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0cf77103 RB |
1 | /* |
2 | * Copyright (C) the libgit2 contributors. All rights reserved. | |
3 | * | |
4 | * This file is part of libgit2, distributed under the GNU GPL v2 with | |
5 | * a Linking Exception. For full terms see the included COPYING file. | |
6 | */ | |
a9f51e43 RB |
7 | #ifndef INCLUDE_git_buf_h__ |
8 | #define INCLUDE_git_buf_h__ | |
0cf77103 RB |
9 | |
10 | #include "common.h" | |
11 | ||
12 | /** | |
13 | * @file git2/buffer.h | |
14 | * @brief Buffer export structure | |
15 | * | |
16 | * @ingroup Git | |
17 | * @{ | |
18 | */ | |
19 | GIT_BEGIN_DECL | |
20 | ||
21 | /** | |
22 | * A data buffer for exporting data from libgit2 | |
23 | * | |
2a7d224f RB |
24 | * Sometimes libgit2 wants to return an allocated data buffer to the |
25 | * caller and have the caller take responsibility for freeing that memory. | |
26 | * This can be awkward if the caller does not have easy access to the same | |
27 | * allocation functions that libgit2 is using. In those cases, libgit2 | |
ac3d33df | 28 | * will fill in a `git_buf` and the caller can use `git_buf_dispose()` to |
a9f51e43 RB |
29 | * release it when they are done. |
30 | * | |
31 | * A `git_buf` may also be used for the caller to pass in a reference to | |
32 | * a block of memory they hold. In this case, libgit2 will not resize or | |
33 | * free the memory, but will read from it as needed. | |
34 | * | |
a9f51e43 RB |
35 | * Some APIs may occasionally do something slightly unusual with a buffer, |
36 | * such as setting `ptr` to a value that was passed in by the user. In | |
37 | * those cases, the behavior will be clearly documented by the API. | |
0cf77103 | 38 | */ |
a9f51e43 | 39 | typedef struct { |
0c9c969a UG |
40 | /** |
41 | * The buffer contents. | |
42 | * | |
43 | * `ptr` points to the start of the allocated memory. If it is NULL, | |
44 | * then the `git_buf` is considered empty and libgit2 will feel free | |
45 | * to overwrite it with new data. | |
46 | */ | |
0cf77103 | 47 | char *ptr; |
0c9c969a UG |
48 | |
49 | /** | |
50 | * `asize` holds the known total amount of allocated memory if the `ptr` | |
51 | * was allocated by libgit2. It may be larger than `size`. If `ptr` | |
52 | * was not allocated by libgit2 and should not be resized and/or freed, | |
53 | * then `asize` will be set to zero. | |
54 | */ | |
55 | size_t asize; | |
56 | ||
57 | /** | |
58 | * `size` holds the size (in bytes) of the data that is actually used. | |
59 | */ | |
60 | size_t size; | |
a9f51e43 | 61 | } git_buf; |
0cf77103 | 62 | |
b47349b8 RB |
63 | /** |
64 | * Static initializer for git_buf from static buffer | |
65 | */ | |
66 | #define GIT_BUF_INIT_CONST(STR,LEN) { (char *)(STR), 0, (size_t)(LEN) } | |
67 | ||
0cf77103 | 68 | /** |
a9f51e43 | 69 | * Free the memory referred to by the git_buf. |
0cf77103 | 70 | * |
a9f51e43 RB |
71 | * Note that this does not free the `git_buf` itself, just the memory |
72 | * pointed to by `buffer->ptr`. This will not free the memory if it looks | |
73 | * like it was not allocated internally, but it will clear the buffer back | |
74 | * to the empty state. | |
0cf77103 | 75 | * |
a9f51e43 | 76 | * @param buffer The buffer to deallocate |
0cf77103 | 77 | */ |
ac3d33df | 78 | GIT_EXTERN(void) git_buf_dispose(git_buf *buffer); |
0cf77103 RB |
79 | |
80 | /** | |
81 | * Resize the buffer allocation to make more space. | |
82 | * | |
b874629b | 83 | * This will attempt to grow the buffer to accommodate the target size. |
a9f51e43 RB |
84 | * |
85 | * If the buffer refers to memory that was not allocated by libgit2 (i.e. | |
86 | * the `asize` field is zero), then `ptr` will be replaced with a newly | |
87 | * allocated block of data. Be careful so that memory allocated by the | |
88 | * caller is not lost. As a special variant, if you pass `target_size` as | |
89 | * 0 and the memory is not allocated by libgit2, this will allocate a new | |
90 | * buffer of size `size` and copy the external data into it. | |
91 | * | |
92 | * Currently, this will never shrink a buffer, only expand it. | |
0cf77103 | 93 | * |
a9f51e43 RB |
94 | * If the allocation fails, this will return an error and the buffer will be |
95 | * marked as invalid for future operations, invaliding the contents. | |
0cf77103 RB |
96 | * |
97 | * @param buffer The buffer to be resized; may or may not be allocated yet | |
a9f51e43 RB |
98 | * @param target_size The desired available size |
99 | * @return 0 on success, -1 on allocation failure | |
0cf77103 | 100 | */ |
a9f51e43 | 101 | GIT_EXTERN(int) git_buf_grow(git_buf *buffer, size_t target_size); |
0cf77103 | 102 | |
2a7d224f RB |
103 | /** |
104 | * Set buffer to a copy of some raw data. | |
105 | * | |
106 | * @param buffer The buffer to set | |
107 | * @param data The data to copy into the buffer | |
108 | * @param datalen The length of the data to copy into the buffer | |
a9f51e43 | 109 | * @return 0 on success, -1 on allocation failure |
2a7d224f | 110 | */ |
a9f51e43 RB |
111 | GIT_EXTERN(int) git_buf_set( |
112 | git_buf *buffer, const void *data, size_t datalen); | |
2a7d224f | 113 | |
b3af2d80 | 114 | /** |
115 | * Check quickly if buffer looks like it contains binary data | |
116 | * | |
117 | * @param buf Buffer to check | |
118 | * @return 1 if buffer looks like non-text data | |
119 | */ | |
120 | GIT_EXTERN(int) git_buf_is_binary(const git_buf *buf); | |
121 | ||
122 | /** | |
123 | * Check quickly if buffer contains a NUL byte | |
124 | * | |
125 | * @param buf Buffer to check | |
126 | * @return 1 if buffer contains a NUL byte | |
127 | */ | |
128 | GIT_EXTERN(int) git_buf_contains_nul(const git_buf *buf); | |
129 | ||
0cf77103 RB |
130 | GIT_END_DECL |
131 | ||
132 | /** @} */ | |
133 | ||
134 | #endif |