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#ifndef AVUTIL_BPRINT_H 22#define AVUTIL_BPRINT_H 23 24#include <stdarg.h> 25 26#include "attributes.h" 27#include "avstring.h" 28 29/** 30 * Define a structure with extra padding to a fixed size 31 * This helps ensuring binary compatibility with future versions. 32 */ 33#define FF_PAD_STRUCTURE(size, ...) \ 34 __VA_ARGS__ \ 35 char reserved_padding[size - sizeof(struct { __VA_ARGS__ })]; 36 37/** 38 * Buffer to print data progressively 39 * 40 * The string buffer grows as necessary and is always 0-terminated. 41 * The content of the string is never accessed, and thus is 42 * encoding-agnostic and can even hold binary data. 43 * 44 * Small buffers are kept in the structure itself, and thus require no 45 * memory allocation at all (unless the contents of the buffer is needed 46 * after the structure goes out of scope). This is almost as lightweight as 47 * declaring a local "char buf[512]". 48 * 49 * The length of the string can go beyond the allocated size: the buffer is 50 * then truncated, but the functions still keep account of the actual total 51 * length. 52 * 53 * In other words, buf->len can be greater than buf->size and records the 54 * total length of what would have been to the buffer if there had been 55 * enough memory. 56 * 57 * Append operations do not need to be tested for failure: if a memory 58 * allocation fails, data stop being appended to the buffer, but the length 59 * is still updated. This situation can be tested with 60 * av_bprint_is_complete(). 61 * 62 * The size_max field determines several possible behaviours: 63 * 64 * size_max = -1 (= UINT_MAX) or any large value will let the buffer be 65 * reallocated as necessary, with an amortized linear cost. 66 * 67 * size_max = 0 prevents writing anything to the buffer: only the total 68 * length is computed. The write operations can then possibly be repeated in 69 * a buffer with exactly the necessary size 70 * (using size_init = size_max = len + 1). 71 * 72 * size_max = 1 is automatically replaced by the exact size available in the 73 * structure itself, thus ensuring no dynamic memory allocation. The 74 * internal buffer is large enough to hold a reasonable paragraph of text, 75 * such as the current paragraph. 76 */ 77typedef struct AVBPrint { 78 FF_PAD_STRUCTURE(1024, 79 char *str; /**< string so far */ 80 unsigned len; /**< length so far */ 81 unsigned size; /**< allocated memory */ 82 unsigned size_max; /**< maximum allocated memory */ 83 char reserved_internal_buffer[1]; 84 ) 85} AVBPrint; 86 87/** 88 * Convenience macros for special values for av_bprint_init() size_max 89 * parameter. 90 */ 91#define AV_BPRINT_SIZE_UNLIMITED ((unsigned)-1) 92#define AV_BPRINT_SIZE_AUTOMATIC 1 93#define AV_BPRINT_SIZE_COUNT_ONLY 0 94 95/** 96 * Init a print buffer. 97 * 98 * @param buf buffer to init 99 * @param size_init initial size (including the final 0) 100 * @param size_max maximum size; 101 * 0 means do not write anything, just count the length; 102 * 1 is replaced by the maximum value for automatic storage; 103 * any large value means that the internal buffer will be 104 * reallocated as needed up to that limit; -1 is converted to 105 * UINT_MAX, the largest limit possible. 106 * Check also AV_BPRINT_SIZE_* macros. 107 */ 108void av_bprint_init(AVBPrint *buf, unsigned size_init, unsigned size_max); 109 110/** 111 * Init a print buffer using a pre-existing buffer. 112 * 113 * The buffer will not be reallocated. 114 * 115 * @param buf buffer structure to init 116 * @param buffer byte buffer to use for the string data 117 * @param size size of buffer 118 */ 119void av_bprint_init_for_buffer(AVBPrint *buf, char *buffer, unsigned size); 120 121/** 122 * Append a formatted string to a print buffer. 123 */ 124void av_bprintf(AVBPrint *buf, const char *fmt, ...) av_printf_format(2, 3); 125 126/** 127 * Append a formatted string to a print buffer. 128 */ 129void av_vbprintf(AVBPrint *buf, const char *fmt, va_list vl_arg); 130 131/** 132 * Append char c n times to a print buffer. 133 */ 134void av_bprint_chars(AVBPrint *buf, char c, unsigned n); 135 136/** 137 * Append data to a print buffer. 138 * 139 * param buf bprint buffer to use 140 * param data pointer to data 141 * param size size of data 142 */ 143void av_bprint_append_data(AVBPrint *buf, const char *data, unsigned size); 144 145struct tm; 146/** 147 * Append a formatted date and time to a print buffer. 148 * 149 * param buf bprint buffer to use 150 * param fmt date and time format string, see strftime() 151 * param tm broken-down time structure to translate 152 * 153 * @note due to poor design of the standard strftime function, it may 154 * produce poor results if the format string expands to a very long text and 155 * the bprint buffer is near the limit stated by the size_max option. 156 */ 157void av_bprint_strftime(AVBPrint *buf, const char *fmt, const struct tm *tm); 158 159/** 160 * Allocate bytes in the buffer for external use. 161 * 162 * @param[in] buf buffer structure 163 * @param[in] size required size 164 * @param[out] mem pointer to the memory area 165 * @param[out] actual_size size of the memory area after allocation; 166 * can be larger or smaller than size 167 */ 168void av_bprint_get_buffer(AVBPrint *buf, unsigned size, 169 unsigned char **mem, unsigned *actual_size); 170 171/** 172 * Reset the string to "" but keep internal allocated data. 173 */ 174void av_bprint_clear(AVBPrint *buf); 175 176/** 177 * Test if the print buffer is complete (not truncated). 178 * 179 * It may have been truncated due to a memory allocation failure 180 * or the size_max limit (compare size and size_max if necessary). 181 */ 182static inline int av_bprint_is_complete(AVBPrint *buf) 183{ 184 return buf->len < buf->size; 185} 186 187/** 188 * Finalize a print buffer. 189 * 190 * The print buffer can no longer be used afterwards, 191 * but the len and size fields are still valid. 192 * 193 * @arg[out] ret_str if not NULL, used to return a permanent copy of the 194 * buffer contents, or NULL if memory allocation fails; 195 * if NULL, the buffer is discarded and freed 196 * @return 0 for success or error code (probably AVERROR(ENOMEM)) 197 */ 198int av_bprint_finalize(AVBPrint *buf, char **ret_str); 199 200/** 201 * Escape the content in src and append it to dstbuf. 202 * 203 * @param dstbuf already inited destination bprint buffer 204 * @param src string containing the text to escape 205 * @param special_chars string containing the special characters which 206 * need to be escaped, can be NULL 207 * @param mode escape mode to employ, see AV_ESCAPE_MODE_* macros. 208 * Any unknown value for mode will be considered equivalent to 209 * AV_ESCAPE_MODE_BACKSLASH, but this behaviour can change without 210 * notice. 211 * @param flags flags which control how to escape, see AV_ESCAPE_FLAG_* macros 212 */ 213void av_bprint_escape(AVBPrint *dstbuf, const char *src, const char *special_chars, 214 enum AVEscapeMode mode, int flags); 215 216#endif /* AVUTIL_BPRINT_H */ 217