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 <stdarg.h>
22 #include <stdio.h>
23 #include <string.h>
24 #include <time.h>
25 #include "avassert.h"
26 #include "avstring.h"
27 #include "bprint.h"
28 #include "common.h"
29 #include "compat/va_copy.h"
30 #include "error.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 
av_bprint_alloc(AVBPrint * buf,unsigned room)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 
av_bprint_grow(AVBPrint * buf,unsigned extra_len)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 
av_bprint_init(AVBPrint * buf,unsigned size_init,unsigned size_max)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 == 1)
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 
av_bprint_init_for_buffer(AVBPrint * buf,char * buffer,unsigned size)85 void av_bprint_init_for_buffer(AVBPrint *buf, char *buffer, unsigned size)
86 {
87     buf->str      = buffer;
88     buf->len      = 0;
89     buf->size     = size;
90     buf->size_max = size;
91     *buf->str = 0;
92 }
93 
av_bprintf(AVBPrint * buf,const char * fmt,...)94 void av_bprintf(AVBPrint *buf, const char *fmt, ...)
95 {
96     unsigned room;
97     char *dst;
98     va_list vl;
99     int extra_len;
100 
101     while (1) {
102         room = av_bprint_room(buf);
103         dst = room ? buf->str + buf->len : NULL;
104         va_start(vl, fmt);
105         extra_len = vsnprintf(dst, room, fmt, vl);
106         va_end(vl);
107         if (extra_len <= 0)
108             return;
109         if (extra_len < room)
110             break;
111         if (av_bprint_alloc(buf, extra_len))
112             break;
113     }
114     av_bprint_grow(buf, extra_len);
115 }
116 
av_vbprintf(AVBPrint * buf,const char * fmt,va_list vl_arg)117 void av_vbprintf(AVBPrint *buf, const char *fmt, va_list vl_arg)
118 {
119     unsigned room;
120     char *dst;
121     int extra_len;
122     va_list vl;
123 
124     while (1) {
125         room = av_bprint_room(buf);
126         dst = room ? buf->str + buf->len : NULL;
127         va_copy(vl, vl_arg);
128         extra_len = vsnprintf(dst, room, fmt, vl);
129         va_end(vl);
130         if (extra_len <= 0)
131             return;
132         if (extra_len < room)
133             break;
134         if (av_bprint_alloc(buf, extra_len))
135             break;
136     }
137     av_bprint_grow(buf, extra_len);
138 }
139 
av_bprint_chars(AVBPrint * buf,char c,unsigned n)140 void av_bprint_chars(AVBPrint *buf, char c, unsigned n)
141 {
142     unsigned room, real_n;
143 
144     while (1) {
145         room = av_bprint_room(buf);
146         if (n < room)
147             break;
148         if (av_bprint_alloc(buf, n))
149             break;
150     }
151     if (room) {
152         real_n = FFMIN(n, room - 1);
153         memset(buf->str + buf->len, c, real_n);
154     }
155     av_bprint_grow(buf, n);
156 }
157 
av_bprint_append_data(AVBPrint * buf,const char * data,unsigned size)158 void av_bprint_append_data(AVBPrint *buf, const char *data, unsigned size)
159 {
160     unsigned room, real_n;
161 
162     while (1) {
163         room = av_bprint_room(buf);
164         if (size < room)
165             break;
166         if (av_bprint_alloc(buf, size))
167             break;
168     }
169     if (room) {
170         real_n = FFMIN(size, room - 1);
171         memcpy(buf->str + buf->len, data, real_n);
172     }
173     av_bprint_grow(buf, size);
174 }
175 
av_bprint_strftime(AVBPrint * buf,const char * fmt,const struct tm * tm)176 void av_bprint_strftime(AVBPrint *buf, const char *fmt, const struct tm *tm)
177 {
178     unsigned room;
179     size_t l;
180 
181     if (!*fmt)
182         return;
183     while (1) {
184         room = av_bprint_room(buf);
185         if (room && (l = strftime(buf->str + buf->len, room, fmt, tm)))
186             break;
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 ? strlen(fmt) + 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 
av_bprint_get_buffer(AVBPrint * buf,unsigned size,unsigned char ** mem,unsigned * actual_size)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 
av_bprint_clear(AVBPrint * buf)227 void av_bprint_clear(AVBPrint *buf)
228 {
229     if (buf->len) {
230         *buf->str = 0;
231         buf->len  = 0;
232     }
233 }
234 
av_bprint_finalize(AVBPrint * buf,char ** ret_str)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_malloc(real_size);
249             if (str)
250                 memcpy(str, buf->str, real_size);
251             else
252                 ret = AVERROR(ENOMEM);
253         }
254         *ret_str = str;
255     } else {
256         if (av_bprint_is_allocated(buf))
257             av_freep(&buf->str);
258     }
259     buf->size = real_size;
260     return ret;
261 }
262 
263 #define WHITESPACES " \n\t\r"
264 
av_bprint_escape(AVBPrint * dstbuf,const char * src,const char * special_chars,enum AVEscapeMode mode,int flags)265 void av_bprint_escape(AVBPrint *dstbuf, const char *src, const char *special_chars,
266                       enum AVEscapeMode mode, int flags)
267 {
268     const char *src0 = src;
269 
270     if (mode == AV_ESCAPE_MODE_AUTO)
271         mode = AV_ESCAPE_MODE_BACKSLASH; /* TODO: implement a heuristic */
272 
273     switch (mode) {
274     case AV_ESCAPE_MODE_QUOTE:
275         /* enclose the string between '' */
276         av_bprint_chars(dstbuf, '\'', 1);
277         for (; *src; src++) {
278             if (*src == '\'')
279                 av_bprintf(dstbuf, "'\\''");
280             else
281                 av_bprint_chars(dstbuf, *src, 1);
282         }
283         av_bprint_chars(dstbuf, '\'', 1);
284         break;
285 
286     case AV_ESCAPE_MODE_XML:
287         /* escape XML non-markup character data as per 2.4 by default: */
288         /*  [^<&]* - ([^<&]* ']]>' [^<&]*) */
289 
290         /* additionally, given one of the AV_ESCAPE_FLAG_XML_* flags, */
291         /* escape those specific characters as required. */
292         for (; *src; src++) {
293             switch (*src) {
294             case '&' : av_bprintf(dstbuf, "%s", "&amp;");  break;
295             case '<' : av_bprintf(dstbuf, "%s", "&lt;");   break;
296             case '>' : av_bprintf(dstbuf, "%s", "&gt;");   break;
297             case '\'':
298                 if (!(flags & AV_ESCAPE_FLAG_XML_SINGLE_QUOTES))
299                     goto XML_DEFAULT_HANDLING;
300 
301                 av_bprintf(dstbuf, "%s", "&apos;");
302                 break;
303             case '"' :
304                 if (!(flags & AV_ESCAPE_FLAG_XML_DOUBLE_QUOTES))
305                     goto XML_DEFAULT_HANDLING;
306 
307                 av_bprintf(dstbuf, "%s", "&quot;");
308                 break;
309 XML_DEFAULT_HANDLING:
310             default: av_bprint_chars(dstbuf, *src, 1);
311             }
312         }
313         break;
314 
315     /* case AV_ESCAPE_MODE_BACKSLASH or unknown mode */
316     default:
317         /* \-escape characters */
318         for (; *src; src++) {
319             int is_first_last       = src == src0 || !*(src+1);
320             int is_ws               = !!strchr(WHITESPACES, *src);
321             int is_strictly_special = special_chars && strchr(special_chars, *src);
322             int is_special          =
323                 is_strictly_special || strchr("'\\", *src) ||
324                 (is_ws && (flags & AV_ESCAPE_FLAG_WHITESPACE));
325 
326             if (is_strictly_special ||
327                 (!(flags & AV_ESCAPE_FLAG_STRICT) &&
328                  (is_special || (is_ws && is_first_last))))
329                 av_bprint_chars(dstbuf, '\\', 1);
330             av_bprint_chars(dstbuf, *src, 1);
331         }
332         break;
333     }
334 }
335