencing a subset of the memory referenced by a raw
  26  * pointer.
  27  *
  28  * @src         Source buffer to reference
  29  * @offset      Offset to apply to the source memory buffer
  30  * @len         Length of the memory contents to reference.
  31  *
  32  * Note that a buffer view never assumes the ownership of the memory it
  33  * references.
  34  */
  35 struct lttng_buffer_view lttng_buffer_view_init(const char *src, size_t offset, ptrdiff_t len);
  36
  37 /**
  38  * Checks if a buffer view is safe to access.
  39  *
  40  * After calling the buffer view creation functions, callers should verify
  41  * if the resquested length (if any is explicitly provided) could be mapped
  42  * to a new view.
  43  *
  44  * @view        Buffer view to validate
  45  */
  46 bool lttng_buffer_view_is_valid(const struct lttng_buffer_view *view);
  47
  48 /**
  49  * Return a buffer view referencing a subset of the memory referenced by another
  50  * view.
  51  *
  52  * @src         Source view to reference
  53  * @offset      Offset to apply to the source memory content
  54  * @len         Length of the memory contents to reference. Passing -1 will
  55  *              cause the view to reference the whole view from the offset
  56  *              provided.
  57  *
  58  * Note that a buffer view never assumes the ownership of the memory it
  59  * references.
  60  */
  61 struct lttng_buffer_view
  62 lttng_buffer_view_from_view(const struct lttng_buffer_view *src, size_t offset, ptrdiff_t len);
  63
  64 /**
  65  * Return a buffer view referencing a subset of the memory referenced by a
  66  * dynamic buffer.
  67  *
  68  * @src         Source dynamic buffer to reference
  69  * @offset      Offset to apply to the source memory content
  70  * @len         Length of the memory contents to reference. Passing -1 will
  71  *              cause the view to reference the whole dynamic buffer from the
  72  *              offset provided.
  73  *
  74  * Note that a buffer view never assumes the ownership of the memory it
  75  * references.
  76  */
  77 struct lttng_buffer_view lttng_buffer_view_from_dynamic_buffer(
  78         const struct lttng_dynamic_buffer *src, size_t offset, ptrdiff_t len);
  79
  80 /**
  81  * Verify that `buf` contains a string starting at `str` of length
  82  * `len_with_null_terminator`.
  83  *
  84  * @buf                         The buffer view
  85  * @str                         The start of the string
  86  * @len_with_null_terminator    Expected length of the string, including the
  87  *                              NULL terminator.
  88  */
  89 bool lttng_buffer_view_contains_string(const struct lttng_buffer_view *buf,
  90                                        const char *str,
  91                                        size_t len_with_null_terminator);
  92
  93 #endif /* LTTNG_BUFFER_VIEW_H */