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 #include <common/dynamic-buffer.h>
19 #include <common/utils.h>
23 * Round to (upper) power of two, val is returned if it already is a power of
27 size_t round_to_power_of_2(size_t val
)
32 order
= utils_get_count_order_u64(val
);
34 rounded
= (1ULL << order
);
35 assert(rounded
>= val
);
41 void lttng_dynamic_buffer_init(struct lttng_dynamic_buffer
*buffer
)
44 memset(buffer
, 0, sizeof(*buffer
));
48 int lttng_dynamic_buffer_append(struct lttng_dynamic_buffer
*buffer
,
49 const void *buf
, size_t len
)
53 if (!buffer
|| (!buf
&& len
)) {
59 /* Not an error, no-op. */
63 assert(buffer
->_capacity
>= buffer
->size
);
64 if (buffer
->_capacity
< (len
+ buffer
->size
)) {
65 ret
= lttng_dynamic_buffer_set_capacity(buffer
,
67 (len
- (buffer
->_capacity
- buffer
->size
)));
73 memcpy(buffer
->data
+ buffer
->size
, buf
, len
);
80 int lttng_dynamic_buffer_append_buffer(struct lttng_dynamic_buffer
*dst_buffer
,
81 struct lttng_dynamic_buffer
*src_buffer
)
85 if (!dst_buffer
|| !src_buffer
) {
90 ret
= lttng_dynamic_buffer_append(dst_buffer
, src_buffer
->data
,
97 int lttng_dynamic_buffer_set_size(struct lttng_dynamic_buffer
*buffer
,
106 if (new_size
== buffer
->size
) {
110 if (new_size
> buffer
->_capacity
) {
111 size_t original_size
= buffer
->size
;
112 size_t original_capacity
= buffer
->_capacity
;
114 ret
= lttng_dynamic_buffer_set_capacity(buffer
, new_size
);
120 * Zero-initialize the space that was left in the buffer at the
121 * before we increased its capacity (original capacity - original size).
122 * The newly acquired capacity (new capacity - original capacity)
123 * is zeroed by lttng_dynamic_buffer_set_capacity().
125 memset(buffer
->data
+ original_size
, 0,
126 original_capacity
- original_size
);
127 } else if (new_size
> buffer
->size
) {
128 memset(buffer
->data
+ buffer
->size
, 0, new_size
- buffer
->size
);
131 * Shrinking size. There is no need to zero-out the newly
132 * released memory as it will either be:
133 * - overwritten by lttng_dynamic_buffer_append,
134 * - expanded later, which will zero-out the memory
136 * Users of external APIs are encouraged to set the buffer's
137 * size _before_ making such calls.
140 buffer
->size
= new_size
;
146 int lttng_dynamic_buffer_set_capacity(struct lttng_dynamic_buffer
*buffer
,
147 size_t demanded_capacity
)
151 size_t new_capacity
= round_to_power_of_2(demanded_capacity
);
153 if (!buffer
|| demanded_capacity
< buffer
->size
) {
155 * Shrinking a buffer's size by changing its capacity is
162 if (new_capacity
== buffer
->_capacity
) {
166 /* Memory is initialized by the size increases. */
167 new_buf
= realloc(buffer
->data
, new_capacity
);
172 buffer
->data
= new_buf
;
173 buffer
->_capacity
= new_capacity
;
178 /* Release any memory used by the dynamic buffer. */
180 void lttng_dynamic_buffer_reset(struct lttng_dynamic_buffer
*buffer
)
186 buffer
->_capacity
= 0;
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