01c5c6371b8e43686f335704a67a59a1d82dbe3b
[git.git] / strbuf.h
blob01c5c6371b8e43686f335704a67a59a1d82dbe3b
1 #ifndef STRBUF_H
2 #define STRBUF_H
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 */
54 /**
55 * Data Structures
56 * ---------------
57 */
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 };
70 extern char strbuf_slopbuf[];
71 #define STRBUF_INIT { 0, 0, strbuf_slopbuf }
73 /**
74 * Life Cycle Functions
75 * --------------------
76 */
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);
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 *);
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 *);
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);
107 /**
108 * Swap the contents of two string buffers.
109 */
110 static inline void strbuf_swap(struct strbuf *a, struct strbuf *b)
112 struct strbuf tmp = *a;
113 *a = *b;
114 *b = tmp;
118 /**
119 * Functions related to the size of the buffer
120 * -------------------------------------------
121 */
123 /**
124 * Determine the amount of allocated but unused memory.
125 */
126 static inline size_t strbuf_avail(const struct strbuf *sb)
128 return sb->alloc ? sb->alloc - sb->len - 1 : 0;
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);
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)
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';
155 /**
156 * Empty the buffer by setting the size of it to zero.
157 */
158 #define strbuf_reset(sb) strbuf_setlen(sb, 0)
161 /**
162 * Functions related to the contents of the buffer
163 * -----------------------------------------------
164 */
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 *);
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);
180 /**
181 * Lowercase each character in the buffer using `tolower`.
182 */
183 extern void strbuf_tolower(struct strbuf *sb);
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 *);
193 /**
194 * Adding data to the buffer
195 * -------------------------
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 */
203 /**
204 * Add a single character to the buffer.
205 */
206 static inline void strbuf_addch(struct strbuf *sb, int c)
208 if (!strbuf_avail(sb))
209 strbuf_grow(sb, 1);
210 sb->buf[sb->len++] = c;
211 sb->buf[sb->len] = '\0';
214 /**
215 * Add a character the specified number of times to the buffer.
216 */
217 extern void strbuf_addchars(struct strbuf *sb, int c, size_t n);
219 /**
220 * Insert data to the given position of the buffer. The remaining contents
221 * will be shifted, not overwritten.
222 */
223 extern void strbuf_insert(struct strbuf *, size_t pos, const void *, size_t);
225 /**
226 * Remove given amount of data from a given position of the buffer.
227 */
228 extern void strbuf_remove(struct strbuf *, size_t pos, size_t len);
230 /**
231 * Remove the bytes between `pos..pos+len` and replace it with the given
232 * data.
233 */
234 extern void strbuf_splice(struct strbuf *, size_t pos, size_t len,
235 const void *, size_t);
237 /**
238 * Add a NUL-terminated string to the buffer. Each line will be prepended
239 * by a comment character and a blank.
240 */
241 extern void strbuf_add_commented_lines(struct strbuf *out, const char *buf, size_t size);
244 /**
245 * Add data of given length to the buffer.
246 */
247 extern void strbuf_add(struct strbuf *, const void *, size_t);
249 /**
250 * Add a NUL-terminated string to the buffer.
252 * NOTE: This function will *always* be implemented as an inline or a macro
253 * using strlen, meaning that this is efficient to write things like:
255 * strbuf_addstr(sb, "immediate string");
257 */
258 static inline void strbuf_addstr(struct strbuf *sb, const char *s)
260 strbuf_add(sb, s, strlen(s));
263 /**
264 * Copy the contents of another buffer at the end of the current one.
265 */
266 static inline void strbuf_addbuf(struct strbuf *sb, const struct strbuf *sb2)
268 strbuf_grow(sb, sb2->len);
269 strbuf_add(sb, sb2->buf, sb2->len);
272 /**
273 * Copy part of the buffer from a given position till a given length to the
274 * end of the buffer.
275 */
276 extern void strbuf_adddup(struct strbuf *sb, size_t pos, size_t len);
278 /**
279 * This function can be used to expand a format string containing
280 * placeholders. To that end, it parses the string and calls the specified
281 * function for every percent sign found.
283 * The callback function is given a pointer to the character after the `%`
284 * and a pointer to the struct strbuf. It is expected to add the expanded
285 * version of the placeholder to the strbuf, e.g. to add a newline
286 * character if the letter `n` appears after a `%`. The function returns
287 * the length of the placeholder recognized and `strbuf_expand()` skips
288 * over it.
290 * The format `%%` is automatically expanded to a single `%` as a quoting
291 * mechanism; callers do not need to handle the `%` placeholder themselves,
292 * and the callback function will not be invoked for this placeholder.
294 * All other characters (non-percent and not skipped ones) are copied
295 * verbatim to the strbuf. If the callback returned zero, meaning that the
296 * placeholder is unknown, then the percent sign is copied, too.
298 * In order to facilitate caching and to make it possible to give
299 * parameters to the callback, `strbuf_expand()` passes a context pointer,
300 * which can be used by the programmer of the callback as she sees fit.
301 */
302 typedef size_t (*expand_fn_t) (struct strbuf *sb, const char *placeholder, void *context);
303 extern void strbuf_expand(struct strbuf *sb, const char *format, expand_fn_t fn, void *context);
305 /**
306 * Used as callback for `strbuf_expand()`, expects an array of
307 * struct strbuf_expand_dict_entry as context, i.e. pairs of
308 * placeholder and replacement string. The array needs to be
309 * terminated by an entry with placeholder set to NULL.
310 */
311 struct strbuf_expand_dict_entry {
312 const char *placeholder;
313 const char *value;
314 };
315 extern size_t strbuf_expand_dict_cb(struct strbuf *sb, const char *placeholder, void *context);
317 /**
318 * Append the contents of one strbuf to another, quoting any
319 * percent signs ("%") into double-percents ("%%") in the
320 * destination. This is useful for literal data to be fed to either
321 * strbuf_expand or to the *printf family of functions.
322 */
323 extern void strbuf_addbuf_percentquote(struct strbuf *dst, const struct strbuf *src);
325 /**
326 * Append the given byte size as a human-readable string (i.e. 12.23 KiB,
327 * 3.50 MiB).
328 */
329 extern void strbuf_humanise_bytes(struct strbuf *buf, off_t bytes);
331 /**
332 * Add a formatted string to the buffer.
333 */
334 __attribute__((format (printf,2,3)))
335 extern void strbuf_addf(struct strbuf *sb, const char *fmt, ...);
337 /**
338 * Add a formatted string prepended by a comment character and a
339 * blank to the buffer.
340 */
341 __attribute__((format (printf, 2, 3)))
342 extern void strbuf_commented_addf(struct strbuf *sb, const char *fmt, ...);
344 __attribute__((format (printf,2,0)))
345 extern void strbuf_vaddf(struct strbuf *sb, const char *fmt, va_list ap);
347 /**
348 * Read a given size of data from a FILE* pointer to the buffer.
350 * NOTE: The buffer is rewound if the read fails. If -1 is returned,
351 * `errno` must be consulted, like you would do for `read(3)`.
352 * `strbuf_read()`, `strbuf_read_file()` and `strbuf_getline()` has the
353 * same behaviour as well.
354 */
355 extern size_t strbuf_fread(struct strbuf *, size_t, FILE *);
357 /**
358 * Read the contents of a given file descriptor. The third argument can be
359 * used to give a hint about the file size, to avoid reallocs. If read fails,
360 * any partial read is undone.
361 */
362 extern ssize_t strbuf_read(struct strbuf *, int fd, size_t hint);
364 /**
365 * Read the contents of a file, specified by its path. The third argument
366 * can be used to give a hint about the file size, to avoid reallocs.
367 */
368 extern int strbuf_read_file(struct strbuf *sb, const char *path, size_t hint);
370 /**
371 * Read the target of a symbolic link, specified by its path. The third
372 * argument can be used to give a hint about the size, to avoid reallocs.
373 */
374 extern int strbuf_readlink(struct strbuf *sb, const char *path, size_t hint);
376 /**
377 * Read a line from a FILE *, overwriting the existing contents
378 * of the strbuf. The second argument specifies the line
379 * terminator character, typically `'\n'`.
380 * Reading stops after the terminator or at EOF. The terminator
381 * is removed from the buffer before returning. Returns 0 unless
382 * there was nothing left before EOF, in which case it returns `EOF`.
383 */
384 extern int strbuf_getline(struct strbuf *, FILE *, int);
386 /**
387 * Like `strbuf_getline`, but keeps the trailing terminator (if
388 * any) in the buffer.
389 */
390 extern int strbuf_getwholeline(struct strbuf *, FILE *, int);
392 /**
393 * Like `strbuf_getwholeline`, but operates on a file descriptor.
394 * It reads one character at a time, so it is very slow. Do not
395 * use it unless you need the correct position in the file
396 * descriptor.
397 */
398 extern int strbuf_getwholeline_fd(struct strbuf *, int, int);
400 /**
401 * Set the buffer to the path of the current working directory.
402 */
403 extern int strbuf_getcwd(struct strbuf *sb);
405 /**
406 * Add a path to a buffer, converting a relative path to an
407 * absolute one in the process. Symbolic links are not
408 * resolved.
409 */
410 extern void strbuf_add_absolute_path(struct strbuf *sb, const char *path);
412 /**
413 * Strip whitespace from a buffer. The second parameter controls if
414 * comments are considered contents to be removed or not.
415 */
416 extern void stripspace(struct strbuf *buf, int skip_comments);
418 static inline int strbuf_strip_suffix(struct strbuf *sb, const char *suffix)
420 if (strip_suffix_mem(sb->buf, &sb->len, suffix)) {
421 strbuf_setlen(sb, sb->len);
422 return 1;
423 } else
424 return 0;
427 /**
428 * Split str (of length slen) at the specified terminator character.
429 * Return a null-terminated array of pointers to strbuf objects
430 * holding the substrings. The substrings include the terminator,
431 * except for the last substring, which might be unterminated if the
432 * original string did not end with a terminator. If max is positive,
433 * then split the string into at most max substrings (with the last
434 * substring containing everything following the (max-1)th terminator
435 * character).
437 * The most generic form is `strbuf_split_buf`, which takes an arbitrary
438 * pointer/len buffer. The `_str` variant takes a NUL-terminated string,
439 * the `_max` variant takes a strbuf, and just `strbuf_split` is a convenience
440 * wrapper to drop the `max` parameter.
442 * For lighter-weight alternatives, see string_list_split() and
443 * string_list_split_in_place().
444 */
445 extern struct strbuf **strbuf_split_buf(const char *, size_t,
446 int terminator, int max);
448 static inline struct strbuf **strbuf_split_str(const char *str,
449 int terminator, int max)
451 return strbuf_split_buf(str, strlen(str), terminator, max);
454 static inline struct strbuf **strbuf_split_max(const struct strbuf *sb,
455 int terminator, int max)
457 return strbuf_split_buf(sb->buf, sb->len, terminator, max);
460 static inline struct strbuf **strbuf_split(const struct strbuf *sb,
461 int terminator)
463 return strbuf_split_max(sb, terminator, 0);
466 /**
467 * Free a NULL-terminated list of strbufs (for example, the return
468 * values of the strbuf_split*() functions).
469 */
470 extern void strbuf_list_free(struct strbuf **);
472 /**
473 * Launch the user preferred editor to edit a file and fill the buffer
474 * with the file's contents upon the user completing their editing. The
475 * third argument can be used to set the environment which the editor is
476 * run in. If the buffer is NULL the editor is launched as usual but the
477 * file's contents are not read into the buffer upon completion.
478 */
479 extern int launch_editor(const char *path, struct strbuf *buffer, const char *const *env);
481 extern void strbuf_add_lines(struct strbuf *sb, const char *prefix, const char *buf, size_t size);
483 /**
484 * Append s to sb, with the characters '<', '>', '&' and '"' converted
485 * into XML entities.
486 */
487 extern void strbuf_addstr_xml_quoted(struct strbuf *sb, const char *s);
489 static inline void strbuf_complete_line(struct strbuf *sb)
491 if (sb->len && sb->buf[sb->len - 1] != '\n')
492 strbuf_addch(sb, '\n');
495 extern int strbuf_branchname(struct strbuf *sb, const char *name);
496 extern int strbuf_check_branch_ref(struct strbuf *sb, const char *name);
498 extern void strbuf_addstr_urlencode(struct strbuf *, const char *,
499 int reserved);
501 __attribute__((format (printf,1,2)))
502 extern int printf_ln(const char *fmt, ...);
503 __attribute__((format (printf,2,3)))
504 extern int fprintf_ln(FILE *fp, const char *fmt, ...);
506 char *xstrdup_tolower(const char *);
508 /**
509 * Create a newly allocated string using printf format. You can do this easily
510 * with a strbuf, but this provides a shortcut to save a few lines.
511 */
512 __attribute__((format (printf, 1, 0)))
513 char *xstrvfmt(const char *fmt, va_list ap);
514 __attribute__((format (printf, 1, 2)))
515 char *xstrfmt(const char *fmt, ...);
517 #endif /* STRBUF_H */