FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavutil/bprint.h
Date: 2024-02-16 17:37:06
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1 /*
2 * Copyright (c) 2012 Nicolas George
3 *
4 * This file is part of FFmpeg.
5 *
6 * FFmpeg is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
10 *
11 * FFmpeg is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21 /**
22 * @file
23 * @ingroup lavu_avbprint
24 * AVBPrint public header
25 */
26
27 #ifndef AVUTIL_BPRINT_H
28 #define AVUTIL_BPRINT_H
29
30 #include <stdarg.h>
31
32 #include "attributes.h"
33 #include "avstring.h"
34
35 /**
36 * @defgroup lavu_avbprint AVBPrint
37 * @ingroup lavu_data
38 *
39 * A buffer to print data progressively
40 * @{
41 */
42
43 /**
44 * Define a structure with extra padding to a fixed size
45 * This helps ensuring binary compatibility with future versions.
46 */
47
48 #define FF_PAD_STRUCTURE(name, size, ...) \
49 struct ff_pad_helper_##name { __VA_ARGS__ }; \
50 typedef struct name { \
51 __VA_ARGS__ \
52 char reserved_padding[size - sizeof(struct ff_pad_helper_##name)]; \
53 } name;
54
55 /**
56 * Buffer to print data progressively
57 *
58 * The string buffer grows as necessary and is always 0-terminated.
59 * The content of the string is never accessed, and thus is
60 * encoding-agnostic and can even hold binary data.
61 *
62 * Small buffers are kept in the structure itself, and thus require no
63 * memory allocation at all (unless the contents of the buffer is needed
64 * after the structure goes out of scope). This is almost as lightweight as
65 * declaring a local `char buf[512]`.
66 *
67 * The length of the string can go beyond the allocated size: the buffer is
68 * then truncated, but the functions still keep account of the actual total
69 * length.
70 *
71 * In other words, AVBPrint.len can be greater than AVBPrint.size and records
72 * the total length of what would have been to the buffer if there had been
73 * enough memory.
74 *
75 * Append operations do not need to be tested for failure: if a memory
76 * allocation fails, data stop being appended to the buffer, but the length
77 * is still updated. This situation can be tested with
78 * av_bprint_is_complete().
79 *
80 * The AVBPrint.size_max field determines several possible behaviours:
81 * - `size_max = -1` (= `UINT_MAX`) or any large value will let the buffer be
82 * reallocated as necessary, with an amortized linear cost.
83 * - `size_max = 0` prevents writing anything to the buffer: only the total
84 * length is computed. The write operations can then possibly be repeated in
85 * a buffer with exactly the necessary size
86 * (using `size_init = size_max = len + 1`).
87 * - `size_max = 1` is automatically replaced by the exact size available in the
88 * structure itself, thus ensuring no dynamic memory allocation. The
89 * internal buffer is large enough to hold a reasonable paragraph of text,
90 * such as the current paragraph.
91 */
92
93 FF_PAD_STRUCTURE(AVBPrint, 1024,
94 char *str; /**< string so far */
95 unsigned len; /**< length so far */
96 unsigned size; /**< allocated memory */
97 unsigned size_max; /**< maximum allocated memory */
98 char reserved_internal_buffer[1];
99 )
100
101 /**
102 * @name Max size special values
103 * Convenience macros for special values for av_bprint_init() size_max
104 * parameter.
105 * @{
106 */
107
108 /**
109 * Buffer will be reallocated as necessary, with an amortized linear cost.
110 */
111 #define AV_BPRINT_SIZE_UNLIMITED ((unsigned)-1)
112 /**
113 * Use the exact size available in the AVBPrint structure itself.
114 *
115 * Thus ensuring no dynamic memory allocation. The internal buffer is large
116 * enough to hold a reasonable paragraph of text, such as the current paragraph.
117 */
118 #define AV_BPRINT_SIZE_AUTOMATIC 1
119 /**
120 * Do not write anything to the buffer, only calculate the total length.
121 *
122 * The write operations can then possibly be repeated in a buffer with
123 * exactly the necessary size (using `size_init = size_max = AVBPrint.len + 1`).
124 */
125 #define AV_BPRINT_SIZE_COUNT_ONLY 0
126 /** @} */
127
128 /**
129 * Init a print buffer.
130 *
131 * @param buf buffer to init
132 * @param size_init initial size (including the final 0)
133 * @param size_max maximum size;
134 * - `0` means do not write anything, just count the length
135 * - `1` is replaced by the maximum value for automatic storage
136 * any large value means that the internal buffer will be
137 * reallocated as needed up to that limit
138 * - `-1` is converted to `UINT_MAX`, the largest limit possible.
139 * Check also `AV_BPRINT_SIZE_*` macros.
140 */
141 void av_bprint_init(AVBPrint *buf, unsigned size_init, unsigned size_max);
142
143 /**
144 * Init a print buffer using a pre-existing buffer.
145 *
146 * The buffer will not be reallocated.
147 * In case size equals zero, the AVBPrint will be initialized to use
148 * the internal buffer as if using AV_BPRINT_SIZE_COUNT_ONLY with
149 * av_bprint_init().
150 *
151 * @param buf buffer structure to init
152 * @param buffer byte buffer to use for the string data
153 * @param size size of buffer
154 */
155 void av_bprint_init_for_buffer(AVBPrint *buf, char *buffer, unsigned size);
156
157 /**
158 * Append a formatted string to a print buffer.
159 */
160 void av_bprintf(AVBPrint *buf, const char *fmt, ...) av_printf_format(2, 3);
161
162 /**
163 * Append a formatted string to a print buffer.
164 */
165 void av_vbprintf(AVBPrint *buf, const char *fmt, va_list vl_arg);
166
167 /**
168 * Append char c n times to a print buffer.
169 */
170 void av_bprint_chars(AVBPrint *buf, char c, unsigned n);
171
172 /**
173 * Append data to a print buffer.
174 *
175 * param buf bprint buffer to use
176 * param data pointer to data
177 * param size size of data
178 */
179 void av_bprint_append_data(AVBPrint *buf, const char *data, unsigned size);
180
181 struct tm;
182 /**
183 * Append a formatted date and time to a print buffer.
184 *
185 * param buf bprint buffer to use
186 * param fmt date and time format string, see strftime()
187 * param tm broken-down time structure to translate
188 *
189 * @note due to poor design of the standard strftime function, it may
190 * produce poor results if the format string expands to a very long text and
191 * the bprint buffer is near the limit stated by the size_max option.
192 */
193 void av_bprint_strftime(AVBPrint *buf, const char *fmt, const struct tm *tm);
194
195 /**
196 * Allocate bytes in the buffer for external use.
197 *
198 * @param[in] buf buffer structure
199 * @param[in] size required size
200 * @param[out] mem pointer to the memory area
201 * @param[out] actual_size size of the memory area after allocation;
202 * can be larger or smaller than size
203 */
204 void av_bprint_get_buffer(AVBPrint *buf, unsigned size,
205 unsigned char **mem, unsigned *actual_size);
206
207 /**
208 * Reset the string to "" but keep internal allocated data.
209 */
210 void av_bprint_clear(AVBPrint *buf);
211
212 /**
213 * Test if the print buffer is complete (not truncated).
214 *
215 * It may have been truncated due to a memory allocation failure
216 * or the size_max limit (compare size and size_max if necessary).
217 */
218 45941 static inline int av_bprint_is_complete(const AVBPrint *buf)
219 {
220 45941 return buf->len < buf->size;
221 }
222
223 /**
224 * Finalize a print buffer.
225 *
226 * The print buffer can no longer be used afterwards,
227 * but the len and size fields are still valid.
228 *
229 * @arg[out] ret_str if not NULL, used to return a permanent copy of the
230 * buffer contents, or NULL if memory allocation fails;
231 * if NULL, the buffer is discarded and freed
232 * @return 0 for success or error code (probably AVERROR(ENOMEM))
233 */
234 int av_bprint_finalize(AVBPrint *buf, char **ret_str);
235
236 /**
237 * Escape the content in src and append it to dstbuf.
238 *
239 * @param dstbuf already inited destination bprint buffer
240 * @param src string containing the text to escape
241 * @param special_chars string containing the special characters which
242 * need to be escaped, can be NULL
243 * @param mode escape mode to employ, see AV_ESCAPE_MODE_* macros.
244 * Any unknown value for mode will be considered equivalent to
245 * AV_ESCAPE_MODE_BACKSLASH, but this behaviour can change without
246 * notice.
247 * @param flags flags which control how to escape, see AV_ESCAPE_FLAG_* macros
248 */
249 void av_bprint_escape(AVBPrint *dstbuf, const char *src, const char *special_chars,
250 enum AVEscapeMode mode, int flags);
251
252 /** @} */
253
254 #endif /* AVUTIL_BPRINT_H */
255