libavutil/bprint.c

   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 #include <limits.h>
  22 #include <stdarg.h>
  23 #include <stdio.h>
  24 #include <string.h>
  25 #include <time.h>
  26 #include "avstring.h"
  27 #include "bprint.h"
  28 #include "compat/va_copy.h"
  29 #include "error.h"
  30 #include "macros.h"
  31 #include "mem.h"
  32
  33 #define av_bprint_room(buf) ((buf)->size - FFMIN((buf)->len, (buf)->size))
  34 #define av_bprint_is_allocated(buf) ((buf)->str != (buf)->reserved_internal_buffer)
  35
  36 static int av_bprint_alloc(AVBPrint *buf, unsigned room)
  37 {
  38     char *old_str, *new_str;
  39     unsigned min_size, new_size;
  40
  41     if (buf->size == buf->size_max)
  42         return AVERROR(EIO);
  43     if (!av_bprint_is_complete(buf))
  44         return AVERROR_INVALIDDATA; /* it is already truncated anyway */
  45     min_size = buf->len + 1 + FFMIN(UINT_MAX - buf->len - 1, room);
  46     new_size = buf->size > buf->size_max / 2 ? buf->size_max : buf->size * 2;
  47     if (new_size < min_size)
  48         new_size = FFMIN(buf->size_max, min_size);
  49     old_str = av_bprint_is_allocated(buf) ? buf->str : NULL;
  50     new_str = av_realloc(old_str, new_size);
  51     if (!new_str)
  52         return AVERROR(ENOMEM);
  53     if (!old_str)
  54         memcpy(new_str, buf->str, buf->len + 1);
  55     buf->str  = new_str;
  56     buf->size = new_size;
  57     return 0;
  58 }
  59
  60 static void av_bprint_grow(AVBPrint *buf, unsigned extra_len)
  61 {
  62     /* arbitrary margin to avoid small overflows */
  63     extra_len = FFMIN(extra_len, UINT_MAX - 5 - buf->len);
  64     buf->len += extra_len;
  65     if (buf->size)
  66         buf->str[FFMIN(buf->len, buf->size - 1)] = 0;
  67 }
  68
  69 void av_bprint_init(AVBPrint *buf, unsigned size_init, unsigned size_max)
  70 {
  71     unsigned size_auto = (char *)buf + sizeof(*buf) -
  72                          buf->reserved_internal_buffer;
  73
  74     if (size_max == AV_BPRINT_SIZE_AUTOMATIC)
  75         size_max = size_auto;
  76     buf->str      = buf->reserved_internal_buffer;
  77     buf->len      = 0;
  78     buf->size     = FFMIN(size_auto, size_max);
  79     buf->size_max = size_max;
  80     *buf->str = 0;
  81     if (size_init > buf->size)
  82         av_bprint_alloc(buf, size_init - 1);
  83 }
  84
  85 void av_bprint_init_for_buffer(AVBPrint *buf, char *buffer, unsigned size)
  86 {
  87     if (size == 0) {
  88         av_bprint_init(buf, 0, AV_BPRINT_SIZE_COUNT_ONLY);
  89         return;
  90     }
  91
  92     buf->str      = buffer;
  93     buf->len      = 0;
  94     buf->size     = size;
  95     buf->size_max = size;
  96     *buf->str = 0;
  97 }
  98
  99 void av_vbprintf(AVBPrint *buf, const char *fmt, va_list vl_arg)
 100 {
 101     unsigned room;
 102     char *dst;
 103     int extra_len;
 104     va_list vl;
 105
 106     while (1) {
 107         room = av_bprint_room(buf);
 108         dst = room ? buf->str + buf->len : NULL;
 109         va_copy(vl, vl_arg);
 110         extra_len = vsnprintf(dst, room, fmt, vl);
 111         va_end(vl);
 112         if (extra_len <= 0)
 113             return;
 114         if (extra_len < room)
 115             break;
 116         if (av_bprint_alloc(buf, extra_len))
 117             break;
 118     }
 119     av_bprint_grow(buf, extra_len);
 120 }
 121
 122 void av_bprintf(AVBPrint *buf, const char *fmt, ...)
 123 {
 124     va_list vl;
 125     va_start(vl, fmt);
 126     av_vbprintf(buf, fmt, vl);
 127     va_end(vl);
 128 }
 129
 130 void av_bprint_chars(AVBPrint *buf, char c, unsigned n)
 131 {
 132     unsigned room, real_n;
 133
 134     while (1) {
 135         room = av_bprint_room(buf);
 136         if (n < room)
 137             break;
 138         if (av_bprint_alloc(buf, n))
 139             break;
 140     }
 141     if (room) {
 142         real_n = FFMIN(n, room - 1);
 143         memset(buf->str + buf->len, c, real_n);
 144     }
 145     av_bprint_grow(buf, n);
 146 }
 147
 148 void av_bprint_append_data(AVBPrint *buf, const char *data, unsigned size)
 149 {
 150     unsigned room, real_n;
 151
 152     while (1) {
 153         room = av_bprint_room(buf);
 154         if (size < room)
 155             break;
 156         if (av_bprint_alloc(buf, size))
 157             break;
 158     }
 159     if (room) {
 160         real_n = FFMIN(size, room - 1);
 161         memcpy(buf->str + buf->len, data, real_n);
 162     }
 163     av_bprint_grow(buf, size);
 164 }
 165
 166 void av_bprint_strftime(AVBPrint *buf, const char *fmt, const struct tm *tm)
 167 {
 168     unsigned room;
 169     size_t l;
 170     size_t fmt_len = strlen(fmt);
 171
 172     if (!*fmt)
 173         return;
 174     while (1) {
 175         room = av_bprint_room(buf);
 176         if (room && (l = strftime(buf->str + buf->len, room, fmt, tm)))
 177             break;
 178
 179         /* Due to the limitations of strftime() it is not possible to know if
 180          * the output buffer is too small or the output is empty.
 181          * However, a 256x output space requirement compared to the format
 182          * string length is so unlikely we can safely assume empty output. This
 183          * allows supporting possibly empty format strings like "%p". */
 184         if (room >> 8 > fmt_len)
 185             break;
 186
 187         /* strftime does not tell us how much room it would need: let us
 188            retry with twice as much until the buffer is large enough */
 189         room = !room ? fmt_len + 1 :
 190                room <= INT_MAX / 2 ? room * 2 : INT_MAX;
 191         if (av_bprint_alloc(buf, room)) {
 192             /* impossible to grow, try to manage something useful anyway */
 193             room = av_bprint_room(buf);
 194             if (room < 1024) {
 195                 /* if strftime fails because the buffer has (almost) reached
 196                    its maximum size, let us try in a local buffer; 1k should
 197                    be enough to format any real date+time string */
 198                 char buf2[1024];
 199                 if ((l = strftime(buf2, sizeof(buf2), fmt, tm))) {
 200                     av_bprintf(buf, "%s", buf2);
 201                     return;
 202                 }
 203             }
 204             if (room) {
 205                 /* if anything else failed and the buffer is not already
 206                    truncated, let us add a stock string and force truncation */
 207                 static const char txt[] = "[truncated strftime output]";
 208                 memset(buf->str + buf->len, '!', room);
 209                 memcpy(buf->str + buf->len, txt, FFMIN(sizeof(txt) - 1, room));
 210                 av_bprint_grow(buf, room); /* force truncation */
 211             }
 212             return;
 213         }
 214     }
 215     av_bprint_grow(buf, l);
 216 }
 217
 218 void av_bprint_get_buffer(AVBPrint *buf, unsigned size,
 219                           unsigned char **mem, unsigned *actual_size)
 220 {
 221     if (size > av_bprint_room(buf))
 222         av_bprint_alloc(buf, size);
 223     *actual_size = av_bprint_room(buf);
 224     *mem = *actual_size ? buf->str + buf->len : NULL;
 225 }
 226
 227 void av_bprint_clear(AVBPrint *buf)
 228 {
 229     if (buf->len) {
 230         *buf->str = 0;
 231         buf->len  = 0;
 232     }
 233 }
 234
 235 int av_bprint_finalize(AVBPrint *buf, char **ret_str)
 236 {
 237     unsigned real_size = FFMIN(buf->len + 1, buf->size);
 238     char *str;
 239     int ret = 0;
 240
 241     if (ret_str) {
 242         if (av_bprint_is_allocated(buf)) {
 243             str = av_realloc(buf->str, real_size);
 244             if (!str)
 245                 str = buf->str;
 246             buf->str = NULL;
 247         } else {
 248             str = av_memdup(buf->str, real_size);
 249             if (!str)
 250                 ret = AVERROR(ENOMEM);
 251         }
 252         *ret_str = str;
 253     } else {
 254         if (av_bprint_is_allocated(buf))
 255             av_freep(&buf->str);
 256     }
 257     buf->size = real_size;
 258     return ret;
 259 }
 260
 261 #define WHITESPACES " \n\t\r"
 262
 263 void av_bprint_escape(AVBPrint *dstbuf, const char *src, const char *special_chars,
 264                       enum AVEscapeMode mode, int flags)
 265 {
 266     const char *src0 = src;
 267
 268     if (mode == AV_ESCAPE_MODE_AUTO)
 269         mode = AV_ESCAPE_MODE_BACKSLASH; /* TODO: implement a heuristic */
 270
 271     switch (mode) {
 272     case AV_ESCAPE_MODE_QUOTE:
 273         /* enclose the string between '' */
 274         av_bprint_chars(dstbuf, '\'', 1);
 275         for (; *src; src++) {
 276             if (*src == '\'')
 277                 av_bprintf(dstbuf, "'\\''");
 278             else
 279                 av_bprint_chars(dstbuf, *src, 1);
 280         }
 281         av_bprint_chars(dstbuf, '\'', 1);
 282         break;
 283
 284     case AV_ESCAPE_MODE_XML:
 285         /* escape XML non-markup character data as per 2.4 by default: */
 286         /*  [^<&]* - ([^<&]* ']]>' [^<&]*) */
 287
 288         /* additionally, given one of the AV_ESCAPE_FLAG_XML_* flags, */
 289         /* escape those specific characters as required. */
 290         for (; *src; src++) {
 291             switch (*src) {
 292             case '&' : av_bprintf(dstbuf, "%s", "&amp;");  break;
 293             case '<' : av_bprintf(dstbuf, "%s", "&lt;");   break;
 294             case '>' : av_bprintf(dstbuf, "%s", "&gt;");   break;
 295             case '\'':
 296                 if (!(flags & AV_ESCAPE_FLAG_XML_SINGLE_QUOTES))
 297                     goto XML_DEFAULT_HANDLING;
 298
 299                 av_bprintf(dstbuf, "%s", "&apos;");
 300                 break;
 301             case '"' :
 302                 if (!(flags & AV_ESCAPE_FLAG_XML_DOUBLE_QUOTES))
 303                     goto XML_DEFAULT_HANDLING;
 304
 305                 av_bprintf(dstbuf, "%s", "&quot;");
 306                 break;
 307 XML_DEFAULT_HANDLING:
 308             default: av_bprint_chars(dstbuf, *src, 1);
 309             }
 310         }
 311         break;
 312
 313     /* case AV_ESCAPE_MODE_BACKSLASH or unknown mode */
 314     default:
 315         /* \-escape characters */
 316         for (; *src; src++) {
 317             int is_first_last       = src == src0 || !*(src+1);
 318             int is_ws               = !!strchr(WHITESPACES, *src);
 319             int is_strictly_special = special_chars && strchr(special_chars, *src);
 320             int is_special          =
 321                 is_strictly_special || strchr("'\\", *src) ||
 322                 (is_ws && (flags & AV_ESCAPE_FLAG_WHITESPACE));
 323
 324             if (is_strictly_special ||
 325                 (!(flags & AV_ESCAPE_FLAG_STRICT) &&
 326                  (is_special || (is_ws && is_first_last))))
 327                 av_bprint_chars(dstbuf, '\\', 1);
 328             av_bprint_chars(dstbuf, *src, 1);
 329         }
 330         break;
 331     }
 332 }