src/common/buffer-view.h

   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.h>
  12 #include <stdbool.h>
  13 #include <stddef.h>
  14 #include <stdint.h>
  15
  16 struct lttng_dynamic_buffer;
  17
  18 struct lttng_buffer_view {
  19         const char *data;
  20         size_t size;
  21 };
  22
  23 /**
  24  * Return a buffer view referencing a subset of the memory referenced by a raw
  25  * pointer.
  26  *
  27  * @src         Source buffer to reference
  28  * @offset      Offset to apply to the source memory buffer
  29  * @len         Length of the memory contents to reference.
  30  *
  31  * Note that a buffer view never assumes the ownership of the memory it
  32  * references.
  33  */
  34 struct lttng_buffer_view lttng_buffer_view_init(
  35                 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 lttng_buffer_view_from_view(
  62                 const struct lttng_buffer_view *src, size_t offset,
  63                 ptrdiff_t len);
  64
  65 /**
  66  * Return a buffer view referencing a subset of the memory referenced by a
  67  * dynamic buffer.
  68  *
  69  * @src         Source dynamic buffer to reference
  70  * @offset      Offset to apply to the source memory content
  71  * @len         Length of the memory contents to reference. Passing -1 will
  72  *              cause the view to reference the whole dynamic buffer from the
  73  *              offset provided.
  74  *
  75  * Note that a buffer view never assumes the ownership of the memory it
  76  * references.
  77  */
  78 struct lttng_buffer_view lttng_buffer_view_from_dynamic_buffer(
  79                 const struct lttng_dynamic_buffer *src, size_t offset,
  80                 ptrdiff_t len);
  81
  82 /**
  83  * Verify that `buf` contains a string starting at `str` of length
  84  * `len_with_null_terminator`.
  85  *
  86  * @buf                         The buffer view
  87  * @str                         The start of the string
  88  * @len_with_null_terminator    Expected length of the string, including the
  89  *                              NULL terminator.
  90  */
  91 bool lttng_buffer_view_contains_string(const struct lttng_buffer_view *buf,
  92                 const char *str,
  93                 size_t len_with_null_terminator);
  94
  95 #endif /* LTTNG_BUFFER_VIEW_H */