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5966417e | 1 | /* |
ab5be9fa | 2 | * Copyright (C) 2017 Jérémie Galarneau <jeremie.galarneau@efficios.com> |
5966417e | 3 | * |
ab5be9fa | 4 | * SPDX-License-Identifier: LGPL-2.1-only |
5966417e | 5 | * |
5966417e JG |
6 | */ |
7 | ||
8 | #ifndef LTTNG_DYNAMIC_BUFFER_H | |
9 | #define LTTNG_DYNAMIC_BUFFER_H | |
10 | ||
11 | #include <stddef.h> | |
12 | #include <stdint.h> | |
c90647fe | 13 | #include <common/macros.h> |
5966417e JG |
14 | |
15 | struct lttng_dynamic_buffer { | |
16 | char *data; | |
63557623 | 17 | /* size is the buffer's currently used capacity. */ |
5966417e | 18 | size_t size; |
63557623 JG |
19 | /* |
20 | * capacity shall not be accessed by users directly, it is meant for | |
21 | * internal use only. | |
22 | */ | |
23 | size_t _capacity; | |
5966417e JG |
24 | }; |
25 | ||
63557623 JG |
26 | /* |
27 | * Initialize a dynamic buffer. This performs no allocation and is meant | |
28 | * to be used instead of memset or explicit initialization of the buffer. | |
29 | */ | |
c90647fe | 30 | LTTNG_HIDDEN |
5966417e JG |
31 | void lttng_dynamic_buffer_init(struct lttng_dynamic_buffer *buffer); |
32 | ||
63557623 JG |
33 | /* |
34 | * Append the content of a raw memory buffer to the end of a dynamic buffer | |
35 | * (after its current "size"). The dynamic buffer's size is increased by | |
36 | * "len", and its capacity is adjusted automatically. | |
37 | */ | |
c90647fe | 38 | LTTNG_HIDDEN |
5966417e JG |
39 | int lttng_dynamic_buffer_append(struct lttng_dynamic_buffer *buffer, |
40 | const void *buf, size_t len); | |
41 | ||
63557623 JG |
42 | /* |
43 | * Performs the same action as lttng_dynamic_buffer_append(), but using another | |
44 | * dynamic buffer as the source buffer. The source buffer's size is used in lieu | |
45 | * of "len". | |
46 | */ | |
c90647fe | 47 | LTTNG_HIDDEN |
5966417e JG |
48 | int lttng_dynamic_buffer_append_buffer(struct lttng_dynamic_buffer *dst_buffer, |
49 | struct lttng_dynamic_buffer *src_buffer); | |
50 | ||
51 | /* | |
52 | * Set the buffer's size to new_size. The capacity of the buffer will | |
53 | * be expanded (if necessary) to accomodate new_size. Areas acquired by | |
63557623 | 54 | * a size increase will be zeroed. |
5966417e JG |
55 | * |
56 | * Be careful to expand the buffer's size _before_ calling out external | |
57 | * APIs (e.g. read(3)) which may populate the buffer as setting the size | |
63557623 JG |
58 | * after will zero-out the result of the operation. |
59 | * | |
60 | * Shrinking a buffer does not zero the old content. If the buffer may contain | |
61 | * sensititve information, it must be cleared manually _before_ changing the | |
62 | * size. | |
63 | * | |
64 | * NOTE: It is striclty _invalid_ to access memory after _size_, regardless | |
65 | * of prior calls to set_capacity(). | |
5966417e | 66 | */ |
c90647fe | 67 | LTTNG_HIDDEN |
5966417e JG |
68 | int lttng_dynamic_buffer_set_size(struct lttng_dynamic_buffer *buffer, |
69 | size_t new_size); | |
70 | ||
71 | /* | |
72 | * Set the buffer's capacity to accomodate the new_capacity, allocating memory | |
63557623 JG |
73 | * as necessary. The buffer's content is preserved. Setting a buffer's capacity |
74 | * is meant as a _hint_ to the underlying buffer and is only optimization; no | |
75 | * guarantee is offered that subsequent calls to append or set_size will succeed. | |
5966417e JG |
76 | * |
77 | * If the current size > new_capacity, the operation will fail. | |
78 | */ | |
c90647fe | 79 | LTTNG_HIDDEN |
5966417e JG |
80 | int lttng_dynamic_buffer_set_capacity(struct lttng_dynamic_buffer *buffer, |
81 | size_t new_capacity); | |
82 | ||
83 | /* Release any memory used by the dynamic buffer. */ | |
c90647fe | 84 | LTTNG_HIDDEN |
5966417e JG |
85 | void lttng_dynamic_buffer_reset(struct lttng_dynamic_buffer *buffer); |
86 | ||
201bd415 JG |
87 | /* Get the space left in the buffer before a new resize is needed. */ |
88 | LTTNG_HIDDEN | |
89 | size_t lttng_dynamic_buffer_get_capacity_left( | |
90 | struct lttng_dynamic_buffer *buffer); | |
91 | ||
5966417e | 92 | #endif /* LTTNG_DYNAMIC_BUFFER_H */ |