1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
|
/*
* 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
*/
#ifndef AVUTIL_BPRINT_H
#define AVUTIL_BPRINT_H
#include "attributes.h"
/**
* Define a structure with extra padding to a fixed size
* This helps ensuring binary compatibility with future versions.
*/
#define FF_PAD_STRUCTURE(size, ...) \
__VA_ARGS__ \
char reserved_padding[size - sizeof(struct { __VA_ARGS__ })];
/**
* 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, buf->len can be greater than buf->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 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.
*/
typedef struct AVBPrint {
FF_PAD_STRUCTURE(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];
)
} AVBPrint;
/**
* Convenience macros for special values for av_bprint_init() size_max
* parameter.
*/
#define AV_BPRINT_SIZE_UNLIMITED ((unsigned)-1)
#define AV_BPRINT_SIZE_AUTOMATIC 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.
*
* @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 formated string to a print buffer.
*/
void av_bprintf(AVBPrint *buf, const char *fmt, ...) av_printf_format(2, 3);
/**
* Append char c n times to a print buffer.
*/
void av_bprint_chars(AVBPrint *buf, char c, unsigned n);
/**
* 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(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);
#endif /* AVUTIL_BPRINT_H */
|
