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 #ifdef __cplusplus
  17 extern "C" {
  18 #endif
  19
  20 struct lttng_dynamic_buffer;
  21
  22 struct lttng_buffer_view {
  23         const char *data;
  24         size_t size;
  25 };
  26
  27 /**
  28  * Return a buffer view referencing a subset of the memory referenced by a raw
  29  * pointer.
  30  *
  31  * @src         Source buffer to reference
  32  * @offset      Offset to apply to the source memory buffer
  33  * @len         Length of the memory contents to reference.
  34  *
  35  * Note that a buffer view never assumes the ownership of the memory it
  36  * references.
  37  */
  38 struct lttng_buffer_view lttng_buffer_view_init(
  39                 const char *src, size_t offset, ptrdiff_t len);
  40
  41 /**
  42  * Checks if a buffer view is safe to access.
  43  *
  44  * After calling the buffer view creation functions, callers should verify
  45  * if the resquested length (if any is explicitly provided) could be mapped
  46  * to a new view.
  47  *
  48  * @view        Buffer view to validate
  49  */
  50 bool lttng_buffer_view_is_valid(const struct lttng_buffer_view *view);
  51
  52 /**
  53  * Return a buffer view referencing a subset of the memory referenced by another
  54  * view.
  55  *
  56  * @src         Source view to reference
  57  * @offset      Offset to apply to the source memory content
  58  * @len         Length of the memory contents to reference. Passing -1 will
  59  *              cause the view to reference the whole view from the offset
  60  *              provided.
  61  *
  62  * Note that a buffer view never assumes the ownership of the memory it
  63  * references.
  64  */
  65 struct lttng_buffer_view lttng_buffer_view_from_view(
  66                 const struct lttng_buffer_view *src, size_t offset,
  67                 ptrdiff_t len);
  68
  69 /**
  70  * Return a buffer view referencing a subset of the memory referenced by a
  71  * dynamic buffer.
  72  *
  73  * @src         Source dynamic buffer to reference
  74  * @offset      Offset to apply to the source memory content
  75  * @len         Length of the memory contents to reference. Passing -1 will
  76  *              cause the view to reference the whole dynamic buffer from the
  77  *              offset provided.
  78  *
  79  * Note that a buffer view never assumes the ownership of the memory it
  80  * references.
  81  */
  82 struct lttng_buffer_view lttng_buffer_view_from_dynamic_buffer(
  83                 const struct lttng_dynamic_buffer *src, size_t offset,
  84                 ptrdiff_t len);
  85
  86 /**
  87  * Verify that `buf` contains a string starting at `str` of length
  88  * `len_with_null_terminator`.
  89  *
  90  * @buf                         The buffer view
  91  * @str                         The start of the string
  92  * @len_with_null_terminator    Expected length of the string, including the
  93  *                              NULL terminator.
  94  */
  95 bool lttng_buffer_view_contains_string(const struct lttng_buffer_view *buf,
  96                 const char *str,
  97                 size_t len_with_null_terminator);
  98
  99 #ifdef __cplusplus
 100 }
 101 #endif
 102
 103 #endif /* LTTNG_BUFFER_VIEW_H */