/src/ffmpeg/libavutil/bprint.h

Source
/*
 * Copyright (c) 2012 Nicolas George
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 * @file
 * @ingroup lavu_avbprint
 * AVBPrint public header
 */

#ifndef AVUTIL_BPRINT_H
#define AVUTIL_BPRINT_H

#include <stdarg.h>

#include "attributes.h"
#include "avstring.h"

/**
 * @defgroup lavu_avbprint AVBPrint
 * @ingroup lavu_data
 *
 * A buffer to print data progressively
 * @{
 */

/**
 * Define a structure with extra padding to a fixed size
 * This helps ensuring binary compatibility with future versions.
 */

#define FF_PAD_STRUCTURE(name, size, ...) \
struct ff_pad_helper_##name { __VA_ARGS__ }; \
typedef struct name { \
    __VA_ARGS__ \
    char reserved_padding[size - sizeof(struct ff_pad_helper_##name)]; \
} name;

/**
 * Buffer to print data progressively
 *
 * The string buffer grows as necessary and is always 0-terminated.
 * The content of the string is never accessed, and thus is
 * encoding-agnostic and can even hold binary data.
 *
 * Small buffers are kept in the structure itself, and thus require no
 * memory allocation at all (unless the contents of the buffer is needed
 * after the structure goes out of scope). This is almost as lightweight as
 * declaring a local `char buf[512]`.
 *
 * The length of the string can go beyond the allocated size: the buffer is
 * then truncated, but the functions still keep account of the actual total
 * length.
 *
 * In other words, AVBPrint.len can be greater than AVBPrint.size and records
 * the total length of what would have been to the buffer if there had been
 * enough memory.
 *
 * Append operations do not need to be tested for failure: if a memory
 * allocation fails, data stop being appended to the buffer, but the length
 * is still updated. This situation can be tested with
 * av_bprint_is_complete().
 *
 * The AVBPrint.size_max field determines several possible behaviours:
 * - `size_max = -1` (= `UINT_MAX`) or any large value will let the buffer be
 *   reallocated as necessary, with an amortized linear cost.
 * - `size_max = 0` prevents writing anything to the buffer: only the total
 *   length is computed. The write operations can then possibly be repeated in
 *   a buffer with exactly the necessary size
 *   (using `size_init = size_max = len + 1`).
 * - `size_max = 1` is automatically replaced by the exact size available in the
 *   structure itself, thus ensuring no dynamic memory allocation. The
 *   internal buffer is large enough to hold a reasonable paragraph of text,
 *   such as the current paragraph.
 */

FF_PAD_STRUCTURE(AVBPrint, 1024,
    char *str;         /**< string so far */
    unsigned len;      /**< length so far */
    unsigned size;     /**< allocated memory */
    unsigned size_max; /**< maximum allocated memory */
    char reserved_internal_buffer[1];
)

/**
 * @name Max size special values
 * Convenience macros for special values for av_bprint_init() size_max
 * parameter.
 * @{
 */

/**
 * Buffer will be reallocated as necessary, with an amortized linear cost.
 */
#define AV_BPRINT_SIZE_UNLIMITED  ((unsigned)-1)
/**
 * Use the exact size available in the AVBPrint structure itself.
 *
 * Thus ensuring no dynamic memory allocation. The internal buffer is large
 * enough to hold a reasonable paragraph of text, such as the current paragraph.
 */
#define AV_BPRINT_SIZE_AUTOMATIC  1
/**
 * Do not write anything to the buffer, only calculate the total length.
 *
 * The write operations can then possibly be repeated in a buffer with
 * exactly the necessary size (using `size_init = size_max = AVBPrint.len + 1`).
 */
#define AV_BPRINT_SIZE_COUNT_ONLY 0
/** @} */

/**
 * Init a print buffer.
 *
 * @param buf        buffer to init
 * @param size_init  initial size (including the final 0)
 * @param size_max   maximum size;
 *                   - `0` means do not write anything, just count the length
 *                   - `1` is replaced by the maximum value for automatic storage
 *                       any large value means that the internal buffer will be
 *                       reallocated as needed up to that limit
 *                   - `-1` is converted to `UINT_MAX`, the largest limit possible.
 *                   Check also `AV_BPRINT_SIZE_*` macros.
 */
void av_bprint_init(AVBPrint *buf, unsigned size_init, unsigned size_max);

/**
 * Init a print buffer using a pre-existing buffer.
 *
 * The buffer will not be reallocated.
 * In case size equals zero, the AVBPrint will be initialized to use
 * the internal buffer as if using AV_BPRINT_SIZE_COUNT_ONLY with
 * av_bprint_init().
 *
 * @param buf     buffer structure to init
 * @param buffer  byte buffer to use for the string data
 * @param size    size of buffer
 */
void av_bprint_init_for_buffer(AVBPrint *buf, char *buffer, unsigned size);

/**
 * Append a formatted string to a print buffer.
 */
void av_bprintf(AVBPrint *buf, const char *fmt, ...) av_printf_format(2, 3);

/**
 * Append a formatted string to a print buffer.
 */
void av_vbprintf(AVBPrint *buf, const char *fmt, va_list vl_arg);

/**
 * Append char c n times to a print buffer.
 */
void av_bprint_chars(AVBPrint *buf, char c, unsigned n);

/**
 * Append data to a print buffer.
 *
 * @param buf  bprint buffer to use
 * @param data pointer to data
 * @param size size of data
 */
void av_bprint_append_data(AVBPrint *buf, const char *data, unsigned size);

struct tm;
/**
 * Append a formatted date and time to a print buffer.
 *
 * @param buf  bprint buffer to use
 * @param fmt  date and time format string, see strftime()
 * @param tm   broken-down time structure to translate
 *
 * @note due to poor design of the standard strftime function, it may
 * produce poor results if the format string expands to a very long text and
 * the bprint buffer is near the limit stated by the size_max option.
 */
void av_bprint_strftime(AVBPrint *buf, const char *fmt, const struct tm *tm);

/**
 * Allocate bytes in the buffer for external use.
 *
 * @param[in]  buf          buffer structure
 * @param[in]  size         required size
 * @param[out] mem          pointer to the memory area
 * @param[out] actual_size  size of the memory area after allocation;
 *                          can be larger or smaller than size
 */
void av_bprint_get_buffer(AVBPrint *buf, unsigned size,
                          unsigned char **mem, unsigned *actual_size);

/**
 * Reset the string to "" but keep internal allocated data.
 */
void av_bprint_clear(AVBPrint *buf);

/**
 * Test if the print buffer is complete (not truncated).
 *
 * It may have been truncated due to a memory allocation failure
 * or the size_max limit (compare size and size_max if necessary).
 */
static inline int av_bprint_is_complete(const AVBPrint *buf)
{
    return buf->len < buf->size;
}

/**
 * Finalize a print buffer.
 *
 * The print buffer can no longer be used afterwards,
 * but the len and size fields are still valid.
 *
 * @arg[out] ret_str  if not NULL, used to return a permanent copy of the
 *                    buffer contents, or NULL if memory allocation fails;
 *                    if NULL, the buffer is discarded and freed
 * @return  0 for success or error code (probably AVERROR(ENOMEM))
 */
int av_bprint_finalize(AVBPrint *buf, char **ret_str);

/**
 * Escape the content in src and append it to dstbuf.
 *
 * @param dstbuf        already inited destination bprint buffer
 * @param src           string containing the text to escape
 * @param special_chars string containing the special characters which
 *                      need to be escaped, can be NULL
 * @param mode          escape mode to employ, see AV_ESCAPE_MODE_* macros.
 *                      Any unknown value for mode will be considered equivalent to
 *                      AV_ESCAPE_MODE_BACKSLASH, but this behaviour can change without
 *                      notice.
 * @param flags         flags which control how to escape, see AV_ESCAPE_FLAG_* macros
 */
void av_bprint_escape(AVBPrint *dstbuf, const char *src, const char *special_chars,
                      enum AVEscapeMode mode, int flags);

/** @} */

#endif /* AVUTIL_BPRINT_H */

Coverage Report

Created: 2026-01-25 07:18

Line	Count	Source
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	0	#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	0	#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	0	#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		static inline int av_bprint_is_complete(const AVBPrint *buf)
219	0	{
220	0	return buf->len < buf->size;
221	0	} Unexecuted instantiation: avfiltergraph.c:av_bprint_is_complete Unexecuted instantiation: formats.c:av_bprint_is_complete Unexecuted instantiation: avfilter.c:av_bprint_is_complete Unexecuted instantiation: id3v2.c:av_bprint_is_complete Unexecuted instantiation: utils.c:av_bprint_is_complete Unexecuted instantiation: aviobuf.c:av_bprint_is_complete Unexecuted instantiation: network.c:av_bprint_is_complete Unexecuted instantiation: avcodec.c:av_bprint_is_complete Unexecuted instantiation: bsf.c:av_bprint_is_complete Unexecuted instantiation: exif.c:av_bprint_is_complete Unexecuted instantiation: tiff_common.c:av_bprint_is_complete Unexecuted instantiation: avstring.c:av_bprint_is_complete Unexecuted instantiation: bprint.c:av_bprint_is_complete Unexecuted instantiation: channel_layout.c:av_bprint_is_complete Unexecuted instantiation: dict.c:av_bprint_is_complete Unexecuted instantiation: log.c:av_bprint_is_complete Unexecuted instantiation: opt.c:av_bprint_is_complete
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 */