1883494ca3ad4931640c2a295c94800e287c1664
[git.git] / strbuf.h
1 #ifndef STRBUF_H
2 #define STRBUF_H
3
4 /**
5 * strbuf's are meant to be used with all the usual C string and memory
6 * APIs. Given that the length of the buffer is known, it's often better to
7 * use the mem* functions than a str* one (memchr vs. strchr e.g.).
8 * Though, one has to be careful about the fact that str* functions often
9 * stop on NULs and that strbufs may have embedded NULs.
10 *
11 * A strbuf is NUL terminated for convenience, but no function in the
12 * strbuf API actually relies on the string being free of NULs.
13 *
14 * strbufs have some invariants that are very important to keep in mind:
15 *
16 * - The `buf` member is never NULL, so it can be used in any usual C
17 * string operations safely. strbuf's _have_ to be initialized either by
18 * `strbuf_init()` or by `= STRBUF_INIT` before the invariants, though.
19 *
20 * Do *not* assume anything on what `buf` really is (e.g. if it is
21 * allocated memory or not), use `strbuf_detach()` to unwrap a memory
22 * buffer from its strbuf shell in a safe way. That is the sole supported
23 * way. This will give you a malloced buffer that you can later `free()`.
24 *
25 * However, it is totally safe to modify anything in the string pointed by
26 * the `buf` member, between the indices `0` and `len-1` (inclusive).
27 *
28 * - The `buf` member is a byte array that has at least `len + 1` bytes
29 * allocated. The extra byte is used to store a `'\0'`, allowing the
30 * `buf` member to be a valid C-string. Every strbuf function ensure this
31 * invariant is preserved.
32 *
33 * NOTE: It is OK to "play" with the buffer directly if you work it this
34 * way:
35 *
36 * strbuf_grow(sb, SOME_SIZE); <1>
37 * strbuf_setlen(sb, sb->len + SOME_OTHER_SIZE);
38 *
39 * <1> Here, the memory array starting at `sb->buf`, and of length
40 * `strbuf_avail(sb)` is all yours, and you can be sure that
41 * `strbuf_avail(sb)` is at least `SOME_SIZE`.
42 *
43 * NOTE: `SOME_OTHER_SIZE` must be smaller or equal to `strbuf_avail(sb)`.
44 *
45 * Doing so is safe, though if it has to be done in many places, adding the
46 * missing API to the strbuf module is the way to go.
47 *
48 * WARNING: Do _not_ assume that the area that is yours is of size `alloc
49 * - 1` even if it's true in the current implementation. Alloc is somehow a
50 * "private" member that should not be messed with. Use `strbuf_avail()`
51 * instead.
52 */
53
54 /**
55 * Data Structures
56 * ---------------
57 */
58
59 /**
60 * This is the string buffer structure. The `len` member can be used to
61 * determine the current length of the string, and `buf` member provides
62 * access to the string itself.
63 */
64 struct strbuf {
65 size_t alloc;
66 size_t len;
67 char *buf;
68 };
69
70 extern char strbuf_slopbuf[];
71 #define STRBUF_INIT { 0, 0, strbuf_slopbuf }
72
73 /**
74 * Life Cycle Functions
75 * --------------------
76 */
77
78 /**
79 * Initialize the structure. The second parameter can be zero or a bigger
80 * number to allocate memory, in case you want to prevent further reallocs.
81 */
82 extern void strbuf_init(struct strbuf *, size_t);
83
84 /**
85 * Release a string buffer and the memory it used. You should not use the
86 * string buffer after using this function, unless you initialize it again.
87 */
88 extern void strbuf_release(struct strbuf *);
89
90 /**
91 * Detach the string from the strbuf and returns it; you now own the
92 * storage the string occupies and it is your responsibility from then on
93 * to release it with `free(3)` when you are done with it.
94 */
95 extern char *strbuf_detach(struct strbuf *, size_t *);
96
97 /**
98 * Attach a string to a buffer. You should specify the string to attach,
99 * the current length of the string and the amount of allocated memory.
100 * The amount must be larger than the string length, because the string you
101 * pass is supposed to be a NUL-terminated string. This string _must_ be
102 * malloc()ed, and after attaching, the pointer cannot be relied upon
103 * anymore, and neither be free()d directly.
104 */
105 extern void strbuf_attach(struct strbuf *, void *, size_t, size_t);
106
107 /**
108 * Swap the contents of two string buffers.
109 */
110 static inline void strbuf_swap(struct strbuf *a, struct strbuf *b)
111 {
112 struct strbuf tmp = *a;
113 *a = *b;
114 *b = tmp;
115 }
116
117
118 /**
119 * Functions related to the size of the buffer
120 * -------------------------------------------
121 */
122
123 /**
124 * Determine the amount of allocated but unused memory.
125 */
126 static inline size_t strbuf_avail(const struct strbuf *sb)
127 {
128 return sb->alloc ? sb->alloc - sb->len - 1 : 0;
129 }
130
131 /**
132 * Ensure that at least this amount of unused memory is available after
133 * `len`. This is used when you know a typical size for what you will add
134 * and want to avoid repetitive automatic resizing of the underlying buffer.
135 * This is never a needed operation, but can be critical for performance in
136 * some cases.
137 */
138 extern void strbuf_grow(struct strbuf *, size_t);
139
140 /**
141 * Set the length of the buffer to a given value. This function does *not*
142 * allocate new memory, so you should not perform a `strbuf_setlen()` to a
143 * length that is larger than `len + strbuf_avail()`. `strbuf_setlen()` is
144 * just meant as a 'please fix invariants from this strbuf I just messed
145 * with'.
146 */
147 static inline void strbuf_setlen(struct strbuf *sb, size_t len)
148 {
149 if (len > (sb->alloc ? sb->alloc - 1 : 0))
150 die("BUG: strbuf_setlen() beyond buffer");
151 sb->len = len;
152 sb->buf[len] = '\0';
153 }
154
155 /**
156 * Empty the buffer by setting the size of it to zero.
157 */
158 #define strbuf_reset(sb) strbuf_setlen(sb, 0)
159
160
161 /**
162 * Functions related to the contents of the buffer
163 * -----------------------------------------------
164 */
165
166 /**
167 * Strip whitespace from the beginning (`ltrim`), end (`rtrim`), or both side
168 * (`trim`) of a string.
169 */
170 extern void strbuf_trim(struct strbuf *);
171 extern void strbuf_rtrim(struct strbuf *);
172 extern void strbuf_ltrim(struct strbuf *);
173
174 /**
175 * Replace the contents of the strbuf with a reencoded form. Returns -1
176 * on error, 0 on success.
177 */
178 extern int strbuf_reencode(struct strbuf *sb, const char *from, const char *to);
179
180 /**
181 * Lowercase each character in the buffer using `tolower`.
182 */
183 extern void strbuf_tolower(struct strbuf *sb);
184
185 /**
186 * Compare two buffers. Returns an integer less than, equal to, or greater
187 * than zero if the first buffer is found, respectively, to be less than,
188 * to match, or be greater than the second buffer.
189 */
190 extern int strbuf_cmp(const struct strbuf *, const struct strbuf *);
191
192
193 /**
194 * Adding data to the buffer
195 * -------------------------
196 *
197 * NOTE: All of the functions in this section will grow the buffer as
198 * necessary. If they fail for some reason other than memory shortage and the
199 * buffer hadn't been allocated before (i.e. the `struct strbuf` was set to
200 * `STRBUF_INIT`), then they will free() it.
201 */
202
203 /**
204 * Add a single character to the buffer.
205 */
206 static inline void strbuf_addch(struct strbuf *sb, int c)
207 {
208 strbuf_grow(sb, 1);
209 sb->buf[sb->len++] = c;
210 sb->buf[sb->len] = '\0';
211 }
212
213 /**
214 * Add a character the specified number of times to the buffer.
215 */
216 extern void strbuf_addchars(struct strbuf *sb, int c, size_t n);
217
218 /**
219 * Insert data to the given position of the buffer. The remaining contents
220 * will be shifted, not overwritten.
221 */
222 extern void strbuf_insert(struct strbuf *, size_t pos, const void *, size_t);
223
224 /**
225 * Remove given amount of data from a given position of the buffer.
226 */
227 extern void strbuf_remove(struct strbuf *, size_t pos, size_t len);
228
229 /**
230 * Remove the bytes between `pos..pos+len` and replace it with the given
231 * data.
232 */
233 extern void strbuf_splice(struct strbuf *, size_t pos, size_t len,
234 const void *, size_t);
235
236 /**
237 * Add a NUL-terminated string to the buffer. Each line will be prepended
238 * by a comment character and a blank.
239 */
240 extern void strbuf_add_commented_lines(struct strbuf *out, const char *buf, size_t size);
241
242
243 /**
244 * Add data of given length to the buffer.
245 */
246 extern void strbuf_add(struct strbuf *, const void *, size_t);
247
248 /**
249 * Add a NUL-terminated string to the buffer.
250 *
251 * NOTE: This function will *always* be implemented as an inline or a macro
252 * using strlen, meaning that this is efficient to write things like:
253 *
254 * strbuf_addstr(sb, "immediate string");
255 *
256 */
257 static inline void strbuf_addstr(struct strbuf *sb, const char *s)
258 {
259 strbuf_add(sb, s, strlen(s));
260 }
261
262 /**
263 * Copy the contents of another buffer at the end of the current one.
264 */
265 static inline void strbuf_addbuf(struct strbuf *sb, const struct strbuf *sb2)
266 {
267 strbuf_grow(sb, sb2->len);
268 strbuf_add(sb, sb2->buf, sb2->len);
269 }
270
271 /**
272 * Copy part of the buffer from a given position till a given length to the
273 * end of the buffer.
274 */
275 extern void strbuf_adddup(struct strbuf *sb, size_t pos, size_t len);
276
277 /**
278 * This function can be used to expand a format string containing
279 * placeholders. To that end, it parses the string and calls the specified
280 * function for every percent sign found.
281 *
282 * The callback function is given a pointer to the character after the `%`
283 * and a pointer to the struct strbuf. It is expected to add the expanded
284 * version of the placeholder to the strbuf, e.g. to add a newline
285 * character if the letter `n` appears after a `%`. The function returns
286 * the length of the placeholder recognized and `strbuf_expand()` skips
287 * over it.
288 *
289 * The format `%%` is automatically expanded to a single `%` as a quoting
290 * mechanism; callers do not need to handle the `%` placeholder themselves,
291 * and the callback function will not be invoked for this placeholder.
292 *
293 * All other characters (non-percent and not skipped ones) are copied
294 * verbatim to the strbuf. If the callback returned zero, meaning that the
295 * placeholder is unknown, then the percent sign is copied, too.
296 *
297 * In order to facilitate caching and to make it possible to give
298 * parameters to the callback, `strbuf_expand()` passes a context pointer,
299 * which can be used by the programmer of the callback as she sees fit.
300 */
301 typedef size_t (*expand_fn_t) (struct strbuf *sb, const char *placeholder, void *context);
302 extern void strbuf_expand(struct strbuf *sb, const char *format, expand_fn_t fn, void *context);
303
304 /**
305 * Used as callback for `strbuf_expand()`, expects an array of
306 * struct strbuf_expand_dict_entry as context, i.e. pairs of
307 * placeholder and replacement string. The array needs to be
308 * terminated by an entry with placeholder set to NULL.
309 */
310 struct strbuf_expand_dict_entry {
311 const char *placeholder;
312 const char *value;
313 };
314 extern size_t strbuf_expand_dict_cb(struct strbuf *sb, const char *placeholder, void *context);
315
316 /**
317 * Append the contents of one strbuf to another, quoting any
318 * percent signs ("%") into double-percents ("%%") in the
319 * destination. This is useful for literal data to be fed to either
320 * strbuf_expand or to the *printf family of functions.
321 */
322 extern void strbuf_addbuf_percentquote(struct strbuf *dst, const struct strbuf *src);
323
324 /**
325 * Append the given byte size as a human-readable string (i.e. 12.23 KiB,
326 * 3.50 MiB).
327 */
328 extern void strbuf_humanise_bytes(struct strbuf *buf, off_t bytes);
329
330 /**
331 * Add a formatted string to the buffer.
332 */
333 __attribute__((format (printf,2,3)))
334 extern void strbuf_addf(struct strbuf *sb, const char *fmt, ...);
335
336 /**
337 * Add a formatted string prepended by a comment character and a
338 * blank to the buffer.
339 */
340 __attribute__((format (printf, 2, 3)))
341 extern void strbuf_commented_addf(struct strbuf *sb, const char *fmt, ...);
342
343 __attribute__((format (printf,2,0)))
344 extern void strbuf_vaddf(struct strbuf *sb, const char *fmt, va_list ap);
345
346 /**
347 * Read a given size of data from a FILE* pointer to the buffer.
348 *
349 * NOTE: The buffer is rewound if the read fails. If -1 is returned,
350 * `errno` must be consulted, like you would do for `read(3)`.
351 * `strbuf_read()`, `strbuf_read_file()` and `strbuf_getline()` has the
352 * same behaviour as well.
353 */
354 extern size_t strbuf_fread(struct strbuf *, size_t, FILE *);
355
356 /**
357 * Read the contents of a given file descriptor. The third argument can be
358 * used to give a hint about the file size, to avoid reallocs. If read fails,
359 * any partial read is undone.
360 */
361 extern ssize_t strbuf_read(struct strbuf *, int fd, size_t hint);
362
363 /**
364 * Read the contents of a file, specified by its path. The third argument
365 * can be used to give a hint about the file size, to avoid reallocs.
366 */
367 extern int strbuf_read_file(struct strbuf *sb, const char *path, size_t hint);
368
369 /**
370 * Read the target of a symbolic link, specified by its path. The third
371 * argument can be used to give a hint about the size, to avoid reallocs.
372 */
373 extern int strbuf_readlink(struct strbuf *sb, const char *path, size_t hint);
374
375 /**
376 * Read a line from a FILE *, overwriting the existing contents
377 * of the strbuf. The second argument specifies the line
378 * terminator character, typically `'\n'`.
379 * Reading stops after the terminator or at EOF. The terminator
380 * is removed from the buffer before returning. Returns 0 unless
381 * there was nothing left before EOF, in which case it returns `EOF`.
382 */
383 extern int strbuf_getline(struct strbuf *, FILE *, int);
384
385 /**
386 * Like `strbuf_getline`, but keeps the trailing terminator (if
387 * any) in the buffer.
388 */
389 extern int strbuf_getwholeline(struct strbuf *, FILE *, int);
390
391 /**
392 * Like `strbuf_getwholeline`, but operates on a file descriptor.
393 * It reads one character at a time, so it is very slow. Do not
394 * use it unless you need the correct position in the file
395 * descriptor.
396 */
397 extern int strbuf_getwholeline_fd(struct strbuf *, int, int);
398
399 /**
400 * Set the buffer to the path of the current working directory.
401 */
402 extern int strbuf_getcwd(struct strbuf *sb);
403
404 /**
405 * Add a path to a buffer, converting a relative path to an
406 * absolute one in the process. Symbolic links are not
407 * resolved.
408 */
409 extern void strbuf_add_absolute_path(struct strbuf *sb, const char *path);
410
411 /**
412 * Strip whitespace from a buffer. The second parameter controls if
413 * comments are considered contents to be removed or not.
414 */
415 extern void stripspace(struct strbuf *buf, int skip_comments);
416
417 static inline int strbuf_strip_suffix(struct strbuf *sb, const char *suffix)
418 {
419 if (strip_suffix_mem(sb->buf, &sb->len, suffix)) {
420 strbuf_setlen(sb, sb->len);
421 return 1;
422 } else
423 return 0;
424 }
425
426 /**
427 * Split str (of length slen) at the specified terminator character.
428 * Return a null-terminated array of pointers to strbuf objects
429 * holding the substrings. The substrings include the terminator,
430 * except for the last substring, which might be unterminated if the
431 * original string did not end with a terminator. If max is positive,
432 * then split the string into at most max substrings (with the last
433 * substring containing everything following the (max-1)th terminator
434 * character).
435 *
436 * The most generic form is `strbuf_split_buf`, which takes an arbitrary
437 * pointer/len buffer. The `_str` variant takes a NUL-terminated string,
438 * the `_max` variant takes a strbuf, and just `strbuf_split` is a convenience
439 * wrapper to drop the `max` parameter.
440 *
441 * For lighter-weight alternatives, see string_list_split() and
442 * string_list_split_in_place().
443 */
444 extern struct strbuf **strbuf_split_buf(const char *, size_t,
445 int terminator, int max);
446
447 static inline struct strbuf **strbuf_split_str(const char *str,
448 int terminator, int max)
449 {
450 return strbuf_split_buf(str, strlen(str), terminator, max);
451 }
452
453 static inline struct strbuf **strbuf_split_max(const struct strbuf *sb,
454 int terminator, int max)
455 {
456 return strbuf_split_buf(sb->buf, sb->len, terminator, max);
457 }
458
459 static inline struct strbuf **strbuf_split(const struct strbuf *sb,
460 int terminator)
461 {
462 return strbuf_split_max(sb, terminator, 0);
463 }
464
465 /**
466 * Free a NULL-terminated list of strbufs (for example, the return
467 * values of the strbuf_split*() functions).
468 */
469 extern void strbuf_list_free(struct strbuf **);
470
471 /**
472 * Launch the user preferred editor to edit a file and fill the buffer
473 * with the file's contents upon the user completing their editing. The
474 * third argument can be used to set the environment which the editor is
475 * run in. If the buffer is NULL the editor is launched as usual but the
476 * file's contents are not read into the buffer upon completion.
477 */
478 extern int launch_editor(const char *path, struct strbuf *buffer, const char *const *env);
479
480 extern void strbuf_add_lines(struct strbuf *sb, const char *prefix, const char *buf, size_t size);
481
482 /**
483 * Append s to sb, with the characters '<', '>', '&' and '"' converted
484 * into XML entities.
485 */
486 extern void strbuf_addstr_xml_quoted(struct strbuf *sb, const char *s);
487
488 static inline void strbuf_complete_line(struct strbuf *sb)
489 {
490 if (sb->len && sb->buf[sb->len - 1] != '\n')
491 strbuf_addch(sb, '\n');
492 }
493
494 extern int strbuf_branchname(struct strbuf *sb, const char *name);
495 extern int strbuf_check_branch_ref(struct strbuf *sb, const char *name);
496
497 extern void strbuf_addstr_urlencode(struct strbuf *, const char *,
498 int reserved);
499
500 __attribute__((format (printf,1,2)))
501 extern int printf_ln(const char *fmt, ...);
502 __attribute__((format (printf,2,3)))
503 extern int fprintf_ln(FILE *fp, const char *fmt, ...);
504
505 char *xstrdup_tolower(const char *);
506
507 /**
508 * Create a newly allocated string using printf format. You can do this easily
509 * with a strbuf, but this provides a shortcut to save a few lines.
510 */
511 __attribute__((format (printf, 1, 0)))
512 char *xstrvfmt(const char *fmt, va_list ap);
513 __attribute__((format (printf, 1, 2)))
514 char *xstrfmt(const char *fmt, ...);
515
516 #endif /* STRBUF_H */