LCOV - code coverage report
Current view: top level - libavutil - bprint.h (source / functions) Hit Total Coverage
Test: coverage.info Lines: 2 2 100.0 %
Date: 2017-12-15 02:19:58 Functions: 1 1 100.0 %

          Line data    Source code
       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             : 
      34             : #define FF_PAD_STRUCTURE(name, size, ...) \
      35             : struct ff_pad_helper_##name { __VA_ARGS__ }; \
      36             : typedef struct name { \
      37             :     __VA_ARGS__ \
      38             :     char reserved_padding[size - sizeof(struct ff_pad_helper_##name)]; \
      39             : } name;
      40             : 
      41             : /**
      42             :  * Buffer to print data progressively
      43             :  *
      44             :  * The string buffer grows as necessary and is always 0-terminated.
      45             :  * The content of the string is never accessed, and thus is
      46             :  * encoding-agnostic and can even hold binary data.
      47             :  *
      48             :  * Small buffers are kept in the structure itself, and thus require no
      49             :  * memory allocation at all (unless the contents of the buffer is needed
      50             :  * after the structure goes out of scope). This is almost as lightweight as
      51             :  * declaring a local "char buf[512]".
      52             :  *
      53             :  * The length of the string can go beyond the allocated size: the buffer is
      54             :  * then truncated, but the functions still keep account of the actual total
      55             :  * length.
      56             :  *
      57             :  * In other words, buf->len can be greater than buf->size and records the
      58             :  * total length of what would have been to the buffer if there had been
      59             :  * enough memory.
      60             :  *
      61             :  * Append operations do not need to be tested for failure: if a memory
      62             :  * allocation fails, data stop being appended to the buffer, but the length
      63             :  * is still updated. This situation can be tested with
      64             :  * av_bprint_is_complete().
      65             :  *
      66             :  * The size_max field determines several possible behaviours:
      67             :  *
      68             :  * size_max = -1 (= UINT_MAX) or any large value will let the buffer be
      69             :  * reallocated as necessary, with an amortized linear cost.
      70             :  *
      71             :  * size_max = 0 prevents writing anything to the buffer: only the total
      72             :  * length is computed. The write operations can then possibly be repeated in
      73             :  * a buffer with exactly the necessary size
      74             :  * (using size_init = size_max = len + 1).
      75             :  *
      76             :  * size_max = 1 is automatically replaced by the exact size available in the
      77             :  * structure itself, thus ensuring no dynamic memory allocation. The
      78             :  * internal buffer is large enough to hold a reasonable paragraph of text,
      79             :  * such as the current paragraph.
      80             :  */
      81             : 
      82             : FF_PAD_STRUCTURE(AVBPrint, 1024,
      83             :     char *str;         /**< string so far */
      84             :     unsigned len;      /**< length so far */
      85             :     unsigned size;     /**< allocated memory */
      86             :     unsigned size_max; /**< maximum allocated memory */
      87             :     char reserved_internal_buffer[1];
      88             : )
      89             : 
      90             : /**
      91             :  * Convenience macros for special values for av_bprint_init() size_max
      92             :  * parameter.
      93             :  */
      94             : #define AV_BPRINT_SIZE_UNLIMITED  ((unsigned)-1)
      95             : #define AV_BPRINT_SIZE_AUTOMATIC  1
      96             : #define AV_BPRINT_SIZE_COUNT_ONLY 0
      97             : 
      98             : /**
      99             :  * Init a print buffer.
     100             :  *
     101             :  * @param buf        buffer to init
     102             :  * @param size_init  initial size (including the final 0)
     103             :  * @param size_max   maximum size;
     104             :  *                   0 means do not write anything, just count the length;
     105             :  *                   1 is replaced by the maximum value for automatic storage;
     106             :  *                   any large value means that the internal buffer will be
     107             :  *                   reallocated as needed up to that limit; -1 is converted to
     108             :  *                   UINT_MAX, the largest limit possible.
     109             :  *                   Check also AV_BPRINT_SIZE_* macros.
     110             :  */
     111             : void av_bprint_init(AVBPrint *buf, unsigned size_init, unsigned size_max);
     112             : 
     113             : /**
     114             :  * Init a print buffer using a pre-existing buffer.
     115             :  *
     116             :  * The buffer will not be reallocated.
     117             :  *
     118             :  * @param buf     buffer structure to init
     119             :  * @param buffer  byte buffer to use for the string data
     120             :  * @param size    size of buffer
     121             :  */
     122             : void av_bprint_init_for_buffer(AVBPrint *buf, char *buffer, unsigned size);
     123             : 
     124             : /**
     125             :  * Append a formatted string to a print buffer.
     126             :  */
     127             : void av_bprintf(AVBPrint *buf, const char *fmt, ...) av_printf_format(2, 3);
     128             : 
     129             : /**
     130             :  * Append a formatted string to a print buffer.
     131             :  */
     132             : void av_vbprintf(AVBPrint *buf, const char *fmt, va_list vl_arg);
     133             : 
     134             : /**
     135             :  * Append char c n times to a print buffer.
     136             :  */
     137             : void av_bprint_chars(AVBPrint *buf, char c, unsigned n);
     138             : 
     139             : /**
     140             :  * Append data to a print buffer.
     141             :  *
     142             :  * param buf  bprint buffer to use
     143             :  * param data pointer to data
     144             :  * param size size of data
     145             :  */
     146             : void av_bprint_append_data(AVBPrint *buf, const char *data, unsigned size);
     147             : 
     148             : struct tm;
     149             : /**
     150             :  * Append a formatted date and time to a print buffer.
     151             :  *
     152             :  * param buf  bprint buffer to use
     153             :  * param fmt  date and time format string, see strftime()
     154             :  * param tm   broken-down time structure to translate
     155             :  *
     156             :  * @note due to poor design of the standard strftime function, it may
     157             :  * produce poor results if the format string expands to a very long text and
     158             :  * the bprint buffer is near the limit stated by the size_max option.
     159             :  */
     160             : void av_bprint_strftime(AVBPrint *buf, const char *fmt, const struct tm *tm);
     161             : 
     162             : /**
     163             :  * Allocate bytes in the buffer for external use.
     164             :  *
     165             :  * @param[in]  buf          buffer structure
     166             :  * @param[in]  size         required size
     167             :  * @param[out] mem          pointer to the memory area
     168             :  * @param[out] actual_size  size of the memory area after allocation;
     169             :  *                          can be larger or smaller than size
     170             :  */
     171             : void av_bprint_get_buffer(AVBPrint *buf, unsigned size,
     172             :                           unsigned char **mem, unsigned *actual_size);
     173             : 
     174             : /**
     175             :  * Reset the string to "" but keep internal allocated data.
     176             :  */
     177             : void av_bprint_clear(AVBPrint *buf);
     178             : 
     179             : /**
     180             :  * Test if the print buffer is complete (not truncated).
     181             :  *
     182             :  * It may have been truncated due to a memory allocation failure
     183             :  * or the size_max limit (compare size and size_max if necessary).
     184             :  */
     185        2512 : static inline int av_bprint_is_complete(const AVBPrint *buf)
     186             : {
     187        2512 :     return buf->len < buf->size;
     188             : }
     189             : 
     190             : /**
     191             :  * Finalize a print buffer.
     192             :  *
     193             :  * The print buffer can no longer be used afterwards,
     194             :  * but the len and size fields are still valid.
     195             :  *
     196             :  * @arg[out] ret_str  if not NULL, used to return a permanent copy of the
     197             :  *                    buffer contents, or NULL if memory allocation fails;
     198             :  *                    if NULL, the buffer is discarded and freed
     199             :  * @return  0 for success or error code (probably AVERROR(ENOMEM))
     200             :  */
     201             : int av_bprint_finalize(AVBPrint *buf, char **ret_str);
     202             : 
     203             : /**
     204             :  * Escape the content in src and append it to dstbuf.
     205             :  *
     206             :  * @param dstbuf        already inited destination bprint buffer
     207             :  * @param src           string containing the text to escape
     208             :  * @param special_chars string containing the special characters which
     209             :  *                      need to be escaped, can be NULL
     210             :  * @param mode          escape mode to employ, see AV_ESCAPE_MODE_* macros.
     211             :  *                      Any unknown value for mode will be considered equivalent to
     212             :  *                      AV_ESCAPE_MODE_BACKSLASH, but this behaviour can change without
     213             :  *                      notice.
     214             :  * @param flags         flags which control how to escape, see AV_ESCAPE_FLAG_* macros
     215             :  */
     216             : void av_bprint_escape(AVBPrint *dstbuf, const char *src, const char *special_chars,
     217             :                       enum AVEscapeMode mode, int flags);
     218             : 
     219             : #endif /* AVUTIL_BPRINT_H */

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