/* * 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, ...) … /** * 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, … } /** * @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 … /** * 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 … /** * 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 … /** @} */ /** * 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) { … } /** * 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 */
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