2 * Copyright (C) 2017 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
4 * This program is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU Lesser General Public License, version 2.1 only,
6 * as published by the Free Software Foundation.
8 * This program is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
13 * You should have received a copy of the GNU Lesser General Public License
14 * along with this program; if not, write to the Free Software Foundation,
15 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
18 #ifndef LTTNG_DYNAMIC_BUFFER_H
19 #define LTTNG_DYNAMIC_BUFFER_H
23 #include <common/macros.h>
25 struct lttng_dynamic_buffer
{
27 /* size is the buffer's currently used capacity. */
30 * capacity shall not be accessed by users directly, it is meant for
37 * Initialize a dynamic buffer. This performs no allocation and is meant
38 * to be used instead of memset or explicit initialization of the buffer.
41 void lttng_dynamic_buffer_init(struct lttng_dynamic_buffer
*buffer
);
44 * Append the content of a raw memory buffer to the end of a dynamic buffer
45 * (after its current "size"). The dynamic buffer's size is increased by
46 * "len", and its capacity is adjusted automatically.
49 int lttng_dynamic_buffer_append(struct lttng_dynamic_buffer
*buffer
,
50 const void *buf
, size_t len
);
53 * Performs the same action as lttng_dynamic_buffer_append(), but using another
54 * dynamic buffer as the source buffer. The source buffer's size is used in lieu
58 int lttng_dynamic_buffer_append_buffer(struct lttng_dynamic_buffer
*dst_buffer
,
59 struct lttng_dynamic_buffer
*src_buffer
);
62 * Set the buffer's size to new_size. The capacity of the buffer will
63 * be expanded (if necessary) to accomodate new_size. Areas acquired by
64 * a size increase will be zeroed.
66 * Be careful to expand the buffer's size _before_ calling out external
67 * APIs (e.g. read(3)) which may populate the buffer as setting the size
68 * after will zero-out the result of the operation.
70 * Shrinking a buffer does not zero the old content. If the buffer may contain
71 * sensititve information, it must be cleared manually _before_ changing the
74 * NOTE: It is striclty _invalid_ to access memory after _size_, regardless
75 * of prior calls to set_capacity().
78 int lttng_dynamic_buffer_set_size(struct lttng_dynamic_buffer
*buffer
,
82 * Set the buffer's capacity to accomodate the new_capacity, allocating memory
83 * as necessary. The buffer's content is preserved. Setting a buffer's capacity
84 * is meant as a _hint_ to the underlying buffer and is only optimization; no
85 * guarantee is offered that subsequent calls to append or set_size will succeed.
87 * If the current size > new_capacity, the operation will fail.
90 int lttng_dynamic_buffer_set_capacity(struct lttng_dynamic_buffer
*buffer
,
93 /* Release any memory used by the dynamic buffer. */
95 void lttng_dynamic_buffer_reset(struct lttng_dynamic_buffer
*buffer
);
97 /* Get the space left in the buffer before a new resize is needed. */
99 size_t lttng_dynamic_buffer_get_capacity_left(
100 struct lttng_dynamic_buffer
*buffer
);
102 #endif /* LTTNG_DYNAMIC_BUFFER_H */
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