FFmpeg
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
avstring.h
Go to the documentation of this file.
1 /*
2  * Copyright (c) 2007 Mans Rullgard
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_AVSTRING_H
22 #define AVUTIL_AVSTRING_H
23 
24 #include <stddef.h>
25 #include <stdint.h>
26 #include "attributes.h"
27 
28 /**
29  * @addtogroup lavu_string
30  * @{
31  */
32 
33 /**
34  * Return non-zero if pfx is a prefix of str. If it is, *ptr is set to
35  * the address of the first character in str after the prefix.
36  *
37  * @param str input string
38  * @param pfx prefix to test
39  * @param ptr updated if the prefix is matched inside str
40  * @return non-zero if the prefix matches, zero otherwise
41  */
42 int av_strstart(const char *str, const char *pfx, const char **ptr);
43 
44 /**
45  * Return non-zero if pfx is a prefix of str independent of case. If
46  * it is, *ptr is set to the address of the first character in str
47  * after the prefix.
48  *
49  * @param str input string
50  * @param pfx prefix to test
51  * @param ptr updated if the prefix is matched inside str
52  * @return non-zero if the prefix matches, zero otherwise
53  */
54 int av_stristart(const char *str, const char *pfx, const char **ptr);
55 
56 /**
57  * Locate the first case-independent occurrence in the string haystack
58  * of the string needle. A zero-length string needle is considered to
59  * match at the start of haystack.
60  *
61  * This function is a case-insensitive version of the standard strstr().
62  *
63  * @param haystack string to search in
64  * @param needle string to search for
65  * @return pointer to the located match within haystack
66  * or a null pointer if no match
67  */
68 char *av_stristr(const char *haystack, const char *needle);
69 
70 /**
71  * Locate the first occurrence of the string needle in the string haystack
72  * where not more than hay_length characters are searched. A zero-length
73  * string needle is considered to match at the start of haystack.
74  *
75  * This function is a length-limited version of the standard strstr().
76  *
77  * @param haystack string to search in
78  * @param needle string to search for
79  * @param hay_length length of string to search in
80  * @return pointer to the located match within haystack
81  * or a null pointer if no match
82  */
83 char *av_strnstr(const char *haystack, const char *needle, size_t hay_length);
84 
85 /**
86  * Copy the string src to dst, but no more than size - 1 bytes, and
87  * null-terminate dst.
88  *
89  * This function is the same as BSD strlcpy().
90  *
91  * @param dst destination buffer
92  * @param src source string
93  * @param size size of destination buffer
94  * @return the length of src
95  *
96  * @warning since the return value is the length of src, src absolutely
97  * _must_ be a properly 0-terminated string, otherwise this will read beyond
98  * the end of the buffer and possibly crash.
99  */
100 size_t av_strlcpy(char *dst, const char *src, size_t size);
101 
102 /**
103  * Append the string src to the string dst, but to a total length of
104  * no more than size - 1 bytes, and null-terminate dst.
105  *
106  * This function is similar to BSD strlcat(), but differs when
107  * size <= strlen(dst).
108  *
109  * @param dst destination buffer
110  * @param src source string
111  * @param size size of destination buffer
112  * @return the total length of src and dst
113  *
114  * @warning since the return value use the length of src and dst, these
115  * absolutely _must_ be a properly 0-terminated strings, otherwise this
116  * will read beyond the end of the buffer and possibly crash.
117  */
118 size_t av_strlcat(char *dst, const char *src, size_t size);
119 
120 /**
121  * Append output to a string, according to a format. Never write out of
122  * the destination buffer, and always put a terminating 0 within
123  * the buffer.
124  * @param dst destination buffer (string to which the output is
125  * appended)
126  * @param size total size of the destination buffer
127  * @param fmt printf-compatible format string, specifying how the
128  * following parameters are used
129  * @return the length of the string that would have been generated
130  * if enough space had been available
131  */
132 size_t av_strlcatf(char *dst, size_t size, const char *fmt, ...) av_printf_format(3, 4);
133 
134 /**
135  * Get the count of continuous non zero chars starting from the beginning.
136  *
137  * @param len maximum number of characters to check in the string, that
138  * is the maximum value which is returned by the function
139  */
140 static inline size_t av_strnlen(const char *s, size_t len)
141 {
142  size_t i;
143  for (i = 0; i < len && s[i]; i++)
144  ;
145  return i;
146 }
147 
148 /**
149  * Print arguments following specified format into a large enough auto
150  * allocated buffer. It is similar to GNU asprintf().
151  * @param fmt printf-compatible format string, specifying how the
152  * following parameters are used.
153  * @return the allocated string
154  * @note You have to free the string yourself with av_free().
155  */
156 char *av_asprintf(const char *fmt, ...) av_printf_format(1, 2);
157 
158 /**
159  * Convert a number to a av_malloced string.
160  */
161 char *av_d2str(double d);
162 
163 /**
164  * Unescape the given string until a non escaped terminating char,
165  * and return the token corresponding to the unescaped string.
166  *
167  * The normal \ and ' escaping is supported. Leading and trailing
168  * whitespaces are removed, unless they are escaped with '\' or are
169  * enclosed between ''.
170  *
171  * @param buf the buffer to parse, buf will be updated to point to the
172  * terminating char
173  * @param term a 0-terminated list of terminating chars
174  * @return the malloced unescaped string, which must be av_freed by
175  * the user, NULL in case of allocation failure
176  */
177 char *av_get_token(const char **buf, const char *term);
178 
179 /**
180  * Split the string into several tokens which can be accessed by
181  * successive calls to av_strtok().
182  *
183  * A token is defined as a sequence of characters not belonging to the
184  * set specified in delim.
185  *
186  * On the first call to av_strtok(), s should point to the string to
187  * parse, and the value of saveptr is ignored. In subsequent calls, s
188  * should be NULL, and saveptr should be unchanged since the previous
189  * call.
190  *
191  * This function is similar to strtok_r() defined in POSIX.1.
192  *
193  * @param s the string to parse, may be NULL
194  * @param delim 0-terminated list of token delimiters, must be non-NULL
195  * @param saveptr user-provided pointer which points to stored
196  * information necessary for av_strtok() to continue scanning the same
197  * string. saveptr is updated to point to the next character after the
198  * first delimiter found, or to NULL if the string was terminated
199  * @return the found token, or NULL when no token is found
200  */
201 char *av_strtok(char *s, const char *delim, char **saveptr);
202 
203 /**
204  * Locale-independent conversion of ASCII isdigit.
205  */
206 int av_isdigit(int c);
207 
208 /**
209  * Locale-independent conversion of ASCII isgraph.
210  */
211 int av_isgraph(int c);
212 
213 /**
214  * Locale-independent conversion of ASCII isspace.
215  */
216 int av_isspace(int c);
217 
218 /**
219  * Locale-independent conversion of ASCII characters to uppercase.
220  */
221 static inline int av_toupper(int c)
222 {
223  if (c >= 'a' && c <= 'z')
224  c ^= 0x20;
225  return c;
226 }
227 
228 /**
229  * Locale-independent conversion of ASCII characters to lowercase.
230  */
231 static inline int av_tolower(int c)
232 {
233  if (c >= 'A' && c <= 'Z')
234  c ^= 0x20;
235  return c;
236 }
237 
238 /**
239  * Locale-independent conversion of ASCII isxdigit.
240  */
241 int av_isxdigit(int c);
242 
243 /**
244  * Locale-independent case-insensitive compare.
245  * @note This means only ASCII-range characters are case-insensitive
246  */
247 int av_strcasecmp(const char *a, const char *b);
248 
249 /**
250  * Locale-independent case-insensitive compare.
251  * @note This means only ASCII-range characters are case-insensitive
252  */
253 int av_strncasecmp(const char *a, const char *b, size_t n);
254 
255 
256 /**
257  * Thread safe basename.
258  * @param path the path, on DOS both \ and / are considered separators.
259  * @return pointer to the basename substring.
260  */
261 const char *av_basename(const char *path);
262 
263 /**
264  * Thread safe dirname.
265  * @param path the path, on DOS both \ and / are considered separators.
266  * @return the path with the separator replaced by the string terminator or ".".
267  * @note the function may change the input string.
268  */
269 const char *av_dirname(char *path);
270 
271 /**
272  * Match instances of a name in a comma-separated list of names.
273  * @param name Name to look for.
274  * @param names List of names.
275  * @return 1 on match, 0 otherwise.
276  */
277 int av_match_name(const char *name, const char *names);
278 
280  AV_ESCAPE_MODE_AUTO, ///< Use auto-selected escaping mode.
281  AV_ESCAPE_MODE_BACKSLASH, ///< Use backslash escaping.
282  AV_ESCAPE_MODE_QUOTE, ///< Use single-quote escaping.
283 };
284 
285 /**
286  * Consider spaces special and escape them even in the middle of the
287  * string.
288  *
289  * This is equivalent to adding the whitespace characters to the special
290  * characters lists, except it is guaranteed to use the exact same list
291  * of whitespace characters as the rest of libavutil.
292  */
293 #define AV_ESCAPE_FLAG_WHITESPACE 0x01
294 
295 /**
296  * Escape only specified special characters.
297  * Without this flag, escape also any characters that may be considered
298  * special by av_get_token(), such as the single quote.
299  */
300 #define AV_ESCAPE_FLAG_STRICT 0x02
301 
302 /**
303  * Escape string in src, and put the escaped string in an allocated
304  * string in *dst, which must be freed with av_free().
305  *
306  * @param dst pointer where an allocated string is put
307  * @param src string to escape, must be non-NULL
308  * @param special_chars string containing the special characters which
309  * need to be escaped, can be NULL
310  * @param mode escape mode to employ, see AV_ESCAPE_MODE_* macros.
311  * Any unknown value for mode will be considered equivalent to
312  * AV_ESCAPE_MODE_BACKSLASH, but this behaviour can change without
313  * notice.
314  * @param flags flags which control how to escape, see AV_ESCAPE_FLAG_ macros
315  * @return the length of the allocated string, or a negative error code in case of error
316  * @see av_bprint_escape()
317  */
318 int av_escape(char **dst, const char *src, const char *special_chars,
319  enum AVEscapeMode mode, int flags);
320 
321 #define AV_UTF8_FLAG_ACCEPT_INVALID_BIG_CODES 1 ///< accept codepoints over 0x10FFFF
322 #define AV_UTF8_FLAG_ACCEPT_NON_CHARACTERS 2 ///< accept non-characters - 0xFFFE and 0xFFFF
323 #define AV_UTF8_FLAG_ACCEPT_SURROGATES 4 ///< accept UTF-16 surrogates codes
324 #define AV_UTF8_FLAG_EXCLUDE_XML_INVALID_CONTROL_CODES 8 ///< exclude control codes not accepted by XML
325 
326 #define AV_UTF8_FLAG_ACCEPT_ALL \
327  AV_UTF8_FLAG_ACCEPT_INVALID_BIG_CODES|AV_UTF8_FLAG_ACCEPT_NON_CHARACTERS|AV_UTF8_FLAG_ACCEPT_SURROGATES
328 
329 /**
330  * Read and decode a single UTF-8 code point (character) from the
331  * buffer in *buf, and update *buf to point to the next byte to
332  * decode.
333  *
334  * In case of an invalid byte sequence, the pointer will be updated to
335  * the next byte after the invalid sequence and the function will
336  * return an error code.
337  *
338  * Depending on the specified flags, the function will also fail in
339  * case the decoded code point does not belong to a valid range.
340  *
341  * @note For speed-relevant code a carefully implemented use of
342  * GET_UTF8() may be preferred.
343  *
344  * @param codep pointer used to return the parsed code in case of success.
345  * The value in *codep is set even in case the range check fails.
346  * @param bufp pointer to the address the first byte of the sequence
347  * to decode, updated by the function to point to the
348  * byte next after the decoded sequence
349  * @param buf_end pointer to the end of the buffer, points to the next
350  * byte past the last in the buffer. This is used to
351  * avoid buffer overreads (in case of an unfinished
352  * UTF-8 sequence towards the end of the buffer).
353  * @param flags a collection of AV_UTF8_FLAG_* flags
354  * @return >= 0 in case a sequence was successfully read, a negative
355  * value in case of invalid sequence
356  */
357 int av_utf8_decode(int32_t *codep, const uint8_t **bufp, const uint8_t *buf_end,
358  unsigned int flags);
359 
360 /**
361  * Check if a name is in a list.
362  * @returns 0 if not found, or the 1 based index where it has been found in the
363  * list.
364  */
365 int av_match_list(const char *name, const char *list, char separator);
366 
367 /**
368  * @}
369  */
370 
371 #endif /* AVUTIL_AVSTRING_H */