text: /*
   * 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 <stdarg.h>
  
  #include "attributes.h"
  #include "avstring.h"
  
  /**
   * 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, 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.
   */
  
  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];
  )
  
  /**
   * 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 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 */
  